1XAllocColor(3)                  XLIB FUNCTIONS                  XAllocColor(3)
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NAME

6       XAllocColor, XAllocNamedColor, XAllocColorCells, XAllocColorPlanes,
7       XFreeColors - allocate and free colors
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SYNTAX

10       Status XAllocColor(Display *display, Colormap colormap, XColor
11              *screen_in_out);
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13       Status XAllocNamedColor(Display *display, Colormap colormap, char
14              *color_name, XColor *screen_def_return, XColor
15              *exact_def_return);
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17       Status XAllocColorCells(Display *display, Colormap colormap, Bool con‐
18              tig, unsigned long plane_masks_return[], unsigned int nplanes,
19              unsigned long pixels_return[], unsigned int npixels);
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21       Status XAllocColorPlanes(Display *display, Colormap colormap, Bool con‐
22              tig, unsigned long pixels_return[], int ncolors, int nreds, int
23              ngreens, int nblues, unsigned long *rmask_return, unsigned long
24              *gmask_return, unsigned long *bmask_return);
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26       int XFreeColors(Display *display, Colormap colormap, unsigned long pix‐
27              els[], int npixels, unsigned long planes);
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29       color_name
30                 Specifies the color name string (for example, red) whose
31                 color definition structure you want returned.
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33       colormap  Specifies the colormap.
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35       contig    Specifies a Boolean value that indicates whether the planes
36                 must be contiguous.
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38       display   Specifies the connection to the X server.
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40       exact_def_return
41                 Returns the exact RGB values.
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43       ncolors   Specifies the number of pixel values that are to be returned
44                 in the pixels_return array.
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46       npixels   Specifies the number of pixels.
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48       nplanes   Specifies the number of plane masks that are to be returned
49                 in the plane masks array.
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51       nreds
52       ngreens
53       nblues
54                 Specify the number of red, green, and blue planes.  The value
55                 you pass must be nonnegative.
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57       pixels    Specifies an array of pixel values.
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59       pixels_return
60                 Returns an array of pixel values.
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62       plane_mask_return
63                 Returns an array of plane masks.
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65       planes    Specifies the planes you want to free.
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67       rmask_return
68       gmask_return
69       bmask_return
70                 Return bit masks for the red, green, and blue planes.
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72       screen_def_return
73                 Returns the closest RGB values provided by the hardware.
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75       screen_in_out
76                 Specifies and returns the values actually used in the col‐
77                 ormap.
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DESCRIPTION

