graph(n) BLT Built-In Commands graph(n)______________________________________________________________________________NAME
graph - 2D graph for plotting X-Y coordinate data.
SYNOPSIS
graph pathName ?option value?...
_________________________________________________________________DESCRIPTION
The graph command creates a graph for plotting two-dimensional data
(X-Y coordinates). It has many configurable components: coordinate
axes, elements, legend, grid lines, cross hairs, etc. They allow you
to customize the look and feel of the graph.
INTRODUCTION
The graph command creates a new window for plotting two-dimensional
data (X-Y coordinates). Data points are plotted in a rectangular area
displayed in the center of the new window. This is the plotting area.
The coordinate axes are drawn in the margins around the plotting area.
By default, the legend is displayed in the right margin. The title is
displayed in top margin.
The graph widget is composed of several components: coordinate axes,
data elements, legend, grid, cross hairs, pens, postscript, and annota‐
tion markers.
axis The graph has four standard axes (x, x2, y, and y2), but you
can create and display any number of axes. Axes control what
region of data is displayed and how the data is scaled. Each
axis consists of the axis line, title, major and minor ticks,
and tick labels. Tick labels display the value at each major
tick.
crosshairs
Cross hairs are used to position the mouse pointer relative
to the X and Y coordinate axes. Two perpendicular lines,
intersecting at the current location of the mouse, extend
across the plotting area to the coordinate axes.
element An element represents a set of data points. Elements can be
plotted with a symbol at each data point and lines connecting
the points. The appearance of the element, such as its sym‐
bol, line width, and color is configurable.
grid Extends the major and minor ticks of the X-axis and/or Y-axis
across the plotting area.
legend The legend displays the name and symbol of each data element.
The legend can be drawn in any margin or in the plotting
area.
marker Markers are used annotate or highlight areas of the graph.
For example, you could use a polygon marker to fill an area
under a curve, or a text marker to label a particular data
point. Markers come in various forms: text strings, bitmaps,
connected line segments, images, polygons, or embedded wid‐
gets.
pen Pens define attributes (both symbol and line style) for ele‐
ments. Data elements use pens to specify how they should be
drawn. A data element may use many pens at once. Here, the
particular pen used for a data point is determined from each
element's weight vector (see the element's -weight and -style
options).
postscript
The widget can generate encapsulated PostScript output. This
component has several options to configure how the PostScript
is generated.
SYNTAX
graph pathName ?option value?... The graph command creates a new win‐
dow pathName and makes it into a graph widget. At the time this com‐
mand is invoked, there must not exist a window named pathName, but
pathName's parent must exist. Additional options may be specified on
the command line or in the option database to configure aspects of the
graph such as its colors and font. See the configure operation below
for the exact details about what option and value pairs are valid.
If successful, graph returns the path name of the widget. It also cre‐
ates a new Tcl command by the same name. You can use this command to
invoke various operations that query or modify the graph. The general
form is: pathName operation ?arg?... Both operation and its arguments
determine the exact behavior of the command. The operations available
for the graph are described in the GRAPH OPERATIONS section.
The command can also be used to access components of the graph. path‐
Name component operation ?arg?... The operation, now located after the
name of the component, is the function to be performed on that compo‐
nent. Each component has its own set of operations that manipulate that
component. They will be described below in their own sections.
EXAMPLE
The graph command creates a new graph.
# Create a new graph. Plotting area is black.
graph .g -plotbackground black
A new Tcl command .g is also created. This command can be used to
query and modify the graph. For example, to change the title of the
graph to "My Plot", you use the new command and the graph's configure
operation.
# Change the title.
.g configure -title "My Plot"
A graph has several components. To access a particular component you
use the component's name. For example, to add data elements, you use
the new command and the element component.
# Create a new element named "line1"
.g element create line1 \
-xdata { 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 } \
-ydata { 26.18 50.46 72.85 93.31 111.86 128.47 143.14
155.85 166.60 175.38 }
The element's X-Y coordinates are specified using lists of numbers.
Alternately, BLT vectors could be used to hold the X-Y coordinates.
# Create two vectors and add them to the graph.
vector xVec yVec
xVec set { 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 }
yVec set { 26.18 50.46 72.85 93.31 111.86 128.47 143.14 155.85
166.60 175.38 }
.g element create line1 -xdata xVec -ydata yVec
The advantage of using vectors is that when you modify one, the graph
is automatically redrawn to reflect the new values.
# Change the y coordinate of the first point.
set yVector(0) 25.18
An element named e1 is now created in .b. It is automatically added to
the display list of elements. You can use this list to control in what
order elements are displayed. To query or reset the element display
list, you use the element's show operation.
# Get the current display list
set elemList [.b element show]
# Remove the first element so it won't be displayed.
.b element show [lrange $elemList 0 end]
The element will be displayed by as many bars as there are data points
(in this case there are ten). The bars will be drawn centered at the
x-coordinate of the data point. All the bars will have the same
attributes (colors, stipple, etc). The width of each bar is by default
one unit. You can change this with using the -barwidth option.
# Change the X-Y coordinates of the first point.
set xVec(0) 0.18
set yVec(0) 25.18
An element named line1 is now created in .g. By default, the element's
label in the legend will be also line1. You can change the label, or
specify no legend entry, again using the element's configure operation.
# Don't display "line1" in the legend.
.g element configure line1 -label ""
You can configure more than just the element's label. An element has
many attributes such as symbol type and size, dashed or solid lines,
colors, line width, etc.
.g element configure line1 -symbol square -color red \
-dashes { 2 4 2 } -linewidth 2 -pixels 2c
Four coordinate axes are automatically created: x, x2, y, and y2. And
by default, elements are mapped onto the axes x and y. This can be
changed with the -mapx and -mapy options.
# Map "line1" on the alternate Y-axis "y2".
.g element configure line1 -mapy y2
Axes can be configured in many ways too. For example, you change the
scale of the Y-axis from linear to log using the axis component.
# Y-axis is log scale.
.g axis configure y -logscale yes
One important way axes are used is to zoom in on a particular data
region. Zooming is done by simply specifying new axis limits using the
-min and -max configuration options.
.g axis configure x -min 1.0 -max 1.5
.g axis configure y -min 12.0 -max 55.15
To zoom interactively, you link the axis configure operations with some
user interaction (such as pressing the mouse button), using the bind
command. To convert between screen and graph coordinates, use the
invtransform operation.
# Click the button to set a new minimum
bind .g <ButtonPress-1> {
%W axis configure x -min [%W axis invtransform x %x]
%W axis configure x -min [%W axis invtransform x %y]
}
By default, the limits of the axis are determined from data values. To
reset back to the default limits, set the -min and -max options to the
empty value.
# Reset the axes to autoscale again.
.g axis configure x -min {} -max {}
.g axis configure y -min {} -max {}
By default, the legend is drawn in the right margin. You can change
this or any legend configuration options using the legend component.
# Configure the legend font, color, and relief
.g legend configure -position left -relief raised \
-font fixed -fg blue
To prevent the legend from being displayed, turn on the -hide option.
# Don't display the legend.
.g legend configure -hide yes
The graph widget has simple drawing procedures called markers. They
can be used to highlight or annotate data in the graph. The types of
markers available are bitmaps, images, polygons, lines, or windows.
Markers can be used, for example, to mark or brush points. In this
example, is a text marker that labels the data first point. Markers
are created using the marker component.
# Create a label for the first data point of "line1".
.g marker create text -name first_marker -coords { 0.2 26.18 } \
-text "start" -anchor se -xoffset -10 -yoffset -10
This creates a text marker named first_marker. It will display the
text "start" near the coordinates of the first data point. The
-anchor, -xoffset, and -yoffset options are used to display the marker
above and to the left of the data point, so that the data point isn't
covered by the marker. By default, markers are drawn last, on top of
data. You can change this with the -under option.
# Draw the label before elements are drawn.
.g marker configure first_marker -under yes
You can add cross hairs or grid lines using the crosshairs and grid
components.
# Display both cross hairs and grid lines.
.g crosshairs configure -hide no -color red
.g grid configure -hide no -dashes { 2 2 }
# Set up a binding to reposition the crosshairs.
bind .g <Motion> {
.g crosshairs configure -position @%x,%y
}
The crosshairs are repositioned as the mouse pointer is moved in the
graph. The pointer X-Y coordinates define the center of the
crosshairs.
Finally, to get hardcopy of the graph, use the postscript component.
# Print the graph into file "file.ps"
.g postscript output file.ps -maxpect yes -decorations no
This generates a file file.ps containing the encapsulated PostScript of
the graph. The option -maxpect says to scale the plot to the size of
the page. Turning off the -decorations option denotes that no borders
or color backgrounds should be drawn (i.e. the background of the mar‐
gins, legend, and plotting area will be white).
GRAPH OPERATIONS
pathName axis operation ?arg?...
See the AXIS COMPONENTS section.
pathName bar elemName ?option value?...
Creates a new barchart element elemName. It's an error if an
element elemName already exists. See the manual for barchart
for details about what option and value pairs are valid.
pathName cget option
Returns the current value of the configuration option given by
option. Option may be any option described below for the con‐
figure operation.
pathName configure ?option value?...
