XAllocColor(3X11) MIT X11R4 XAllocColor(3X11)
Name
XAllocColor, XAllocNamedColor, XAllocColorCells, XAllocColorPlanes, 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) 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 function allocates a read-only colormap entry corresponding to the closest RGB values supported by the hardware. 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 corre-
sponding colormap cell is read-only. In addition, returns nonzero if it succeeded or zero if it failed. Multiple clients that request the
same effective RGB values 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. does not use or affect the flags in the structure.
can generate a error.
The 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.
can generate a error.
The function allocates read/write color cells. The number of colors must be positive and the number of planes nonnegative, or a 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 dis-
tinct pixels can be produced. All of these are allocated writable by the request. For or each mask has exactly one bit set to 1. For
each has exactly three bits set to 1. If contig is and if all masks are ORed together, a single contiguous set of bits set to 1 will be
formed for or and three contiguous sets of bits set to 1 (one within each pixel subfield) for The RGB values of the allocated entries are
undefined. returns nonzero if it succeeded or zero if it failed.
can generate and errors.
The specified ncolors must be positive; and nreds, ngreens, and nblues must be nonnegative, or a 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 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 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 When the colormap entry of a pixel value is changed (using or the
pixel is decomposed according to the masks, and the corresponding independent entries are updated. returns nonzero if it succeeded or zero
if it failed.
can generate and errors.
The 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 and Note that freeing an individual pixel obtained from 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 speci-
fied pixel is not a valid index into the colormap, a error results. If a specified pixel is not allocated by the client (that is, is unal-
located or is only allocated by another client), a error results. If more than one pixel is in error, the one that gets reported is arbi-
trary.
can generate and errors.
Diagnostics
A client attempted
to free a color map entry that it did not already allocate.
A client attempted
to store into a read-only color map entry.
A value for a Colormap argument does not name a defined Colormap.
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)
X Window System: The Complete Reference, Second Edition, Robert W. Scheifler and James Gettys
XAllocColor(3X11)