lots of lots of work. USE AT YOUR OWN RISK

This commit is contained in:
Jonathan Blandford 1999-11-02 01:17:41 +00:00
parent c3b9b0f7f4
commit 5dcc2ddd51

View File

@ -51,6 +51,19 @@
typedef unsigned char CMap[3][MAXCOLORMAPSIZE];
/* Possible states we can be in. */
enum {
GIF_START = 1,
GIF_GET_COLORMAP = 2,
GIF_GET_NEXT_STEP = 3,
GIF_GET_EXTENTION = 4,
GIF_GET_COLORMAP2 = 5,
GIF_PREPARE_LZW = 6,
GIF_GET_LZW = 7,
GIF_DONE = 8
};
typedef struct _Gif89 Gif89;
struct _Gif89
{
@ -63,6 +76,7 @@ struct _Gif89
typedef struct _GifContext GifContext;
struct _GifContext
{
int state; /* really only relevant for progressive loading */
unsigned int width;
unsigned int height;
CMap color_map;
@ -73,7 +87,6 @@ struct _GifContext
int gray_scale;
GdkPixbuf *pixbuf;
Gif89 gif89;
gint stage;
/* stuff per frame. As we only support the first one, not so
* relevant. But still needed */
@ -90,103 +103,207 @@ struct _GifContext
guchar *buf;
guint ptr;
guint size;
guint amount_needed;
/* our colormap context */
gint colormap_index;
gint colormap_flag;
/* our extension context */
guchar extension_label;
guchar extension_flag;
/* get block context */
guchar block_count;
guchar block_buf[256];
gint block_ptr;
/* our lwz context */
int lwz_fresh;
int lwz_code_size;
int lwz_set_code_size;
int lwz_max_code;
int lwz_max_code_size;
int lwz_firstcode;
int lwz_oldcode;
int lwz_clear_code;
int lwz_end_code;
int lwz_table[2][(1 << MAX_LWZ_BITS)];
int lwz_stack[(1 << (MAX_LWZ_BITS)) * 2];
int *lwz_sp;
gint lwz_fresh;
gint lwz_code_size;
guchar lwz_set_code_size;
gint lwz_max_code;
gint lwz_max_code_size;
gint lwz_firstcode;
gint lwz_oldcode;
gint lwz_clear_code;
gint lwz_end_code;
gint lwz_table[2][(1 << MAX_LWZ_BITS)];
gint lwz_stack[(1 << (MAX_LWZ_BITS)) * 2];
gint *lwz_sp;
};
static int ReadColorMap (GifContext *, int, CMap, int *);
static int DoExtension (GifContext *, int label);
static int GetDataBlock (GifContext *, unsigned char *);
static int GetCode (GifContext *, int, int);
static int LWZReadByte (GifContext *, int, int);
static void ReadImage (GifContext *context);
static int LWZReadByte (GifContext *);
static int
ReadOK (GifContext *context, guchar *buffer, size_t len)
{
static int count = 0;
count += len;
g_print ("size :%d\tcount :%d\n", len, count);
if (context->file)
return fread(buffer, len, 1, context->file) != 0;
else {
if ((context->size - context->ptr) < len) {
memcpy (buffer, context->buf + context->ptr, len);
context->ptr += len;
context->amount_needed = 0;
return 0;
}
context->amount_needed = len - (context->size - context->ptr);
}
return 1;
}
/*
* Return vals.
*
* for the gif_get* functions,
*-1 -> more bytes needed.