Queries or modifies the configuration options of the graph. If
option isn't specified, a list describing the current options
for pathName is returned. If option is specified, but not
value, then a list describing option is returned. If one or
more option and value pairs are specified, then for each pair,
the option option is set to value. The following options are
valid.
-aspect width/height
Force a fixed aspect ratio of width/height, a floating
point number.
-background color
Sets the background color. This includes the margins and
legend, but not the plotting area.
-borderwidth pixels
Sets the width of the 3-D border around the outside edge
of the widget. The -relief option determines if the bor‐
der is to be drawn. The default is 2.
-bottommargin pixels
If non-zero, overrides the computed size of the margin
extending below the X-coordinate axis. If pixels is 0,
the automatically computed size is used. The default is
0.
-bufferelements boolean
Indicates whether an internal pixmap to buffer the dis‐
play of data elements should be used. If boolean is
true, data elements are drawn to an internal pixmap.
This option is especially useful when the graph is
redrawn frequently while the remains data unchanged (for
example, moving a marker across the plot). See the SPEED
TIPS section. The default is 1.
-cursor cursor
Specifies the widget's cursor. The default cursor is
crosshair.
-font fontName
Specifies the font of the graph title. The default is
*-Helvetica-Bold-R-Normal-*-18-180-*.
-halo pixels
Specifies a maximum distance to consider when searching
for the closest data point (see the element's closest
operation below). Data points further than pixels away
are ignored. The default is 0.5i.
-height pixels
Specifies the requested height of widget. The default is
4i.
-invertxy boolean
Indicates whether the placement X-axis and Y-axis should
be inverted. If boolean is true, the X and Y axes are
swapped. The default is 0.
-justify justify
Specifies how the title should be justified. This mat‐
ters only when the title contains more than one line of
text. Justify must be left, right, or center. The
default is center.
-leftmargin pixels
If non-zero, overrides the computed size of the margin
extending from the left edge of the window to the Y-coor‐
dinate axis. If pixels is 0, the automatically computed
size is used. The default is 0.
-plotbackground color
Specifies the background color of the plotting area. The
default is white.
-plotborderwidth pixels
Sets the width of the 3-D border around the plotting
area. The -plotrelief option determines if a border is
drawn. The default is 2.
-plotpadx pad
Sets the amount of padding to be added to the left and
right sides of the plotting area. Pad can be a list of
one or two screen distances. If pad has two elements,
the left side of the plotting area entry is padded by the
first distance and the right side by the second. If pad
is just one distance, both the left and right sides are
padded evenly. The default is 8.
-plotpady pad
Sets the amount of padding to be added to the top and
bottom of the plotting area. Pad can be a list of one or
two screen distances. If pad has two elements, the top
of the plotting area is padded by the first distance and
the bottom by the second. If pad is just one distance,
both the top and bottom are padded evenly. The default
is 8.
-plotrelief relief
Specifies the 3-D effect for the plotting area. Relief
specifies how the interior of the plotting area should
appear relative to rest of the graph; for example, raised
means the plot should appear to protrude from the graph,
relative to the surface of the graph. The default is
sunken.
-relief relief
Specifies the 3-D effect for the graph widget. Relief
specifies how the graph should appear relative to widget
it is packed into; for example, raised means the graph
should appear to protrude. The default is flat.
-rightmargin pixels
If non-zero, overrides the computed size of the margin
extending from the plotting area to the right edge of the
window. By default, the legend is drawn in this margin.
If pixels is 0, the automatically computed size is used.
The default is 0.
-takefocus focus
Provides information used when moving the focus from win‐
dow to window via keyboard traversal (e.g., Tab and
Shift-Tab). If focus is 0, this means that this window
should be skipped entirely during keyboard traversal. 1
means that the this window should always receive the
input focus. An empty value means that the traversal
scripts make the decision whether to focus on the window.
The default is "".
-tile image
Specifies a tiled background for the widget. If image
isn't "", the background is tiled using image. Other‐
wise, the normal background color is drawn (see the
-background option). Image must be an image created
using the Tk image command. The default is "".
-title text
Sets the title to text. If text is "", no title will be
displayed.
-topmargin pixels
If non-zero, overrides the computed size of the margin
above the x2 axis. If pixels is 0, the automatically
computed size is used. The default is 0.
-width pixels
Specifies the requested width of the widget. The default
is 5i.
pathName crosshairs operation ?arg?
See the CROSSHAIRS COMPONENT section.
pathName element operation ?arg?...
See the ELEMENT COMPONENTS section.
pathName extents item
Returns the size of a particular item in the graph. Item must
be either leftmargin, rightmargin, topmargin, bottommargin,
plotwidth, or plotheight.
pathName grid operation ?arg?...
See the GRID COMPONENT section.
pathName invtransform winX winY
Performs an inverse coordinate transformation, mapping window
coordinates back to graph coordinates, using the standard X-axis
and Y-axis. Returns a list of containing the X-Y graph coordi‐
nates.
pathName inside x y
Returns 1 is the designated screen coordinate (x and y) is
inside the plotting area and 0 otherwise.
pathName legend operation ?arg?...
See the LEGEND COMPONENT section.
pathName line operation arg...
The operation is the same as element.
pathName marker operation ?arg?...
See the MARKER COMPONENTS section.
pathName postscript operation ?arg?...
See the POSTSCRIPT COMPONENT section.
pathName snap ?switches? outputName
Takes a snapshot of the graph, saving the output in outputName.
The following switches are available.
-format format
Specifies how the snapshot is output. Format may be
one of the following listed below. The default is
photo.
photo Saves a Tk photo image. OutputName represents
the name of a Tk photo image that must already
have been created.
wmf Saves an Aldus Placeable Metafile. OutputName
represents the filename where the metafile is
written. If outputName is CLIPBOARD, then out‐
put is written directly to the Windows clip‐
board. This format is available only under Mi‐
crosoft Windows.
emf Saves an Enhanced Metafile. OutputName repre‐
sents the filename where the metafile is writ‐
ten. If outputName is CLIPBOARD, then output
is written directly to the Windows clipboard.
This format is available only under Microsoft
Windows.
-height size
Specifies the height of the graph. Size is a screen
distance. The graph will be redrawn using this dimen‐
sion, rather than its current window height.
-width size
Specifies the width of the graph. Size is a screen
distance. The graph will be redrawn using this dimen‐
sion, rather than its current window width.
pathName transform x y
Performs a coordinate transformation, mapping graph coordinates
to window coordinates, using the standard X-axis and Y-axis.
Returns a list containing the X-Y screen coordinates.
pathName xaxis operation ?arg?...
pathName x2axis operation ?arg?...
pathName yaxis operation ?arg?...
pathName y2axis operation ?arg?...
See the AXIS COMPONENTS section.
GRAPH COMPONENTS
A graph is composed of several components: coordinate axes, data ele‐
ments, legend, grid, cross hairs, postscript, and annotation markers.
Instead of one big set of configuration options and operations, the
graph is partitioned, where each component has its own configuration
options and operations that specifically control that aspect or part of
the graph.
AXIS COMPONENTS
Four coordinate axes are automatically created: two X-coordinate axes
(x and x2) and two Y-coordinate axes (y, and y2). By default, the axis
x is located in the bottom margin, y in the left margin, x2 in the top
margin, and y2 in the right margin.
An axis consists of the axis line, title, major and minor ticks, and
tick labels. Major ticks are drawn at uniform intervals along the
axis. Each tick is labeled with its coordinate value. Minor ticks are
drawn at uniform intervals within major ticks.
The range of the axis controls what region of data is plotted. Data
points outside the minimum and maximum limits of the axis are not plot‐
ted. By default, the minimum and maximum limits are determined from
the data, but you can reset either limit.
You can have several axes. To create an axis, invoke the axis component
and its create operation.
# Create a new axis called "tempAxis"
.g axis create tempAxis
You map data elements to an axis using the element's -mapy and -mapx
configuration options. They specify the coordinate axes an element is
mapped onto.
# Now map the tempAxis data to this axis.
.g element create "e1" -xdata $x -ydata $y -mapy tempAxis
Any number of axes can be displayed simultaneously. They are drawn in
the margins surrounding the plotting area. The default axes x and y
are drawn in the bottom and left margins. The axes x2 and y2 are drawn
in top and right margins. By default, only x and y are shown. Note
that the axes can have different scales.
To display a different axis or more than one axis, you invoke one of
the following components: xaxis, yaxis, x2axis, and y2axis. Each com‐
ponent has a use operation that designates the axis (or axes) to be
drawn in that corresponding margin: xaxis in the bottom, yaxis in the
left, x2axis in the top, and y2axis in the right.
# Display the axis tempAxis in the left margin.
.g yaxis use tempAxis
The use operation takes a list of axis names as its last argument.
This is the list of axes to be drawn in this margin.
