XAllocColor(3X11) XLIB FUNCTIONS XAllocColor(3X11)
XAllocColor, XAllocNamedColor, XAllocColorCells, XAlloc-
ColorPlanes, XFreeColors - allocate and free colors
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 longplane_masks_return[],
unsigned int nplanes, unsigned long pixels_return[],
unsigned int npixels);
Status XAllocColorPlanes(Display *display, Colormap color-
map, 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
XFree86 Version 4.5.0 1
XAllocColor(3X11) XLIB FUNCTIONS XAllocColor(3X11)
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.
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, XAl-
locColor 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 allow-
ing 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
XFree86 Version 4.5.0 2
XAllocColor(3X11) XLIB FUNCTIONS XAllocColor(3X11)
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 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 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.
XFree86 Version 4.5.0 3
XAllocColor(3X11) XLIB FUNCTIONS XAllocColor(3X11)
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, XAllocColor-
Cells, and XAllocColorPlanes). Note that freeing an indivi-
dual 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 arbi-
trary.
XFreeColors can generate BadAccess, BadColor, and BadValue
errors.
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 gen-
erate this error.
XCreateColormap(3X11), XQueryColor(3X11), XStoreColors(3X11)
Xlib - C Language X Interface
XFree86 Version 4.5.0 4
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