]> Pileus Git - ~andy/gtk/blobdiff - gdk/gdkpixbuf-drawable.c
Small documentation fixes for frame synchronization
[~andy/gtk] / gdk / gdkpixbuf-drawable.c
index 0dd668406c2c68c70b31bd923266966742ccf06f..f8736bac7c802a08f03b9f5f694a7a4f6ae47016 100644 (file)
-/*
- * Creates an GdkPixbuf from a Drawable
+/* GdkPixbuf library - convert X drawable information to RGB
  *
- * Authors:
- *   Cody Russell <bratsche@dfw.net>
- *   Michael Zucchi  <zucchi@zedzone.mmc.com.au>
+ * Copyright (C) 1999 Michael Zucchi
+ *
+ * Authors: Michael Zucchi <zucchi@zedzone.mmc.com.au>
+ *          Cody Russell <bratsche@dfw.net>
+ *         Federico Mena-Quintero <federico@gimp.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <config.h>
-#include <stdio.h>
-#include <string.h>
-#include <glib.h>
-#include <gmodule.h>
-#include "gdk-pixbuf.h"
-#include "gdk-pixbuf-drawable.h"
-
-
-#if (G_BYTE_ORDER == G_LITTLE_ENDIAN)
-#define LITTLE
-#endif
-#define d(x)
-
-unsigned long mask_table[] = {
-  0x00000000, 0x00000001, 0x00000003, 0x00000007,
-  0x0000000f, 0x0000001f, 0x0000003f, 0x0000007f,
-  0x000000ff, 0x000001ff, 0x000003ff, 0x000007ff,
-  0x00000fff, 0x00001fff, 0x00003fff, 0x00007fff,
-  0x0000ffff, 0x0001ffff, 0x0003ffff, 0x0007ffff,
-  0x000fffff, 0x001fffff, 0x003fffff, 0x007fffff,
-  0x00ffffff, 0x01ffffff, 0x03ffffff, 0x07ffffff,
-  0x0fffffff, 0x1fffffff, 0x3fffffff, 0x7fffffff,
-  0xffffffff
-};
-
-static GdkPixbuf *
-gdk_pixbuf_from_drawable_core (GdkPixmap * window, gint x, gint y, gint width,
-                              gint height, gint with_alpha)
+#include "config.h"
+
+#include "gdkpixbuf.h"
+
+#include "gdkcolor.h"
+#include "gdkwindow.h"
+#include "gdkinternals.h"
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+
+/**
+ * SECTION:pixbufs
+ * @Short_description: Functions for obtaining pixbufs
+ * @Title: Pixbufs
+ *
+ * Pixbufs are client-side images. For details on how to create
+ * and manipulate pixbufs, see the #GdkPixbuf API documentation.
+ *
+ * The functions described here allow to obtain pixbufs from
+ * #GdkWindows and cairo surfaces.
+ */
+
+
+/**
+ * gdk_pixbuf_get_from_window:
+ * @window: Source window
+ * @src_x: Source X coordinate within @window
+ * @src_y: Source Y coordinate within @window
+ * @width: Width in pixels of region to get
+ * @height: Height in pixels of region to get
+ *
+ * Transfers image data from a #GdkWindow and converts it to an RGB(A)
+ * representation inside a #GdkPixbuf. In other words, copies
+ * image data from a server-side drawable to a client-side RGB(A) buffer.
+ * This allows you to efficiently read individual pixels on the client side.
+ *
+ * This function will create an RGB pixbuf with 8 bits per channel with
+ * the same size specified by the @width and @height arguments. The pixbuf
+ * will contain an alpha channel if the @window contains one.
+ *
+ * If the window is off the screen, then there is no image data in the
+ * obscured/offscreen regions to be placed in the pixbuf. The contents of
+ * portions of the pixbuf corresponding to the offscreen region are undefined.
+ *
+ * If the window you're obtaining data from is partially obscured by
+ * other windows, then the contents of the pixbuf areas corresponding
+ * to the obscured regions are undefined.
