XAllocColor, XAllocNamedColor, XAllocColorCells, XAlloc-
       ColorPlanes, XFreeColors - allocate and free colors


SYNTAX

       Status XAllocColor(display, colormap, screen_in_out)
             Display *display;
             Colormap colormap;
             XColor *screen_in_out;

       Status XAllocNamedColor(display, colormap, color_name,
       screen_def_return, exact_def_return)
             Display *display;
             Colormap colormap;
             char *color_name;
             XColor *screen_def_return, *exact_def_return;

       Status XAllocColorCells(display, colormap, contig,
       plane_masks_return, nplanes,
                                 pixels_return, npixels)
             Display *display;
             Colormap colormap;
             Bool contig;
             unsigned long plane_masks_return[];
             unsigned int nplanes;
             unsigned long pixels_return[];
             unsigned int npixels;

       Status XAllocColorPlanes(display, colormap, contig,
       pixels_return, ncolors, nreds, ngreens,
                                  nblues, rmask_return,
       gmask_return, bmask_return)
             Display *display;
             Colormap colormap;
             Bool contig;
             unsigned long pixels_return[];
             int ncolors;
             int nreds, ngreens, nblues;
             unsigned long *rmask_return, *gmask_return,
       *bmask_return;

       XFreeColors(display, colormap, pixels, npixels, planes)
             Display *display;
             Colormap colormap;
             unsigned long pixels[];
             int npixels;
             unsigned long planes;


ARGUMENTS

       color_name
                 Specifies the color name string (for example,
                 red) whose color definition structure you want
                 returned.

       npixels   Specifies the number of pixels.

       nplanes   Specifies the number of plane masks that are to
                 be returned in the plane masks array.

       nreds
       ngreens
       nblues
                 Specify the number of red, green, and blue
                 planes.  The value you pass must be nonnegative.

       pixels    Specifies an array of pixel values.

       pixels_return
                 Returns an array of pixel values.

       plane_mask_return
                 Returns an array of plane masks.

       planes    Specifies the planes you want to free.

       rmask_return
       gmask_return
       bmask_return
                 Return bit masks for the red, green, and blue
                 planes.

       screen_def_return
                 Returns the closest RGB values provided by the
                 hardware.

       screen_in_out
                 Specifies and returns the values actually used
                 in the colormap.


DESCRIPTION

       The XAllocColor function allocates a read-only colormap
       entry corresponding to the closest RGB value supported by
       the hardware.  XAllocColor returns the pixel value of the
       color closest to the specified RGB elements supported by
       the hardware and returns the RGB value actually used.  The
       corresponding colormap cell is read-only.  In addition,
       XAllocColor returns nonzero if it succeeded or zero if it
       failed.  Multiple clients that request the same effective
       RGB value can be assigned the same read-only entry, thus
       allowing entries to be shared.  When the last client deal-
       locates a shared cell, it is deallocated.  XAllocColor
       does not use or affect the flags in the XColor structure.

       XAllocColor can generate a BadColor error.

       The XAllocNamedColor function looks up the named color

       The XAllocColorCells function allocates read/write color
       cells.  The number of colors must be positive and the num-
       ber of planes nonnegative, or a BadValue error results.
       If ncolors and nplanes are requested, then ncolors pixels
       and nplane plane masks are returned.  No mask will have
       any bits set to 1 in common with any other mask or with
       any of the pixels.  By ORing together each pixel with zero
       or more masks, ncolors * 2nplanes distinct pixels can be
       produced.  All of these are allocated writable by the
       request.  For GrayScale or PseudoColor, each mask has
       exactly one bit set to 1.  For DirectColor, each has
       exactly three bits set to 1.  If contig is True and if all
       masks are ORed together, a single contiguous set of bits
       set to 1 will be formed for GrayScale or PseudoColor and
       three contiguous sets of bits set to 1 (one within each
       pixel subfield) for DirectColor.  The RGB values of the
       allocated entries are undefined.  XAllocColorCells returns
       nonzero if it succeeded or zero if it failed.

       XAllocColorCells can generate BadColor and BadValue
       errors.

       The specified ncolors must be positive; and nreds,
       ngreens, and nblues must be nonnegative, or a BadValue
       error results.  If ncolors colors, nreds reds, ngreens
       greens, and nblues blues are requested, ncolors pixels are
       returned; and the masks have nreds, ngreens, and nblues
       bits set to 1, respectively.  If contig is True, each mask
       will have a contiguous set of bits set to 1.  No mask will
       have any bits set to 1 in common with any other mask or
       with any of the pixels.  For DirectColor, each mask will
       lie within the corresponding pixel subfield.  By ORing
       together subsets of masks with each pixel value, ncolors *
       2(nreds+ngreens+nblues) distinct pixel values can be pro-
       duced.  All of these are allocated by the request.  How-
       ever, in the colormap, there are only ncolors * 2nreds
       independent red entries, ncolors * 2ngreens independent
       green entries, and ncolors * 2nblues independent blue
       entries.  This is true even for PseudoColor.  When the
       colormap entry of a pixel value is changed (using
       XStoreColors, XStoreColor, or XStoreNamedColor), the pixel
       is decomposed according to the masks, and the correspond-
       ing independent entries are updated.  XAllocColorPlanes
       returns nonzero if it succeeded or zero if it failed.

       XAllocColorPlanes can generate BadColor and BadValue
       errors.

       The XFreeColors function frees the cells represented by
       pixels whose values are in the pixels array.  The planes
       argument should not have any bits set to 1 in common with
       All specified pixels that are allocated by the client in
       the colormap are freed, even if one or more pixels produce
       an error.  If a specified pixel is not a valid index into
       the colormap, a BadValue error results.  If a specified
       pixel is not allocated by the client (that is, is unallo-
       cated or is only allocated by another client) or if the
       colormap was created with all entries writable (by passing
       AllocAll to XCreateColormap), a BadAccess error results.
       If more than one pixel is in error, the one that gets
       reported is arbitrary.

       XFreeColors can generate BadAccess, BadColor, and BadValue
       errors.


DIAGNOSTICS

       BadAccess A client attempted to free a color map entry
                 that it did not already allocate.

       BadAccess A client attempted to store into a read-only
                 color map entry.

       BadColor  A value for a Colormap argument does not name a
                 defined Colormap.

       BadValue  Some numeric value falls outside the range of
                 values accepted by the request.  Unless a spe-
                 cific 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.


SEE ALSO

       XCreateColormap(3X11), XQueryColor(3X11), XStoreCol-
       ors(3X11)
       Xlib - C Language X Interface



X Version 11               Release 6.4                          1