netsurf/riscos/gif.c
Philip Pemberton bedeee808c [project @ 2003-06-05 13:24:28 by philpem]
Added GIF decode support

svn path=/import/netsurf/; revision=161
2003-06-05 13:24:28 +00:00

330 lines
10 KiB
C

/*******************
* 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);
}