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XAllocColor(3X11)
X11R6
NAME
  XAllocColor, XAllocNamedColor, XAllocColorCells, XAllocColorPlanes,
  XFreeColors - allocate and free colors

SYNOPSIS
  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.

  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 * 2**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.

  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 * 2**nreds) independent red
  entries, (ncolors * 2**ngreens) independent green entries, and (ncolors *
  2**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(3X11), XQueryColor(3X11), XStoreColors(3X11)

  Xlib -- C Language X Interface

Index for Section 3X11

Alphabetical listing for X

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