You can configure axes in many ways. The axis scale can be linear or
logarithmic. The values along the axis can either monotonically
increase or decrease. If you need custom tick labels, you can specify
a Tcl procedure to format the label any way you wish. You can control
how ticks are drawn, by changing the major tick interval or the number
of minor ticks. You can define non-uniform tick intervals, such as for
time-series plots.
pathName axis bind tagName ?sequence? ?command?
Associates command with tagName such that whenever the event
sequence given by sequence occurs for an axis with this tag,
command will be invoked. The syntax is similar to the bind com‐
mand except that it operates on graph axes, rather than widgets.
See the bind manual entry for complete details on sequence and
the substitutions performed on command before invoking it.
If all arguments are specified then a new binding is created,
replacing any existing binding for the same sequence and tag‐
Name. If the first character of command is + then command aug‐
ments an existing binding rather than replacing it. If no com‐
mand argument is provided then the command currently associated
with tagName and sequence (it's an error occurs if there's no
such binding) is returned. If both command and sequence are
missing then a list of all the event sequences for which bind‐
ings have been defined for tagName.
pathName axis cget axisName option
Returns the current value of the option given by option for
axisName. Option may be any option described below for the axis
configure operation.
pathName axis configure axisName ?axisName?... ?option value?...
Queries or modifies the configuration options of axisName. Sev‐
eral axes can be changed. If option isn't specified, a list
describing all the current options for axisName is returned. If
option is specified, but not value, then a list describing
option is returned. If one or more option and value pairs are
specified, then for each pair, the axis option option is set to
value. The following options are valid for axes.
-bindtags tagList
Specifies the binding tags for the axis. TagList is a
list of binding tag names. The tags and their order will
determine how events for axes are handled. Each tag in
the list matching the current event sequence will have
its Tcl command executed. Implicitly the name of the
element is always the first tag in the list. The default
value is all.
-color color
Sets the color of the axis and tick labels. The default
is black.
-command prefix
Specifies a Tcl command to be invoked when formatting the
axis tick labels. Prefix is a string containing the name
of a Tcl proc and any extra arguments for the procedure.
This command is invoked for each major tick on the axis.
Two additional arguments are passed to the procedure: the
pathname of the widget and the current the numeric value
of the tick. The procedure returns the formatted tick
label. If "" is returned, no label will appear next to
the tick. You can get the standard tick labels again by
setting prefix to "". The default is "".
Please note that this procedure is invoked while the
graph is redrawn. You may query configuration options.
But do not them, because this can have unexpected
results.
-descending boolean
Indicates whether the values along the axis are monotoni‐
cally increasing or decreasing. If boolean is true, the
axis values will be decreasing. The default is 0.
-hide boolean
Indicates if the axis is displayed. If boolean is false
the axis will be displayed. Any element mapped to the
axis is displayed regardless. The default value is 0.
-justify justify
Specifies how the axis title should be justified. This
matters only when the axis title contains more than one
line of text. Justify must be left, right, or center.
The default is center.
-limits formatStr
Specifies a printf-like description to format the minimum
and maximum limits of the axis. The limits are displayed
at the top/bottom or left/right sides of the plotting
area. FormatStr is a list of one or two format descrip‐
tions. If one description is supplied, both the minimum
and maximum limits are formatted in the same way. If
two, the first designates the format for the minimum
limit, the second for the maximum. If "" is given as
either description, then the that limit will not be dis‐
played. The default is "".
-linewidth pixels
Sets the width of the axis and tick lines. The default
is 1 pixel.
-logscale boolean
Indicates whether the scale of the axis is logarithmic or
linear. If boolean is true, the axis is logarithmic.
The default scale is linear.
-loose boolean
Indicates whether the limits of the axis should fit the
data points tightly, at the outermost data points, or
loosely, at the outer tick intervals. If the axis limit
is set with the -min or -max option, the axes are dis‐
played tightly. If boolean is true, the axis range is
"loose". The default is 0.
-majorticks majorList
Specifies where to display major axis ticks. You can use
this option to display ticks at non-uniform intervals.
MajorList is a list of axis coordinates designating the
location of major ticks. No minor ticks are drawn. If
majorList is "", major ticks will be automatically com‐
puted. The default is "".
-max value
Sets the maximum limit of axisName. Any data point
greater than value is not displayed. If value is "", the
maximum limit is calculated using the largest data value.
The default is "".
-min value
Sets the minimum limit of axisName. Any data point less
than value is not displayed. If value is "", the minimum
limit is calculated using the smallest data value. The
default is "".
-minorticks minorList
Specifies where to display minor axis ticks. You can use
this option to display minor ticks at non-uniform inter‐
vals. MinorList is a list of real values, ranging from
0.0 to 1.0, designating the placement of a minor tick.
No minor ticks are drawn if the -majortick option is also
set. If minorList is "", minor ticks will be automati‐
cally computed. The default is "".
-rotate theta
Specifies the how many degrees to rotate the axis tick
labels. Theta is a real value representing the number of
degrees to rotate the tick labels. The default is 0.0
degrees.
-scrollcommand command
Specify the prefix for a command used to communicate with
scrollbars for this axis, such as .sbar set.
-scrollmax value
Sets the maximum limit of the axis scroll region. If
value is "", the maximum limit is calculated using the
largest data value. The default is "".
-scrollmin value
Sets the minimum limit of axis scroll region. If value
is "", the minimum limit is calculated using the smallest
data value. The default is "".
-showticks boolean
Indicates whether axis ticks should be drawn. If boolean
is true, ticks are drawn. If false, only the axis line
is drawn. The default is 1.
-stepsize value
Specifies the interval between major axis ticks. If
value isn't a valid interval (must be less than the axis
range), the request is ignored and the step size is auto‐
matically calculated.
-subdivisions number
Indicates how many minor axis ticks are to be drawn. For
example, if number is two, only one minor tick is drawn.
If number is one, no minor ticks are displayed. The
default is 2.
-tickfont fontName
Specifies the font for axis tick labels. The default is
*-Courier-Bold-R-Normal-*-100-*.
-ticklength pixels
Sets the length of major and minor ticks (minor ticks are
half the length of major ticks). If pixels is less than
zero, the axis will be inverted with ticks drawn pointing
towards the plot. The default is 0.1i.
-title text
Sets the title of the axis. If text is "", no axis title
will be displayed.
-titlealternate boolean
Indicates to display the axis title in its alternate
location. Normally the axis title is centered along the
axis. This option places the axis either to the right
(horizontal axes) or above (vertical axes) the axis. The
default is 0.
-titlecolor color
Sets the color of the axis title. The default is black.
-titlefont fontName
Specifies the font for axis title. The default is *-Hel‐
vetica-Bold-R-Normal-*-14-140-*.
Axis configuration options may be also be set by the option com‐
mand. The resource class is Axis. The resource names are the
names of the axes (such as x or x2).
option add *Graph.Axis.Color blue
option add *Graph.x.LogScale true
option add *Graph.x2.LogScale false
pathName axis create axisName ?option value?...
Creates a new axis by the name axisName. No axis by the same
name can already exist. Option and value are described in above
in the axis configure operation.
pathName axis delete ?axisName?...
Deletes the named axes. An axis is not really deleted until it
is not longer in use, so it's safe to delete axes mapped to ele‐
ments.
pathName axis invtransform axisName value
Performs the inverse transformation, changing the screen coordi‐
nate value to a graph coordinate, mapping the value mapped to
axisName. Returns the graph coordinate.
pathName axis limits axisName
Returns a list of the minimum and maximum limits for axisName.
The order of the list is min max.
pathName axis names ?pattern?...
Returns a list of axes matching zero or more patterns. If no
pattern argument is give, the names of all axes are returned.
pathName axis transform axisName value
Transforms the coordinate value to a screen coordinate by map‐
ping the it to axisName. Returns the transformed screen coordi‐
nate.
pathName axis view axisName
Change the viewable area of this axis. Use as an argument to a
scrollbar's "-command".
The default axes are x, y, x2, and y2. But you can display more than
four axes simultaneously. You can also swap in a different axis with
use operation of the special axis components: xaxis, x2axis, yaxis, and
y2axis.
.g create axis temp
.g create axis time
...
.g xaxis use temp
.g yaxis use time
Only the axes specified for use are displayed on the screen.
The xaxis, x2axis, yaxis, and y2axis components operate on an axis
location rather than a specific axis like the more general axis compo‐
nent does. They implicitly control the axis that is currently using to
that location. By default, xaxis uses the x axis, yaxis uses y, x2axis
uses x2, and y2axis uses y2. When more than one axis is displayed in a
margin, it represents the first axis displayed.
The following operations are available for axes. They mirror exactly
the operations of the axis component. The axis argument must be xaxis,
x2axis, yaxis, or y2axis. This feature is deprecated since more than
one axis can now be used a margin. You should only use the xaxis,
x2axis, yaxis, and y2axis components with the use operation. For all
other operations, use the general axis component instead.
pathName axis cget option
pathName axis configure ?option value?...
pathName axis invtransform value
pathName axis limits
pathName axis transform value
pathName axis use ?axisName?
Designates the axis axisName is to be displayed at this loca‐
tion. AxisName can not be already in use at another location.
