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| #include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#define EXTENSION_INTRODUCER 0x21
#define IMAGE_DESCRIPTOR 0x2C
#define TRAILER 0x3B
#define GRAPHIC_CONTROL 0xF9
#define APPLICATION_EXTENSION 0xFF
#define COMMENT_EXTENSION 0xFE
#define PLAINTEXT_EXTENSION 0x01
typedef struct
{
unsigned short width;
unsigned short height;
unsigned char fields;
unsigned char background_color_index;
unsigned char pixel_aspect_ratio;
}
screen_descriptor_t;
typedef struct
{
unsigned char r;
unsigned char g;
unsigned char b;
}
rgb;
typedef struct
{
unsigned short image_left_position;
unsigned short image_top_position;
unsigned short image_width;
unsigned short image_height;
unsigned char fields;
}
image_descriptor_t;
typedef struct
{
unsigned char byte;
int prev;
int len;
}
dictionary_entry_t;
typedef struct
{
unsigned char extension_code;
unsigned char block_size;
}
extension_t;
typedef struct
{
unsigned char fields;
unsigned short delay_time;
unsigned char transparent_color_index;
}
graphic_control_extension_t;
typedef struct
{
unsigned char application_id[ 8 ];
unsigned char version[ 3 ];
}
application_extension_t;
typedef struct
{
unsigned short left;
unsigned short top;
unsigned short width;
unsigned short height;
unsigned char cell_width;
unsigned char cell_height;
unsigned char foreground_color;
unsigned char background_color;
}
plaintext_extension_t;
// ajout jpt
int frame_count = 0;
/* int uncompress( int code_length, */
void uncompress( int code_length,
const unsigned char *input,
int input_length,
unsigned char *out )
{
// int maxbits;
int i, bit;
int code, prev = -1;
dictionary_entry_t *dictionary;
int dictionary_ind;
unsigned int mask = 0x01;
int reset_code_length;
int clear_code; // This varies depending on code_length
int stop_code; // one more than clear code
int match_len;
clear_code = 1 << ( code_length );
stop_code = clear_code + 1;
// To handle clear codes
reset_code_length = code_length;
// Create a dictionary large enough to hold "code_length" entries.
// Once the dictionary overflows, code_length increases
dictionary = ( dictionary_entry_t * )
malloc( sizeof( dictionary_entry_t ) * ( 1 << ( code_length + 1 ) ) );
// Initialize the first 2^code_len entries of the dictionary with their
// indices. The rest of the entries will be built up dynamically.
// Technically, it shouldn't be necessary to initialize the
// dictionary. The spec says that the encoder "should output a
// clear code as the first code in the image data stream". It doesn't
// say must, though...
for ( dictionary_ind = 0;
dictionary_ind < ( 1 << code_length );
dictionary_ind++ )
{
dictionary[ dictionary_ind ].byte = dictionary_ind;
// XXX this only works because prev is a 32-bit int (> 12 bits)
dictionary[ dictionary_ind ].prev = -1;
dictionary[ dictionary_ind ].len = 1;
}
// 2^code_len + 1 is the special "end" code; don't give it an entry here
dictionary_ind++;
dictionary_ind++;
// TODO verify that the very last byte is clear_code + 1
while ( input_length )
{
code = 0x0;
// Always read one more bit than the code length
for ( i = 0; i < ( code_length + 1 ); i++ )
{
// This is different than in the file read example; that
// was a call to "next_bit"
bit = ( *input & mask ) ? 1 : 0;
mask <<= 1;
if ( mask == 0x100 )
{
mask = 0x01;
input++;
input_length--;
}
code = code | ( bit << i );
}
if ( code == clear_code )
{
code_length = reset_code_length;
dictionary = ( dictionary_entry_t * ) realloc( dictionary,
sizeof( dictionary_entry_t ) * ( 1 << ( code_length + 1 ) ) );
for ( dictionary_ind = 0;
dictionary_ind < ( 1 << code_length );
dictionary_ind++ )
{
dictionary[ dictionary_ind ].byte = dictionary_ind;
// XXX this only works because prev is a 32-bit int (> 12 bits)
dictionary[ dictionary_ind ].prev = -1;
dictionary[ dictionary_ind ].len = 1;
}
dictionary_ind++;
dictionary_ind++;
prev = -1;
continue;
}
else if ( code == stop_code )
{
if ( input_length > 1 )
{
fprintf( stderr, "Malformed GIF (early stop code)\n" );
