Manual pages › X Window and screen libraries (3X)

XAllColor(3X)

allocate and free colors

From the original Amiga UNIX 2.1 manual. Some things it mentions may not be in this release.

NAME

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)

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               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 XWIN 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.

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DESCRIPTION

The XAllocColor function allocates a read-only colormap
entry corresponding to the closest RGB values 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 values actually used.  The
corresponding colormap cell is read-only.  In addition, XAl-
locColor returns nonzero if it succeeded or zero if it
failed.  Read-only colormap cells are shared among clients.
When the last client deallocates a shared cell, it is deal-
located.  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.  You should use the ISO Latin-1
encoding; uppercase and lowercase do not matter.

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 sin-
gle 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.  XAl-
locColorCells 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, respec-
     tively.  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

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     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 pix-
els whose values are in the pixels array.  The planes argu-
ment 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, XAlloc-
ColorCells, and XAllocColorPlanes).  Note that freeing an
individual pixel obtained from XAllocColorPlanes may not
actually allow it to be reused until all of its related pix-
els are also 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), 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