This command returns the name of the axis currently using this
location.
CROSSHAIRS COMPONENT
Cross hairs consist of two intersecting lines (one vertical and one
horizontal) drawn completely across the plotting area. They are used
to position the mouse in relation to the coordinate axes. Cross hairs
differ from line markers in that they are implemented using XOR drawing
primitives. This means that they can be quickly drawn and erased with‐
out redrawing the entire graph.
The following operations are available for cross hairs:
pathName crosshairs cget option
Returns the current value of the cross hairs configuration
option given by option. Option may be any option described
below for the cross hairs configure operation.
pathName crosshairs configure ?option value?...
Queries or modifies the configuration options of the cross
hairs. If option isn't specified, a list describing all the
current options for the cross hairs is returned. If option is
specified, but not value, then a list describing option is
returned. If one or more option and value pairs are specified,
then for each pair, the cross hairs option option is set to
value. The following options are available for cross hairs.
-color color
Sets the color of the cross hairs. The default is black.
-dashes dashList
Sets the dash style of the cross hairs. DashList is a
list of up to 11 numbers that alternately represent the
lengths of the dashes and gaps on the cross hair lines.
Each number must be between 1 and 255. If dashList is
"", the cross hairs will be solid lines.
-hide boolean
Indicates whether cross hairs are drawn. If boolean is
true, cross hairs are not drawn. The default is yes.
-linewidth pixels
Set the width of the cross hair lines. The default is 1.
-position pos
Specifies the screen position where the cross hairs
intersect. Pos must be in the form "@x,y", where x and y
are the window coordinates of the intersection.
Cross hairs configuration options may be also be set by the
option command. The resource name and class are crosshairs and
Crosshairs respectively.
option add *Graph.Crosshairs.LineWidth 2
option add *Graph.Crosshairs.Color red
pathName crosshairs off
Turns off the cross hairs.
pathName crosshairs on
Turns on the display of the cross hairs.
pathName crosshairs toggle
Toggles the current state of the cross hairs, alternately map‐
ping and unmapping the cross hairs.
ELEMENT COMPONENTS
A data element represents a set of data. It contains x and y vectors
containing the coordinates of the data points. Elements can be dis‐
played with a symbol at each data point and lines connecting the
points. Elements also control the appearance of the data, such as the
symbol type, line width, color etc.
When new data elements are created, they are automatically added to a
list of displayed elements. The display list controls what elements
are drawn and in what order.
The following operations are available for elements.
pathName element activate elemName ?index?...
Specifies the data points of element elemName to be drawn using
active foreground and background colors. ElemName is the name
of the element and index is a number representing the index of
the data point. If no indices are present then all data points
become active.
pathName element bind tagName ?sequence? ?command?
Associates command with tagName such that whenever the event
sequence given by sequence occurs for an element with this tag,
command will be invoked. The syntax is similar to the bind com‐
mand except that it operates on graph elements, rather than wid‐
gets. See the bind manual entry for complete details on sequence
and the substitutions performed on command before invoking it.
If all arguments are specified then a new binding is created,
replacing any existing binding for the same sequence and tag‐
Name. If the first character of command is + then command aug‐
ments an existing binding rather than replacing it. If no com‐
mand argument is provided then the command currently associated
with tagName and sequence (it's an error occurs if there's no
such binding) is returned. If both command and sequence are
missing then a list of all the event sequences for which bind‐
ings have been defined for tagName.
pathName element cget elemName option
Returns the current value of the element configuration option
given by option. Option may be any of the options described
below for the element configure operation.
pathName element closest x y varName ?option value?... ?elemName?...
Searches for the data point closest to the window coordinates x
and y. By default, all elements are searched. Hidden elements
(see the -hide option is false) are ignored. You can limit the
search by specifying only the elements you want to be consid‐
ered. ElemName must be the name of an element that is not be
hidden. VarName is the name of a Tcl array variable and will
contain the search results: the name of the closest element, the
index of the closest data point, and the graph coordinates of
the point. Returns 0, if no data point within the threshold dis‐
tance can be found, otherwise 1 is returned. The following
option-value pairs are available.
-along direction
Search for the closest element using the following crite‐
ria:
x Find closest element vertically from the given X-
coordinate.
y Find the closest element horizontally from the
given Y-coordinate.
both Find the closest element for the given point
(using both the X and Y coordinates).
-halo pixels
Specifies a threshold distance where selected data points
are ignored. Pixels is a valid screen distance, such as
2 or 1.2i. If this option isn't specified, then it
defaults to the value of the graph's -halo option.
-interpolate string
Indicates whether to consider projections that lie along
the line segments connecting data points when searching
for the closest point. The default value is 0. The val‐
ues for string are described below.
no Search only for the closest data point.
yes Search includes projections that lie along
the line segments connecting the data points.
pathName element configure elemName ?elemName... ?option value?...
Queries or modifies the configuration options for elements.
Several elements can be modified at the same time. If option
isn't specified, a list describing all the current options for
elemName is returned. If option is specified, but not value,
then a list describing the option option is returned. If one or
more option and value pairs are specified, then for each pair,
the element option option is set to value. The following
options are valid for elements.
-activepen penName
Specifies pen to use to draw active element. If penName
is "", no active elements will be drawn. The default is
activeLine.
-bindtags tagList
Specifies the binding tags for the element. TagList is a
list of binding tag names. The tags and their order will
determine how events are handled for elements. Each tag
in the list matching the current event sequence will have
its Tcl command executed. Implicitly the name of the
element is always the first tag in the list. The default
value is all.
-color color
Sets the color of the traces connecting the data points.
-dashes dashList
Sets the dash style of element line. DashList is a list
of up to 11 numbers that alternately represent the
lengths of the dashes and gaps on the element line. Each
number must be between 1 and 255. If dashList is "", the
lines will be solid.
-data coordList
Specifies the X-Y coordinates of the data. CoordList is
a list of numeric expressions representing the X-Y coor‐
dinate pairs of each data point.
-fill color
Sets the interior color of symbols. If color is "", then
the interior of the symbol is transparent. If color is
defcolor, then the color will be the same as the -color
option. The default is defcolor.
-hide boolean
Indicates whether the element is displayed. The default
is no.
-label text
Sets the element's label in the legend. If text is "",
the element will have no entry in the legend. The
default label is the element's name.
-linewidth pixels
Sets the width of the connecting lines between data
points. If pixels is 0, no connecting lines will be
drawn between symbols. The default is 0.
-mapx xAxis
Selects the X-axis to map the element's X-coordinates
onto. XAxis must be the name of an axis. The default is
x.
-mapy yAxis
Selects the Y-axis to map the element's Y-coordinates
onto. YAxis must be the name of an axis. The default is
y.
-offdash color
Sets the color of the stripes when traces are dashed (see
the -dashes option). If color is "", then the "off" pix‐
els will represent gaps instead of stripes. If color is
defcolor, then the color will be the same as the -color
option. The default is defcolor.
-outline color
Sets the color or the outline around each symbol. If
color is "", then no outline is drawn. If color is def‐
color, then the color will be the same as the -color
option. The default is defcolor.
-pen penname
Set the pen to use for this element.
-outlinewidth pixels
Sets the width of the outline bordering each symbol. If
pixels is 0, no outline will be drawn. The default is 1.
-pixels pixels
Sets the size of symbols. If pixels is 0, no symbols
will be drawn. The default is 0.125i.
-scalesymbols boolean
If boolean is true, the size of the symbols drawn for
elemName will change with scale of the X-axis and Y-axis.
At the time this option is set, the current ranges of the
axes are saved as the normalized scales (i.e scale factor
is 1.0) and the element is drawn at its designated size
(see the -pixels option). As the scale of the axes
change, the symbol will be scaled according to the
smaller of the X-axis and Y-axis scales. If boolean is
false, the element's symbols are drawn at the designated
size, regardless of axis scales. The default is 0.
-smooth smooth
Specifies how connecting line segments are drawn between
data points. Smooth can be either linear, step, natural,
or quadratic. If smooth is linear, a single line segment
is drawn, connecting both data points. When smooth is
step, two line segments are drawn. The first is a hori‐
zontal line segment that steps the next X-coordinate.
The second is a vertical line, moving to the next Y-coor‐
dinate. Both natural and quadratic generate multiple
segments between data points. If natural, the segments
are generated using a cubic spline. If quadratic, a qua‐
dratic spline is used. The default is linear.
-styles styleList
Specifies what pen to use based on the range of weights
given. StyleList is a list of style specifications. Each
style specification, in turn, is a list consisting of a
pen name, and optionally a minimum and maximum range.
Data points whose weight (see the -weight option) falls
in this range, are drawn with this pen. If no range is
specified it defaults to the index of the pen in the
list. Note that this affects only symbol attributes.
Line attributes, such as line width, dashes, etc. are
ignored.
-symbol symbol
Specifies the symbol for data points. Symbol can be
either square, circle, diamond, plus, cross, splus,
scross, triangle, "" (where no symbol is drawn), or a
bitmap. Bitmaps are specified as "source ?mask?", where
source is the name of the bitmap, and mask is the bit‐
map's optional mask. The default is circle.
