XlibRGB

XlibRGB — Rendering RGB buffers to X drawables.

Synopsis

#include <gdk-pixbuf/gdk-pixbuf.h>


            XlibRgbCmap;
enum        XlibRgbDither;
void        xlib_rgb_init                   (Display *display,
                                             Screen *screen);
void        xlib_rgb_init_with_depth        (Display *display,
                                             Screen *screen,
                                             int prefDepth);
void        xlib_rgb_gc_set_foreground      (GC gc,
                                             guint32 rgb);
void        xlib_rgb_gc_set_background      (GC gc,
                                             guint32 rgb);
void        xlib_draw_rgb_image             (Drawable drawable,
                                             GC gc,
                                             int x,
                                             int y,
                                             int width,
                                             int height,
                                             XlibRgbDither dith,
                                             unsigned char *rgb_buf,
                                             int rowstride);
void        xlib_draw_rgb_image_dithalign   (Drawable drawable,
                                             GC gc,
                                             int x,
                                             int y,
                                             int width,
                                             int height,
                                             XlibRgbDither dith,
                                             unsigned char *rgb_buf,
                                             int rowstride,
                                             int xdith,
                                             int ydith);
void        xlib_draw_rgb_32_image          (Drawable drawable,
                                             GC gc,
                                             int x,
                                             int y,
                                             int width,
                                             int height,
                                             XlibRgbDither dith,
                                             unsigned char *buf,
                                             int rowstride);
void        xlib_draw_gray_image            (Drawable drawable,
                                             GC gc,
                                             int x,
                                             int y,
                                             int width,
                                             int height,
                                             XlibRgbDither dith,
                                             unsigned char *buf,
                                             int rowstride);
XlibRgbCmap* xlib_rgb_cmap_new              (guint32 *colors,
                                             int n_colors);
void        xlib_rgb_cmap_free              (XlibRgbCmap *cmap);
void        xlib_draw_indexed_image         (Drawable drawable,
                                             GC gc,
                                             int x,
                                             int y,
                                             int width,
                                             int height,
                                             XlibRgbDither dith,
                                             unsigned char *buf,
                                             int rowstride,
                                             XlibRgbCmap *cmap);
Bool        xlib_rgb_ditherable             (void);
void        xlib_rgb_set_verbose            (Bool verbose);
void        xlib_rgb_set_install            (Bool install);
void        xlib_rgb_set_min_colors         (int min_colors);
Colormap    xlib_rgb_get_cmap               (void);
Visual*     xlib_rgb_get_visual             (void);
XVisualInfo* xlib_rgb_get_visual_info       (void);
int         xlib_rgb_get_depth              (void);
Display*    xlib_rgb_get_display            (void);
Screen*     xlib_rgb_get_screen             (void);

Description

The XlibRGB set of functions is a port of the GdkRGB library to use plain Xlib and X drawables. You can use these functions to render RGB buffers into drawables very quickly with high-quality dithering.

Details

XlibRgbCmap

typedef struct {
  unsigned int colors[256];
  unsigned char lut[256]; /* for 8-bit modes */
} XlibRgbCmap;

FIXME: Describe this.

unsigned int colors[256];FIXME.
unsigned char lut[256];FIXME.

enum XlibRgbDither

typedef enum
{
  XLIB_RGB_DITHER_NONE,
  XLIB_RGB_DITHER_NORMAL,
  XLIB_RGB_DITHER_MAX
} XlibRgbDither;

These values are used to specify which dithering method should be used. XLIB_RGB_DITHER_NONE will use no dithering and simply map the colors in an RGB buffer to the closest colors that the display can provide. XLIB_RGB_DITHER_NORMAL will provide dithering only on pseudocolor displays. XLIB_RGB_DITHER_MAX will provide dithering on pseudocolor and 16-bit truecolor or “high color” displays.