* 0 -> success
* 1 -> failure; abort the load
*/
/* Changes the stage to be GIF_GET_COLORMAP */
static void
gif_set_get_colormap (GifContext *context)
{
context->colormap_flag = TRUE;
context->colormap_index = 0;
context->state = GIF_GET_COLORMAP;
}
static void
gif_set_get_colormap2 (GifContext *context)
{
context->colormap_flag = TRUE;
context->colormap_index = 0;
context->state = GIF_GET_COLORMAP2;
}
static gint
gif_get_colormap (GifContext *context)
{
unsigned char rgb[3];
while (context->colormap_index < context->bit_pixel) {
if (!ReadOK (context, rgb, sizeof (rgb))) {
/*g_message (_("GIF: bad colormap\n"));*/
return -1;
}
context->color_map[CM_RED][context->colormap_index] = rgb[0];
context->color_map[CM_GREEN][context->colormap_index] = rgb[1];
context->color_map[CM_BLUE][context->colormap_index] = rgb[2];
context->colormap_flag &= (rgb[0] == rgb[1] && rgb[1] == rgb[2]);
context->colormap_index ++;
}
context->gray_scale = (context->colormap_flag) ? GRAYSCALE : COLOR;
return 0;
}
/*
* in order for this function to work, we need to perform some black magic.
* We want to return -1 to let the calling function know, as before, that it needs
* more bytes. If we return 0, we were able to successfully read all block->count bytes.
* Problem is, we don't want to reread block_count every time, so we check to see if
* context->block_count is 0 before we read in the function.
*
* As a result, context->block_count MUST be 0 the first time the get_data_block is called
* within a context.
*/
static int
ReadColorMap (GifContext *context,
int number,
CMap buffer,
int *format)
get_data_block (GifContext *context,
unsigned char *buf,
gint *empty_block)
{
int i;
unsigned char rgb[3];
int flag;
flag = TRUE;
for (i = 0; i < number; ++i) {
if (!ReadOK (context, rgb, sizeof (rgb))) {
/*g_message (_("GIF: bad colormap\n"));*/
return TRUE;
if (context->block_count == 0) {
if (!ReadOK (context, &context->block_count, 1)) {
return -1;
}
}
buffer[CM_RED][i] = rgb[0];
buffer[CM_GREEN][i] = rgb[1];
buffer[CM_BLUE][i] = rgb[2];
if (context->block_count == 0)
if (empty_block)
*empty_block = TRUE;
flag &= (rgb[0] == rgb[1] && rgb[1] == rgb[2]);
return 0;
if (!ReadOK (context, buf, context->block_count)) {
return -1;
}
*format = (flag) ? GRAYSCALE : COLOR;
return 0;
}
return FALSE;
static void
gif_set_get_extension (GifContext *context)
{
g_print ("getting the extension woooooo\n");
context->state = GIF_GET_EXTENTION;
context->extension_flag = TRUE;
context->extension_label = '\000';
context->block_count = 0;
context->block_ptr = 0;
}
static int
DoExtension (GifContext *context, int label)
gif_get_extension (GifContext *context)
{
static guchar buf[256];
gint retval;
gint empty_block = FALSE;
switch (label) {
g_print ("in gif_get_extension\n");
if (context->extension_flag) {
if (!context->extension_label) {
if (!ReadOK (context, &context->extension_label , 1)) {
return -1;
}
}
switch (context->extension_label) {
case 0xf9: /* Graphic Control Extension */
(void) GetDataBlock (context, (unsigned char *) buf);
context->gif89.disposal = (buf[0] >> 2) & 0x7;
context->gif89.input_flag = (buf[0] >> 1) & 0x1;
context->gif89.delay_time = LM_to_uint (buf[1], buf[2]);
retval = get_data_block (context, (unsigned char *) context->block_buf, NULL);
if (retval != 0)
return retval;
context->gif89.disposal = (context->block_buf[0] >> 2) & 0x7;
context->gif89.input_flag = (context->block_buf[0] >> 1) & 0x1;
context->gif89.delay_time = LM_to_uint (context->block_buf[1], context->block_buf[2]);
if (context->pixbuf == NULL) {
/* I only want to set the transparency if I haven't
* created the pixbuf yet. */
if ((buf[0] & 0x1) != 0)
context->gif89.transparent = buf[3];
if ((context->block_buf[0] & 0x1) != 0)
