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XAllocColor(3)                  XLIB FUNCTIONS                  XAllocColor(3)



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 con-
              tig, unsigned longplane_masks_return[], unsigned int nplanes,
              unsigned long pixels_return[], unsigned int npixels);

       Status XAllocColorPlanes(Display *display, Colormap colormap, Bool con-
              tig, 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 pix-
              els[], 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 col-
                 ormap.

DESCRIPTION
       The XAllocColor function allocates a read-only colormap entry corre-
       sponding to the closest RGB value supported by the hardware.  XAlloc-
       Color 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, XAl-
       locColor returns nonzero if it succeeded or zero if it failed.  Multi-
       ple 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 Pseu-
       doColor, 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 ncol-
       ors 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 sub-
       field.  By ORing together subsets of masks with each pixel value, ncol-
       ors * %2 sup (nreds+ngreens+nblues)% distinct pixel values can be pro-
       duced.  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 ncol-
       ors * %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 allo-
       cated by the client (using XAllocColor, XAllocNamedColor, XAllocColor-
       Cells, 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 unal-
       located or is only allocated by another client) or if the colormap was
       created with all entries writable (by passing AllocAll to XCreateCol-
       ormap), 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 Col-
                 ormap.

       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(3X11), XQueryColor(3X11), XStoreColors(3X11)
       Xlib - C Language X Interface



X Version 11                     libX11 1.1.5                   XAllocColor(3)