-trace direction
Indicates whether connecting lines between data points
(whose X-coordinate values are either increasing or
decreasing) are drawn. Direction must be increasing,
decreasing, or both. For example, if direction is
increasing, connecting lines will be drawn only between
those data points where X-coordinate values are monotoni‐
cally increasing. If direction is both, connecting lines
will be draw between all data points. The default is
both.
-weights wVec
Specifies the weights of the individual data points.
This, with the list pen styles (see the -styles option),
controls how data points are drawn. WVec is the name of
a BLT vector or a list of numeric expressions represent‐
ing the weights for each data point.
-xdata xVec
Specifies the X-coordinates of the data. XVec is the
name of a BLT vector or a list of numeric expressions.
-ydata yVec
Specifies the Y-coordinates of the data. YVec is the
name of a BLT vector or a list of numeric expressions.
Element configuration options may also be set by the option com‐
mand. The resource class is Element. The resource name is the
name of the element.
option add *Graph.Element.symbol line
option add *Graph.e1.symbol line
pathName element create elemName ?option value?...
Creates a new element elemName. It's an error is an element
elemName already exists. If additional arguments are present,
they specify options valid for the element configure operation.
pathName element deactivate elemName ?elemName?...
Deactivates all the elements matching pattern. Elements whose
names match any of the patterns given are redrawn using their
normal colors.
pathName element delete ?elemName?...
Deletes all the named elements. The graph is automatically
redrawn.
pathName element exists elemName
Returns 1 if an element elemName currently exists and 0 other‐
wise.
pathName element names ?pattern?...
Returns the elements matching one or more pattern. If no pat‐
tern is given, the names of all elements is returned.
pathName element show ?nameList?
Queries or modifies the element display list. The element dis‐
play list designates the elements drawn and in what order.
NameList is a list of elements to be displayed in the order they
are named. If there is no nameList argument, the current dis‐
play list is returned.
pathName element type elemName
Returns the type of elemName. If the element is a bar element,
the commands returns the string "bar", otherwise it returns
"line".
GRID COMPONENT
Grid lines extend from the major and minor ticks of each axis horizon‐
tally or vertically across the plotting area. The following operations
are available for grid lines.
pathName grid cget option
Returns the current value of the grid line configuration option
given by option. Option may be any option described below for
the grid configure operation.
pathName grid configure ?option value?...
Queries or modifies the configuration options for grid lines.
If option isn't specified, a list describing all the current
grid options for pathName is returned. If option is specified,
but not value, then a list describing option is returned. If
one or more option and value pairs are specified, then for each
pair, the grid line option option is set to value. The follow‐
ing options are valid for grid lines.
-color color
Sets the color of the grid lines. The default is black.
-dashes dashList
Sets the dash style of the grid lines. DashList is a list
of up to 11 numbers that alternately represent the
lengths of the dashes and gaps on the grid lines. Each
number must be between 1 and 255. If dashList is "", the
grid will be solid lines.
-hide boolean
Indicates whether the grid should be drawn. If boolean is
true, grid lines are not shown. The default is yes.
-linewidth pixels
Sets the width of grid lines. The default width is 1.
-mapx xAxis
Specifies the X-axis to display grid lines. XAxis must
be the name of an axis or "" for no grid lines. The
default is "".
-mapy yAxis
Specifies the Y-axis to display grid lines. YAxis must
be the name of an axis or "" for no grid lines. The
default is y.
-minor boolean
Indicates whether the grid lines should be drawn for
minor ticks. If boolean is true, the lines will appear
at minor tick intervals. The default is 1.
Grid configuration options may also be set by the option com‐
mand. The resource name and class are grid and Grid respec‐
tively.
option add *Graph.grid.LineWidth 2
option add *Graph.Grid.Color black
pathName grid off
Turns off the display the grid lines.
pathName grid on
Turns on the display the grid lines.
pathName grid toggle
Toggles the display of the grid.
LEGEND COMPONENT
The legend displays a list of the data elements. Each entry consists
of the element's symbol and label. The legend can appear in any margin
(the default location is in the right margin). It can also be posi‐
tioned anywhere within the plotting area.
The following operations are valid for the legend.
pathName legend activate pattern...
Selects legend entries to be drawn using the active legend col‐
ors and relief. All entries whose element names match pattern
are selected. To be selected, the element name must match only
one pattern.
pathName legend bind tagName ?sequence? ?command?
Associates command with tagName such that whenever the event
sequence given by sequence occurs for a legend entry with this
tag, command will be invoked. Implicitly the element names in
the entry are tags. The syntax is similar to the bind command
except that it operates on legend entries, rather than widgets.
See the bind manual entry for complete details on sequence and
the substitutions performed on command before invoking it.
If all arguments are specified then a new binding is created,
replacing any existing binding for the same sequence and tag‐
Name. If the first character of command is + then command aug‐
ments an existing binding rather than replacing it. If no com‐
mand argument is provided then the command currently associated
with tagName and sequence (it's an error occurs if there's no
such binding) is returned. If both command and sequence are
missing then a list of all the event sequences for which bind‐
ings have been defined for tagName.
pathName legend cget option
Returns the current value of a legend configuration option.
Option may be any option described below in the legend configure
operation.
pathName legend configure ?option value?...
Queries or modifies the configuration options for the legend.
If option isn't specified, a list describing the current legend
options for pathName is returned. If option is specified, but
not value, then a list describing option is returned. If one or
more option and value pairs are specified, then for each pair,
the legend option option is set to value. The following options
are valid for the legend.
-activebackground color
Sets the background color for active legend entries. All
legend entries marked active (see the legend activate
operation) are drawn using this background color.
-activeborderwidth pixels
Sets the width of the 3-D border around the outside edge
of the active legend entries. The default is 2.
-activeforeground color
Sets the foreground color for active legend entries. All
legend entries marked as active (see the legend activate
operation) are drawn using this foreground color.
-activerelief relief
Specifies the 3-D effect desired for active legend
entries. Relief denotes how the interior of the entry
should appear relative to the legend; for example, raised
means the entry should appear to protrude from the leg‐
end, relative to the surface of the legend. The default
is flat.
-anchor anchor
Tells how to position the legend relative to the posi‐
tioning point for the legend. This is dependent on the
value of the -position option. The default is center.
left or right
The anchor describes how to position the leg‐
end vertically.
top or bottom
The anchor describes how to position the leg‐
end horizontally.
@x,y The anchor specifies how to position the leg‐
end relative to the positioning point. For
example, if anchor is center then the legend
is centered on the point; if anchor is n then
the legend will be drawn such that the top
center point of the rectangular region occu‐
pied by the legend will be at the positioning
point.
plotarea The anchor specifies how to position the leg‐
end relative to the plotting area. For exam‐
ple, if anchor is center then the legend is
centered in the plotting area; if anchor is
ne then the legend will be drawn such that
occupies the upper right corner of the plot‐
ting area.
-background color
Sets the background color of the legend. If color is "",
the legend background with be transparent.
-bindtags tagList
Specifies the binding tags for legend entries. TagList
is a list of binding tag names. The tags and their order
will determine how events are handled for legend entries.
Each tag in the list matching the current event sequence
will have its Tcl command executed. The default value is
all.
-borderwidth pixels
Sets the width of the 3-D border around the outside edge
of the legend (if such border is being drawn; the relief
option determines this). The default is 2 pixels.
-font fontName
FontName specifies a font to use when drawing the labels
of each element into the legend. The default is *-Hel‐
vetica-Bold-R-Normal-*-12-120-*.
-foreground color
Sets the foreground color of the text drawn for the ele‐
ment's label. The default is black.
-hide boolean
Indicates whether the legend should be displayed. If
boolean is true, the legend will not be draw. The
default is no.
-ipadx pad
Sets the amount of internal padding to be added to the
width of each legend entry. Pad can be a list of one or
two screen distances. If pad has two elements, the left
side of the legend entry is padded by the first distance
and the right side by the second. If pad is just one
distance, both the left and right sides are padded
evenly. The default is 2.
-ipady pad
Sets an amount of internal padding to be added to the
height of each legend entry. Pad can be a list of one or
two screen distances. If pad has two elements, the top
of the entry is padded by the first distance and the bot‐
tom by the second. If pad is just one distance, both the
top and bottom of the entry are padded evenly. The
default is 2.
-padx pad
Sets the padding to the left and right exteriors of the
legend. Pad can be a list of one or two screen dis‐
tances. If pad has two elements, the left side of the
legend is padded by the first distance and the right side
by the second. If pad has just one distance, both the
left and right sides are padded evenly. The default is
4.
-pady pad
Sets the padding above and below the legend. Pad can be
a list of one or two screen distances. If pad has two
elements, the area above the legend is padded by the
first distance and the area below by the second. If pad
is just one distance, both the top and bottom areas are
padded evenly. The default is 0.