context->gif89.transparent = context->block_buf[3];
else
context->gif89.transparent = -1;
}
while (GetDataBlock (context, (unsigned char *) buf) != 0)
;
return FALSE;
break;
/* Now we've successfully loaded this one, we continue on our way */
context->extension_flag = FALSE;
default:
/* Unhandled extension */
break;
}
}
/* read all blocks, until I get an empty block */
/* not sure why, but it makes it work. -jrb */
do {
retval = get_data_block (context, (unsigned char *) context->block_buf, &empty_block);
if (retval != 0)
return retval;
} while (!empty_block);
while (GetDataBlock (context, (unsigned char *) buf) != 0)
;
return FALSE;
return 0;
}
static int ZeroDataBlock = FALSE;
@ -195,23 +312,24 @@ static int
GetDataBlock (GifContext *context,
unsigned char *buf)
{
unsigned char count;
// unsigned char count;
if (!ReadOK (context, &count, 1)) {
if (!ReadOK (context, &context->block_count, 1)) {
/*g_message (_("GIF: error in getting DataBlock size\n"));*/
return -1;
}
ZeroDataBlock = count == 0;
ZeroDataBlock = context->block_count == 0;
if ((count != 0) && (!ReadOK (context, buf, count))) {
if ((context->block_count != 0) && (!ReadOK (context, buf, context->block_count))) {
/*g_message (_("GIF: error in reading DataBlock\n"));*/
return -1;
}
return count;
return context->block_count;
}
static int
GetCode (GifContext *context,
int code_size,
@ -258,36 +376,12 @@ GetCode (GifContext *context,
}
static int
LWZReadByte (GifContext *context,
int flag,
int input_code_size)
LWZReadByte (GifContext *context)
{
int code, incode;
register int i;
if (flag) {
context->lwz_set_code_size = input_code_size;
context->lwz_code_size = context->lwz_set_code_size + 1;
context->lwz_clear_code = 1 << context->lwz_set_code_size;
context->lwz_end_code = context->lwz_clear_code + 1;
context->lwz_max_code_size = 2 * context->lwz_clear_code;
context->lwz_max_code = context->lwz_clear_code + 2;
GetCode (context, 0, TRUE);
context->lwz_fresh = TRUE;
for (i = 0; i < context->lwz_clear_code; ++i) {
context->lwz_table[0][i] = 0;
context->lwz_table[1][i] = i;
}
for (; i < (1 << MAX_LWZ_BITS); ++i)
context->lwz_table[0][i] = context->lwz_table[1][0] = 0;
context->lwz_sp = context->lwz_stack;
return 0;
} else if (context->lwz_fresh) {
if (context->lwz_fresh) {
context->lwz_fresh = FALSE;
do {
context->lwz_firstcode = context->lwz_oldcode = GetCode (context, context->lwz_code_size, FALSE);
@ -367,26 +461,12 @@ LWZReadByte (GifContext *context,
}
static void
ReadImage (GifContext *context)
gif_get_lzw (GifContext *context)
{
guchar *dest, *temp;
guchar c;
gint xpos = 0, ypos = 0, pass = 0;
gint v;
/*
** Initialize the Compression routines
*/
if (!ReadOK (context, &c, 1)) {
/*g_message (_("GIF: EOF / read error on image data\n"));*/
return;
}
if (LWZReadByte (context, TRUE, c) < 0) {
/*g_message (_("GIF: error while reading\n"));*/
return;
}
context->pixbuf = gdk_pixbuf_new (ART_PIX_RGB,
context->gif89.transparent,
8,
@ -394,7 +474,7 @@ ReadImage (GifContext *context)
context->height);
dest = gdk_pixbuf_get_pixels (context->pixbuf);
while ((v = LWZReadByte ( context, FALSE, c)) >= 0) {
while ((v = LWZReadByte ( context)) >= 0) {
if (context->gif89.transparent) {
temp = dest + ypos * gdk_pixbuf_get_rowstride (context->pixbuf) + xpos * 4;
*temp = context->color_map [0][(guchar) v];
@ -438,7 +518,7 @@ ReadImage (GifContext *context)
ypos = 1;
break;
default:
goto fini;
goto done;
}
}
} else {
@ -449,29 +529,52 @@ ReadImage (GifContext *context)
break;
}
fini:
ypos = 0;
if (LWZReadByte (context, FALSE, c) >= 0)
g_print ("GIF: too much input data, ignoring extra...\n");
done:
/* we got enough data. there may be more (ie, newer layers) but we can quit now */
context->state = GIF_DONE;
}
/* called until 1 is returned.