+ *
+ * If the window is not mapped (typically because it's iconified/minimized
+ * or not on the current workspace), then %NULL will be returned.
+ *
+ * If memory can't be allocated for the return value, %NULL will be returned
+ * instead.
+ *
+ * (In short, there are several ways this function can fail, and if it fails
+ *  it returns %NULL; so check the return value.)
+ *
+ * Return value: (transfer full): A newly-created pixbuf with a reference
+ *     count of 1, or %NULL on error
+ */
+GdkPixbuf *
+gdk_pixbuf_get_from_window (GdkWindow *src,
+                            gint       src_x,
+                            gint       src_y,
+                            gint       width,
+                            gint       height)
 {
-  GdkImage *image;
-  ArtPixBuf *art_pixbuf;
-  GdkColormap *colormap;
-  art_u8 *buff;
-  art_u8 *pixels;
-  gulong pixel;
-  gint rowstride;
-  art_u8 r, g, b;
-  gint xx, yy;
-  gint fatness;
-  gint screen_width, screen_height;
-  gint window_width, window_height, window_x, window_y;
-  int bpl;
-
-  g_return_val_if_fail (window != NULL, NULL);
-
-  /* always returns image in ZPixmap format ... */
-  image = gdk_image_get (window, x, y, width, height);
-
-  fatness = with_alpha ? 4 : 3;
-  rowstride = width * fatness;
-
-  buff = art_alloc (rowstride * height);
-  pixels = buff;
-
-#if 0
-  printf ("bpp = %d\n", image->bpp);
-  printf ("depth = %d\n", image->depth);
-  printf ("byte order = %d\n", image->byte_order);
-  printf ("bytes/line = %d\n", image->bpl);
-#endif
-
-  bpl = image->bpl;
-
-  switch (image->bpp)
+  cairo_surface_t *surface;
+  GdkPixbuf *dest;
+
+  g_return_val_if_fail (GDK_IS_WINDOW (src), NULL);
+  g_return_val_if_fail (gdk_window_is_viewable (src), NULL);
+
+  surface = _gdk_window_ref_cairo_surface (src);
+  dest = gdk_pixbuf_get_from_surface (surface,
+                                      src_x, src_y,
+                                      width, height);
+  cairo_surface_destroy (surface);
+
+  return dest;
+}
+
+static cairo_format_t
+gdk_cairo_format_for_content (cairo_content_t content)
+{
+  switch (content)
     {
-    case 1:
-      {
-       unsigned char *s;
-       register unsigned char bits;
-       register unsigned char data;
-       unsigned char *o;
-       unsigned char *srow = image->mem, *orow = pixels;
-       int i, base;
-
-       d (printf ("1 bits/pixel\n"));
-
-       /* convert upto 8 pixels/time */
-       colormap = gdk_rgb_get_cmap ();
-       for (yy = 0; yy < height; yy++)
-         {
-           s = srow;
-           o = orow;
-
-           for (xx = 0; xx < width; xx += 8)
-             {
-               bits = *s++;
-
-               if (xx + 8 >= width)
-                 base = 7 - (xx + 8 - width);
-               else
-                 base = 0;
-
-               for (i = 7; i >= base; i--)
-                 {
-                   data = (bits & (0x80 >> i)) & 1;
-                   *o++ = colormap->colors[data].red;
-                   *o++ = colormap->colors[data].green;
-                   *o++ = colormap->colors[data].blue;
-                 }
-             }
-
-           srow += bpl;
-           orow += rowstride;
-         }
-       break;
-      }
-
-    case 8:
-      {
-       unsigned char *s;
-       unsigned long mask;
-       register unsigned long data;
-       unsigned char *o;
-       unsigned char *srow = image->mem, *orow = pixels;
-
-       d (printf ("8 bits/pixel\n"));
-
-       colormap = gdk_rgb_get_cmap ();
-       mask = mask_table[image->depth];
-
-       for (yy = 0; yy < height; yy++)
-         {
-           s = srow;
-           o = orow;
-           for (xx = 0; xx < width; xx++)
-             {
-               data = *s++ & mask;
-               *o++ = colormap->colors[data].red;
-               *o++ = colormap->colors[data].green;
