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gif.c
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gif.c
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#include "algif.h"
#include "lzw.h"
#include <stdlib.h>
#include <string.h>
GIF_ANIMATION *
algif_create_raw_animation (int frames_count)
{
GIF_ANIMATION *gif = calloc (1, sizeof *gif);
/* Create frames. */
gif->frames_count = frames_count;
gif->frames = calloc (gif->frames_count, sizeof *gif->frames);
return gif;
}
/* Destroy a complete gif, including all frames. */
void
algif_destroy_raw_animation (GIF_ANIMATION *gif)
{
int i;
for (i = 0; i < gif->frames_count; i++)
{
GIF_FRAME *frame = gif->frames + i;
if (frame->bitmap_8_bit)
destroy_bitmap (frame->bitmap_8_bit);
}
if (gif->store)
destroy_bitmap (gif->store);
free (gif->frames);
free (gif);
}
static void
write_palette (PACKFILE *file, GIF_PALETTE *palette, int bits)
{
int i;
for (i = 0; i < (1 << bits); i++)
{
pack_putc (palette->colors[i].r, file);
pack_putc (palette->colors[i].g, file);
pack_putc (palette->colors[i].b, file);
}
}
static void
read_palette (PACKFILE * file, GIF_PALETTE *palette)
{
int i;
for (i = 0; i < palette->colors_count; i++)
{
palette->colors[i].r = pack_getc (file);
palette->colors[i].g = pack_getc (file);
palette->colors[i].b = pack_getc (file);
}
}
/*
* Compresses all the frames in the animation and writes to a gif file.
* Nothing else like extensions or comments is written.
*
* Returns 0 on success.
*
* Note: All bitmaps must have a color depth of 8.
*/
int
algif_save_raw_animation (const char *filename, GIF_ANIMATION *gif)
{
int frame;
int i, j;
PACKFILE *file;
file = pack_fopen (filename, "w");
if (!file)
return -1;
pack_fwrite ("GIF89a", 6, file);
pack_iputw (gif->width, file);
pack_iputw (gif->height, file);
/* 7 global palette
* 456 color richness
* 3 sorted
* 012 palette bits
*/
for (i = 1, j = 0; i < gif->palette.colors_count; i *= 2, j++);
pack_putc ((j ? 128 : 0) + 64 + 32 + 16 + (j ? j - 1 : 0), file);
pack_putc (gif->background_index, file);
pack_putc (0, file); /* No aspect ratio. */
if (j)
write_palette (file, &gif->palette, j);
if (gif->loop != -1)
/* Loop count extension. */
{
pack_putc (0x21, file); /* Extension Introducer. */
pack_putc (0xff, file); /* Application Extension. */
pack_putc (11, file); /* Size. */
pack_fwrite ("NETSCAPE2.0", 11, file);
pack_putc (3, file); /* Size. */
pack_putc (1, file);
pack_iputw (gif->loop, file);
pack_putc (0, file);
}
for (frame = 0; frame < gif->frames_count; frame++)
{
int w = gif->frames[frame].bitmap_8_bit->w;
int h = gif->frames[frame].bitmap_8_bit->h;
pack_putc (0x21, file); /* Extension Introducer. */
pack_putc (0xf9, file); /* Graphic Control Extension. */
pack_putc (4, file); /* Size. */
/* Disposal method, and enable transparency. */
i = gif->frames[frame].disposal_method << 2;
if (gif->frames[frame].transparent_index != -1)
i |= 1;
pack_putc (i, file);
pack_iputw (gif->frames[frame].duration, file); /* In 1/100th seconds. */
if (gif->frames[frame].transparent_index != -1)
pack_putc (gif->frames[frame].transparent_index, file); /* Transparent color index. */
else
pack_putc (0, file);
pack_putc (0x00, file); /* Terminator. */
pack_putc (0x2c, file); /* Image Descriptor. */
pack_iputw (gif->frames[frame].xoff, file);
pack_iputw (gif->frames[frame].yoff, file);
pack_iputw (w, file);
pack_iputw (h, file);
/* 7: local palette
* 6: interlaced
* 5: sorted
* 012: palette bits
*/
for (i = 1, j = 0; i < gif->frames[frame].palette.colors_count; i *= 2, j++);
pack_putc ((j ? 128 : 0) + (j ? j - 1 : 0), file);
if (j)
write_palette (file, &gif->frames[frame].palette, j);
LZW_encode (file, gif->frames[frame].bitmap_8_bit);
pack_putc (0x00, file); /* Terminator. */
}
pack_putc (0x3b, file); /* Trailer. */
pack_fclose (file);
return 0;
}
static void
deinterlace (BITMAP *bmp)
{
BITMAP *n = create_bitmap_ex (bitmap_color_depth (bmp), bmp->w, bmp->h);
