XCreateColormap(3X11) XLIB FUNCTIONS XCreateColormap(3X11)NAME
XCreateColormap, XCopyColormapAndFree, XFreeColormap,
XColor - create, copy, or destroy colormaps and color
structure
SYNTAX
Colormap XCreateColormap(display, w, visual, alloc)
Display *display;
Window w;
Visual *visual;
int alloc;
Colormap XCopyColormapAndFree(display, colormap)
Display *display;
Colormap colormap;
XFreeColormap(display, colormap)
Display *display;
Colormap colormap;
ARGUMENTS
alloc Specifies the colormap entries to be allocated.
You can pass AllocNone or AllocAll.
colormap Specifies the colormap that you want to create,
copy, set, or destroy.
display Specifies the connection to the X server.
visual Specifies a visual type supported on the screen.
If the visual type is not one supported by the
screen, a BadMatch error results.
w Specifies the window on whose screen you want to
create a colormap.
DESCRIPTION
The XCreateColormap function creates a colormap of the
specified visual type for the screen on which the speci-
fied window resides and returns the colormap ID associated
with it. Note that the specified window is only used to
determine the screen.
The initial values of the colormap entries are undefined
for the visual classes GrayScale, PseudoColor, and
DirectColor. For StaticGray, StaticColor, and TrueColor,
the entries have defined values, but those values are spe-
cific to the visual and are not defined by X. For
StaticGray, StaticColor, and TrueColor, alloc must be
AllocNone, or a BadMatch error results. For the other
visual classes, if alloc is AllocNone, the colormap ini-
tially has no allocated entries, and clients can allocate
them. For information about the visual types, see section
3.1.
X Version 11 Release 6.4 1
XCreateColormap(3X11) XLIB FUNCTIONS XCreateColormap(3X11)
If alloc is AllocAll, the entire colormap is allocated
writable. The initial values of all allocated entries are
undefined. For GrayScale and PseudoColor, the effect is
as if an XAllocColorCells call returned all pixel values
from zero to N - 1, where N is the colormap entries value
in the specified visual. For DirectColor, the effect is
as if an XAllocColorPlanes call returned a pixel value of
zero and red_mask, green_mask, and blue_mask values con-
taining the same bits as the corresponding masks in the
specified visual. However, in all cases, none of these
entries can be freed by using XFreeColors.
XCreateColormap can generate BadAlloc, BadMatch, BadValue,
and BadWindow errors.
The XCopyColormapAndFree function creates a colormap of
the same visual type and for the same screen as the speci-
fied colormap and returns the new colormap ID. It also
moves all of the client's existing allocation from the
specified colormap to the new colormap with their color
values intact and their read-only or writable characteris-
tics intact and frees those entries in the specified col-
ormap. Color values in other entries in the new colormap
are undefined. If the specified colormap was created by
the client with alloc set to AllocAll, the new colormap is
also created with AllocAll, all color values for all
entries are copied from the specified colormap, and then
all entries in the specified colormap are freed. If the
specified colormap was not created by the client with
AllocAll, the allocations to be moved are all those pixels
and planes that have been allocated by the client using
XAllocColor, XAllocNamedColor, XAllocColorCells, or XAl-
locColorPlanes and that have not been freed since they
were allocated.
XCopyColormapAndFree can generate BadAlloc and BadColor
errors.
The XFreeColormap function deletes the association between
the colormap resource ID and the colormap and frees the
colormap storage. However, this function has no effect on
the default colormap for a screen. If the specified col-
ormap is an installed map for a screen, it is uninstalled
(see XUninstallColormap). If the specified colormap is
defined as the colormap for a window (by XCreateWindow,
XSetWindowColormap, or XChangeWindowAttributes), XFreeCol-
ormap changes the colormap associated with the window to
None and generates a ColormapNotify event. X does not
define the colors displayed for a window with a colormap
of None.
XFreeColormap can generate a BadColor error.
X Version 11 Release 6.4 2
XCreateColormap(3X11) XLIB FUNCTIONS XCreateColormap(3X11)STRUCTURES
The XColor structure contains:
typedef struct {
unsigned long pixel;/* pixel value */
unsigned short red, green, blue;/* rgb values */
char flags; /* DoRed, DoGreen, DoBlue */
char pad;
} XColor;
The red, green, and blue values are always in the range 0
to 65535 inclusive, independent of the number of bits
actually used in the display hardware. The server scales
these values down to the range used by the hardware.
Black is represented by (0,0,0), and white is represented
by (65535,65535,65535). In some functions, the flags mem-
ber controls which of the red, green, and blue members is
used and can be the inclusive OR of zero or more of DoRed,
DoGreen, and DoBlue.
DIAGNOSTICS
BadAlloc The server failed to allocate the requested
resource or server memory.
BadColor A value for a Colormap argument does not name a
defined Colormap.
BadMatch An InputOnly window is used as a Drawable.
BadMatch Some argument or pair of arguments has the cor-
rect type and range but fails to match in some
other way required by the request.
BadValue Some numeric value falls outside the range of
values accepted by the request. Unless a spe-
cific range is specified for an argument, the
full range defined by the argument's type is
accepted. Any argument defined as a set of
alternatives can generate this error.
BadWindow A value for a Window argument does not name a
defined Window.
SEE ALSOXAllocColor(3X11), XChangeWindowAtrributes(3X11), XCre-
ateWindow(3X11), XQueryColor(3X11), XStoreColors(3X11)
Xlib - C Language X Interface
X Version 11 Release 6.4 3