-               *o++ = colormap->colors[data].blue;
-             }
-           srow += bpl;
-           orow += rowstride;
-         }
-       break;
-      }
-
-      /*#define SIMPLE_16  this is really quite slow ! */
-    case 16:
-      {
-#ifdef SIMPLE_16
-       unsigned short *s;
-#else
-       unsigned long *s;       /* read 2 pixels at once */
-#endif
-       register unsigned long data;
-       unsigned short *o;
-       unsigned char *srow = image->mem, *orow = pixels;
-
-       printf ("16 bits/pixel\n");
-
-       for (yy = 0; yy < height; yy++)
-         {
-           s = srow;
-           o = orow;
-
-           if (image->byte_order == GDK_LSB_FIRST)
-             {
-#ifdef SIMPLE_16
-               for (xx = 0; xx < width; xx++)
-                 {
-                   data = *s++;
-                   *o++ = (data >> 8) & 0xf8;
-                   *o++ = (data >> 3) & 0xfc;
-                   *o++ = (data << 3) & 0xf8;
-                 }
-#else
-               switch (image->depth)
-                 {
-                 case 15:
-                   /* starts at 1, so we dont over-flow the conversion */
-                   for (xx = 0; xx < width; xx += 2)
-                     {
-                       /* read/convert 2 pixels at a time */
-
-                       /* little endian, lsb data */
-#ifdef LITTLE
-                       /*7c 3e 1f */
-                       data = *s++;
-                       *o++ = (data & 0x7c00) >> 7 | (data & 0x3e0) << 6;
-                       *o++ = (data & 0x1f) << 3 | (data & 0x7c000000) >> 15;
-                       *o++ =
-                         ((data & 0x3e00000) >> 18) | (data & 0x1f0000) >> 5;
-#else
-                       /* big endian, lsb data */
-                       /* swap endianness first */
-                       data = (unsigned long) ((unsigned char *) s)[3] << 24
-                         | (unsigned long) ((unsigned char *) s)[2] << 16
-                         | (unsigned long) ((unsigned char *) s)[1] << 8
-                         | (unsigned long) ((unsigned char *) s)[0];
-                       s++;
-                       *o++ = (data & 0x7c00) << 1 | (data & 0x3e0) >> 2;
-                       *o++ =
-                         (data & 0x1f) << 11 | (data & 0x7c000000) >> 23;
-                       *o++ =
-                         ((data & 0x3e00000) >> 10) | (data & 0x1f0000) >>
-                         13;
-#endif
-                     }
-                   /* check for last remaining pixel */
-                   if (width & 1)
-                     {
-                       register unsigned short data;
-#ifdef LITTLE
-                       data = *((short *) s);
-#else
-                       data = *((short *) s);
-                       data = ((data >> 8) & 0xff) | ((data & 0xff) << 8);
-                       data &= mask;
-#endif
-                       ((char *) o)[0] = (data & 0x7c0) >> 7;
-                       ((char *) o)[1] = (data & 0x3e0) >> 2;
-                       ((char *) o)[2] = (data & 0x1f) << 3;
-                     }
-                   break;
-                 case 16:
-                   for (xx = 0; xx < width; xx += 2)
-                     {
-                       /* read/convert 2 pixels at a time */
-
-                       /* little endian, lsb data */
-#ifdef LITTLE
-                       data = *s++;
-                       *o++ = (data & 0xf800) >> 8 | (data & 0x7e0) << 5;
-                       *o++ = (data & 0x1f) << 3 | (data & 0xf8000000) >> 16;
-                       *o++ =
-                         ((data & 0x7e00000) >> 19) | (data & 0x1f0000) >> 5;
-#else
-                       /* big endian, lsb data */
-                       /* swap endianness first */
-                       data = (unsigned long) ((unsigned char *) s)[3] << 24
