Visual

Description A GdkVisual describes a particular video hardware display format. It includes information about the number of bits used for each color, the way the bits are translated into an RGB value for display, and the way the bits are stored in memory. For example, a piece of display hardware might support 24-bit color, 16-bit color, or 8-bit color; meaning 24/16/8-bit pixel sizes. For a given pixel size, pixels can be in different formats; for example the "red" element of an RGB pixel may be in the top 8 bits of the pixel, or may be in the lower 4 bits. Usually you can avoid thinking about visuals in GTK+. Visuals are useful to interpret the contents of a GdkImage, but you should avoid GdkImage precisely because its contents depend on the display hardware; use GdkPixbuf instead, for all but the most low-level purposes. Also, anytime you provide a GdkColormap, the visual is implied as part of the colormap (gdk_colormap_get_visual()), so you won't have to provide a visual in addition. There are several standard visuals. The visual returned by gdk_visual_get_system() is the system's default visual. gdk_rgb_get_visual() return the visual most suited to displaying full-color image data. If you use the calls in GdkRGB, you should create your windows using this visual (and the colormap returned by gdk_rgb_get_colormap()). A number of functions are provided for determining the "best" available visual. For the purposes of making this determination, higher bit depths are considered better, and for visuals of the same bit depth, GDK_VISUAL_PSEUDO_COLOR is preferred at 8bpp, otherwise, the visual types are ranked in the order of (highest to lowest) GDK_VISUAL_DIRECT_COLOR, GDK_VISUAL_TRUE_COLOR, GDK_VISUAL_PSEUDO_COLOR, GDK_VISUAL_STATIC_COLOR, GDK_VISUAL_GRAYSCALE, then GDK_VISUAL_STATIC_GRAY.

class Visual {

protected

GdkVisual* gdkVisual;

GdkVisual* getVisualStruct();

void* getStruct();

this(GdkVisual* gdkVisual);

static void gdkQueryDepths(int[] depths);

static void gdkQueryVisualTypes(GdkVisualType[] visualTypes);

static ListG gdkListVisuals();

static int getBestDepth();

static GdkVisualType getBestType();

static Visual getSystem();

static Visual getBest();

static Visual getBestWithDepth(int depth);

static Visual getBestWithType(GdkVisualType visualType);

static Visual getBestWithBoth(int depth, GdkVisualType visualType);

Screen getScreen();

int getBitsPerRgb();

void getBluePixelDetails(uint mask, int shift, int precision);

GdkByteOrder getByteOrder();

int getColormapSize();

int getDepth();

void getGreenPixelDetails(uint mask, int shift, int precision);

void getRedPixelDetails(uint mask, int shift, int precision);

GdkVisualType getVisualType();

}

Constructors

this this(GdkVisual* gdkVisual): Sets our main struct and passes it to the parent class

Members

Functions

getBitsPerRgb int getBitsPerRgb(): Returns the number of significant bits per red, green and blue value. Since 2.22
getBluePixelDetails void getBluePixelDetails(uint mask, int shift, int precision): Obtains values that are needed to calculate blue pixel values in TrueColor and DirectColor. The "mask" is the significant bits within the pixel. The "shift" is the number of bits left we must shift a primary for it to be in position (according to the "mask"). Finally, "precision" refers to how much precision the pixel value contains for a particular primary. Since 2.22
getByteOrder GdkByteOrder getByteOrder(): Returns the byte order of this visual. Since 2.22
getColormapSize int getColormapSize(): Returns the size of a colormap for this visual. Since 2.22
getDepth int getDepth(): Returns the bit depth of this visual. Since 2.22
getGreenPixelDetails void getGreenPixelDetails(uint mask, int shift, int precision): Obtains values that are needed to calculate green pixel values in TrueColor and DirectColor. The "mask" is the significant bits within the pixel. The "shift" is the number of bits left we must shift a primary for it to be in position (according to the "mask"). Finally, "precision" refers to how much precision the pixel value contains for a particular primary. Since 2.22
getRedPixelDetails void getRedPixelDetails(uint mask, int shift, int precision): Obtains values that are needed to calculate red pixel values in TrueColor and DirectColor. The "mask" is the significant bits within the pixel. The "shift" is the number of bits left we must shift a primary for it to be in position (according to the "mask"). Finally, "precision" refers to how much precision the pixel value contains for a particular primary. Since 2.22
getScreen Screen getScreen(): Gets the screen to which this visual belongs Since 2.2
getStruct void* getStruct(): the main Gtk struct as a void*
getVisualStruct GdkVisual* getVisualStruct(): Undocumented in source. Be warned that the author may not have intended to support it.
getVisualType GdkVisualType getVisualType(): Returns the type of visual this is (PseudoColor, TrueColor, etc). Since 2.22

Static functions

gdkListVisuals ListG gdkListVisuals(): Lists the available visuals for the default screen. (See gdk_screen_list_visuals()) A visual describes a hardware image data format. For example, a visual might support 24-bit color, or 8-bit color, and might expect pixels to be in a certain format. Call g_list_free() on the return value when you're finished with it.
gdkQueryDepths void gdkQueryDepths(int[] depths): This function returns the available bit depths for the default screen. It's equivalent to listing the visuals (gdk_list_visuals()) and then looking at the depth field in each visual, removing duplicates. The array returned by this function should not be freed.
gdkQueryVisualTypes void gdkQueryVisualTypes(GdkVisualType[] visualTypes): This function returns the available visual types for the default screen. It's equivalent to listing the visuals (gdk_list_visuals()) and then looking at the type field in each visual, removing duplicates. The array returned by this function should not be freed.
getBest Visual getBest(): Get the visual with the most available colors for the default GDK screen. The return value should not be freed.
getBestDepth int getBestDepth(): Get the best available depth for the default GDK screen. "Best" means "largest," i.e. 32 preferred over 24 preferred over 8 bits per pixel.
getBestType GdkVisualType getBestType(): Return the best available visual type for the default GDK screen.
getBestWithBoth Visual getBestWithBoth(int depth, GdkVisualType visualType): Combines gdk_visual_get_best_with_depth() and gdk_visual_get_best_with_type().
getBestWithDepth Visual getBestWithDepth(int depth): Get the best visual with depth depth for the default GDK screen. Color visuals and visuals with mutable colormaps are preferred over grayscale or fixed-colormap visuals. The return value should not be freed. NULL may be returned if no visual supports depth.
getBestWithType Visual getBestWithType(GdkVisualType visualType): Get the best visual of the given visual_type for the default GDK screen. Visuals with higher color depths are considered better. The return value should not be freed. NULL may be returned if no visual has type visual_type.
getSystem Visual getSystem(): Get the system's default visual for the default GDK screen. This is the visual for the root window of the display. The return value should not be freed.

Variables

gdkVisual GdkVisual* gdkVisual;: the main Gtk struct