* if -1 is returned, then there was an error, and we must stop loading the image
* if 0 is returned, we need more bytes. However, this isn't handled correctly currently,
* so we assume that the initial 128 bytes is enough to get us started.
* If 1 is returned, then we are ready to start loading the image. */
static int
gif_prepare_lzw (GifContext *context)
{
gint i;
if (!ReadOK (context, &(context->lwz_set_code_size), 1)) {
/*g_message (_("GIF: EOF / read error on image data\n"));*/
return -1;
}
context->lwz_code_size = context->lwz_set_code_size + 1;
context->lwz_clear_code = 1 << context->lwz_set_code_size;
context->lwz_end_code = context->lwz_clear_code + 1;
context->lwz_max_code_size = 2 * context->lwz_clear_code;
context->lwz_max_code = context->lwz_clear_code + 2;
GetCode (context, 0, TRUE);
context->lwz_fresh = TRUE;
for (i = 0; i < context->lwz_clear_code; ++i) {
context->lwz_table[0][i] = 0;
context->lwz_table[1][i] = i;
}
for (; i < (1 << MAX_LWZ_BITS); ++i)
context->lwz_table[0][i] = context->lwz_table[1][0] = 0;
context->lwz_sp = context->lwz_stack;
return 0;
}
/* needs 13 bytes to proceed. */
static gint
prepare_iter_loop (GifContext *context)
gif_init (GifContext *context)
{
unsigned char buf[16];
unsigned char c;
char version[4];
if (!ReadOK (context, buf, 6)) {
/* Unable to read magic number */
return 0;
return -1;
}
if (strncmp ((char *) buf, "GIF", 3) != 0) {
@ -490,7 +593,7 @@ prepare_iter_loop (GifContext *context)
/* read the screen descriptor */
if (!ReadOK (context, buf, 7)) {
/* Failed to read screen descriptor */
return 0;
return -1;
}
context->width = LM_to_uint (buf[0], buf[1]);
@ -502,66 +605,135 @@ prepare_iter_loop (GifContext *context)
context->pixbuf = NULL;
if (BitSet (buf[4], LOCALCOLORMAP)) {
/* Global Colormap */
if (ReadColorMap (context, context->bit_pixel,
context->color_map,
&context->gray_scale)) {
return -1;
}
gif_set_get_colormap (context);
} else {
context->state = GIF_GET_NEXT_STEP;
}
return 0;
}
context->stage = 1;
static gint
gif_get_next_step (GifContext *context)
{
unsigned char buf[16];
unsigned char c;
for (;;) {
if (!ReadOK (context, &c, 1)) {
return 0;
return -1;
}
g_print ("c== %c\n", c);
if (c == ';') {
/* GIF terminator */
/* hmm. Not 100% sure what to do about this. Should
* i try to return a blank image instead? */
return -1;
context->state = GIF_DONE;
return 1;
}
if (c == '!') {
/* Check the extention */
if (!ReadOK (context, &c, 1)) {
return 0;
}
DoExtension (context, c);
gif_set_get_extension (context);
continue;
}
/* look for frame */
if (c != ',') {
/* Not a valid start character */
continue;
}
if (!ReadOK (context, buf, 9)) {
return 0;
return -1;
}
/* Okay, we got all the info we need. Lets record it */
context->frame_len = LM_to_uint (buf[4], buf[5]);
context->frame_height = LM_to_uint (buf[6], buf[7]);
if (context->frame_height >context->height)
