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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,  _Xconst  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.

       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 * 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 produced.  All of these are
       allocated  by  the  request.   However,  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 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