XCreateColormap
XCreateColormap(3X11) XLIB FUNCTIONS XCreateColormap(3X11)
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 Stat-
icGray, 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 cor-
responding 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 BadWin-
dow 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 exist-
ing 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 col-
ormap. Color values in other entries in the new colormap are unde-
fined. 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, XAlloc-
ColorCells, 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 col-
ormap 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, XSetWindow-
Colormap, or XChangeWindowAttributes), XFreeColormap changes the col-
ormap associated with the window to None and generates a ColormapNo-
tify 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 dis-
play hardware. The server scales these values down to the range used
by the hardware. Black is represented by (0,0,0), and white is repre-
sented 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 Col-
ormap.
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 speci-
fied for an argument, the full range defined by the argu-
ment’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 Win-
dow.
SEE ALSO
XAllocColor(3X11), XChangeWindowAttributes(3X11), XCreateWindow(3X11),
XQueryColor(3X11), XStoreColors(3X11)
Xlib - C Language X Interface
XCreateColormap(3X11)