int y, i = 0;
for (y = 0; y < n->h; y += 8)
{
blit (bmp, n, 0, i++, 0, y, n->w, 1);
}
for (y = 4; y < n->h; y += 8)
{
blit (bmp, n, 0, i++, 0, y, n->w, 1);
}
for (y = 2; y < n->h; y += 4)
{
blit (bmp, n, 0, i++, 0, y, n->w, 1);
}
for (y = 1; y < n->h; y += 2)
{
blit (bmp, n, 0, i++, 0, y, n->w, 1);
}
blit (n, bmp, 0, 0, 0, 0, n->w, n->h);
destroy_bitmap (n);
}
static GIF_ANIMATION *
load_object (PACKFILE * file, long size)
{
int version;
BITMAP *bmp = NULL;
int i, j;
GIF_ANIMATION *gif = calloc (1, sizeof *gif);
GIF_FRAME frame;
int have_global_palette = 0;
(void) size;
gif->frames_count = 0;
/* is it really a GIF? */
if (pack_getc (file) != 'G')
goto error;
if (pack_getc (file) != 'I')
goto error;
if (pack_getc (file) != 'F')
goto error;
if (pack_getc (file) != '8')
goto error;
/* '7' or '9', for 87a or 89a. */
version = pack_getc (file);
if (version != '7' && version != '9')
goto error;
if (pack_getc (file) != 'a')
goto error;
gif->width = pack_igetw (file);
gif->height = pack_igetw (file);
i = pack_getc (file);
/* Global color table? */
if (i & 128)
gif->palette.colors_count = 1 << ((i & 7) + 1);
else
gif->palette.colors_count = 0;
/* Background color is only valid with a global palette. */
gif->background_index = pack_getc (file);
/* Skip aspect ratio. */
pack_fseek (file, 1);
if (gif->palette.colors_count)
{
read_palette (file, &gif->palette);
have_global_palette = 1;
}
memset(&frame, 0, sizeof frame); /* For first frame. */
frame.transparent_index = -1;
do
{
i = pack_getc (file);
switch (i)
{
case 0x2c: /* Image Descriptor */
{
int w, h;
int interlaced = 0;
frame.xoff = pack_igetw (file);
frame.yoff = pack_igetw (file);
w = pack_igetw (file);
h = pack_igetw (file);
bmp = create_bitmap_ex (8, w, h);
if (!bmp)
goto error;
i = pack_getc (file);
/* Local palette. */
if (i & 128)
{
frame.palette.colors_count = 1 << ((i & 7) + 1);
read_palette (file, &frame.palette);
}
else
{
frame.palette.colors_count = 0;
}
if (i & 64)
interlaced = 1;
if (LZW_decode (file, bmp))
goto error;
if (interlaced)
deinterlace (bmp);
frame.bitmap_8_bit = bmp;
bmp = NULL;
gif->frames_count++;
gif->frames =
realloc (gif->frames,
gif->frames_count * sizeof *gif->frames);
gif->frames[gif->frames_count - 1] = frame;
memset(&frame, 0, sizeof frame); /* For next frame. */
frame.transparent_index = -1;
break;
}
case 0x21: /* Extension Introducer. */
j = pack_getc (file); /* Extension Type. */
i = pack_getc (file); /* Size. */
if (j == 0xf9) /* Graphic Control Extension. */
{
/* size must be 4 */
if (i != 4)
goto error;
i = pack_getc (file);
frame.disposal_method = (i >> 2) & 7;
frame.duration = pack_igetw (file);
if (i & 1) /* Transparency? */
{
frame.transparent_index = pack_getc (file);
}
else
{
pack_fseek (file, 1);
frame.transparent_index = -1;
}
i = pack_getc (file); /* Size. */
}
/* Application Extension. */
else if (j == 0xff)
{
if (i == 11)
{
char name[12];
pack_fread (name, 11, file);
i = pack_getc (file); /* Size. */
name[11] = '\0';
if (!strcmp (name, "NETSCAPE2.0"))
{
if (i == 3)
{
j = pack_getc (file);
gif->loop = pack_igetw (file);
if (j != 1)
gif->loop = 0;
i = pack_getc (file); /* Size. */
}
}
}
}
/* Possibly more blocks until terminator block (0). */
while (i)
{
pack_fseek (file, i);
i = pack_getc (file);
}
break;
case 0x3b:
/* GIF Trailer. */
pack_fclose (file);
return gif;
}
}
while (TRUE);
error:
if (file)
pack_fclose (file);
if (gif)
algif_destroy_raw_animation (gif);
if (bmp)
destroy_bitmap (bmp);
return NULL;
}
/*
* Allocates and reads a GIF_ANIMATION structure, filling in all the
* frames found in the file. On error, nothing is allocated, and NULL is
* returned. No extensions or comments are read in. If the gif contains
* a transparency index, and it is no 0, it is swapped with 0 - so index
* 0 will be the transparent color. There is no way to know when a file
* contained no transparency originally. Frame duration is specified in
* 1/100th seconds.