XLIB_RGB_DITHER_NONESpecifies no dithering.
XLIB_RGB_DITHER_NORMALSpecifies dithering only on pseudocolor displays.
XLIB_RGB_DITHER_MAXSpecifies dithering on high color displays.

xlib_rgb_init ()

void        xlib_rgb_init                   (Display *display,
                                             Screen *screen);

Initializes the XlibRGB machinery with the default depth. If you use this function XlibRGB will automatically pick the best visual available on your display. This function or xlib_rgb_init_with_depth() must be called before using any of the other functions in XlibRGB.

display : X Display to use.
screen : Screen to use.

xlib_rgb_init_with_depth ()

void        xlib_rgb_init_with_depth        (Display *display,
                                             Screen *screen,
                                             int prefDepth);

Initializes the XlibRGB machinery with a particular depth you specify, instead of automatically picking the best depth in the display. This function or xlib_rgb_init() must be called before using any of the other functions in XlibRGB.

display : X display to use.
screen : Screen to use.
prefDepth : Visual depth to use for color substitution tables. This must be one of the supported visual depths in the specified display.

xlib_rgb_gc_set_foreground ()

void        xlib_rgb_gc_set_foreground      (GC gc,
                                             guint32 rgb);

This is a convenience function to set the foreground of a GC from an RGB triplet. It calls xlib_rgb_xpixel_from_rgb() internally and uses the returned pixel value to set the GC's foreground.

gc : A graphic context.
rgb : 32-bit representation of an RGB value, specified as 0x00RRGGBB.

xlib_rgb_gc_set_background ()

void        xlib_rgb_gc_set_background      (GC gc,
                                             guint32 rgb);

This is a convenience function to set the background of a GC from an RGB triplet. It calls xlib_rgb_xpixel_from_rgb() internally and uses the returned pixel value to set the GC's background.

gc : A graphic context.
rgb : 32-bit representation of an RGB value, specified as 0x00RRGGBB.

xlib_draw_rgb_image ()

void        xlib_draw_rgb_image             (Drawable drawable,
                                             GC gc,
                                             int x,
                                             int y,
                                             int width,
                                             int height,
                                             XlibRgbDither dith,
                                             unsigned char *rgb_buf,
                                             int rowstride);

Renders an RGB buffer to a drawable. Pixels are specified as RGB triplets with 8 bits per channel. An image will thus look like an RGBRGBRGBRGB sequence of 8-bit values. This function does not let you specify dither offsets; applications that need to render partial regions of a buffer to build the final image should use xlib_draw_rgb_image_dithalign() instead.

drawable : Destination drawable.
gc : A graphic context.
x : Leftmost coordinate of the destination rectangle.
y : Upper coordinate of the destination rectangle.
width : Width of the destination rectangle, in pixels.
height : Height of the destination rectangle, in pixels.
dith : Dithering method to use.
rgb_buf : Pointer to the pixel in the RGB buffer that corresponds to the upper-left corner of the rectangular region to render.
rowstride : Offset between pixel rows in the RGB buffer, in bytes.

xlib_draw_rgb_image_dithalign ()

void        xlib_draw_rgb_image_dithalign   (Drawable drawable,
                                             GC gc,
                                             int x,
                                             int y,
                                             int width,
                                             int height,
                                             XlibRgbDither dith,
                                             unsigned char *rgb_buf,
                                             int rowstride,
                                             int xdith,
                                             int ydith);

Renders an RGB buffer to a drawable. Pixels are specified as RGB triplets with 8 bits per channel. An image will thus look like an RGBRGBRGBRGB sequence of 8-bit values. This function lets you specify a pair of dither offsets. It should be used when you need to render regions of an RGB buffer separately to form the final image; the dither offsets let you align the dither mask appropriately.

drawable : Destination drawable.
gc : A graphic context.
x : Leftmost coordinate of the destination rectangle.
y : Upper coordinate of the destination rectangle.
width : Width of the destination rectangle, in pixels.
height : Height of the destination rectangle, in pixels.
dith : Dithering method to use.
rgb_buf : Pointer to the pixel in the RGB buffer that corresponds to the upper-left corner of the rectangular region to render.
rowstride : Offset between pixel rows in the RGB buffer, in bytes.
xdith : X offset for the dither mask.
ydith : Y offset for the dither mask.

xlib_draw_rgb_32_image ()

void        xlib_draw_rgb_32_image          (Drawable drawable,
                                             GC gc,
                                             int x,
                                             int y,
                                             int width,
                                             int height,
                                             XlibRgbDither dith,
                                             unsigned char *buf,
                                             int rowstride);

This function is analogous to xlib_draw_rgb_image(), but it lets you use 32-bit RGB buffers with pixels specified as 0xRRGGBB00. The least-significant 8 bits are actually discarded. This function can lead to faster results than xlib_draw_rgb_image() since the pixels are aligned on 32-bit boundaries.

