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NAME

       XAllocColor, XAllocNamedColor, XAllocColorCells, XAllocColorPlanes, XFreeColors - allocate
       and free colors

SYNTAX

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

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

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

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

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

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

       colormap  Specifies the colormap.

       contig    Specifies a Boolean value that indicates whether the planes must be contiguous.

       display   Specifies the connection to the X server.

       exact_def_return
                 Returns the exact RGB values.

       ncolors   Specifies the number of pixel values that are to be returned in the
                 pixels_return array.

       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 deallocates 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 with respect to the screen that is
       associated with the specified colormap.  It returns both the exact database definition and
       the closest color supported by the screen.  The allocated color cell is read-only.  The
       pixel value is returned in screen_def_return.  If the color name is not in the Host
       Portable Character Encoding, the result is implementation-dependent.  Use of uppercase or
       lowercase does not matter.  If screen_def_return and exact_def_return point to the same
       structure, the pixel field will be set correctly, but the color values are undefined.
       XAllocNamedColor returns nonzero if a cell is allocated; otherwise, it returns zero.

       XAllocNamedColor can generate a BadColor error.

       delim %% The XAllocColorCells function allocates read/write color cells.  The number of
       colors must be positive and the number 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 * %2 sup
       nplanes% 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.

       delim %% 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 sup (nreds+ngreens+nblues)% distinct pixel values can be produced.  All of
       these are allocated by the request.  However, in the colormap, there are only ncolors * %2
       sup nreds% independent red entries, ncolors * %2 sup ngreens% independent green entries,
       and ncolors * %2 sup nblues% 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 corresponding
       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 any of
       the pixels.  The set of all pixels is produced by ORing together subsets of the planes
       argument with the pixels.  The request frees all of these pixels that were allocated by
       the client (using XAllocColor, XAllocNamedColor, XAllocColorCells, and XAllocColorPlanes).
       Note that freeing an individual pixel obtained from XAllocColorPlanes may not actually
       allow it to be reused until all of its related pixels are also freed.  Similarly, a read-
       only entry is not actually freed until it has been freed by all clients, and if a client
       allocates the same read-only entry multiple times, it must free the entry that many times
       before the entry is actually freed.

       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 unallocated 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 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.

SEE ALSO

       XCreateColormap(3), XQueryColor(3), XStoreColors(3)
       Xlib - C Language X Interface