exit( 0 );
}
break;
}
// Update the dictionary with this character plus the _entry_
// (character or string) that came before it
if ( ( prev > -1 ) && ( code_length < 12 ) )
{
if ( code > dictionary_ind )
{
fprintf( stderr, "code = %.02x, but dictionary_ind = %.02x\n",
code, dictionary_ind );
exit( 0 );
}
// Special handling for KwKwK
if ( code == dictionary_ind )
{
int ptr = prev;
while ( dictionary[ ptr ].prev != -1 )
{
ptr = dictionary[ ptr ].prev;
}
dictionary[ dictionary_ind ].byte = dictionary[ ptr ].byte;
}
else
{
int ptr = code;
while ( dictionary[ ptr ].prev != -1 )
{
ptr = dictionary[ ptr ].prev;
}
dictionary[ dictionary_ind ].byte = dictionary[ ptr ].byte;
}
dictionary[ dictionary_ind ].prev = prev;
dictionary[ dictionary_ind ].len = dictionary[ prev ].len + 1;
dictionary_ind++;
// GIF89a mandates that this stops at 12 bits
if ( ( dictionary_ind == ( 1 << ( code_length + 1 ) ) ) &&
( code_length < 11 ) )
{
code_length++;
dictionary = ( dictionary_entry_t * ) realloc( dictionary,
sizeof( dictionary_entry_t ) * ( 1 << ( code_length + 1 ) ) );
}
}
prev = code;
// Now copy the dictionary entry backwards into "out"
match_len = dictionary[ code ].len;
while ( code != -1 )
{
out[ dictionary[ code ].len - 1 ] = dictionary[ code ].byte;
if ( dictionary[ code ].prev == code )
{
fprintf( stderr, "Internal error; self-reference." );
exit( 0 );
}
code = dictionary[ code ].prev;
}
out += match_len;
}
}
static int read_sub_blocks( int gif_file, unsigned char **data )
{
int data_length;
int index;
unsigned char block_size;
// Everything following are data sub-blocks, until a 0-sized block is
// encountered.
data_length = 0;
*data = NULL;
index = 0;
while ( 1 )
{
if ( read( gif_file, &block_size, 1 ) < 1 )
{
perror( "Invalid GIF file (too short): " );
return -1;
}
if ( block_size == 0 ) // end of sub-blocks
{
break;
}
data_length += block_size;
*data = realloc( *data, data_length );
// TODO this could be split across block size boundaries
if ( read( gif_file, *data + index, block_size ) <
block_size )
{
perror( "Invalid GIF file (too short): " );
return -1;
}
index += block_size;
}
return data_length;
}
static int process_image_descriptor( int gif_file,
rgb *gct,
int gct_size,
int resolution_bits )
{
image_descriptor_t image_descriptor;
int disposition;
int compressed_data_length;
unsigned char *compressed_data = NULL;
unsigned char lzw_code_size;
int uncompressed_data_length = 0;
unsigned char *uncompressed_data = NULL;
// TODO there could actually be lots of these
if ( read( gif_file, &image_descriptor, 9 ) < 9 )
{
perror( "Invalid GIF file (too short)" );
disposition = 0;
goto done;
}
// TODO if LCT = true, read the LCT
disposition = 1;
if ( read( gif_file, &lzw_code_size, 1 ) < 1 )
{
perror( "Invalid GIF file (too short): " );
disposition = 0;
goto done;
}
compressed_data_length = read_sub_blocks( gif_file, &compressed_data );
uncompressed_data_length = image_descriptor.image_width *
image_descriptor.image_height;
uncompressed_data = malloc( uncompressed_data_length );
uncompress( lzw_code_size, compressed_data, compressed_data_length,
uncompressed_data );
done:
if ( compressed_data )
free( compressed_data );
if ( uncompressed_data )
free( uncompressed_data );
return disposition;
}
static int process_extension( int gif_file )
{
extension_t extension;
graphic_control_extension_t gce;
application_extension_t application;
plaintext_extension_t plaintext;
unsigned char *extension_data = NULL;
// int extension_data_length;
if ( read( gif_file, &extension, 2 ) < 2 )
{
perror( "Invalid GIF file (too short): " );
return 0;
}
switch ( extension.extension_code )
{
case GRAPHIC_CONTROL:
if ( read( gif_file, &gce, 4 ) < 4 )
{
perror( "Invalid GIF file (too short): " );
return 0;
}
break;
case APPLICATION_EXTENSION:
if ( read( gif_file, &application, 11 ) < 11 )
{
perror( "Invalid GIF file (too short): " );
return 0;
}
break;
case 0xFE:
// comment extension; do nothing - all the data is in the
// sub-blocks that follow.
