Colormaps and Colors

GDK Reference Manual
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struct GdkColor

struct GdkColor
{
  gulong  pixel;
  gushort red;
  gushort green;
  gushort blue;
};

The GdkColor structure is used to describe an allocated or unallocated color.

`pixel`	For allocated colors, the value used to draw this color on the screen.
`red`	The red component of the color. This is a value between 0 and 65535, with 65535 indicating full intensitiy.
`green`	the blue component of the color.
`blue`	the green component of the color..

struct GdkColormap

struct GdkColormap
{
  gint      size;
  GdkColor *colors;
};

The colormap structure contains the following public fields.

`size`	For pseudo-color colormaps, the number of colors in the colormap..
`colors`	An array containing the current values in the colormap. This can be used to map from pixel values back to RGB values. This is only meaningful for pseudo-color colormaps.

gdk_colormap_new ()

GdkColormap* gdk_colormap_new               (GdkVisual *visual,
                                             gint allocate);

Create a new colormap for the given visual.

`visual` :	a GdkVisual.
`allocate` :	if `TRUE`, the newly created colormap will be a private colormap, and all colors in it will be allocated for the applications use.
Returns :	the new GdkColormap.

gdk_colormap_ref ()

GdkColormap* gdk_colormap_ref               (GdkColormap *cmap);

Increase the reference count of a colormap.

`cmap` :	a GdkColormap.
Returns :	`cmap`

gdk_colormap_unref ()

void        gdk_colormap_unref              (GdkColormap *cmap);

Decrease the reference count of a colormap. If the resulting reference count is zero, destroys the colormap.

cmap : a GdkColormap.

gdk_colormap_get_system ()

GdkColormap* gdk_colormap_get_system        (void);

Returns the system's default colormap.

Returns :

the default colormap.

gdk_colormap_get_system_size ()

gint        gdk_colormap_get_system_size    (void);

Returns the size of the system's default colormap. (See the description of struct GdkColormap for an explanation of the size of a colormap.)

Returns :

the size of the system's default colormap.

gdk_colormap_change ()

void        gdk_colormap_change             (GdkColormap *colormap,
                                             gint ncolors);

Change the value of the first ncolors in a private colormap to match the values in the colors array in the color map. This function is obsolete and should not be used. See gdk_color_change().

`colormap` :	a GdkColormap.
`ncolors` :	the number of colors to change.

gdk_colormap_alloc_colors ()

gint        gdk_colormap_alloc_colors       (GdkColormap *colormap,
                                             GdkColor *colors,
                                             gint ncolors,
                                             gboolean writeable,
                                             gboolean best_match,
                                             gboolean *success);

Allocates colors from a colormap.

`colormap` :	a GdkColormap.
`colors` :	The color values to allocate. On return, the pixel values for allocated colors will be filled in.
`ncolors` :	The number of colors in `colors`.
`writeable` :	If `TRUE`, the colors are allocated writeable (their values can later be changed using gdk_color_change()). Writeable colors cannot be shared between applications.
`best_match` :	If `TRUE`, GDK will attempt to do matching against existing colors if the colors cannot be allocated as requested.
`success` :	An array of length `ncolors`. On return, this indicates whether the corresponding color in `colors` was sucessfully allocated or not.
Returns :	The number of colors that were not sucessfully allocated.

gdk_colormap_alloc_color ()

gboolean    gdk_colormap_alloc_color        (GdkColormap *colormap,
                                             GdkColor *color,
                                             gboolean writeable,
                                             gboolean best_match);

Allocate a single color from a colormap.

`colormap` :	a GdkColormap.
`color` :	the color to allocate. On return the `pixel` field will be filled in if allocation succeeds.
`writeable` :	If `TRUE`, the color is allocated writeable (their values can later be changed using gdk_color_change()). Writeable colors cannot be shared between applications.
`best_match` :	If `TRUE`, GDK will attempt to do matching against existing colors if the color cannot be allocated as requested.
Returns :	`TRUE` if the allocation succeeded.

gdk_colormap_free_colors ()

void        gdk_colormap_free_colors        (GdkColormap *colormap,
                                             GdkColor *colors,
                                             gint ncolors);

Free previously allocated colors.

`colormap` :	a GdkColormap.
`colors` :	the colors to free.
`ncolors` :	the number of colors in `colors`.

gdk_colormap_get_visual ()

GdkVisual*  gdk_colormap_get_visual         (GdkColormap *colormap);

Return the visual for which a given colormap was created.

