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renamed ReadOK to gif_read. Added a lot of comments to the file.

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1999-11-03  Jonathan Blandford  <jrb@redhat.com>

	* src/io-gif.c (gif_read): renamed ReadOK to gif_read.
	Added a lot of comments to the file.
This commit is contained in:
Jonathan Blandford 1999-11-03 23:22:27 +00:00 committed by Jonathan Blandford
parent 5ee4989714
commit 7cdf9176e1
2 changed files with 48 additions and 25 deletions
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3
gdk-pixbuf/ChangeLog
View File

@ -1,5 +1,8 @@
1999-11-03 Jonathan Blandford <jrb@redhat.com>
* src/io-gif.c (gif_read): renamed ReadOK to gif_read.
Added a lot of comments to the file.
* src/Makefile.am (libpixbuf_gif_la_LIBADD): Remove dependency on
lib*gif!!!!

70
gdk-pixbuf/io-gif.c
View File

@ -24,6 +24,38 @@
* Boston, MA 02111-1307, USA.
*/
/* This loader is very hairy code.
*
* The main loop was not designed for incremental loading, so when it was hacked
* in it got a bit messy. Basicly, every function is written to expect a failed
* read_gif, and lets you call it again assuming that the bytes are there.
*
* A note on Animations:
* It actually wouldn't be that hard to add support for Gif Animations. You'd
* need, of course, to get the necessary info from the extension, and read the
* private colormap into it's own frame, instead of context->color_map. You'd
* also need to stop it from moving to GIF_DONE at the end of gif_get_lzw, (and
* of course generate the necessary frames.
*
* Return vals.
* Unless otherwise specified, these are the return vals for most functions:
*
* 0 -> success
* -1 -> more bytes needed.
* -2 -> failure; abort the load
* -3 -> control needs to be passed back to the main loop
* \_ (most of the time returning 0 will get this, but not always)
* >1 -> for functions that get a guchar, the char will be returned.
*
* -jrb (11/03/1999)
*/
/*
* If you have any images that crash this code, please, please let me know and
* send them to me.
* <jrb@redhat.com>
*/
#include <config.h>
#include <stdio.h>
#include <glib.h>
@ -144,10 +176,10 @@ static int GetDataBlock (GifContext *, unsigned char *);
static int count = 0;
#endif
/* Returns TRUE if Read is OK,
/* Returns TRUE if read is OK,
* FALSE if more memory is needed. */
static int
ReadOK (GifContext *context, guchar *buffer, size_t len)
gif_read (GifContext *context, guchar *buffer, size_t len)
{
gint retval;
#ifdef IO_GIFDEBUG
@ -194,18 +226,6 @@ ReadOK (GifContext *context, guchar *buffer, size_t len)
}
/*
* Return vals.
* Unless otherwise specified, these are the return vals for most functions:
*
* 0 -> success
* -1 -> more bytes needed.
* -2 -> failure; abort the load
* -3 -> control needs to be passed back to the main loop
* \_ (most of the time returning 0 will get this, but not always)
*/
/* Changes the stage to be GIF_GET_COLORMAP */
static void
@ -230,7 +250,7 @@ gif_get_colormap (GifContext *context)
unsigned char rgb[3];
while (context->colormap_index < context->bit_pixel) {
if (!ReadOK (context, rgb, sizeof (rgb))) {
if (!gif_read (context, rgb, sizeof (rgb))) {
/*g_message (_("GIF: bad colormap\n"));*/
return -1;
}
@ -264,7 +284,7 @@ get_data_block (GifContext *context,
{
if (context->block_count == 0) {
if (!ReadOK (context, &context->block_count, 1)) {
if (!gif_read (context, &context->block_count, 1)) {
return -1;
}
}
@ -275,7 +295,7 @@ get_data_block (GifContext *context,
return 0;
}
if (!ReadOK (context, buf, context->block_count)) {
if (!gif_read (context, buf, context->block_count)) {
return -1;
}
@ -302,7 +322,7 @@ gif_get_extension (GifContext *context)
if (context->extension_label == 0) {
/* I guess bad things can happen if we have an extension of 0 )-: */
/* I should look into this sometime */
if (!ReadOK (context, & context->extension_label , 1)) {
if (!gif_read (context, & context->extension_label , 1)) {
return -1;
}
}
@ -349,14 +369,14 @@ GetDataBlock (GifContext *context,
{
// unsigned char count;
if (!ReadOK (context, &context->block_count, 1)) {
if (!gif_read (context, &context->block_count, 1)) {
/*g_message (_("GIF: error in getting DataBlock size\n"));*/
return -1;
}
ZeroDataBlock = context->block_count == 0;
if ((context->block_count != 0) && (!ReadOK (context, buf, context->block_count))) {
if ((context->block_count != 0) && (!gif_read (context, buf, context->block_count))) {
/*g_message (_("GIF: error in reading DataBlock\n"));*/
return -1;
}
@ -715,7 +735,7 @@ gif_prepare_lzw (GifContext *context)
{
gint i;
if (!ReadOK (context, &(context->lzw_set_code_size), 1)) {
if (!gif_read (context, &(context->lzw_set_code_size), 1)) {
/*g_message (_("GIF: EOF / read error on image data\n"));*/
return -1;
}
@ -751,7 +771,7 @@ gif_init (GifContext *context)
unsigned char buf[16];
char version[4];
if (!ReadOK (context, buf, 6)) {
if (!gif_read (context, buf, 6)) {
/* Unable to read magic number */
return -1;
}
@ -770,7 +790,7 @@ gif_init (GifContext *context)
}
/* read the screen descriptor */
if (!ReadOK (context, buf, 7)) {
if (!gif_read (context, buf, 7)) {
/* Failed to read screen descriptor */
return -1;
}
@ -801,7 +821,7 @@ static gint
gif_get_frame_info (GifContext *context)
{
unsigned char buf[9];
if (!ReadOK (context, buf, 9)) {
if (!gif_read (context, buf, 9)) {
return -1;
}
/* Okay, we got all the info we need. Lets record it */
@ -833,7 +853,7 @@ gif_get_next_step (GifContext *context)
{
unsigned char c;
while (TRUE) {
if (!ReadOK (context, &c, 1)) {
if (!gif_read (context, &c, 1)) {
return -1;
}
if (c == ';') {