Colormaps and Colors

struct GdkColor

struct GdkColor
{
  guint32 pixel;
  guint16 red;
  guint16 green;
  guint16 blue;
};

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

struct GdkColormap

struct GdkColormap
{
  GObject parent_instance;

  /*< public >*/
  gint      size;
  GdkColor *colors;

  /*< private >*/
  GdkVisual *visual;
  
  gpointer windowing_data;
};

The colormap structure contains the following public fields.

gdk_colormap_new ()

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

Creates a new colormap for the given visual.

gdk_colormap_ref ()

GdkColormap* gdk_colormap_ref               (GdkColormap *cmap);

Deprecated function; use g_object_ref() instead.

gdk_colormap_unref ()

void        gdk_colormap_unref              (GdkColormap *cmap);

Deprecated function; use g_object_ref() instead.

gdk_colormap_get_system ()

GdkColormap* gdk_colormap_get_system        (void);

Gets the system's default colormap for the default screen. (See gdk_colormap_get_system_for_screen())

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.)

gdk_colormap_change ()

void        gdk_colormap_change             (GdkColormap *colormap,
                                             gint ncolors);

Changes 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 This function is obsolete and should not be used.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().

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.

gdk_colormap_alloc_color ()

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

Allocates a single color from a colormap.

gdk_colormap_free_colors ()

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

Frees previously allocated colors.

gdk_colormap_query_color ()

void        gdk_colormap_query_color        (GdkColormap *colormap,
                                             gulong pixel,
                                             GdkColor *result);

Locates the RGB color in colormap corresponding to the given hardware pixel pixel. pixel must be a valid pixel in the colormap; it's a programmer error to call this function with a pixel which is not in the colormap. Hardware pixels are normally obtained from gdk_colormap_alloc_colors(), or from a GdkImage. (A GdkImage contains image data in hardware format, a GdkPixbuf contains image data in a canonical 24-bit RGB format.)

This function is rarely useful, it's used for example to implement the eyedropper feature in GtkColorSelection.

gdk_colormap_get_visual ()

GdkVisual*  gdk_colormap_get_visual         (GdkColormap *colormap);

Returns the visual for which a given colormap was created.

gdk_colors_store ()

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

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

gdk_color_copy ()

GdkColor*   gdk_color_copy                  (const GdkColor *color);

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

gdk_color_free ()

void        gdk_color_free                  (GdkColor *color);

Frees a color structure created with gdk_color_copy().

gdk_colors_alloc ()

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

Allocates 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().

gdk_colors_free ()

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

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

gdk_color_white ()

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

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

gdk_color_black ()

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

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

gdk_color_parse ()

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

Parses 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.

gdk_color_alloc ()

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

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

gdk_color_change ()

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

Changes 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.

gdk_color_equal ()

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

Compares two colors.

gdk_color_hash ()

guint       gdk_color_hash                  (const GdkColor *colora);

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