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class="shortcuts"><nobr><a href="#id3125115" class="shortcut">Top</a>  |  <a href="#id3126035" class="shortcut">Description</a></nobr></td></tr></table><div class="refentry" lang="en"><a name="gdk-GdkRGB"></a><div class="titlepage"></div><div class="refnamediv"><table width="100%"><tr><td valign="top"><h2><a name="id3125115"></a><span class="refentrytitle">GdkRGB</span></h2><p>GdkRGB — Renders RGB, grayscale, or indexed image data to a GdkDrawable</p></td><td valign="top" align="right"></td></tr></table></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">#include <gdk/gdk.h>void <a class="link" href="gdk-GdkRGB.html#gdk-rgb-init">gdk_rgb_init</a> (void);void <a class="link" href="gdk-GdkRGB.html#gdk-draw-rgb-image">gdk_draw_rgb_image</a> (<a class="link" href="gdk-Drawing-Primitives.html#GdkDrawable">GdkDrawable</a> *drawable, <a class="link" href="gdk-Graphics-Contexts.html#GdkGC">GdkGC</a> *gc, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> x, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> y, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> width, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> height, <a class="link" href="gdk-GdkRGB.html#GdkRgbDither">GdkRgbDither</a> dith, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guchar">guchar</a> *rgb_buf, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> rowstride);void <a class="link" href="gdk-GdkRGB.html#gdk-draw-rgb-image-dithalign">gdk_draw_rgb_image_dithalign</a> (<a class="link" href="gdk-Drawing-Primitives.html#GdkDrawable">GdkDrawable</a> *drawable, <a class="link" href="gdk-Graphics-Contexts.html#GdkGC">GdkGC</a> *gc, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> x, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> y, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> width, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> height, <a class="link" href="gdk-GdkRGB.html#GdkRgbDither">GdkRgbDither</a> dith, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guchar">guchar</a> *rgb_buf, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> rowstride, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> xdith, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> ydith);void <a class="link" href="gdk-GdkRGB.html#gdk-draw-indexed-image">gdk_draw_indexed_image</a> (<a class="link" href="gdk-Drawing-Primitives.html#GdkDrawable">GdkDrawable</a> *drawable, <a class="link" href="gdk-Graphics-Contexts.html#GdkGC">GdkGC</a> *gc, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> x, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> y, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> width, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> height, <a class="link" href="gdk-GdkRGB.html#GdkRgbDither">GdkRgbDither</a> dith, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guchar">guchar</a> *buf, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> rowstride, <a class="link" href="gdk-GdkRGB.html#GdkRgbCmap">GdkRgbCmap</a> *cmap);void <a class="link" href="gdk-GdkRGB.html#gdk-draw-gray-image">gdk_draw_gray_image</a> (<a class="link" href="gdk-Drawing-Primitives.html#GdkDrawable">GdkDrawable</a> *drawable, <a class="link" href="gdk-Graphics-Contexts.html#GdkGC">GdkGC</a> *gc, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> x, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> y, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> width, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> height, <a class="link" href="gdk-GdkRGB.html#GdkRgbDither">GdkRgbDither</a> dith, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guchar">guchar</a> *buf, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> rowstride);void <a class="link" href="gdk-GdkRGB.html#gdk-draw-rgb-32-image">gdk_draw_rgb_32_image</a> (<a class="link" href="gdk-Drawing-Primitives.html#GdkDrawable">GdkDrawable</a> *drawable, <a class="link" href="gdk-Graphics-Contexts.html#GdkGC">GdkGC</a> *gc, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> x, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> y, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> width, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> height, <a class="link" href="gdk-GdkRGB.html#GdkRgbDither">GdkRgbDither</a> dith, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guchar">guchar</a> *buf, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> rowstride);void <a class="link" href="gdk-GdkRGB.html#gdk-draw-rgb-32-image-dithalign">gdk_draw_rgb_32_image_dithalign</a> (<a class="link" href="gdk-Drawing-Primitives.html#GdkDrawable">GdkDrawable</a> *drawable, <a class="link" href="gdk-Graphics-Contexts.html#GdkGC">GdkGC</a> *gc, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> x, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> y, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> width, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> height, <a class="link" href="gdk-GdkRGB.html#GdkRgbDither">GdkRgbDither</a> dith, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guchar">guchar</a> *buf, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> rowstride, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> xdith, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> ydith);enum <a class="link" href="gdk-GdkRGB.html#GdkRgbDither">GdkRgbDither</a>;<a class="link" href="gdk-GdkRGB.html#GdkRgbCmap">GdkRgbCmap</a>* <a