-                         | (unsigned long) ((unsigned char *) s)[2] << 16
-                         | (unsigned long) ((unsigned char *) s)[1] << 8
-                         | (unsigned long) ((unsigned char *) s)[0];
-                       s++;
-                       *o++ = (data & 0xf800) | (data & 0x7e0) >> 3;
-                       *o++ =
-                         (data & 0x1f) << 11 | (data & 0xf8000000) >> 24;
-                       *o++ =
-                         ((data & 0x7e00000) >> 11) | (data & 0x1f0000) >>
-                         13;
-#endif
-                     }
-                   /* check for last remaining pixel */
-                   if (width & 1)
-                     {
-                       register unsigned short data;
-#ifdef LITTLE
-                       data = *((short *) s);
-#else
-                       data = *((short *) s);
-                       data = ((data >> 8) & 0xff) | ((data & 0xff) << 8);
-#endif
-                       ((char *) o)[0] = (data >> 8) & 0xf8;
-                       ((char *) o)[1] = (data >> 3) & 0xfc;
-                       ((char *) o)[2] = (data << 3) & 0xf8;
-                     }
-                   break;
-                 }
-#endif /* SIMPLE_16 */
-             }
-           else
-             {
-               switch (image->depth)
-                 {
-                 case 15:
-                   for (xx = 0; xx < width; xx += 2)
-                     {
-                       /* read/convert 2 pixels at a time */
-#ifdef LITTLE
-                       /* little endian, msb data */
-                       /* swap endianness first */
-                       data = (unsigned long) ((unsigned char *) s)[0] << 24
-                         | (unsigned long) ((unsigned char *) s)[1] << 16
-                         | (unsigned long) ((unsigned char *) s)[2] << 8
-                         | (unsigned long) ((unsigned char *) s)[3];
-                       s++;
-                       /*7c 3e 1f */
-                       *o++ = (data & 0x7c00) >> 7 | (data & 0x3e0) << 6;
-                       *o++ = (data & 0x1f) << 3 | (data & 0x7c000000) >> 15;
-                       *o++ =
-                         ((data & 0x3e00000) >> 18) | (data & 0x1f0000) >> 5;
-#else
-                       /* big endian, lsb data */
-                       data = *s++;
-                       *o++ = (data & 0x7c00) << 1 | (data & 0x3e0) >> 2;
-                       *o++ =
-                         (data & 0x1f) << 11 | (data & 0x7c000000) >> 23;
-                       *o++ =
-                         ((data & 0x3e00000) >> 10) | (data & 0x1f0000) >>
-                         13;
-#endif
-                     }
-                   /* check for last remaining pixel */
-                   if (width & 1)
-                     {
-                       register unsigned short data;
-#ifdef LITTLE
-                       data = *((short *) s);
-                       data = ((data >> 8) & 0xff) | ((data & 0xff) << 8);
-#else
-                       data = *((short *) s);
-#endif
-                       ((char *) o)[0] = (data >> 8) & 0xf8;
-                       ((char *) o)[1] = (data >> 3) & 0xfc;
-                       ((char *) o)[2] = (data << 3) & 0xf8;
-                     }
-                   break;
-                 case 16:
-                   for (xx = 0; xx < width; xx += 2)
-                     {
-                       /* read/convert 2 pixels at a time */
-#ifdef LITTLE
-                       /* little endian, msb data */
-                       /* swap endianness first */
-                       data = (unsigned long) ((unsigned char *) s)[0] << 24
-                         | (unsigned long) ((unsigned char *) s)[1] << 16
-                         | (unsigned long) ((unsigned char *) s)[2] << 8
