[Emacs-diffs] /srv/bzr/emacs/trunk r104519: * src/image.c (gif_load): Implement gif89a spec "no disposal" method.

[Chong Yidong]

------------------------------------------------------------
revno: 104519
committer: Chong Yidong <address@hidden>
branch nick: trunk
timestamp: Mon 2011-06-06 17:03:43 -0400
message:
  * src/image.c (gif_load): Implement gif89a spec "no disposal" method.
modified:
  src/ChangeLog
  src/image.c

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2011-06-06 19:43:39 +0000
+++ b/src/ChangeLog     2011-06-06 21:03:43 +0000
@@ -1,3 +1,7 @@
+2011-06-06  Chong Yidong  <address@hidden>
+
+       * image.c (gif_load): Implement gif89a spec "no disposal" method.
+
 2011-06-06  Paul Eggert  <address@hidden>
 
        Cons<->int and similar integer overflow fixes (Bug#8794).

=== modified file 'src/image.c'
--- a/src/image.c       2011-06-06 19:43:39 +0000
+++ b/src/image.c       2011-06-06 21:03:43 +0000
@@ -7074,22 +7074,19 @@
 static int
 gif_load (struct frame *f, struct image *img)
 {
-  Lisp_Object file, specified_file;
-  Lisp_Object specified_data;
-  int rc, width, height, x, y, i;
-  boolean transparent_p = 0;
+  Lisp_Object file;
+  int rc, width, height, x, y, i, j;
   XImagePtr ximg;
   ColorMapObject *gif_color_map;
   unsigned long pixel_colors[256];
   GifFileType *gif;
-  Lisp_Object image;
-  int ino, image_height, image_width;
+  int image_height, image_width;
   gif_memory_source memsrc;
-  unsigned char *raster;
-  unsigned int transparency_color_index IF_LINT (= 0);
-
-  specified_file = image_spec_value (img->spec, QCfile, NULL);
-  specified_data = image_spec_value (img->spec, QCdata, NULL);
+  Lisp_Object specified_bg = image_spec_value (img->spec, QCbackground, NULL);
+  Lisp_Object specified_file = image_spec_value (img->spec, QCfile, NULL);
+  Lisp_Object specified_data = image_spec_value (img->spec, QCdata, NULL);
+  unsigned long bgcolor = 0;
+  int idx;
 
   if (NILP (specified_data))
     {
@@ -7140,40 +7137,31 @@
 
   /* Read entire contents.  */
   rc = fn_DGifSlurp (gif);
-  if (rc == GIF_ERROR)
+  if (rc == GIF_ERROR || gif->ImageCount <= 0)
     {
       image_error ("Error reading `%s'", img->spec, Qnil);
       fn_DGifCloseFile (gif);
       return 0;
     }
 
-  image = image_spec_value (img->spec, QCindex, NULL);
-  ino = INTEGERP (image) ? XFASTINT (image) : 0;
-  if (ino >= gif->ImageCount)
-    {
-      image_error ("Invalid image number `%s' in image `%s'",
-                  image, img->spec);
-      fn_DGifCloseFile (gif);
-      return 0;
-    }
-
-  for (i = 0; i < gif->SavedImages[ino].ExtensionBlockCount; i++)
-    if ((gif->SavedImages[ino].ExtensionBlocks[i].Function
-        == GIF_LOCAL_DESCRIPTOR_EXTENSION)
-       && gif->SavedImages[ino].ExtensionBlocks[i].ByteCount == 4
-       /* Transparency enabled?  */
-       && gif->SavedImages[ino].ExtensionBlocks[i].Bytes[0] & 1)
+  /* Which sub-image are we to display?  */
+  {
+    Lisp_Object index = image_spec_value (img->spec, QCindex, NULL);
+    idx = INTEGERP (index) ? XFASTINT (index) : 0;
+    if (idx < 0 || idx >= gif->ImageCount)
       {
-       transparent_p = 1;
-       transparency_color_index
-         = (unsigned char) gif->SavedImages[ino].ExtensionBlocks[i].Bytes[3];
+       image_error ("Invalid image number `%s' in image `%s'",
+                    index, img->spec);
+       fn_DGifCloseFile (gif);
+       return 0;
       }
+  }
 