break;
case 0x01:
if ( read( gif_file, &plaintext, 12 ) < 12 )
{
perror( "Invalid GIF file (too short): " );
return 0;
}
break;
default:
fprintf( stderr, "Unrecognized extension code.\n" );
exit( 0 );
}
// All extensions are followed by data sub-blocks; even if it's
// just a single data sub-block of length 0
// extension_data_length =
read_sub_blocks( gif_file, &extension_data );
if ( extension_data != NULL )
free( extension_data );
return 1;
}
/**
* @param gif_file the file descriptor of a file containing a
* GIF-encoded file. This should point to the first byte in
* the file when invoked.
*/
static void process_gif_stream( int gif_file )
{
// unsigned char header[ 7 ];
char header[ 7 ];
screen_descriptor_t screen_descriptor;
int color_resolution_bits;
int global_color_table_size; // number of entries in global_color_table
rgb *global_color_table;
unsigned char block_type = 0x0;
// A GIF file starts with a Header (section 17)
if ( read( gif_file, header, 6 ) != 6 )
{
perror( "Invalid GIF file (too short)" );
return;
}
header[ 6 ] = 0x0;
// XXX there's another format, GIF87a, that you may still find
// floating around.
if ( strcmp( "GIF89a", header ) )
{
fprintf( stderr,
"Invalid GIF file (header is '%s', should be 'GIF89a')\n",
header );
return;
}
// Followed by a logical screen descriptor
// Note that this works because GIFs specify little-endian order; on a
// big-endian machine, the height & width would need to be reversed.
// Can't use sizeof here since GCC does byte alignment;
// sizeof( screen_descriptor_t ) = 8!
if ( read( gif_file, &screen_descriptor, 7 ) < 7 )
{
perror( "Invalid GIF file (too short)" );
return;
}
color_resolution_bits = ( ( screen_descriptor.fields & 0x70 ) >> 4 ) + 1;
if ( screen_descriptor.fields & 0x80 )
{
// If bit 7 is set, the next block is a global color table; read it
global_color_table_size = 1 <<
( ( ( screen_descriptor.fields & 0x07 ) + 1 ) );
global_color_table = ( rgb * ) malloc( 3 * global_color_table_size );
// XXX this could conceivably return a short count...
if ( read( gif_file, global_color_table, 3 * global_color_table_size ) <
3 * global_color_table_size )
{
perror( "Unable to read global color table" );
return;
}
}
// while ( block_type != TRAILER )
while ( ( block_type != TRAILER ) && ( block_type != '\n' ) )
{
if ( read( gif_file, &block_type, 1 ) < 1 )
{
perror( "Invalid GIF file (too short)" );
return;
}
fprintf( stderr, "block_type: %d\n", block_type );
switch ( block_type )
{
case IMAGE_DESCRIPTOR:
// ajout jpt
frame_count = frame_count + 1;
if ( !process_image_descriptor( gif_file,
global_color_table,
global_color_table_size,
color_resolution_bits ) )
{
return;
}
break;
case EXTENSION_INTRODUCER:
if ( !process_extension( gif_file ) )
{
return;
}
break;
case TRAILER:
break;
default:
fprintf( stderr, "Bailing on unrecognized block type %.02x\n",
block_type );
return;
}
fprintf( stderr, "global_color_table_size: %d\n", global_color_table_size );
}
}
int main( int argc, char *argv[] )
{
int gif_file;
if ( argc < 2 )
{
fprintf( stderr, "Usage: %s <path-to-gif-file>\n", argv[ 0 ] );
exit( 0 );
}
gif_file = open( argv[ 1 ], O_RDONLY );
if ( gif_file == -1 )
{
fprintf( stderr, "Unable to open file '%s'", argv[ 1 ] );
perror( ": " );
}
process_gif_stream( gif_file );
close( gif_file );
// ajout jpt
fprintf( stderr, "frame_count: %d\n", frame_count );
return 0;
} |
Répondre avec citation
Envoyé par Jipété
, mais comme j'ai changé "Language" en "Langage" dans l'IHM, ben quand je bascule en "en" ça m'affiche "Langage", pas top.
. Je vais modifié dans sens. Bien vu 
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