-                         | (unsigned long) ((unsigned char *) s)[3];
-                       s++;
-                       *o++ = (data & 0xf800) >> 8 | (data & 0x7e0) << 5;
-                       *o++ = (data & 0x1f) << 3 | (data & 0xf8000000) >> 16;
-                       *o++ =
-                         ((data & 0x7e00000) >> 19) | (data & 0x1f0000) >> 5;
-#else
-                       /* big endian, lsb data */
-                       data = *s++;
-                       *o++ = (data & 0xf800) | (data & 0x7e0) >> 3;
-                       *o++ =
-                         (data & 0x1f) << 11 | (data & 0xf8000000) >> 24;
-                       *o++ =
-                         ((data & 0x7e00000) >> 11) | (data & 0x1f0000) >>
-                         13;
-#endif
-                     }
-                   /* check for last remaining pixel */
-                   if (width & 1)
-                     {
-                       register unsigned short data;
-#ifdef LITTLE
-                       data = *((short *) s);
-                       data = ((data >> 8) & 0xff) | ((data & 0xff) << 8);
-#else
-                       data = *((short *) s);
-#endif
-                       ((char *) o)[0] = (data >> 8) & 0xf8;
-                       ((char *) o)[1] = (data >> 3) & 0xfc;
-                       ((char *) o)[2] = (data << 3) & 0xf8;
-                     }
-                   break;
-                 }
-             }
-           srow += bpl;
-           orow += rowstride;
-         }
-       break;
-      }
-      /*#define HAIRY_32  this is slowest implementation */
-#define SIMPLE_32              /* this is fastest implementation */
-    case 32:
-      {
-#ifdef SIMPLE_32
-       unsigned char *s;       /* read 1 pixels at once */
-#else
-       unsigned long *s;       /* read 1 pixels at once */
-#endif
-#ifdef HAIRY_32
-       register unsigned long data2;
-       unsigned short *o;
-#else
-       unsigned char *o;
-#endif
-       register unsigned long data;
-       unsigned char *srow = image->mem, *orow = pixels;
-
-       printf ("32 bits/pixel\n");
-
-       for (yy = 0; yy < height; yy++)
-         {
-           s = srow;
-           o = orow;
-
-           if (image->byte_order == GDK_LSB_FIRST)
-             {
-#ifdef HAIRY_32
-               for (xx = 0; xx < width; xx += 2)
-                 {
-#else
-               for (xx = 0; xx < width; xx++)
-                 {
-#endif
-                   /* read/convert 2 pixels at a time */
-
-                   /* little endian, lsb data */
-#ifdef SIMPLE_32
-                   *o++ = s[2];
-                   *o++ = s[1];
-                   *o++ = s[0];
-                   s += 4;
-#else
-
-#ifdef LITTLE
-#ifdef HAIRY_32
-                   data = *s++;
-                   data2 = *s++;
-#else
-                   data = *s++;
-#endif
-#else
-                   /* big endian, lsb data */
-                   /* swap endianness first */
-                   data = (unsigned long) ((unsigned char *) s)[3] << 24
-                     | (unsigned long) ((unsigned char *) s)[2] << 16
-                     | (unsigned long) ((unsigned char *) s)[1] << 8
-                     | (unsigned long) ((unsigned char *) s)[0];
-                   s++;
-#endif
-#ifdef HAIRY_32
-                   *o++ = (data & 0xff0000) >> 16 | (data & 0xff00);
-                   *o++ = (data & 0xff) | (data2 & 0xff0000) >> 8;
-                   *o++ = ((data2 & 0xff00) >> 8) | (data2 & 0xff) << 8;
-#else
-                   /* FIXME: endianness conversion can be done here .. doh! */
-                   *o++ = data & 0xff0000 >> 16;
-                   *o++ = data & 0x00ff00 >> 8;
-                   *o++ = data & 0x0000ff;
-#endif
-
-#endif /* SIMPLE_32 */
-                 }
-             }
-           else
-             {
