GDK Reference Manual

　　buf : The pixel data, represented as 8-bit color indices.

　　rowstride : The number of bytes from the start of one row in buf to the start of the next.

　　cmap : The GdkRgbCmap used to assign colors to the color indices.

gdk_draw_gray_image ()
voidgdk_draw_gray_image (GdkDrawable *drawable,
GdkGC *gc,gint x,gint y,gint width,gint height,
GdkRgbDither dith,guchar *buf,gint rowstride); 

　　Draws a grayscale image in the drawable.

　　drawable : The GdkDrawable to draw in (usually a GdkWindow).

　　gc : The graphics context.

　　x : The x coordinate of the top-left corner in the drawable.

　　y : The y coordinate of the top-left corner in the drawable.

　　width : The width of the rectangle to be drawn.

　　height : The height of the rectangle to be drawn.

　　dith : A GdkRgbDither value, selecting the desired dither mode.

　　buf : The pixel data, represented as 8-bit gray values.

　　rowstride : The number of bytes from the start of one row in buf to the start of the next.

gdk_draw_rgb_32_image ()
voidgdk_draw_rgb_32_image (GdkDrawable *drawable,
GdkGC *gc,gint x,gint y,gint width,gint height,
GdkRgbDither dith,guchar *buf,gint rowstride); 

　　Draws a padded RGB image in the drawable. The image is stored as one pixel per 32-bit word. It is laid out as a red byte, a green byte, a blue byte, and a padding byte.

　　It's unlikely that this function will give significant performance gains in practice. In my experience, the performance gain from having pixels aligned to 32-bit boundaries is cancelled out by the increased memory bandwidth.

　　drawable : The GdkDrawable to draw in (usually a GdkWindow).

　　gc : The graphics context.

　　x : The x coordinate of the top-left corner in the drawable.

　　y : The y coordinate of the top-left corner in the drawable.

　　width : The width of the rectangle to be drawn.

　　height : The height of the rectangle to be drawn.

　　dith : A GdkRgbDither value, selecting the desired dither mode.

　　buf : The pixel data, represented as padded 32-bit data.

　　rowstride : The number of bytes from the start of one row in buf to the start of the next.

　　enum GdkRgbDither

typedef enum
{
GDK_RGB_DITHER_NONE,
GDK_RGB_DITHER_NORMAL,
GDK_RGB_DITHER_MAX
} GdkRgbDither; 

　　Selects whether or not GdkRgb applies dithering to the image on display. There are three values:

　　GDK_RGB_DITHER_NONE: Never use dithering.

　　GDK_RGB_DITHER_NORMAL: Use dithering in 8 bits per pixel (and below) only.

　　GDK_RGB_DITHER_MAX: Use dithering in 16 bits per pixel and below.

　　Since GdkRgb currently only handles images with 8 bits per component, dithering on 24 bit per pixel displays is a moot point.

gdk_rgb_cmap_new ()
GdkRgbCmap* gdk_rgb_cmap_new(guint32 *colors,gint n_colors); 

　　Creates a new GdkRgbCmap structure. The cmap maps color indexes to RGB colors. If n_colors is less than 256, then images containing color values greater than or equal to n_colors will produce undefined results, including possibly segfaults.

　　colors : The colors, represented as 0xRRGGBB integer values.

　　n_colors : The number of colors in the cmap.

　　Returns : The newly created GdkRgbCmap

gdk_rgb_cmap_free ()
voidgdk_rgb_cmap_free (GdkRgbCmap *cmap); 

　　Frees the memory associated with a GdkRgbCmap created by gdk_rgb_cmap_new().

　　cmap : The GdkRgbCmap to free.

　　struct GdkRgbCmap

struct GdkRgbCmap {
guint32 colors[256];
guchar lut[256]; /* for 8-bit modes */
}; 

　　A private data structure which maps color indices to actual RGB colors. This is used only for gdk_draw_indexed_image().

gdk_rgb_gc_set_foreground ()
voidgdk_rgb_gc_set_foreground (GdkGC *gc,guint32 rgb); 

　　Sets the foreground color in gc to the specified color (or the closest approximation, in the case of limited visuals).

　　gc : The GdkGC to modify.

　　rgb : The color, represented as a 0xRRGGBB integer value.