XAllocColor(3X11) XLIB FUNCTIONS XAllocColor(3X11)
NAME
XAllocColor, XAllocNamedColor, XAllocColorCells, XAlloc-
ColorPlanes, XFreeColors - allocate and free colors
SYNTAX
Status XAllocColor(display, colormap, screeninout)
Display *display;
Colormap colormap;
XColor *screeninout;
Status XAllocNamedColor(display, colormap, colorname,
screendefreturn, exactdefreturn)
Display *display;
Colormap colormap;
char *colorname;
XColor *screendefreturn, *exactdefreturn;
Status XAllocColorCells(display, colormap, contig,
planemasksreturn, nplanes,
pixelsreturn, npixels)
Display *display;
Colormap colormap;
Bool contig;
unsigned long planemasksreturn[];
unsigned int nplanes;
unsigned long pixelsreturn[];
unsigned int npixels;
Status XAllocColorPlanes(display, colormap, contig,
pixelsreturn, ncolors, nreds, ngreens,
nblues, rmaskreturn,
gmaskreturn, bmaskreturn)
Display *display;
Colormap colormap;
Bool contig;
unsigned long pixelsreturn[];
int ncolors;
int nreds, ngreens, nblues;
unsigned long *rmaskreturn, *gmaskreturn,
*bmaskreturn;
XFreeColors(display, colormap, pixels, npixels, planes)
Display *display;
Colormap colormap;
unsigned long pixels[];
int npixels;
unsigned long planes;
ARGUMENTS
colorname
Specifies the color name string (for example,
red) whose color definition structure you want
returned.
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XAllocColor(3X11) XLIB FUNCTIONS XAllocColor(3X11)
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.
exactdefreturn
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.
pixelsreturn
Returns an array of pixel values.
planemaskreturn
Returns an array of plane masks.
planes Specifies the planes you want to free.
rmaskreturn
gmaskreturn
bmaskreturn
Return bit masks for the red, green, and blue
planes.
screendefreturn
Returns the closest RGB values provided by the
hardware.
screeninout
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
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XAllocColor(3X11) XLIB FUNCTIONS XAllocColor(3X11)
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 deal-
locates 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. XLookupColor 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 pos-
itive 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 allo-
cated 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.
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 Bad-
Value 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
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XAllocColor(3X11) XLIB FUNCTIONS XAllocColor(3X11)
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, ncolors * %2 sup (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 sup nreds% independent red entries, ncolors *
%2 sup ngreens% independent green entries, and ncolors *
%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 suc-
ceeded 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 actu-
ally 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 unallo-
cated 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.
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XAllocColor(3X11) XLIB FUNCTIONS XAllocColor(3X11)
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 spe-
cific 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), XStoreCol-
ors(3X11)
Xlib - C Language X Interface
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