class="link" href="gdk-GdkRGB.html#gdk-rgb-cmap-new">gdk_rgb_cmap_new</a> (<ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint32">guint32</a> *colors, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> n_colors);void <a class="link" href="gdk-GdkRGB.html#gdk-rgb-cmap-free">gdk_rgb_cmap_free</a> (<a class="link" href="gdk-GdkRGB.html#GdkRgbCmap">GdkRgbCmap</a> *cmap); <a class="link" href="gdk-GdkRGB.html#GdkRgbCmap">GdkRgbCmap</a>;void <a class="link" href="gdk-GdkRGB.html#gdk-rgb-gc-set-foreground">gdk_rgb_gc_set_foreground</a> (<a class="link" href="gdk-Graphics-Contexts.html#GdkGC">GdkGC</a> *gc, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint32">guint32</a> rgb);void <a class="link" href="gdk-GdkRGB.html#gdk-rgb-gc-set-background">gdk_rgb_gc_set_background</a> (<a class="link" href="gdk-Graphics-Contexts.html#GdkGC">GdkGC</a> *gc, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint32">guint32</a> rgb);<ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gulong">gulong</a> <a class="link" href="gdk-GdkRGB.html#gdk-rgb-xpixel-from-rgb">gdk_rgb_xpixel_from_rgb</a> (<ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint32">guint32</a> rgb);void <a class="link" href="gdk-GdkRGB.html#gdk-rgb-find-color">gdk_rgb_find_color</a> (<a class="link" href="gdk-Colormaps-and-Colors.html#GdkColormap">GdkColormap</a> *colormap, <a class="link" href="gdk-Colormaps-and-Colors.html#GdkColor">GdkColor</a> *color);void <a class="link" href="gdk-GdkRGB.html#gdk-rgb-set-install">gdk_rgb_set_install</a> (<ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean">gboolean</a> install);void <a class="link" href="gdk-GdkRGB.html#gdk-rgb-set-min-colors">gdk_rgb_set_min_colors</a> (<ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint">gint</a> min_colors);<a class="link" href="gdk-Visuals.html#GdkVisual">GdkVisual</a>* <a class="link" href="gdk-GdkRGB.html#gdk-rgb-get-visual">gdk_rgb_get_visual</a> (void);<a class="link" href="gdk-Colormaps-and-Colors.html#GdkColormap">GdkColormap</a>* <a class="link" href="gdk-GdkRGB.html#gdk-rgb-get-colormap">gdk_rgb_get_colormap</a> (void);#define <a class="link" href="gdk-GdkRGB.html#gdk-rgb-get-cmap">gdk_rgb_get_cmap</a><ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean">gboolean</a> <a class="link" href="gdk-GdkRGB.html#gdk-rgb-ditherable">gdk_rgb_ditherable</a> (void);<ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean">gboolean</a> <a class="link" href="gdk-GdkRGB.html#gdk-rgb-colormap-ditherable">gdk_rgb_colormap_ditherable</a> (<a class="link" href="gdk-Colormaps-and-Colors.html#GdkColormap">GdkColormap</a> *cmap);void <a class="link" href="gdk-GdkRGB.html#gdk-rgb-set-verbose">gdk_rgb_set_verbose</a> (<ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean">gboolean</a> verbose);</pre></div><div class="refsect1" lang="en"><a name="id3126035"></a><h2>Description</h2><p>GdkRGB is a low-level module which renders RGB, grayscale, and indexedcolormap images to a <a class="link" href="gdk-Drawing-Primitives.html#GdkDrawable"><span class="type">GdkDrawable</span></a>. It does this as efficiently aspossible, handling issues such as colormaps, visuals, dithering,temporary buffers, and so on. Most code should use the higher-level<ahref="/usr/share/gtk-doc/html/gdk-pixbuf/gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"><span class="type">GdkPixbuf</span></a> features in place of this module; for example,<a class="link" href="gdk-Drawing-Primitives.html#gdk-draw-pixbuf"><code class="function">gdk_draw_pixbuf()</code></a> uses GdkRGB in its implementation.</p><p>GdkRGB allocates a color cube to use when rendering images. You canset the threshold for installing colormaps with<a class="link" href="gdk-GdkRGB.html#gdk-rgb-set-min-colors"><code class="function">gdk_rgb_set_min_colors()</code></a>. The default is 5x5x5 (125). If a colorcubeof this size or larger can be allocated in the default colormap, thenthat's done. Otherwise, GdkRGB creates its own private colormap.Setting it to 0 means that it always tries to use the defaultcolormap, and setting it to 216 means that it always creates a privateone if it cannot allocate the 6x6x6 colormap in the default. If youalways want a private colormap (to avoid consuming too many colormapentries for other apps, say), you can use <code class="literal">gdk_rgb_set_install(TRUE)</code>.Setting the value greater than 216 exercises a bug in older versionsof GdkRGB. Note, however, that setting it to 0 doesn't let you getaway with ignoring the colormap and visual - a colormap is alwayscreated in grayscale and direct color modes, and the visual is changedin cases where a "better" visual than the default is available.</p><p>If GDK is built with the Sun mediaLib library, the GdkRGB functions areaccelerated using mediaLib, which provides hardware acceleration on Intel,AMD, and Sparc chipsets. If desired, mediaLib support can be turned offby setting the GDK_DISABLE_MEDIALIB environment variable.</p><div class="example"><a name="id3126125"></a><p class="title"><b>Example 4. A simple example program using GdkRGB</b></p><div class="example-contents"><pre class="programlisting">#include <gtk/gtk.h>#define IMAGE_WIDTH 256#define IMAGE_HEIGHT 256guchar rgbbuf[IMAGE_WIDTH * IMAGE_HEIGHT * 3];gboolean on_darea_expose (GtkWidget *widget, GdkEventExpose *event, gpointer user_data);⌨️ 快捷键说明
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