X Version 11 (Release 5) 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 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.
Licensed material--property of copyright holder(s) Page 1
X Version 11 (Release 5)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 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.
Licensed material--property of copyright holder(s) Page 2
X Version 11 (Release 5)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), 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(3X11), XChangeWindowAtrributes(3X11),
XCreateWindow(3X11), XQueryColor(3X11), XStoreColors(3X11)
Xlib - C Language X Interface
Licensed material--property of copyright holder(s) Page 3