[project @ 2003-06-05 13:24:28 by philpem]

Added GIF decode support

svn path=/import/netsurf/; revision=161

1 files changed, 329 insertions, 0 deletions

diff --git a/riscos/gif.c b/riscos/gif.c
new file mode 100644
index 000000000..b2a9768b3
--- /dev/null
+++ b/riscos/gif.c
@@ -0,0 +1,329 @@
+/*******************
+ * GIF loader for Netsurf
+ * Developed by Philip Pemberton for the Netsurf project
+ *
+ * Yes, this is an evil hack. You will not be tested on your understanding of
+ * this code. Beware - dragons lurketh here.
+ *
+ * TO-DO:
+ *   Add support for GIF transparency
+ *   Add better error handling
+ *      - especially where bad GIFs are concerned.
+ *
+ * $Id: gif.c,v 1.1 2003/06/05 13:24:28 philpem Exp $
+ */
+
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+#include "libungif/gif_lib.h"
+#include "oslib/colourtrans.h"
+#include "oslib/os.h"
+#include "oslib/osspriteop.h"
+#include "netsurf/content/content.h"
+#include "netsurf/riscos/gif.h"
+#include "netsurf/utils/log.h"
+#include "netsurf/utils/utils.h"
+
+/* maps colours to 256 mode colour numbers */
+static os_colour_number colour_table[4096];
+
+static int
+    InterlacedOffset[] = { 0, 4, 2, 1 }, /* The way Interlaced image should. */
+    InterlacedJumps[] = { 8, 8, 4, 2 };    /* be read - offsets and jumps... */
+
+
+void nsgif_init(void)
+{
+  // Generate a colour lookup table
+  // TODO: Use the PNG colour table instead of the GIF table...
+	unsigned int red, green, blue;
+	for (red = 0; red != 0xf; red++)
+		for (green = 0; green != 0xf; green++)
+			for (blue = 0; blue != 0xf; blue++)
+				colour_table[red << 8 | green << 4 | blue] =
+					colourtrans_return_colour_number_for_mode(
+						blue << 28 | blue << 24 |
+						green << 20 | green << 16 |
+						red << 12 | red << 8, 21, 0);
+}
+
+// Called when Netsurf wants us to prepare to decode a GIF
+void nsgif_create(struct content *c)
+{
+  // Clear the sprite area
+  c->data.gif.sprite_area = 0;
+
+  // Allocate some memory for the GIF file
+  c->data.gif.data = xcalloc(0, 1);
+  // Set the length and buffer position to zero (we haven't loaded any data
+  // yet)
+  c->data.gif.length = 0;
+  c->data.gif.buffer_pos = 0;
+
+  LOG(("gif object created"));
+}
+
+// Called when Netsurf has got some more data for us
+void nsgif_process_data(struct content *c, char *data, unsigned long size)
+{
+  // We've just been given some more data!
+  // Reallocate the memory block
+  c->data.gif.data = xrealloc(c->data.gif.data, c->data.gif.length + size);
+  // Copy the new data into our buffer
+  memcpy(c->data.gif.data + c->data.gif.length, data, size);
+  // Update the data length variables
+  c->data.gif.length += size;
+  c->size += size;
+}
+
+// This is the callback for the GIF loader. It grabs some data from the buffer
+// and hands it over to Libungif.
+// Returns the number of bytes successfully read from the buffer
+int nsgif_input_callback(GifFileType *giffile, GifByteType *data, int length)
+{
+  struct content *c;
+
+  // We need to set up the content block pointer first
+  c = (struct content *)giffile->UserData;
+
+  // Now check that there's enough data in the buffer
+  if ((c->data.gif.buffer_pos + length) > c->data.gif.length)
+  {
+    // We don't have enough data in the buffer. Give libungif the data we've
+    // got.
+    memcpy(data, &c->data.gif.data[c->data.gif.buffer_pos], (c->data.gif.length - c->data.gif.buffer_pos));
+    c->data.gif.buffer_pos += length;
+    return (c->data.gif.length - c->data.gif.buffer_pos);
+  }
+
+  // Well, we've got enough data. Give libungif as much as it wants.
