XCreateColormap(3) XLIB FUNCTIONS XCreateColormap(3)

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

X Version 11 libX11 1.8.10 XCreateColormap(3)