return -1;
if (context->frame_height > context->height) {
context->state = GIF_DONE;
return 1;
}
context->frame_interlace = BitSet (buf[8], INTERLACE);
if (!BitSet (buf[8], LOCALCOLORMAP)) {
if (BitSet (buf[8], LOCALCOLORMAP)) {
/* Does this frame have it's own colormap. */
/* really only relevant when looking at the first frame
* of an animated gif. */
/* if it does, we need to re-read in the colormap,
* the gray_scale, and the bit_pixel */
context->bit_pixel = 1 << ((buf[8] & 0x07) + 1);
if (ReadColorMap (context, context->bit_pixel, context->color_map, &context->gray_scale)) {
return -1;
gif_set_get_colormap2 (context);
return 0;
}
}
return 1;
context->state = GIF_PREPARE_LZW;
return 0;
}
g_assert_not_reached ();
return -1;
return 1;
}
static gint
gif_main_loop (GifContext *context)
{
gint retval = 0;
do {
switch (context->state) {
case GIF_START:
g_print ("in GIF_START\n");
retval = gif_init (context);
break;
case GIF_GET_COLORMAP:
g_print ("in GIF_GET_COLORMAP\n");
retval = gif_get_colormap (context);
if (retval == 0)
context->state = GIF_GET_NEXT_STEP;
break;
case GIF_GET_NEXT_STEP:
g_print ("in GIF_GET_NEXT_STEP\n");
retval = gif_get_next_step (context);
break;
case GIF_GET_EXTENTION:
g_print ("in GIF_GET_EXTENTION\n");
retval = gif_get_extension (context);
if (retval == 0)
context->state = GIF_GET_NEXT_STEP;
break;
case GIF_GET_COLORMAP2:
g_print ("in GIF_GET_COLORMAP2\n");
retval = gif_get_colormap (context);
if (retval == 0)
context->state = GIF_PREPARE_LZW;
break;
case GIF_PREPARE_LZW:
g_print ("in GIF_PREPARE_LZW\n");
retval = gif_prepare_lzw (context);
if (retval == 0)
context->state = GIF_GET_LZW;
break;
case GIF_GET_LZW:
g_print ("in GIF_GET_LZW\n");
gif_get_lzw (context);
retval = 0;
break;
case GIF_DONE:
default:
g_print ("in GIF_DONE\n");
retval = 0;
goto done;
};
} while (retval == 0);
done:
return retval;
}
/* Shared library entry point */
@ -576,10 +748,10 @@ image_load (FILE *file)
context->lwz_fresh = FALSE;
context->file = file;
context->pixbuf = NULL;
context->stage = 0;
context->state = GIF_START;
gif_main_loop (context);
prepare_iter_loop (context);
ReadImage (context);
return context->pixbuf;
}
@ -594,7 +766,7 @@ image_begin_load (ModulePreparedNotifyFunc func, gpointer user_data)
context->lwz_fresh = FALSE;
context->file = NULL;
context->pixbuf = NULL;
context->stage = 0;
context->state = GIF_START;
return (gpointer) context;
}
@ -612,7 +784,20 @@ image_stop_load (gpointer data)
gboolean
image_load_increment (gpointer data, guchar *buf, guint size)
{
gint retval;
GifContext *context = (GifContext *) data;
return FALSE;
if (context->amount_needed == 0) {
/* we aren't looking for some bytes. */
context->buf = buf;
context->ptr = 0;
context->size = size;
}
retval = gif_main_loop (context);
if (retval == 1)
return FALSE;
if (retval == -1) {
}
return TRUE;
}