Provided by: libx11-doc_1.8.1-2_all 
NAME
XCreateColormap, XCopyColormapAndFree, XFreeColormap, XColor - create, copy, or destroy
colormaps and color structure
SYNTAX
Colormap XCreateColormap(Display *display, Window w, Visual *visual, int alloc);
Colormap XCopyColormapAndFree(Display *display, Colormap colormap);
int XFreeColormap(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 specified 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 specific 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 initially has
no allocated entries, and clients can allocate them. For information about the visual
types, see section 3.1.
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 containing 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 specified 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 characteristics intact and frees
those entries in the specified colormap. 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
XAllocColorPlanes 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 colormap 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), XFreeColormap 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.
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 member 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 correct 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 specific 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 ALSO
XAllocColor(3), XChangeWindowAttributes(3), XCreateWindow(3), XQueryColor(3),
XStoreColors(3)
Xlib - C Language X Interface