`colormap` :	a GdkColormap.
Returns :	the visual of the colormap.

gdk_colors_store ()

void        gdk_colors_store                (GdkColormap *colormap,
                                             GdkColor *colors,
                                             gint ncolors);

Change the value of the first ncolors colors in a private colormap. This function is obsolete and should not be used. See gdk_color_change().

`colormap` :	a GdkColormap.
`colors` :	the new color values.
`ncolors` :	the number of colors to change.

gdk_color_copy ()

GdkColor*   gdk_color_copy                  (GdkColor *color);

Make a copy of a color structure. The result must be freed using gdk_color_free().

`color` :	a GdkColor.
Returns :	a copy of `color`.

gdk_color_free ()

void        gdk_color_free                  (GdkColor *color);

Free a color structure created with gdk_color_copy().

color : a GdkColor.

gdk_colors_alloc ()

gboolean    gdk_colors_alloc                (GdkColormap *colormap,
                                             gint contiguous,
                                             gulong *planes,
                                             gint nplanes,
                                             gulong *pixels,
                                             gint npixels);

Allocate colors from a colormap. This function is obsolete. See gdk_colormap_alloc_colors(). For full documentation of the fields, see the Xlib documentation for XAllocColorCells.

`colormap` :	a GdkColormap.
`contiguous` :	if `TRUE`, the colors should be allocated in contiguous color cells.
`planes` :	an array in which to store the plane masks.
`nplanes` :	the number of planes to allocate. (Or zero, to indicate that the color allocation should not be planar.)
`pixels` :	an array into which to store allocated pixel values.
`npixels` :	the number of pixels in each plane to allocate.
Returns :

gdk_colors_free ()

void        gdk_colors_free                 (GdkColormap *colormap,
                                             gulong *pixels,
                                             gint npixels,
                                             gulong planes);

Free colors allocated with gdk_colors_alloc(). This function is obsolete. See gdk_colormap_free_colors().

`colormap` :	a GdkColormap.
`pixels` :	the pixel values of the colors to free.
`npixels` :	the number of values in `pixels`.
`planes` :	the plane masks for all planes to free, OR'd together.

gdk_color_white ()

gboolean    gdk_color_white                 (GdkColormap *colormap,
                                             GdkColor *color);

Return the white color for a given colormap. The resulting value has already allocated been allocated.

`colormap` :	a GdkColormap.
`color` :	the location to store the color.
Returns :	`TRUE` if the allocation succeeded.

gdk_color_black ()

gboolean    gdk_color_black                 (GdkColormap *colormap,
                                             GdkColor *color);

Return the black color for a given colormap. The resulting value has already benn allocated.

`colormap` :	a GdkColormap.
`color` :	the location to store the color.
Returns :	`TRUE` if the allocation succeeded.

gdk_color_parse ()

gboolean    gdk_color_parse                 (const gchar *spec,
                                             GdkColor *color);

Parse a textual specification of a color and fill in the red, green, and blue fields of a GdkColor structure. The color is not allocated, you must call gdk_colormap_alloc_color() yourself. The text string can be in any of the forms accepted by XParseColor; these include name for a color from rgb.txt, such as DarkSlateGray, or a hex specification such as 305050.

`spec` :	the string specifying the color.
`color` :	the GdkColor to fill in
Returns :

gdk_color_alloc ()

gboolean    gdk_color_alloc                 (GdkColormap *colormap,
                                             GdkColor *color);

Allocate a single color from a colormap. This function is obsolete. See gdk_colormap_alloc_color().

`colormap` :	a GdkColormap.
`color` :	The color to allocate. On return, the `pixel` field will be filled in.
Returns :	`TRUE` if the allocation succeeded.

gdk_color_change ()

gboolean    gdk_color_change                (GdkColormap *colormap,
                                             GdkColor *color);

Change the value of a color that has already been allocated. If colormap is not a private colormap, then the color must have been allocated using gdk_colormap_alloc_colors() with the writeable set to TRUE.

`colormap` :	a GdkColormap.
`color` :	a GdkColor, with the color to change in the `pixel` field, and the new value in the remaining fields.
Returns :

gdk_color_equal ()

gint        gdk_color_equal                 (const GdkColor *colora,
                                             const GdkColor *colorb);

Compare two colors.

`colora` :	a GdkColor.
`colorb` :	another GdkColor.
Returns :	`TRUE` if the two colors compare equal

gdk_color_hash ()

guint       gdk_color_hash                  (const GdkColor *colora,
                                             const GdkColor *colorb);

A hash function suitable for using for a hash table that stores GdkColor's.

`colora` :	a GdkColor.
`colorb` :	NOT USED.
Returns :	The hash function appled to `colora`