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
struct XlibRgbCmap
struct XlibRgbCmap {
unsigned int colors[256];
unsigned char lut[256]; /* for 8-bit modes */
};
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.
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.
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.
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);
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);
This is primarily a debugging function. Sets whether you want XlibRGB to
print information about the visual and colormap it chooses. You normally do
not need to use this function.
verbose :
Whether to print visual/colormap debugging information.
xlib_rgb_set_install ()
void xlib_rgb_set_install (Bool install);
Sets whether XlibRGB should install its own private colormap instead of
trying to allocate color cells from the system colormap. This should be
called before initializing XlibRGB.
install :
Whether to install a private colormap.
xlib_rgb_set_min_colors ()
void xlib_rgb_set_min_colors (int min_colors);
Sets the minimum number of free color cells that must be available in the
system color map for XlibRGB to use it. If the specified number of colors is
not available, XlibRGB will install its own private colormap.
min_colors :
Minimum number of colors to look for in the system colormap.
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.