gtk/gdk/gdkvisual.c

/* GDK - The GIMP Drawing Kit
 * gdkvisual.c
 * 
 * Copyright 2001 Sun Microsystems Inc. 
 *
 * Erwann Chenede <erwann.chenede@sun.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include "config.h"

#include "gdkinternals.h"
#include "gdkvisual.h"

#include "gdkscreen.h"


/**
 * SECTION:visuals
 * @Short_description: Low-level display hardware information
 * @Title: Visuals
 *
 * 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.
 *
 * There are several standard visuals. The visual returned by
 * gdk_screen_get_system_visual() is the system's default visual.
 *
 * 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.
 */


/**
 * gdk_list_visuals:
 * 
 * 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.
 * 
 * Return value: (transfer container) (element-type GdkVisual):
 *     a list of visuals; the list must be freed, but not its contents
 **/
GList*
gdk_list_visuals (void)
{
  return gdk_screen_list_visuals (gdk_screen_get_default ());
}

/**
 * gdk_visual_get_system:
 * 
 * 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.
 * 
 * Return value: (transfer none): system visual
 **/
GdkVisual*
gdk_visual_get_system (void)
{
  return gdk_screen_get_system_visual (gdk_screen_get_default());
}

/**
 * gdk_visual_get_best_depth:
 *
 * 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.
 *
 * Return value: best available depth
 **/
gint
gdk_visual_get_best_depth (void)
{
  GdkScreen *screen = gdk_screen_get_default();

  return GDK_SCREEN_GET_CLASS(screen)->visual_get_best_depth (screen);
}

/**
 * gdk_visual_get_best_type:
 *
 * Return the best available visual type for the default GDK screen.
 *
 * Return value: best visual type
 **/
GdkVisualType
gdk_visual_get_best_type (void)
{
  GdkScreen *screen = gdk_screen_get_default();

  return GDK_SCREEN_GET_CLASS(screen)->visual_get_best_type (screen);
}

/**
 * gdk_visual_get_best:
 *
 * Get the visual with the most available colors for the default
 * GDK screen. The return value should not be freed.
 *
 * Return value: (transfer none): best visual
 **/
GdkVisual*
gdk_visual_get_best (void)
{
  GdkScreen *screen = gdk_screen_get_default();

  return GDK_SCREEN_GET_CLASS(screen)->visual_get_best (screen);
}

/**
 * gdk_visual_get_best_with_depth:
 * @depth: a bit 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.
 *
 * Return value: (transfer none): best visual for the given depth
 **/
GdkVisual*
gdk_visual_get_best_with_depth (gint depth)
{
  GdkScreen *screen = gdk_screen_get_default();

  return GDK_SCREEN_GET_CLASS(screen)->visual_get_best_with_depth (screen, depth);
}

/**
 * gdk_visual_get_best_with_type:
 * @visual_type: a visual type
 *
 * 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.
 *
 * Return value: (transfer none): best visual of the given type
 **/
GdkVisual*
gdk_visual_get_best_with_type (GdkVisualType visual_type)
{
  GdkScreen *screen = gdk_screen_get_default();

  return GDK_SCREEN_GET_CLASS(screen)->visual_get_best_with_type (screen,
								  visual_type);
}

/**
 * gdk_visual_get_best_with_both:
 * @depth: a bit depth
 * @visual_type: a visual type
 *
 * Combines gdk_visual_get_best_with_depth() and gdk_visual_get_best_with_type().
 *
 * Return value: (transfer none): best visual with both @depth and
 *     @visual_type, or %NULL if none
 **/
GdkVisual*
gdk_visual_get_best_with_both (gint          depth,
			       GdkVisualType visual_type)
{
  GdkScreen *screen = gdk_screen_get_default();

  return GDK_SCREEN_GET_CLASS(screen)->visual_get_best_with_both (screen, depth, visual_type);
}

/**
 * gdk_query_depths:
 * @depths: (out) (array): return location for available depths
 * @count: (out): return location for number of available 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.
 *
 **/
void
gdk_query_depths  (gint **depths,
		   gint  *count)
{
  GdkScreen *screen = gdk_screen_get_default();

  GDK_SCREEN_GET_CLASS(screen)->query_depths (screen, depths, count);
}

/**
 * gdk_query_visual_types:
 * @visual_types: return location for the available visual types
 * @count: return location for the number of available visual types
 *
 * 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.
 **/
void
gdk_query_visual_types (GdkVisualType **visual_types,
			gint           *count)
{
  GdkScreen *screen = gdk_screen_get_default();

  GDK_SCREEN_GET_CLASS(screen)->query_visual_types (screen, visual_types, count);
}