+  memcpy(data, &c->data.gif.data[c->data.gif.buffer_pos], length);
+  c->data.gif.buffer_pos += length;
+
+  return length;
+}
+
+// Called when Netsurf wants us to convert the image
+int nsgif_convert(struct content *c, unsigned int width, unsigned int height)
+{
+  char *row, **row_pointers;
+  int i, j, bit_depth, color_type, log2bpp, interlace;
+  unsigned int rowbytes, sprite_size;
+  unsigned long width, height;
+  os_palette *palette;
+  os_sprite_palette *sprite_palette;
+  osspriteop_area *sprite_area;
+  osspriteop_header *sprite;
+  // The next three lines are for vars. used by the gif decoding engine
+  int recordtype, cur_row, extcode, count, got_image_data;
+  GifByteType *extension;
+  GifColorType *colormap;
+
+  LOG(("Opening GIF file"));
+
+  got_image_data = 0;   // we haven't read any image data yet
+
+  // Now decode the GIF
+  c->data.gif.giffile = DGifOpen(c, &nsgif_input_callback);
+//  assert(c->data.gif.giffile != NULL);
+  if (c->data.gif.giffile == NULL)
+  {
+    LOG(("ERROR: giffile is null! error %d", GifLastError()));
+//    assert(1 == 2);
+    return 0;  // more graceful exit
+  }
+  // TODO: ^^^ Error checking
+
+  // Start creating the sprite
+  width = c->data.gif.giffile->SWidth;
+  height = c->data.gif.giffile->SHeight;
+
+  LOG(("gif image width = %d, height = %d", width, height));
+
+  sprite_size = sizeof(*sprite_area) + sizeof(*sprite);
+
+  // GIFs can't be more than 256 colours (8 bits).
+  sprite_size += 8 * 256 + height * ((width + 3) & ~3u);
+
+  sprite_area = xcalloc(sprite_size + 1000, 1);
+  sprite_area->size = sprite_size;
+  sprite_area->sprite_count = 1;
+  sprite_area->first = sizeof(*sprite_area);
+  sprite_area->used = sprite_size;
+  sprite = (osspriteop_header *) (sprite_area + 1);
+  sprite->size = sprite_size - sizeof(*sprite_area);
+  strcpy(sprite->name, "gif");
+  sprite->height = height -1;
+  c->data.gif.sprite_area = sprite_area;
+  sprite->width = ((width + 3) & ~3u) / 4 - 1;
+  sprite->left_bit = 0;
+  sprite->right_bit = (8 * (((width - 1) % 4) + 1)) -1;
+  sprite->mask = sprite->image = sizeof(*sprite) + 8 * 256;
+  sprite->mode = (os_mode) 21;
+  sprite_palette = (os_sprite_palette *) (sprite + 1);
+  c->data.gif.sprite_image = ((char *) sprite) + sprite->image;
+  c->width = width;
+  c->height = height;
+
+  do
+  {
+    if (DGifGetRecordType(c->data.gif.giffile, &recordtype) == GIF_ERROR)
+    {
+      LOG(("gif error %d", GifLastError()));
+//      assert(1 == 2);
+      return(0); // more graceful exit
+    }
+    // TODO: ^^^ better error checking
+    switch (recordtype)
+    {
+      case IMAGE_DESC_RECORD_TYPE:
+        // The next line is used to handle animated GIFs
+        if (!got_image_data)
+        {
+          assert(DGifGetImageDesc(c->data.gif.giffile) != GIF_ERROR);
+        // TODO: ^^^ better error checking
+
+          c->data.gif.sprite_area = sprite_area;
+
+          if (c->data.gif.giffile->Image.Interlace)
+          {
+            // The image is interlaced, therefore we need to perform four
+            // passes over the image
+            for (count = i = 0; i < 4; i++)
+            {
+              LOG(("Interlaced GIF file"));
+              for (j=InterlacedOffset[i]; j < height; j += InterlacedJumps[i])
+              {
+                LOG(("gif line %d", count));
+                count++;
+                assert (DGifGetLine(c->data.gif.giffile, c->data.gif.sprite_image + j * ((c->width + 3) & ~3u), width) != GIF_ERROR);
+                // TODO: ^^^ better error checking
+              }
+            }
+          }
+          else
+          {
+            LOG(("running DGifGetLine"));
+            for (i=0; i<height; i++)
+            {
+  //            assert(DGifGetLine(c->data.gif.giffile, c->data.gif.sprite_image + i * ((c->width + 3) & ~3u), width) != GIF_ERROR);
+              if (DGifGetLine(c->data.gif.giffile, c->data.gif.sprite_image + i * ((c->width + 3) & ~3u), width) == GIF_ERROR)
+              {
+                LOG(("error: gif line %d - error %d", i, GifLastError()));
+                LOG(("exp height = %d, width = %d", height, width));
+                assert(1 == 2);
+              }
+              // TODO: ^^^ better error checking
+              LOG(("gif line %d", i));
+            }
+          }
+          got_image_data = -1;
+        } else recordtype = TERMINATE_RECORD_TYPE;
+        break;
+      case EXTENSION_RECORD_TYPE:
+        // Skip any extension blocks in the file
+        assert (DGifGetExtension(c->data.gif.giffile, &extcode, &extension) != GIF_ERROR);
+        // TODO: ^^^ better error checking
+        while (extension != NULL)
+        {
+          DGifGetExtensionNext(c->data.gif.giffile, &extension);
+          // TODO: ^^^ better error checking
+        }
+        break;
+      case TERMINATE_RECORD_TYPE:
+        break;
+      default:       // Should be trapped by DGifGetRecordType
+        break;
+    }
+  } while (recordtype != TERMINATE_RECORD_TYPE);
+
+  LOG(("all done"));
+
+/*
+   And now for the obligatory quote from "The Matrix"
+   "Before you can bend the spoon, you must realise the truth."