-position pos
Specifies where the legend is drawn. The -anchor option
also affects where the legend is positioned. If pos is
left, left, top, or bottom, the legend is drawn in the
specified margin. If pos is plotarea, then the legend is
drawn inside the plotting area at a particular anchor.
If pos is in the form "@x,y", where x and y are the win‐
dow coordinates, the legend is drawn in the plotting area
at the specified coordinates. The default is right.
-raised boolean
Indicates whether the legend is above or below the data
elements. This matters only if the legend is in the
plotting area. If boolean is true, the legend will be
drawn on top of any elements that may overlap it. The
default is no.
-relief relief
Specifies the 3-D effect for the border around the leg‐
end. Relief specifies how the interior of the legend
should appear relative to the graph; for example, raised
means the legend should appear to protrude from the
graph, relative to the surface of the graph. The default
is sunken.
Legend configuration options may also be set by the option com‐
mand. The resource name and class are legend and Legend respec‐
tively.
option add *Graph.legend.Foreground blue
option add *Graph.Legend.Relief raised
pathName legend deactivate pattern...
Selects legend entries to be drawn using the normal legend col‐
ors and relief. All entries whose element names match pattern
are selected. To be selected, the element name must match only
one pattern.
pathName legend get pos
Returns the name of the element whose entry is at the screen
position pos in the legend. Pos must be in the form "@x,y",
where x and y are window coordinates. If the given coordinates
do not lie over a legend entry, "" is returned.
PEN COMPONENTS
Pens define attributes (both symbol and line style) for elements. Pens
mirror the configuration options of data elements that pertain to how
symbols and lines are drawn. Data elements use pens to determine how
they are drawn. A data element may use several pens at once. In this
case, the pen used for a particular data point is determined from each
element's weight vector (see the element's -weight and -style options).
One pen, called activeLine, is automatically created. It's used as the
default active pen for elements. So you can change the active
attributes for all elements by simply reconfiguring this pen.
.g pen configure "activeLine" -color green
You can create and use several pens. To create a pen, invoke the pen
component and its create operation.
.g pen create myPen
You map pens to a data element using either the element's -pen or
-activepen options.
.g element create "line1" -xdata $x -ydata $tempData \
-pen myPen
An element can use several pens at once. This is done by specifying the
name of the pen in the element's style list (see the -styles option).
.g element configure "line1" -styles { myPen 2.0 3.0 }
This says that any data point with a weight between 2.0 and 3.0 is to
be drawn using the pen myPen. All other points are drawn with the ele‐
ment's default attributes.
The following operations are available for pen components.
pathName pen cget penName option
Returns the current value of the option given by option for pen‐
Name. Option may be any option described below for the pen con‐
figure operation.
pathName pen configure penName ?penName... ?option value?...
Queries or modifies the configuration options of penName. Sev‐
eral pens can be modified at once. If option isn't specified, a
list describing the current options for penName is returned. If
option is specified, but not value, then a list describing
option is returned. If one or more option and value pairs are
specified, then for each pair, the pen option option is set to
value. The following options are valid for pens.
-color color
Sets the color of the traces connecting the data points.
-dashes dashList
Sets the dash style of element line. DashList is a list
of up to 11 numbers that alternately represent the
lengths of the dashes and gaps on the element line. Each
number must be between 1 and 255. If dashList is "", the
lines will be solid.
-fill color
Sets the interior color of symbols. If color is "", then
the interior of the symbol is transparent. If color is
defcolor, then the color will be the same as the -color
option. The default is defcolor.
-linewidth pixels
Sets the width of the connecting lines between data
points. If pixels is 0, no connecting lines will be
drawn between symbols. The default is 0.
-offdash color
Sets the color of the stripes when traces are dashed (see
the -dashes option). If color is "", then the "off" pix‐
els will represent gaps instead of stripes. If color is
defcolor, then the color will be the same as the -color
option. The default is defcolor.
-outline color
Sets the color or the outline around each symbol. If
color is "", then no outline is drawn. If color is def‐
color, then the color will be the same as the -color
option. The default is defcolor.
-outlinewidth pixels
Sets the width of the outline bordering each symbol. If
pixels is 0, no outline will be drawn. The default is 1.
-pixels pixels
Sets the size of symbols. If pixels is 0, no symbols
will be drawn. The default is 0.125i.
-symbol symbol
Specifies the symbol for data points. Symbol can be
either square, circle, diamond, plus, cross, splus,
scross, triangle, "" (where no symbol is drawn), or a
bitmap. Bitmaps are specified as "source ?mask?", where
source is the name of the bitmap, and mask is the bit‐
map's optional mask. The default is circle.
-type elemType
Specifies the type of element the pen is to be used with.
This option should only be employed when creating the
pen. This is for those that wish to mix different types
of elements (bars and lines) on the same graph. The
default type is "line".
Pen configuration options may be also be set by the option com‐
mand. The resource class is Pen. The resource names are the
names of the pens.
option add *Graph.Pen.Color blue
option add *Graph.activeLine.color green
pathName pen create penName ?option value?...
Creates a new pen by the name penName. No pen by the same name
can already exist. Option and value are described in above in
the pen configure operation.
pathName pen delete ?penName?...
Deletes the named pens. A pen is not really deleted until it is
not longer in use, so it's safe to delete pens mapped to ele‐
ments.
pathName pen names ?pattern?...
Returns a list of pens matching zero or more patterns. If no
pattern argument is give, the names of all pens are returned.
POSTSCRIPT COMPONENT
The graph can generate encapsulated PostScript output. There are sev‐
eral configuration options you can specify to control how the plot will
be generated. You can change the page dimensions and borders. The
plot itself can be scaled, centered, or rotated to landscape. The
PostScript output can be written directly to a file or returned through
the interpreter.
The following postscript operations are available.
pathName postscript cget option
Returns the current value of the postscript option given by
option. Option may be any option described below for the post‐
script configure operation.
pathName postscript configure ?option value?...
Queries or modifies the configuration options for PostScript
generation. If option isn't specified, a list describing the
current postscript options for pathName is returned. If option
is specified, but not value, then a list describing option is
returned. If one or more option and value pairs are specified,
then for each pair, the postscript option option is set to
value. The following postscript options are available.
-center boolean
Indicates whether the plot should be centered on the
PostScript page. If boolean is false, the plot will be
placed in the upper left corner of the page. The default
is 1.
-colormap varName
VarName must be the name of a global array variable that
specifies a color mapping from the X color name to Post‐
Script. Each element of varName must consist of Post‐
Script code to set a particular color value (e.g. ``1.0
1.0 0.0 setrgbcolor''). When generating color informa‐
tion in PostScript, the array variable varName is checked
if an element of the name as the color exists. If so, it
uses its value as the PostScript command to set the
color. If this option hasn't been specified, or if there
isn't an entry in varName for a given color, then it uses
the red, green, and blue intensities from the X color.
-colormode mode
Specifies how to output color information. Mode must be
either color (for full color output), gray (convert all
colors to their gray-scale equivalents) or mono (convert
foreground colors to black and background colors to
white). The default mode is color.
-fontmap varName
VarName must be the name of a global array variable that
specifies a font mapping from the X font name to Post‐
Script. Each element of varName must consist of a Tcl
list with one or two elements; the name and point size of
a PostScript font. When outputting PostScript commands
for a particular font, the array variable varName is
checked to see if an element by the specified font
exists. If there is such an element, then the font
information contained in that element is used in the
PostScript output. (If the point size is omitted from
the list, the point size of the X font is used). Other‐
wise the X font is examined in an attempt to guess what
PostScript font to use. This works only for fonts whose
foundry property is Adobe (such as Times, Helvetica,
Courier, etc.). If all of this fails then the font
defaults to Helvetica-Bold.
-decorations boolean
Indicates whether PostScript commands to generate color
backgrounds and 3-D borders will be output. If boolean
is false, the background will be white and no 3-D borders
will be generated. The default is 1.
-height pixels
Sets the height of the plot. This lets you print the
graph with a height different from the one drawn on the
screen. If pixels is 0, the height is the same as the
widget's height. The default is 0.
-landscape boolean
If boolean is true, this specifies the printed area is to
be rotated 90 degrees. In non-rotated output the X-axis
of the printed area runs along the short dimension of the
page (``portrait'' orientation); in rotated output the
X-axis runs along the long dimension of the page (``land‐
scape'' orientation). Defaults to 0.
-maxpect boolean
Indicates to scale the plot so that it fills the Post‐
Script page. The aspect ratio of the graph is still
retained. The default is 0.
-padx pad
Sets the horizontal padding for the left and right page
borders. The borders are exterior to the plot. Pad can
be a list of one or two screen distances. If pad has two
elements, the left border is padded by the first distance
and the right border by the second. If pad has just one
distance, both the left and right borders are padded
evenly. The default is 1i.
-pady pad
Sets the vertical padding for the top and bottom page
borders. The borders are exterior to the plot. Pad can
be a list of one or two screen distances. If pad has two
elements, the top border is padded by the first distance
and the bottom border by the second. If pad has just one
distance, both the top and bottom borders are padded
evenly. The default is 1i.