-  img->corners[TOP_CORNER] = gif->SavedImages[ino].ImageDesc.Top;
-  img->corners[LEFT_CORNER] = gif->SavedImages[ino].ImageDesc.Left;
-  image_height = gif->SavedImages[ino].ImageDesc.Height;
+  img->corners[TOP_CORNER] = gif->SavedImages[idx].ImageDesc.Top;
+  img->corners[LEFT_CORNER] = gif->SavedImages[idx].ImageDesc.Left;
+  image_height = gif->SavedImages[idx].ImageDesc.Height;
   img->corners[BOT_CORNER] = img->corners[TOP_CORNER] + image_height;
-  image_width = gif->SavedImages[ino].ImageDesc.Width;
+  image_width = gif->SavedImages[idx].ImageDesc.Width;
   img->corners[RIGHT_CORNER] = img->corners[LEFT_CORNER] + image_width;
 
   width = img->width = max (gif->SWidth,
@@ -7197,44 +7185,10 @@
       return 0;
     }
 
-  /* Allocate colors.  */
-  gif_color_map = gif->SavedImages[ino].ImageDesc.ColorMap;
-  if (!gif_color_map)
-    gif_color_map = gif->SColorMap;
-  init_color_table ();
-  memset (pixel_colors, 0, sizeof pixel_colors);
-
-  if (gif_color_map)
-    for (i = 0; i < gif_color_map->ColorCount; ++i)
-      {
-       if (transparent_p && transparency_color_index == i)
-         {
-           Lisp_Object specified_bg
-             = image_spec_value (img->spec, QCbackground, NULL);
-           pixel_colors[i] = STRINGP (specified_bg)
-             ? x_alloc_image_color (f, img, specified_bg,
-                                    FRAME_BACKGROUND_PIXEL (f))
-             : FRAME_BACKGROUND_PIXEL (f);
-         }
-       else
-         {
-           int r = gif_color_map->Colors[i].Red << 8;
-           int g = gif_color_map->Colors[i].Green << 8;
-           int b = gif_color_map->Colors[i].Blue << 8;
-           pixel_colors[i] = lookup_rgb_color (f, r, g, b);
-         }
-      }
-
-#ifdef COLOR_TABLE_SUPPORT
-  img->colors = colors_in_color_table (&img->ncolors);
-  free_color_table ();
-#endif /* COLOR_TABLE_SUPPORT */
-
-  /* Clear the part of the screen image that are not covered by
-     the image from the GIF file.  Full animated GIF support
-     requires more than can be done here (see the gif89 spec,
-     disposal methods).  Let's simply assume that the part
-     not covered by a sub-image is in the frame's background color.  */
+  /* Clear the part of the screen image not covered by the image.
+     Full animated GIF support requires more here (see the gif89 spec,
+     disposal methods).  Let's simply assume that the part not covered
+     by a sub-image is in the frame's background color.  */
   for (y = 0; y < img->corners[TOP_CORNER]; ++y)
     for (x = 0; x < width; ++x)
       XPutPixel (ximg, x, y, FRAME_BACKGROUND_PIXEL (f));
@@ -7251,55 +7205,119 @@
        XPutPixel (ximg, x, y, FRAME_BACKGROUND_PIXEL (f));
     }
 