+   "And what is the truth?"
+   "There is no spoon."
+ */
+
+//		for (i = 0; i != palette_size; i++)
+//			sprite_palette->entries[i].on =
+//			sprite_palette->entries[i].off =
+//					png_palette[i].blue << 24 |
+//					png_palette[i].green << 16 |
+//					png_palette[i].red << 8 | 16;
+
+  // FIXME: 255 is the size of the GIF palette
+  // FIXME: Load the palette instead of creating a greyscale palette
+
+  colormap = (c->data.gif.giffile->Image.ColorMap ?
+              c->data.gif.giffile->Image.ColorMap->Colors :
+              c->data.gif.giffile->SColorMap->Colors);
+
+  for (i=0; i != 255; i++)
+    sprite_palette->entries[i].on =
+    sprite_palette->entries[i].off =
+      (colormap[i].Blue << 24) |
+      (colormap[i].Green << 16) |
+      (colormap[i].Red << 8) |
+      16;
+
+  DGifCloseFile(c->data.gif.giffile);
+
+  c->width = width;
+  c->height = height;
+
+  c->title = xcalloc(100, 1);
+  sprintf(c->title, "GIF image (%ux%u)", c->width, c->height);
+
+//  xosspriteop_save_sprite_file(osspriteop_USER_AREA, c->data.gif.sprite_area,
+//          "gif");
+  return 0;
+}
+
+
+void nsgif_revive(struct content *c, unsigned int width, unsigned int height)
+{
+}
+
+
+void nsgif_reformat(struct content *c, unsigned int width, unsigned int height)
+{
+}
+
+// Called when Netsurf is finished with us
+void nsgif_destroy(struct content *c)
+{
+  xfree(c->title);
+  xfree(c->data.gif.sprite_area);
+  xfree(c->data.gif.data);
+}
+
+// Called when Netsurf wants us to draw the image
+void nsgif_redraw(struct content *c, long x, long y,
+		unsigned long width, unsigned long height)
+{
+	/* TODO: scale to width, height */
+	int size;
+	osspriteop_trans_tab *table;
+
+  LOG(("Redraw fired"));
+
+	xcolourtrans_generate_table_for_sprite(c->data.gif.sprite_area,
+			(osspriteop_id) (c->data.gif.sprite_area + 1),
+			colourtrans_CURRENT_MODE, colourtrans_CURRENT_PALETTE,
+			0, colourtrans_GIVEN_SPRITE, 0, 0, &size);
+	table = xcalloc(size, 1);
+	xcolourtrans_generate_table_for_sprite(c->data.gif.sprite_area,
+			(osspriteop_id) (c->data.gif.sprite_area + 1),
+			colourtrans_CURRENT_MODE, colourtrans_CURRENT_PALETTE,
+			table, colourtrans_GIVEN_SPRITE, 0, 0, 0);
+
+	xosspriteop_put_sprite_scaled(osspriteop_PTR,
+			c->data.gif.sprite_area,
+			(osspriteop_id) (c->data.gif.sprite_area + 1),
+			x, y, 0, 0, table);
+
+	xfree(table);
+}