-paperheight pixels
Sets the height of the postscript page. This can be used
to select between different page sizes (letter, A4, etc).
The default height is 11.0i.
-paperwidth pixels
Sets the width of the postscript page. This can be used
to select between different page sizes (letter, A4, etc).
The default width is 8.5i.
-width pixels
Sets the width of the plot. This lets you generate a
plot of a width different from that of the widget. If
pixels is 0, the width is the same as the widget's width.
The default is 0.
Postscript configuration options may be also be set by the
option command. The resource name and class are postscript and
Postscript respectively.
option add *Graph.postscript.Decorations false
option add *Graph.Postscript.Landscape true
pathName postscript output ?fileName? ?option value?...
Outputs a file of encapsulated PostScript. If a fileName argu‐
ment isn't present, the command returns the PostScript. If any
option-value pairs are present, they set configuration options
controlling how the PostScript is generated. Option and value
can be anything accepted by the postscript configure operation
above.
MARKER COMPONENTS
Markers are simple drawing procedures used to annotate or highlight
areas of the graph. Markers have various types: text strings, bitmaps,
images, connected lines, windows, or polygons. They can be associated
with a particular element, so that when the element is hidden or un-
hidden, so is the marker. By default, markers are the last items
drawn, so that data elements will appear in behind them. You can
change this by configuring the -under option.
Markers, in contrast to elements, don't affect the scaling of the coor‐
dinate axes. They can also have elastic coordinates (specified by -Inf
and Inf respectively) that translate into the minimum or maximum limit
of the axis. For example, you can place a marker so it always remains
in the lower left corner of the plotting area, by using the coordinates
-Inf,-Inf.
The following operations are available for markers.
pathName marker after markerId ?afterId?
Changes the order of the markers, drawing the first marker after
the second. If no second afterId argument is specified, the
marker is placed at the end of the display list. This command
can be used to control how markers are displayed since markers
are drawn in the order of this display list.
pathName marker before markerId ?beforeId?
Changes the order of the markers, drawing the first marker
before the second. If no second beforeId argument is specified,
the marker is placed at the beginning of the display list. This
command can be used to control how markers are displayed since
markers are drawn in the order of this display list.
pathName marker bind tagName ?sequence? ?command?
Associates command with tagName such that whenever the event
sequence given by sequence occurs for a marker with this tag,
command will be invoked. The syntax is similar to the bind com‐
mand except that it operates on graph markers, rather than wid‐
gets. See the bind manual entry for complete details on sequence
and the substitutions performed on command before invoking it.
If all arguments are specified then a new binding is created,
replacing any existing binding for the same sequence and tag‐
Name. If the first character of command is + then command aug‐
ments an existing binding rather than replacing it. If no com‐
mand argument is provided then the command currently associated
with tagName and sequence (it's an error occurs if there's no
such binding) is returned. If both command and sequence are
missing then a list of all the event sequences for which bind‐
ings have been defined for tagName.
pathName marker cget option
Returns the current value of the marker configuration option
given by option. Option may be any option described below in
the configure operation.
pathName marker configure markerId ?option value?...
Queries or modifies the configuration options for markers. If
option isn't specified, a list describing the current options
for markerId is returned. If option is specified, but not
value, then a list describing option is returned. If one or
more option and value pairs are specified, then for each pair,
the marker option option is set to value.
The following options are valid for all markers. Each type of
marker also has its own type-specific options. They are
described in the sections below.
-bindtags tagList
Specifies the binding tags for the marker. TagList is a
list of binding tag names. The tags and their order will
determine how events for markers are handled. Each tag
in the list matching the current event sequence will have
its Tcl command executed. Implicitly the name of the
marker is always the first tag in the list. The default
value is all.
-coords coordList
Specifies the coordinates of the marker. CoordList is a
list of graph coordinates. The number of coordinates
required is dependent on the type of marker. Text,
image, and window markers need only two coordinates (an
X-Y coordinate). Bitmap markers can take either two or
four coordinates (if four, they represent the corners of
the bitmap). Line markers need at least four coordinates,
polygons at least six. If coordList is "", the marker
will not be displayed. The default is "".
-element elemName
Links the marker with the element elemName. The marker
is drawn only if the element is also currently displayed
(see the element's show operation). If elemName is "",
the marker is always drawn. The default is "".
-hide boolean
Indicates whether the marker is drawn. If boolean is
true, the marker is not drawn. The default is no.
-mapx xAxis
Specifies the X-axis to map the marker's X-coordinates
onto. XAxis must the name of an axis. The default is x.
-mapy yAxis
Specifies the Y-axis to map the marker's Y-coordinates
onto. YAxis must the name of an axis. The default is y.
-name markerId
Changes the identifier for the marker. The identifier
markerId can not already be used by another marker. If
this option isn't specified, the marker's name is
uniquely generated.
-under boolean
Indicates whether the marker is drawn below/above data
elements. If boolean is true, the marker is be drawn
underneath the data element symbols and lines. Other‐
wise, the marker is drawn on top of the element. The
default is 0.
-xoffset pixels
Specifies a screen distance to offset the marker horizon‐
tally. Pixels is a valid screen distance, such as 2 or
1.2i. The default is 0.
-yoffset pixels
Specifies a screen distance to offset the markers verti‐
cally. Pixels is a valid screen distance, such as 2 or
1.2i. The default is 0.
Marker configuration options may also be set by the option com‐
mand. The resource class is either BitmapMarker, ImageMarker,
LineMarker, PolygonMarker, TextMarker, or WindowMarker, depend‐
ing on the type of marker. The resource name is the name of the
marker.
option add *Graph.TextMarker.Foreground white
option add *Graph.BitmapMarker.Foreground white
option add *Graph.m1.Background blue
pathName marker create type ?option value?...
Creates a marker of the selected type. Type may be either text,
line, bitmap, image, polygon, or window. This command returns
the marker identifier, used as the markerId argument in the
other marker-related commands. If the -name option is used,
this overrides the normal marker identifier. If the name pro‐
vided is already used for another marker, the new marker will
replace the old.
pathName marker delete ?name?...
Removes one of more markers. The graph will automatically be
redrawn without the marker..
pathName marker exists markerId
Returns 1 if the marker markerId exists and 0 otherwise.
pathName marker names ?pattern?
Returns the names of all the markers that currently exist. If
pattern is supplied, only those markers whose names match it
will be returned.
pathName marker type markerId
Returns the type of the marker given by markerId, such as line
or text. If markerId is not a valid a marker identifier, "" is
returned.
BITMAP MARKERS
A bitmap marker displays a bitmap. The size of the bitmap is con‐
trolled by the number of coordinates specified. If two coordinates,
they specify the position of the top-left corner of the bitmap. The
bitmap retains its normal width and height. If four coordinates, the
first and second pairs of coordinates represent the corners of the bit‐
map. The bitmap will be stretched or reduced as necessary to fit into
the bounding rectangle.
Bitmap markers are created with the marker's create operation in the
form: pathName marker create bitmap ?option value?... There may be
many option-value pairs, each sets a configuration options for the
marker. These same option-value pairs may be used with the marker's
configure operation.
The following options are specific to bitmap markers:
-background color
Same as the -fill option.
-bitmap bitmap
Specifies the bitmap to be displayed. If bitmap is "", the
marker will not be displayed. The default is "".
-fill color
Sets the background color of the bitmap. If color is the empty
string, no background will be transparent. The default back‐
ground color is "".
-foreground color
Same as the -outline option.
-mask mask
Specifies a mask for the bitmap to be displayed. This mask is a
bitmap itself, denoting the pixels that are transparent. If
mask is "", all pixels of the bitmap will be drawn. The default
is "".
-outline color
Sets the foreground color of the bitmap. The default value is
black.
-rotate theta
Sets the rotation of the bitmap. Theta is a real number repre‐
senting the angle of rotation in degrees. The marker is first
rotated and then placed according to its anchor position. The
default rotation is 0.0.
IMAGE MARKERS
A image marker displays an image. Image markers are created with the
marker's create operation in the form: pathName marker create image
?option value?... There may be many option-value pairs, each sets a
configuration option for the marker. These same option-value pairs may
be used with the marker's configure operation.
The following options are specific to image markers:
-anchor anchor
Anchor tells how to position the image relative to the position‐
ing point for the image. For example, if anchor is center then
the image is centered on the point; if anchor is n then the
image will be drawn such that the top center point of the rec‐
tangular region occupied by the image will be at the positioning
point. This option defaults to center.
-image image
Specifies the image to be drawn. If image is "", the marker
will not be drawn. The default is "".
LINE MARKERS
A line marker displays one or more connected line segments. Line mark‐
ers are created with marker's create operation in the form: pathName
marker create line ?option value?... There may be many option-value
pairs, each sets a configuration option for the marker. These same
option-value pairs may be used with the marker's configure operation.
The following options are specific to line markers:
-dashes dashList
Sets the dash style of the line. DashList is a list of up to 11
numbers that alternately represent the lengths of the dashes and
gaps on the line. Each number must be between 1 and 255. If
dashList is "", the marker line will be solid.