-  /* Read the GIF image into the X image.  We use a local variable
-     `raster' here because RasterBits below is a char *, and invites
-     problems with bytes >= 0x80.  */
-  raster = (unsigned char *) gif->SavedImages[ino].RasterBits;
-
-  if (gif->SavedImages[ino].ImageDesc.Interlace)
+  /* Read the GIF image into the X image.   */
+
+  /* FIXME: With the current implementation, loading an animated gif
+     is quadratic in the number of animation frames, since each frame
+     is a separate struct image.  We must provide a way for a single
+     gif_load call to construct and save all animation frames.  */
+
+  init_color_table ();
+  if (STRINGP (specified_bg))
+    bgcolor = x_alloc_image_color (f, img, specified_bg,
+                                  FRAME_BACKGROUND_PIXEL (f));
+  for (j = 0; j <= idx; ++j)
     {
-      int pass;
-      int row = interlace_start[0];
-
-      pass = 0;
-
-      for (y = 0; y < image_height; y++)
+      /* We use a local variable `raster' here because RasterBits is a
+        char *, which invites problems with bytes >= 0x80.  */
+      struct SavedImage *subimage = gif->SavedImages + j;
+      unsigned char *raster = (unsigned char *) subimage->RasterBits;
+      int transparency_color_index = -1;
+      int disposal = 0;
+
+      /* Find the Graphic Control Extension block for this sub-image.
+        Extract the disposal method and transparency color.  */
+      for (i = 0; i < subimage->ExtensionBlockCount; i++)
        {
-         if (row >= image_height)
-           {
-             row = interlace_start[++pass];
-             while (row >= image_height)
-               row = interlace_start[++pass];
-           }
-
-         for (x = 0; x < image_width; x++)
-           {
-             int c = raster[(y * image_width) + x];
-             XPutPixel (ximg, x + img->corners[LEFT_CORNER],
-                        row + img->corners[TOP_CORNER], pixel_colors[c]);
-           }
-
-         row += interlace_increment[pass];
+         ExtensionBlock *extblock = subimage->ExtensionBlocks + i;
+
+         if ((extblock->Function == GIF_LOCAL_DESCRIPTOR_EXTENSION)
+             && extblock->ByteCount == 4
+             && extblock->Bytes[0] & 1)
+           {
+             /* From gif89a spec: 1 = "keep in place", 2 = "restore
+                to background".  Treat any other value like 2.  */
+             disposal = (extblock->Bytes[0] >> 2) & 7;
+             transparency_color_index = extblock->Bytes[3];
+             break;
+           }
        }
-    }
-  else
-    {
-      for (y = 0; y < image_height; ++y)
-       for (x = 0; x < image_width; ++x)
+
+      /* We can't "keep in place" the first subimage.  */
+      if (j == 0)
+       disposal = 2;
+
+      /* Allocate subimage colors.  */
+      memset (pixel_colors, 0, sizeof pixel_colors);
+      gif_color_map = subimage->ImageDesc.ColorMap;
+      if (!gif_color_map)
+       gif_color_map = gif->SColorMap;
+
+      if (gif_color_map)
+       for (i = 0; i < gif_color_map->ColorCount; ++i)
          {
-           int c = raster[y * image_width + x];
-           XPutPixel (ximg, x + img->corners[LEFT_CORNER],
-                      y + img->corners[TOP_CORNER], pixel_colors[c]);
+           if (transparency_color_index == i)
+             pixel_colors[i] = STRINGP (specified_bg)
+               ? bgcolor : FRAME_BACKGROUND_PIXEL (f);
+           else
+             {
+               int r = gif_color_map->Colors[i].Red << 8;
+               int g = gif_color_map->Colors[i].Green << 8;
+               int b = gif_color_map->Colors[i].Blue << 8;
+               pixel_colors[i] = lookup_rgb_color (f, r, g, b);
+             }
          }
+
+      /* Apply the pixel values.  */
+      if (gif->SavedImages[j].ImageDesc.Interlace)
+       {
+         int row, pass;
+
+         for (y = 0, row = interlace_start[0], pass = 0;
+              y < image_height;
+              y++, row += interlace_increment[pass])
+           {
+             if (row >= image_height)
+               {
+                 row = interlace_start[++pass];
+                 while (row >= image_height)
+                   row = interlace_start[++pass];
+               }
+
+             for (x = 0; x < image_width; x++)
+               {
+                 int c = raster[y * image_width + x];
+                 if (transparency_color_index != c || disposal != 1)
+                   XPutPixel (ximg, x + img->corners[LEFT_CORNER],
+                              row + img->corners[TOP_CORNER], pixel_colors[c]);
+               }
+           }
+       }
+      else
+       {
+         for (y = 0; y < image_height; ++y)
+           for (x = 0; x < image_width; ++x)
+             {
+               int c = raster[y * image_width + x];
+               if (transparency_color_index != c || disposal != 1)
+                 XPutPixel (ximg, x + img->corners[LEFT_CORNER],
+                            y + img->corners[TOP_CORNER], pixel_colors[c]);
+             }
+       }
     }
 
+#ifdef COLOR_TABLE_SUPPORT
+  img->colors = colors_in_color_table (&img->ncolors);
+  free_color_table ();
+#endif /* COLOR_TABLE_SUPPORT */
+
   /* Save GIF image extension data for `image-metadata'.
      Format is (count IMAGES extension-data (FUNCTION "BYTES" ...)).  */
   img->data.lisp_val = Qnil;
-  if (gif->SavedImages[ino].ExtensionBlockCount > 0)
+  if (gif->SavedImages[idx].ExtensionBlockCount > 0)
     {
-      ExtensionBlock *ext = gif->SavedImages[ino].ExtensionBlocks;
-      for (i = 0; i < gif->SavedImages[ino].ExtensionBlockCount; i++, ext++)
+      ExtensionBlock *ext = gif->SavedImages[idx].ExtensionBlocks;
+      for (i = 0; i < gif->SavedImages[idx].ExtensionBlockCount; i++, ext++)
        /* Append (... FUNCTION "BYTES") */
        img->data.lisp_val = Fcons (make_unibyte_string (ext->Bytes, 
ext->ByteCount),
                                    Fcons (make_number (ext->Function),