-               for (xx = 0; xx < width; xx++)
-                 {
-                   /* read/convert 2 pixels at a time */
-#ifdef LITTLE
-                   /* little endian, msb data */
-                   /* swap endianness first */
-#if 1                          /* which is faster?? */
-                   data = (unsigned long) ((unsigned char *) s)[0] << 24
-                     | (unsigned long) ((unsigned char *) s)[1] << 16
-                     | (unsigned long) ((unsigned char *) s)[2] << 8
-                     | (unsigned long) ((unsigned char *) s)[3];
-                   s++;
-#else /* this is probably slower */
-                   data = *s++;
-                   data = ((data >> 16) & 0xffff) | ((data & 0xffff) << 16);
-                   data =
-                     ((data & 0xff00ff00) >> 8) | ((data & 0xff00ff) << 8);
-#endif
-#else
-                   /* big endian, lsb data */
-                   data = *s++;
-#endif
-                   /* FIXME: endianness conversion can be done here .. doh! */
-                   *o++ = data & 0xff0000 >> 16;
-                   *o++ = data & 0x00ff00 >> 8;
-                   *o++ = data & 0x0000ff;
-                 }
-             }
-           srow += bpl;
-           orow += rowstride;
-         }
-       break;
-      }
+    case CAIRO_CONTENT_COLOR:
+      return CAIRO_FORMAT_RGB24;
+    case CAIRO_CONTENT_ALPHA:
+      return CAIRO_FORMAT_A8;
+    case CAIRO_CONTENT_COLOR_ALPHA:
     default:
-      g_warning ("gdk_pixbuf_from_drawable: Unsupported image format\n");
+      return CAIRO_FORMAT_ARGB32;
     }
+}
+
+static cairo_surface_t *
+gdk_cairo_surface_coerce_to_image (cairo_surface_t *surface,
+                                   cairo_content_t  content,
+                                   int              src_x,
+                                   int              src_y,
+                                   int              width,
+                                   int              height)
+{
+  cairo_surface_t *copy;
+  cairo_t *cr;
 
-  gdk_image_destroy (image);
+  copy = cairo_image_surface_create (gdk_cairo_format_for_content (content),
+                                     width,
+                                     height);
 
-  art_pixbuf =
-    with_alpha ? art_pixbuf_new_rgba (buff, width, height,
-                                     rowstride) : art_pixbuf_new_rgb (buff,
-                                                                      width,
-                                                                      height,
-                                                                      rowstride);
+  cr = cairo_create (copy);
+  cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
+  cairo_set_source_surface (cr, surface, -src_x, -src_y);
+  cairo_paint (cr);
+  cairo_destroy (cr);
 
-  return gdk_pixbuf_new_from_art_pixbuf (art_pixbuf);
+  return copy;
 }
 
-/* Public functions */
+static void
+convert_alpha (guchar *dest_data,
+               int     dest_stride,
+               guchar *src_data,
+               int     src_stride,
+               int     src_x,
+               int     src_y,
+               int     width,
+               int     height)
+{
+  int x, y;
+
+  src_data += src_stride * src_y + src_x * 4;
+
+  for (y = 0; y < height; y++) {
+    guint32 *src = (guint32 *) src_data;
+
+    for (x = 0; x < width; x++) {
+      guint alpha = src[x] >> 24;
+
+      if (alpha == 0)
+        {
+          dest_data[x * 4 + 0] = 0;
+          dest_data[x * 4 + 1] = 0;
+          dest_data[x * 4 + 2] = 0;
+        }
+      else
+        {
+          dest_data[x * 4 + 0] = (((src[x] & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
+          dest_data[x * 4 + 1] = (((src[x] & 0x00ff00) >>  8) * 255 + alpha / 2) / alpha;
+          dest_data[x * 4 + 2] = (((src[x] & 0x0000ff) >>  0) * 255 + alpha / 2) / alpha;