*
* All bitmaps will have a color depth of 8.
*/
GIF_ANIMATION *
algif_load_raw_animation (const char *filename)
{
PACKFILE *file;
GIF_ANIMATION *gif = NULL;
file = pack_fopen (filename, "r");
if (file)
gif = load_object (file, 0);
return gif;
}
GIF_ANIMATION * algif_load_raw_animation_packfile(PACKFILE * file){
GIF_ANIMATION *gif = NULL;
gif = load_object (file, 0);
return gif;
}
static int
get_rgbcolor (RGB *rgb)
{
return makecol (rgb->r, rgb->g, rgb->b);
}
/* Renders the next frame in a GIF animation to the specified bitmap and
* the given position. You need to call this in order on the same
* destination for frames [0..gif->frames_count - 1] to properly render all
* the frames in the GIF.
*/
void
algif_render_frame (GIF_ANIMATION *gif, BITMAP *bitmap, int frame, int xpos,
int ypos)
{
int x, y, w, h;
GIF_FRAME *f = &gif->frames[frame];
GIF_PALETTE *pal;
if (frame == 0)
rectfill (bitmap, xpos, ypos, xpos + gif->width - 1,
ypos + gif->height - 1, bitmap_mask_color (bitmap));
else
{
GIF_FRAME *p = &gif->frames[frame - 1];
if (p->disposal_method == 2)
rectfill (bitmap, xpos + p->xoff, ypos + p->yoff,
xpos + p->xoff + p->bitmap_8_bit->w - 1,
ypos + p->yoff + p->bitmap_8_bit->h - 1,
bitmap_mask_color (bitmap));
else if (p->disposal_method == 3 && gif->store)
{
blit (gif->store, bitmap, 0, 0, xpos + p->xoff, ypos + p->yoff,
gif->store->w, gif->store->h);
destroy_bitmap (gif->store);
gif->store = NULL;
}
}
w = f->bitmap_8_bit->w;
h = f->bitmap_8_bit->h;
if (f->disposal_method == 3)
{
if (gif->store)
destroy_bitmap (gif->store);
gif->store = create_bitmap_ex (bitmap_color_depth (bitmap), w, h);
blit (bitmap, gif->store, xpos + f->xoff, ypos + f->yoff, 0, 0, w, h);
}
pal = &gif->frames[frame].palette;
if (pal->colors_count == 0)
pal = &gif->palette;
//int i;
//for (i = 0; i < pal->colors_count; i++)
// printf("%d: %d %d %d\n", i, pal->colors[i].r, pal->colors[i].g, pal->colors[i].b);
for (y = 0; y < h; y++)
{
for (x = 0; x < w; x++)
{
int c = getpixel (f->bitmap_8_bit, x, y);
if (c != f->transparent_index)
{
putpixel (bitmap, xpos + f->xoff + x, ypos + f->yoff + y,
get_rgbcolor (&pal->colors[c]));
}
}
}
}
/* Registers gif as bitmap and datafile type. */
void
algif_init (void)
{
register_bitmap_file_type ("gif", load_gif, save_gif);
register_datafile_object (DAT_GIF,
(void *(*)(PACKFILE *, long)) load_object,
(void (*)(void *))
algif_destroy_raw_animation);
}

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