MirBSD manpage: XAllocStandardColormap(3), XGetRGBColormaps(3), XSetRGBColormaps(3), XStandardColormap(3)

XAllocStandardColormap(3X1XLIB FUNCTIXAllocStandardColormap(3X11)


     XAllocStandardColormap, XSetRGBColormaps, XGetRGBColormaps,
     XStandardColormap - allocate, set, or read a standard color-
     map structure


     XStandardColormap *XAllocStandardColormap(void);

     void XSetRGBColormaps(Display *display, Window w, XStandard-
          Colormap *std_colormap, int count, Atom property);

     Status XGetRGBColormaps(Display *display, Window w, XStan-
          dardColormap **std_colormap_return, int *count_return,
          Atom property);


     display   Specifies the connection to the X server.

     count     Specifies the number of colormaps.

               Returns the number of colormaps.

     property  Specifies the property name.

               Specifies the XStandardColormap structure to be

               Returns the XStandardColormap structure.


     The XAllocStandardColormap function allocates and returns a
     pointer to a XStandardColormap structure. Note that all
     fields in the XStandardColormap structure are initially set
     to zero. If insufficient memory is available, XAllocStan-
     dardColormap returns NULL. To free the memory allocated to
     this structure, use XFree.

     The XSetRGBColormaps function replaces the RGB colormap
     definition in the specified property on the named window. If
     the property does not already exist, XSetRGBColormaps sets
     the RGB colormap definition in the specified property on the
     named window. The property is stored with a type of
     RGB_COLOR_MAP and a format of 32. Note that it is the
     caller's responsibility to honor the ICCCM restriction that
     only RGB_DEFAULT_MAP contain more than one definition.

     The XSetRGBColormaps function usually is only used by window
     or session managers. To create a standard colormap, follow
     this procedure:

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XAllocStandardColormap(3X1XLIB FUNCTIXAllocStandardColormap(3X11)

     1.   Open a new connection to the same server.

     2.   Grab the server.

     3.   See if the property is on the property list of the root
          window for the screen.

     4.   If the desired property is not present:

          +    Create a colormap (unless you are using the
               default colormap of the screen).

          +    Determine the color characteristics of the visual.

          +    Allocate cells in the colormap (or create it with

          +    Call XStoreColors to store appropriate color
               values in the colormap.

          +    Fill in the descriptive members in the XStandard-
               Colormap structure.

          +    Attach the property to the root window.

          +    Use XSetCloseDownMode to make the resource per-

     5.   Ungrab the server.

     XSetRGBColormaps can generate BadAlloc, BadAtom, and BadWin-
     dow errors.

     The XGetRGBColormaps function returns the RGB colormap
     definitions stored in the specified property on the named
     window. If the property exists, is of type RGB_COLOR_MAP, is
     of format 32, and is long enough to contain a colormap
     definition, XGetRGBColormaps allocates and fills in space
     for the returned colormaps and returns a nonzero status. If
     the visualid is not present, XGetRGBColormaps assumes the
     default visual for the screen on which the window is
     located; if the killid is not present, None is assumed,
     which indicates that the resources cannot be released. Oth-
     erwise, none of the fields are set, and XGetRGBColormaps
     returns a zero status. Note that it is the caller's respon-
     sibility to honor the ICCCM restriction that only
     RGB_DEFAULT_MAP contain more than one definition.

     XGetRGBColormaps can generate BadAtom and BadWindow errors.


     The XStandardColormap structure contains:

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XAllocStandardColormap(3X1XLIB FUNCTIXAllocStandardColormap(3X11)

     /* Hints */
     #define   Release-               ( (XID)
               ByFreeingColormap      1L);
     /* Values */
     typedef struct {
          Colormap colormap;
          unsigned long red_max;
          unsigned long red_mult;
          unsigned long green_max;
          unsigned long green_mult;
          unsigned long blue_max;
          unsigned long blue_mult;
          unsigned long base_pixel;
          VisualID visualid;
          XID killid;
     } XStandardColormap;

     The colormap member is the colormap created by the
     XCreateColormap function. The red_max, green_max, and
     blue_max members give the maximum red, green, and blue
     values, respectively. Each color coefficient ranges from
     zero to its max, inclusive. For example, a common colormap
     allocation is 3/3/2 (3 planes for red, 3 planes for green,
     and 2 planes for blue). This colormap would have red_max =
     7, green_max = 7, and blue_max = 3. An alternate allocation
     that uses only 216 colors is red_max = 5, green_max = 5, and
     blue_max = 5.

     The red_mult, green_mult, and blue_mult members give the
     scale factors used to compose a full pixel value. (See the
     discussion of the base_pixel members for further informa-
     tion.); For a 3/3/2 allocation, red_mult might be 32,
     green_mult might be 4, and blue_mult might be 1. For a 6-
     colors-each allocation, red_mult might be 36, green_mult
     might be 6, and blue_mult might be 1.

     The base_pixel member gives the base pixel value used to
     compose a full pixel value. Usually, the base_pixel is
     obtained from a call to the XAllocColorPlanes function.
     Given integer red, green, and blue coefficients in their
     appropriate ranges, one then can compute a corresponding
     pixel value by using the following expression:

     (r * red_mult + g * green_mult + b * blue_mult + base_pixel) & 0xFFFFFFFF

     For GrayScale colormaps, only the colormap, red_max,
     red_mult, and base_pixel members are defined. The other
     members are ignored. To compute a GrayScale pixel value, use
     the following expression:

     (gray * red_mult + base_pixel) & 0xFFFFFFFF

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XAllocStandardColormap(3X1XLIB FUNCTIXAllocStandardColormap(3X11)

     Negative multipliers can be represented by converting the
     2's complement representation of the multiplier into an
     unsigned long and storing the result in the appropriate
     _mult field. The step of masking by 0xFFFFFFFF effectively
     converts the resulting positive multiplier into a negative
     one. The masking step will take place automatically on many
     machine architectures, depending on the size of the integer
     type used to do the computation,

     The visualid member gives the ID number of the visual from
     which the colormap was created. The killid member gives a
     resource ID that indicates whether the cells held by this
     standard colormap are to be released by freeing the colormap
     ID or by calling the XKillClient function on the indicated
     resource. (Note that this method is necessary for allocating
     out of an existing colormap.);

     The properties containing the XStandardColormap information
     have the type RGB_COLOR_MAP.


     BadAlloc  The server failed to allocate the requested
               resource or server memory.

     BadAtom   A value for an Atom argument does not name a
               defined Atom.

     BadWindow A value for a Window argument does not name a
               defined Window.


     XAllocColor(3X11), XCreateColormap(3X11), XFree(3X11),
     Xlib - C Language X Interface

XFree86                   Version 4.5.0                         4

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