80       The XAllocColor function allocates a read-only colormap entry corre‐
81       sponding to the closest RGB value supported by the hardware.  XAlloc‐
82       Color returns the pixel value of the color closest to the specified RGB
83       elements supported by the hardware and returns the RGB value actually
84       used.  The corresponding colormap cell is read-only.  In addition, XAl‐
85       locColor returns nonzero if it succeeded or zero if it failed.  Multi‐
86       ple clients that request the same effective RGB value can be assigned
87       the same read-only entry, thus allowing entries to be shared.  When the
88       last client deallocates a shared cell, it is deallocated.  XAllocColor
89       does not use or affect the flags in the XColor structure.
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91       XAllocColor can generate a BadColor error.
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93       The XAllocNamedColor function looks up the named color with respect to
94       the screen that is associated with the specified colormap.  It returns
95       both the exact database definition and the closest color supported by
96       the screen.  The allocated color cell is read-only.  The pixel value is
97       returned in screen_def_return.  If the color name is not in the Host
98       Portable Character Encoding, the result is implementation-dependent.
99       Use of uppercase or lowercase does not matter.  If screen_def_return
100       and exact_def_return point to the same structure, the pixel field will
101       be set correctly, but the color values are undefined.  XAllocNamedColor
102       returns nonzero if a cell is allocated; otherwise, it returns zero.
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104       XAllocNamedColor can generate a BadColor error.
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106       The XAllocColorCells function allocates read/write color cells.  The
107       number of colors must be positive and the number of planes nonnegative,
108       or a BadValue error results.  If ncolors and nplanes are requested,
109       then ncolors pixels and nplane plane masks are returned.  No mask will
110       have any bits set to 1 in common with any other mask or with any of the
111       pixels.  By ORing together each pixel with zero or more masks, ncolors
112       * 2nplanes distinct pixels can be produced.  All of these are allocated
113       writable by the request.  For GrayScale or PseudoColor, each mask has
114       exactly one bit set to 1.  For DirectColor, each has exactly three bits
115       set to 1.  If contig is True and if all masks are ORed together, a sin‐
116       gle contiguous set of bits set to 1 will be formed for GrayScale or
117       PseudoColor and three contiguous sets of bits set to 1 (one within each
118       pixel subfield) for DirectColor.  The RGB values of the allocated
119       entries are undefined.  XAllocColorCells returns nonzero if it suc‐
120       ceeded or zero if it failed.
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122       XAllocColorCells can generate BadColor and BadValue errors.
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124       The specified ncolors must be positive; and nreds, ngreens, and nblues
125       must be nonnegative, or a BadValue error results.  If ncolors colors,
126       nreds reds, ngreens greens, and nblues blues are requested, ncolors
127       pixels are returned; and the masks have nreds, ngreens, and nblues bits
128       set to 1, respectively.  If contig is True, each mask will have a con‐
129       tiguous set of bits set to 1.  No mask will have any bits set to 1 in
130       common with any other mask or with any of the pixels.  For DirectColor,
131       each mask will lie within the corresponding pixel subfield.  By ORing
132       together subsets of masks with each pixel value, ncolors *
133       2(nreds+ngreens+nblues) distinct pixel values can be produced.  All of
134       these are allocated by the request.  However, in the colormap, there
135       are only ncolors * 2nreds independent red entries, ncolors * 2ngreens
136       independent green entries, and ncolors * 2nblues independent blue
137       entries.  This is true even for PseudoColor.  When the colormap entry
138       of a pixel value is changed (using XStoreColors, XStoreColor, or
139       XStoreNamedColor), the pixel is decomposed according to the masks, and
140       the corresponding independent entries are updated.  XAllocColorPlanes
141       returns nonzero if it succeeded or zero if it failed.
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143       XAllocColorPlanes can generate BadColor and BadValue errors.
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145       The XFreeColors function frees the cells represented by pixels whose
146       values are in the pixels array.  The planes argument should not have
147       any bits set to 1 in common with any of the pixels.  The set of all
148       pixels is produced by ORing together subsets of the planes argument
149       with the pixels.  The request frees all of these pixels that were allo‐
150       cated by the client (using XAllocColor, XAllocNamedColor, XAllocColor‐
151       Cells, and XAllocColorPlanes).  Note that freeing an individual pixel
152       obtained from XAllocColorPlanes may not actually allow it to be reused
153       until all of its related pixels are also freed.  Similarly, a read-only
154       entry is not actually freed until it has been freed by all clients, and
155       if a client allocates the same read-only entry multiple times, it must
156       free the entry that many times before the entry is actually freed.
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158       All specified pixels that are allocated by the client in the colormap
159       are freed, even if one or more pixels produce an error.  If a specified
160       pixel is not a valid index into the colormap, a BadValue error results.
161       If a specified pixel is not allocated by the client (that is, is unal‐
162       located or is only allocated by another client) or if the colormap was
163       created with all entries writable (by passing AllocAll to XCreateCol‐
164       ormap), a BadAccess error results.  If more than one pixel is in error,
165       the one that gets reported is arbitrary.
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167       XFreeColors can generate BadAccess, BadColor, and BadValue errors.
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DIAGNOSTICS

170       BadAccess A client attempted to free a color map entry that it did not
171                 already allocate.
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173       BadAccess A client attempted to store into a read-only color map entry.
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175       BadColor  A value for a Colormap argument does not name a defined Col‐
176                 ormap.
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178       BadValue  Some numeric value falls outside the range of values accepted
179                 by the request.  Unless a specific range is specified for an
180                 argument, the full range defined by the argument's type is
181                 accepted.  Any argument defined as a set of alternatives can
182                 generate this error.
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SEE ALSO

185       XCreateColormap(3), XQueryColor(3), XStoreColors(3)
186       Xlib - C Language X Interface
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190X Version 11                     libX11 1.6.7                   XAllocColor(3)
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