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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



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