bitmap(n) BLT Built-In Commands bitmap(n)______________________________________________________________________________NAME
bitmap - Define a new bitmap from a Tcl script
SYNOPSIS
bitmap define bitmapName data ?option value?...
bitmap compose bitmapName text ?option value?...
bitmap exists bitmapName
bitmap source bitmapName
bitmap data bitmapName
bitmap height bitmapName
bitmap width bitmapName
_________________________________________________________________DESCRIPTION
The bitmap command lets you create new bitmaps directly from your Tcl
script. The bitmap can be specified as a list of data or a text string
which is converted into a bitmap. You can arbitrarily scale or rotate
the bitmap too.
INTRODUCTION
Bitmaps are commonly used within Tk. In label and button widgets, you
display bitmaps them instead of text strings and in the canvas and text
widgets, they're used for stippling. But Tk let's you can create new
bitmaps only by reading the bitmap data from a file. This makes bit‐
maps cumbersome to manage, especially in packaging the program as a
wish script, since each bitmap must be its own file. It would be nicer
if you could create new bitmaps directly from your Tcl script.
The bitmap command lets you do just that. You can specify the bitmap
as in various formats (such as the X11 bitmap format). You can also
compose a bitmap from a text string. The bitmap command also lets you
and arbitrarily rotate or scale the bitmap. For example, you could use
this to create button widgets with the text label rotated 90 degrees.
EXAMPLE
<<<<<<< bitmap.mann You can define a new bitmap with the define opera‐
tion. For example, let's say you are using the X11 bitmap "gray1".
Normally to use it, you would specify the location of the file.
label .l -bitmap @/usr/X11R6/include/X11/bitmaps/gray1
But you can simply cut and paste the contents of "gray1" into the bit‐
map command.
bitmap define gray1 {
#define gray1_width 2
#define gray1_height 2
static char gray1_bits[] = {
0x01, 0x02};
}
label .l -bitmap gray1
Tk will recognize "gray1" as a bitmap which can now be used with any
widget that accepts bitmaps.
The bitmap data can be specified in a mulitude of forms. The following
commands are all equivalent.
bitmap define gray1 {
#define gray1_width 2
#define gray1_height 2
static char gray1_bits[] = {
0x01, 0x02};
}
bitmap define gray1 { { 2 2 } { 0x01, 0x02 } }
bitmap define gray1 { { 2 2 } { 0x01 0x02 } }
bitmap define gray1 { { 2 2 } { 1 2 } }
Either the data is in the standard X11 bitmap form, or it's a list of
two lists. The first list contains the height and width of the bitmap.
The second list is the bitmap source data. Each element of that list
is an hexadecimal number specifying which pixels are foreground (1) and
which are background (0) of the bitmap. Note that the format of the
source data is exactly that of the XBM format.
You can scale or rotate the bitmap as you create it, by using the
-scale or-rotate options.
bitmap define gray1 {
#define gray1_width 2
#define gray1_height 2
static char gray1_bits[] = {
0x01, 0x02};
} -scale 2.0 -rotate 90.0
In addition, you can compose bitmaps from text strings. This makes it
easy to create rotated buttons or labels. The text string can have
multi-line.
bitmap compose rot_text "This is rotated\ntext" \
-rotate 90.0 -font fixed
There are also a number of ways to query bitmaps. This isn't limited
to bitmaps that you create, but any bitmap.
bitmap exists rot_text
bitmap width rot_text
bitmap height rot_text
bitmap data rot_text
bitmap source rot_text
The exists operation indicates if a bitmap by that name is defined.
You can query the dimensions of the bitmap using the width and height
operations. The data operation returns the list of the data used to
create the bitmap. For example, you could query the data of a bitmap
and send it across the network to another Tk application.
set data [bitmap data @/usr/X11R6/include/X11/bitmaps/ghost.xbm]
send {wish #2} bitmap define ghost $data
OPERATIONS
The following operations are available for bitmap:
bitmap compose bitmapName text ?option value?...
Creates a bitmap bitmapName from the text string text. A bitmap
bitmapName can not already exist. The following options are
available.
-font fontName
Specifies a font to use when drawing text into the bit‐
map. If this option isn't specified then fontName
defaults to *-Helvetica-Bold-R-Normal-*-140-*.
-rotate theta
Specifies the angle of rotation of the text in the bit‐
map. Theta is a real number representing the angle in
degrees. It defaults to 0.0 degrees.
-scale value
Specifies the scale of the bitmap. Value is a real num‐
ber representing the scale. A scale of 1.0 indicates no
scaling is necessary, while 2.0 would double the size of
the bitmap. There is no way to specify differents scales
for the width and height of the bitmap. The default
scale is 1.0.
bitmap data bitmapName
Returns a list of both the dimensions of the bitmap bitmapName
and its source data.
bitmap define bitmapName data ?option value?...
Associates bitmapName with in-memory bitmap data so that bitmap‐
Name can be used in later calls to Tk_GetBitmap. The bitmapName
argument is the name of the bitmap; it must not previously have
been defined in either a call to Tk_DefineBitmap or bitmap. The
argument data describes the bitmap to be created. It is either
the X11 bitmap format (a C structure) or a list of two lists:
the dimensions and source data. The dimensions are a list of
two numbers which are the width and height of the bitmap. The
source data is a list of hexadecimal values in a format similar
to the X11 or X10 bitmap format. The values may be optionally
separated by commas and do not need to be prefixed with "0x".
The following options are available.
-rotate theta
Specifies how many degrees to rotate the bitmap. Theta
is a real number representing the angle. The default is
0.0 degrees.
-scale value
Specifies how to scale the bitmap. Value is a real num‐
ber representing the scale. A scale of 1.0 indicates no
scaling is necessary, while 2.0 would double the size of
the bitmap. There is no way to specify differents scales
for the width and height of the bitmap. The default
scale is 1.0.
bitmap exists bitmapName
Returns 1 if a bitmap bitmapName exists, otherwise 0.
bitmap height bitmapName
Returns the height in pixels of the bitmap bitmapName.
bitmap source bitmapName
Returns the source data of the bitmap bitmapName. The source
data is a list of the hexadecimal values.
bitmap width bitmapName
Returns the width in pixels of the bitmap bitmapName.
LIMITATIONS
Tk currently offers no way of destroying bitmaps. Once a bitmap is
created, it exists until the application terminates.
KEYWORDS
bitmap
BLT 2.4 bitmap(n)