-fill color
Sets the background color of the line. This color is used with
striped lines (see the -fdashes option). If color is the empty
string, no background color is drawn (the line will be dashed,
not striped). The default background color is "".
-linewidth pixels
Sets the width of the lines. The default width is 0.
-outline color
Sets the foreground color of the line. The default value is
black.
-stipple bitmap
Specifies a stipple pattern used to draw the line, rather than a
solid line. Bitmap specifies a bitmap to use as the stipple
pattern. If bitmap is "", then the line is drawn in a solid
fashion. The default is "".
POLYGON MARKERS
A polygon marker displays a closed region described as two or more con‐
nected line segments. It is assumed the first and last points are con‐
nected. Polygon markers are created using the marker create operation
in the form: pathName marker create polygon ?option value?... There
may be many option-value pairs, each sets a configuration option for
the marker. These same option-value pairs may be used with the marker
configure command to change the marker's configuration. The following
options are supported for polygon markers:
-dashes dashList
Sets the dash style of the outline of the polygon. DashList is a
list of up to 11 numbers that alternately represent the lengths
of the dashes and gaps on the outline. Each number must be
between 1 and 255. If dashList is "", the outline will be a
solid line.
-fill color
Sets the fill color of the polygon. If color is "", then the
interior of the polygon is transparent. The default is white.
-linewidth pixels
Sets the width of the outline of the polygon. If pixels is zero,
no outline is drawn. The default is 0.
-outline color
Sets the color of the outline of the polygon. If the polygon is
stippled (see the -stipple option), then this represents the
foreground color of the stipple. The default is black.
-stipple bitmap
Specifies that the polygon should be drawn with a stippled pat‐
tern rather than a solid color. Bitmap specifies a bitmap to use
as the stipple pattern. If bitmap is "", then the polygon is
filled with a solid color (if the -fill option is set). The
default is "".
TEXT MARKERS
A text marker displays a string of characters on one or more lines of
text. Embedded newlines cause line breaks. They may be used to anno‐
tate regions of the graph. Text markers are created with the create
operation in the form: pathName marker create text ?option value?...
There may be many option-value pairs, each sets a configuration option
for the text marker. These same option-value pairs may be used with
the marker's configure operation.
The following options are specific to text markers:
-anchor anchor
Anchor tells how to position the text relative to the position‐
ing point for the text. For example, if anchor is center then
the text is centered on the point; if anchor is n then the text
will be drawn such that the top center point of the rectangular
region occupied by the text will be at the positioning point.
This default is center.
-background color
Same as the -fill option.
-font fontName
Specifies the font of the text. The default is *-Helvetica-
Bold-R-Normal-*-120-*.
-fill color
Sets the background color of the text. If color is the empty
string, no background will be transparent. The default back‐
ground color is "".
-foreground color
Same as the -outline option.
-justify justify
Specifies how the text should be justified. This matters only
when the marker contains more than one line of text. Justify
must be left, right, or center. The default is center.
-outline color
Sets the color of the text. The default value is black.
-padx pad
Sets the padding to the left and right exteriors of the text.
Pad can be a list of one or two screen distances. If pad has
two elements, the left side of the text is padded by the first
distance and the right side by the second. If pad has just one
distance, both the left and right sides are padded evenly. The
default is 4.
-pady pad
Sets the padding above and below the text. Pad can be a list of
one or two screen distances. If pad has two elements, the area
above the text is padded by the first distance and the area
below by the second. If pad is just one distance, both the top
and bottom areas are padded evenly. The default is 4.
-rotate theta
Specifies the number of degrees to rotate the text. Theta is a
real number representing the angle of rotation. The marker is
first rotated along its center and is then drawn according to
its anchor position. The default is 0.0.
-text text
Specifies the text of the marker. The exact way the text is
displayed may be affected by other options such as -anchor or
-rotate.
WINDOW MARKERS
A window marker displays a widget at a given position. Window markers
are created with the marker's create operation in the form: pathName
marker create window ?option value?... There may be many option-value
pairs, each sets a configuration option for the marker. These same
option-value pairs may be used with the marker's configure command.
The following options are specific to window markers:
-anchor anchor
Anchor tells how to position the widget relative to the posi‐
tioning point for the widget. For example, if anchor is center
then the widget is centered on the point; if anchor is n then
the widget will be displayed such that the top center point of
the rectangular region occupied by the widget will be at the
positioning point. This option defaults to center.
-height pixels
Specifies the height to assign to the marker's window. If this
option isn't specified, or if it is specified as "", then the
window is given whatever height the widget requests internally.
-width pixels
Specifies the width to assign to the marker's window. If this
option isn't specified, or if it is specified as "", then the
window is given whatever width the widget requests internally.
-window pathName
Specifies the widget to be managed by the graph. PathName must
be a child of the graph widget.
GRAPH COMPONENT BINDINGS
Specific graph components, such as elements, markers and legend
entries, can have a command trigger when event occurs in them, much
like canvas items in Tk's canvas widget. Not all event sequences are
valid. The only binding events that may be specified are those related
to the mouse and keyboard (such as Enter, Leave, ButtonPress, Motion,
and KeyPress).
Only one element or marker can be picked during an event. This means,
that if the mouse is directly over both an element and a marker, only
the uppermost component is selected. This isn't true for legend
entries. Both a legend entry and an element (or marker) binding com‐
mands will be invoked if both items are picked.
It is possible for multiple bindings to match a particular event. This
could occur, for example, if one binding is associated with the element
name and another is associated with one of the element's tags (see the
-bindtags option). When this occurs, all of the matching bindings are
invoked. A binding associated with the element name is invoked first,
followed by one binding for each of the element's bindtags. If there
are multiple matching bindings for a single tag, then only the most
specific binding is invoked. A continue command in a binding script
terminates that script, and a break command terminates that script and
skips any remaining scripts for the event, just as for the bind com‐
mand.
The -bindtags option for these components controls addition tag names
which can be matched. Implicitly elements and markers always have tags
matching their names. Setting the value of the -bindtags option
doesn't change this.
C LANGUAGE API
You can manipulate data elements from the C language. There may be
situations where it is too expensive to translate the data values from
ASCII strings. Or you might want to read data in a special file for‐
mat.
Data can manipulated from the C language using BLT vectors. You spec‐
ify the X-Y data coordinates of an element as vectors and manipulate
the vector from C. The graph will be redrawn automatically after the
vectors are updated.
From Tcl, create the vectors and configure the element to use them.
vector X Y
.g element configure line1 -xdata X -ydata Y
To set data points from C, you pass the values as arrays of doubles
using the Blt_ResetVector call. The vector is reset with the new data
and at the next idle point (when Tk re-enters its event loop), the
graph will be redrawn automatically.
#include <tcl.h>
#include <blt.h>
register int i;
Blt_Vector *xVec, *yVec;
double x[50], y[50];
/* Get the BLT vectors "X" and "Y" (created above from Tcl) */
if ((Blt_GetVector(interp, "X", &xVec) != TCL_OK) ||
(Blt_GetVector(interp, "Y", &yVec) != TCL_OK)) {
return TCL_ERROR;
}
for (i = 0; i < 50; i++) {
x[i] = i * 0.02;
y[i] = sin(x[i]);
}
/* Put the data into BLT vectors */
if ((Blt_ResetVector(xVec, x, 50, 50, TCL_VOLATILE) != TCL_OK) ||
(Blt_ResetVector(yVec, y, 50, 50, TCL_VOLATILE) != TCL_OK)) {
return TCL_ERROR;
}
See the vector manual page for more details.
SPEED TIPS
There may be cases where the graph needs to be drawn and updated as
quickly as possible. If drawing speed becomes a big problem, here are
a few tips to speed up displays.
· Try to minimize the number of data points. The more data points the
looked at, the more work the graph must do.
· If your data is generated as floating point values, the time required
to convert the data values to and from ASCII strings can be signifi‐
cant, especially when there any many data points. You can avoid the
redundant string-to-decimal conversions using the C API to BLT vec‐
tors.
· Data elements without symbols are drawn faster than with symbols.
Set the data element's -symbol option to none. If you need to draw
symbols, try using the simple symbols such as splus and scross.
· Don't stipple or dash the element. Solid lines are much faster.
· If you update data elements frequently, try turning off the widget's
-bufferelements option. When the graph is first displayed, it draws
data elements into an internal pixmap. The pixmap acts as a cache,
so that when the graph needs to be redrawn again, and the data ele‐
ments or coordinate axes haven't changed, the pixmap is simply copied
to the screen. This is especially useful when you are using markers
to highlight points and regions on the graph. But if the graph is
updated frequently, changing either the element data or coordinate
axes, the buffering becomes redundant.
LIMITATIONS
Auto-scale routines do not use requested min/max limits as boundaries
when the axis is logarithmically scaled.
The PostScript output generated for polygons with more than 1500 points
may exceed the limits of some printers (See PostScript Language Refer‐
ence Manual, page 568). The work-around is to break the polygon into
separate pieces.
KEYWORDS
graph, widget
BLT 2.4 graph(n)