+        }
+      dest_data[x * 4 + 3] = alpha;
+    }
+
+    src_data += src_stride;
+    dest_data += dest_stride;
+  }
+}
 
-GdkPixbuf *
-gdk_pixbuf_rgb_from_drawable (GdkWindow * window, gint x, gint y, gint width,
-                             gint height)
+static void
+convert_no_alpha (guchar *dest_data,
+                  int     dest_stride,
+                  guchar *src_data,
+                  int     src_stride,
+                  int     src_x,
+                  int     src_y,
+                  int     width,
+                  int     height)
 {
-  return gdk_pixbuf_from_drawable_core (window, x, y, width, height, 0);
+  int x, y;
+
+  src_data += src_stride * src_y + src_x * 4;
+
+  for (y = 0; y < height; y++) {
+    guint32 *src = (guint32 *) src_data;
+
+    for (x = 0; x < width; x++) {
+      dest_data[x * 3 + 0] = src[x] >> 16;
+      dest_data[x * 3 + 1] = src[x] >>  8;
+      dest_data[x * 3 + 2] = src[x];
+    }
+
+    src_data += src_stride;
+    dest_data += dest_stride;
+  }
 }
 
+/**
+ * gdk_pixbuf_get_from_surface:
+ * @surface: surface to copy from
+ * @src_x: Source X coordinate within @surface
+ * @src_y: Source Y coordinate within @surface
+ * @width: Width in pixels of region to get
+ * @height: Height in pixels of region to get
+ *
+ * Transfers image data from a #cairo_surface_t and converts it to an RGB(A)
+ * representation inside a #GdkPixbuf. This allows you to efficiently read
+ * individual pixels from cairo surfaces. For #GdkWindows, use
+ * gdk_pixbuf_get_from_window() instead.
+ *
+ * This function will create an RGB pixbuf with 8 bits per channel.
+ * The pixbuf will contain an alpha channel if the @surface contains one.
+ *
+ * Return value: (transfer full): A newly-created pixbuf with a reference
+ *     count of 1, or %NULL on error
+ */
 GdkPixbuf *
-gdk_pixbuf_rgba_from_drawable (GdkWindow * window, gint x, gint y, gint width,
-                              gint height)
+gdk_pixbuf_get_from_surface  (cairo_surface_t *surface,
+                              gint             src_x,
+                              gint             src_y,
+                              gint             width,
+                              gint             height)
 {
-  return gdk_pixbuf_from_drawable_core (window, x, y, width, height, 1);
+  cairo_content_t content;
+  GdkPixbuf *dest;
+
+  /* General sanity checks */
+  g_return_val_if_fail (surface != NULL, NULL);
+  g_return_val_if_fail (width > 0 && height > 0, NULL);
+
+  content = cairo_surface_get_content (surface) | CAIRO_CONTENT_COLOR;
+  dest = gdk_pixbuf_new (GDK_COLORSPACE_RGB,
+                         !!(content & CAIRO_CONTENT_ALPHA),
+                         8,
+                         width, height);
+
+  surface = gdk_cairo_surface_coerce_to_image (surface, content,
+                                               src_x, src_y,
+                                               width, height);
+  cairo_surface_flush (surface);
+  if (cairo_surface_status (surface) || dest == NULL)
+    {
+      cairo_surface_destroy (surface);
+      return NULL;
+    }
+
+  if (gdk_pixbuf_get_has_alpha (dest))
+    convert_alpha (gdk_pixbuf_get_pixels (dest),
+                   gdk_pixbuf_get_rowstride (dest),
+                   cairo_image_surface_get_data (surface),
+                   cairo_image_surface_get_stride (surface),
+                   0, 0,
+                   width, height);
+  else
+    convert_no_alpha (gdk_pixbuf_get_pixels (dest),
+                      gdk_pixbuf_get_rowstride (dest),
+                      cairo_image_surface_get_data (surface),
+                      cairo_image_surface_get_stride (surface),
+                      0, 0,
+                      width, height);
+
+  cairo_surface_destroy (surface);
+  return dest;
 }