/**
 * gdk_visual_get_visual_type:
 * @visual: A #GdkVisual.
 *
 * Returns the type of visual this is (PseudoColor, TrueColor, etc).
 *
 * Return value: A #GdkVisualType stating the type of @visual.
 *
 * Since: 2.22
 */
GdkVisualType
gdk_visual_get_visual_type (GdkVisual *visual)
{
  g_return_val_if_fail (GDK_IS_VISUAL (visual), 0);

  return visual->type;
}

/**
 * gdk_visual_get_depth:
 * @visual: A #GdkVisual.
 *
 * Returns the bit depth of this visual.
 *
 * Return value: The bit depth of this visual.
 *
 * Since: 2.22
 */
gint
gdk_visual_get_depth (GdkVisual *visual)
{
  g_return_val_if_fail (GDK_IS_VISUAL (visual), 0);

  return visual->depth;
}

/**
 * gdk_visual_get_byte_order:
 * @visual: A #GdkVisual.
 *
 * Returns the byte order of this visual.
 *
 * Return value: A #GdkByteOrder stating the byte order of @visual.
 *
 * Since: 2.22
 */
GdkByteOrder
gdk_visual_get_byte_order (GdkVisual *visual)
{
  g_return_val_if_fail (GDK_IS_VISUAL (visual), 0);

  return visual->byte_order;
}

/**
 * gdk_visual_get_colormap_size:
 * @visual: A #GdkVisual.
 *
 * Returns the size of a colormap for this visual.
 *
 * Return value: The size of a colormap that is suitable for @visual.
 *
 * Since: 2.22
 */
gint
gdk_visual_get_colormap_size (GdkVisual *visual)
{
  g_return_val_if_fail (GDK_IS_VISUAL (visual), 0);

  return visual->colormap_size;
}

/**
 * gdk_visual_get_bits_per_rgb:
 * @visual: a #GdkVisual
 *
 * Returns the number of significant bits per red, green and blue value.
 *
 * Return value: The number of significant bits per color value for @visual.
 *
 * Since: 2.22
 */
gint
gdk_visual_get_bits_per_rgb (GdkVisual *visual)
{
  g_return_val_if_fail (GDK_IS_VISUAL (visual), 0);

  return visual->bits_per_rgb;
}

/**
 * gdk_visual_get_red_pixel_details:
 * @visual: A #GdkVisual.
 * @mask: (out) (allow-none): A pointer to a #guint32 to be filled in, or %NULL.
 * @shift: (out) (allow-none): A pointer to a #gint to be filled in, or %NULL.
 * @precision: (out) (allow-none): A pointer to a #gint to be filled in, or %NULL.
 *
 * 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
 */
void
gdk_visual_get_red_pixel_details (GdkVisual *visual,
                                  guint32   *mask,
                                  gint      *shift,
                                  gint      *precision)
{
  g_return_if_fail (GDK_IS_VISUAL (visual));

  if (mask)
    *mask = visual->red_mask;

  if (shift)
    *shift = visual->red_shift;

  if (precision)
    *precision = visual->red_prec;
}

/**
 * gdk_visual_get_green_pixel_details:
 * @visual: a #GdkVisual
 * @mask: (out) (allow-none): A pointer to a #guint32 to be filled in, or %NULL.
 * @shift: (out) (allow-none): A pointer to a #gint to be filled in, or %NULL.
 * @precision: (out) (allow-none): A pointer to a #gint to be filled in, or %NULL.
 *
 * 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
 */
void
gdk_visual_get_green_pixel_details (GdkVisual *visual,
                                    guint32   *mask,
                                    gint      *shift,
                                    gint      *precision)
{
  g_return_if_fail (GDK_IS_VISUAL (visual));

  if (mask)
    *mask = visual->green_mask;

  if (shift)
    *shift = visual->green_shift;

  if (precision)
    *precision = visual->green_prec;
}

/**
 * gdk_visual_get_blue_pixel_details:
 * @visual: a #GdkVisual
 * @mask: (out) (allow-none): A pointer to a #guint32 to be filled in, or %NULL.
 * @shift: (out) (allow-none): A pointer to a #gint to be filled in, or %NULL.
 * @precision: (out) (allow-none): A pointer to a #gint to be filled in, or %NULL.
 *
 * 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
 */
void
gdk_visual_get_blue_pixel_details (GdkVisual *visual,
                                   guint32   *mask,
                                   gint      *shift,
                                   gint      *precision)
{
  g_return_if_fail (GDK_IS_VISUAL (visual));

  if (mask)
    *mask = visual->blue_mask;

  if (shift)
    *shift = visual->blue_shift;

  if (precision)
    *precision = visual->blue_prec;
}