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XAllocStandardColormap(3)	XLIB FUNCTIONS	     XAllocStandardColormap(3)

NAME
       XAllocStandardColormap, XSetRGBColormaps, XGetRGBColormaps, XStandard-
       Colormap	- allocate, set, or read a standard colormap structure

SYNTAX
       XStandardColormap *XAllocStandardColormap(void);

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

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

ARGUMENTS
       display	 Specifies the connection to the X server.

       count	 Specifies the number of colormaps.

       count_return
		 Returns the number of colormaps.

       property	 Specifies the property	name.

       std_colormap
		 Specifies the XStandardColormap structure to be used.

       std_colormap_return
		 Returns the XStandardColormap structure.

DESCRIPTION
       The XAllocStandardColormap function allocates and returns a pointer to
       a XStandardColormap structure.  Note that all fields in the XStandard-
       Colormap	structure are initially	set to zero.  If insufficient memory
       is available, XAllocStandardColormap 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:

       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:

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

	    o	 Determine the color characteristics of	the visual.

	    o	 Allocate cells	in the colormap	(or create it with AllocAll).

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

	    o	 Fill in the descriptive members in the	XStandardColormap
		 structure.

	    o	 Attach	the property to	the root window.

	    o	 Use XSetCloseDownMode to make the resource permanent.

       5.   Ungrab the server.

       XSetRGBColormaps	can generate BadAlloc, BadAtom,	and BadWindow 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 vis-
       ual 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.  Otherwise, none of the fields	are set, and XGetRGBColormaps
       returns a zero status.  Note that it is the caller's responsibility to
       honor the ICCCM restriction that	only RGB_DEFAULT_MAP contain more than
       one definition.

       XGetRGBColormaps	can generate BadAtom and BadWindow errors.

STRUCTURES
       The XStandardColormap structure contains:

       /* Hints	*/

       #de-    ReleaseByFreeingCol-   (	(XID)
       fine    ormap		      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	maxi-
       mum 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 information.)  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 coeffi-
       cients in their appropriate ranges, one then can	compute	a correspond-
       ing 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

       Negative	multipliers can	be represented by converting the 2's comple-
       ment 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 indi-
       cates whether the cells held by this standard colormap are to be	re-
       leased by freeing the colormap ID or by calling the XKillClient func-
       tion 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.

DIAGNOSTICS
       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.

SEE ALSO
       XAllocColor(3), XCreateColormap(3), XFree(3), XSetCloseDownMode(3)
       Xlib - C	Language X Interface

X Version 11			 libX11	1.6.5	     XAllocStandardColormap(3)

NAME | SYNTAX | ARGUMENTS | DESCRIPTION | STRUCTURES | DIAGNOSTICS | SEE ALSO

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