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