drawable : Destination drawable.
gc : A graphic context.
x : Leftmost coordinate of the destination rectangle.
y : Upper coordinate of the destination rectangle.
width : Width of the destination rectangle, in pixels.
height : Height of the destination rectangle, in pixels.
dith : Dithering method to use.
buf : Pointer to the pixel in the RGB buffer that corresponds to the upper-left corner of the rectangular region to render.
rowstride : Offset between pixel rows in the RGB buffer, in bytes.

xlib_draw_gray_image ()

void        xlib_draw_gray_image            (Drawable drawable,
                                             GC gc,
                                             int x,
                                             int y,
                                             int width,
                                             int height,
                                             XlibRgbDither dith,
                                             unsigned char *buf,
                                             int rowstride);

Renders a grayscale buffer to a drawable. Pixels are specified as 8-bit intensity values. An image will thus look as a GGGGGG sequence of 8-bit values.

drawable : Destination drawable.
gc : A graphic context.
x : Leftmost coordinate of the destination rectangle.
y : Upper coordinate of the destination rectangle.
width : Width of the destination rectangle, in pixels.
height : Height of thd destination rectangle, in pixels.
dith : Dithering method to use.
buf : Pointer to the pixel in the grayscale buffer that corresponds to the upper-left corner of the rectangular region to render.
rowstride : Offset between pixel rows in the grayscale buffer, in pixels.

xlib_rgb_cmap_new ()

XlibRgbCmap* xlib_rgb_cmap_new              (guint32 *colors,
                                             int n_colors);

FIXME

colors : FIXME
n_colors : FIXME
Returns : FIXME

xlib_rgb_cmap_free ()

void        xlib_rgb_cmap_free              (XlibRgbCmap *cmap);

Frees an XlibRGB colormap.

cmap : An XlibRGB colormap.

xlib_draw_indexed_image ()

void        xlib_draw_indexed_image         (Drawable drawable,
                                             GC gc,
                                             int x,
                                             int y,
                                             int width,
                                             int height,
                                             XlibRgbDither dith,
                                             unsigned char *buf,
                                             int rowstride,
                                             XlibRgbCmap *cmap);

FIXME

drawable : FIXME
gc : FIXME
x : FIXME
y : FIXME
width : FIXME
height : FIXME
dith : FIXME
buf : FIXME
rowstride : FIXME
cmap : FIXME

xlib_rgb_ditherable ()

Bool        xlib_rgb_ditherable             (void);

Queries whether XlibRGB supports dithering for its chosen visual.

Returns : TRUE if dithering can be performed for the visual that XlibRGB is using, FALSE otherwise.

xlib_rgb_set_verbose ()

void        xlib_rgb_set_verbose            (Bool verbose);

Enables/disables debug spew.

verbose : True to be verbose

xlib_rgb_set_install ()

void        xlib_rgb_set_install            (Bool install);

Sets whether we install an RGB colormap.

install : True to install a colormap

xlib_rgb_set_min_colors ()

void        xlib_rgb_set_min_colors         (int min_colors);

Sets the minimum number of colors in the color cube.

min_colors : minimum colors to use

xlib_rgb_get_cmap ()

Colormap    xlib_rgb_get_cmap               (void);

Queries the X colormap that XlibRGB is using.

Returns : An X colormap.

xlib_rgb_get_visual ()

Visual*     xlib_rgb_get_visual             (void);

Queries the visual that XlibRGB is using.

Returns : An X visual.

xlib_rgb_get_visual_info ()

XVisualInfo* xlib_rgb_get_visual_info       (void);

Queries the visual info structure for the visual that XlibRGB is using.

Returns : An XVisualInfo structure.

xlib_rgb_get_depth ()

int         xlib_rgb_get_depth              (void);

Queries the depth of the visual that XlibRGB is using.

Returns : Bit depth.

xlib_rgb_get_display ()

Display*    xlib_rgb_get_display            (void);

Queries the X display that XlibRGB is using.

Returns : An X display.

xlib_rgb_get_screen ()

Screen*     xlib_rgb_get_screen             (void);

Queries the screen that XlibRGB is using.

Returns : An X screen.

See Also

GdkRGB