XCreateColormap(3X11)RISC/os Reference ManuaXCreateColormap(3X11)
NAME
XCreateColormap, XCopyColormapAndFree, XFreeColormap,
XSetWindowColormap, XColor - create, copy, or destroy color-
maps 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;
XSetWindowColormap(display, w, colormap)
Display *display;
Window w;
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 pointer to a visual type supported on
the screen. If the visual type is not one sup-
ported by the screen, a BadMatch error results.
w Specifies the window for which you want to create
or set 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 deter-
mine 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
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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 Alloc-
None, 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 writ-
able. The initial values of all allocated entries are unde-
fined. 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 speci-
fied colormap, and then all entries in the specified color-
map 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, XAllocColor-
Cells, 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 color-
map 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, XSetWin-
dowColormap, or XChangeWindowAttributes), XFreeColormap
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XCreateColormap(3X11)RISC/os Reference ManuaXCreateColormap(3X11)
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.
The XSetWindowColormap function sets the specified colormap
of the specified window. The colormap must have the same
visual type as the window, or a BadMatch error results.
XSetWindowColormap can generate BadColor, BadMatch, and
BadWindow errors.
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 scaled between 0 and
65535. On full in a color is a value of 65535 independent of
the number of bits actually used in the display hardware.
Half brightness in a color is a value of 32767, and off is
0. This representation gives uniform results for color
values across different screens. In some functions, the
flags member controls which of the red, green, and blue
members is used and can be one 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 gen-
erate this error.
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XCreateColormap(3X11)RISC/os Reference ManuaXCreateColormap(3X11)
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
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