605 lines
15 KiB
C
605 lines
15 KiB
C
/*
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IMGLIB: An example image loading library for use with SDL
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Copyright (C) 1999 Sam Lantinga
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with this library; if not, write to the Free
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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Sam Lantinga
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5635-34 Springhouse Dr.
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Pleasanton, CA 94588 (USA)
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slouken@devolution.com
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*/
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/* This is a GIF image file loading framework */
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#include <stdio.h>
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#include <string.h>
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#include "SDL_image.h"
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#ifdef LOAD_GIF
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/* See if an image is contained in a data source */
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int IMG_isGIF(SDL_RWops *src)
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{
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int is_GIF;
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char magic[6];
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is_GIF = 0;
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if ( SDL_RWread(src, magic, 6, 1) ) {
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if ( (strncmp(magic, "GIF", 3) == 0) &&
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((memcmp(magic + 3, "87a", 3) == 0) ||
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(memcmp(magic + 3, "89a", 3) == 0)) ) {
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is_GIF = 1;
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}
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}
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return(is_GIF);
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}
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/* Code from here to end of file has been adapted from XPaint: */
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/* +-------------------------------------------------------------------+ */
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/* | Copyright 1990, 1991, 1993 David Koblas. | */
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/* | Copyright 1996 Torsten Martinsen. | */
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/* | Permission to use, copy, modify, and distribute this software | */
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/* | and its documentation for any purpose and without fee is hereby | */
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/* | granted, provided that the above copyright notice appear in all | */
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/* | copies and that both that copyright notice and this permission | */
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/* | notice appear in supporting documentation. This software is | */
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/* | provided "as is" without express or implied warranty. | */
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/* +-------------------------------------------------------------------+ */
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/* Adapted for use in SDL by Sam Lantinga -- 7/20/98 */
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#define USED_BY_SDL
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#include <stdio.h>
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#include <string.h>
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#ifdef USED_BY_SDL
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/* Changes to work with SDL:
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Include SDL header file
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Use SDL_Surface rather than xpaint Image structure
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Define SDL versions of RWSetMsg(), ImageNewCmap() and ImageSetCmap()
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*/
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#include "SDL.h"
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#define Image SDL_Surface
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#define RWSetMsg IMG_SetError
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#define ImageNewCmap(w, h, s) SDL_AllocSurface(SDL_SWSURFACE,w,h,8,0,0,0,0)
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#define ImageSetCmap(s, i, R, G, B) do { \
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s->format->palette->colors[i].r = R; \
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s->format->palette->colors[i].g = G; \
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s->format->palette->colors[i].b = B; \
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} while (0)
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/* * * * * */
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#else
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/* Original XPaint sources */
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#include "image.h"
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#include "rwTable.h"
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#define SDL_RWops FILE
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#define SDL_RWclose fclose
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#endif /* USED_BY_SDL */
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#define MAXCOLORMAPSIZE 256
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#define TRUE 1
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#define FALSE 0
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#define CM_RED 0
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#define CM_GREEN 1
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#define CM_BLUE 2
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#define MAX_LWZ_BITS 12
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#define INTERLACE 0x40
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#define LOCALCOLORMAP 0x80
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#define BitSet(byte, bit) (((byte) & (bit)) == (bit))
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#define ReadOK(file,buffer,len) SDL_RWread(file, buffer, len, 1)
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#define LM_to_uint(a,b) (((b)<<8)|(a))
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static struct {
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unsigned int Width;
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unsigned int Height;
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unsigned char ColorMap[3][MAXCOLORMAPSIZE];
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unsigned int BitPixel;
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unsigned int ColorResolution;
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unsigned int Background;
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unsigned int AspectRatio;
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int GrayScale;
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} GifScreen;
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static struct {
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int transparent;
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int delayTime;
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int inputFlag;
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int disposal;
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} Gif89;
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static int ReadColorMap(SDL_RWops * src, int number,
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unsigned char buffer[3][MAXCOLORMAPSIZE], int *flag);
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static int DoExtension(SDL_RWops * src, int label);
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static int GetDataBlock(SDL_RWops * src, unsigned char *buf);
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static int GetCode(SDL_RWops * src, int code_size, int flag);
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static int LWZReadByte(SDL_RWops * src, int flag, int input_code_size);
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static Image *ReadImage(SDL_RWops * src, int len, int height, int,
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unsigned char cmap[3][MAXCOLORMAPSIZE],
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int gray, int interlace, int ignore);
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Image *
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IMG_LoadGIF_RW(SDL_RWops *src)
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{
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unsigned char buf[16];
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unsigned char c;
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unsigned char localColorMap[3][MAXCOLORMAPSIZE];
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int grayScale;
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int useGlobalColormap;
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int bitPixel;
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int imageCount = 0;
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char version[4];
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int imageNumber = 1;
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Image *image = NULL;
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if ( src == NULL ) {
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goto done;
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}
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if (!ReadOK(src, buf, 6)) {
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RWSetMsg("error reading magic number");
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goto done;
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}
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if (strncmp((char *) buf, "GIF", 3) != 0) {
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RWSetMsg("not a GIF file");
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goto done;
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}
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strncpy(version, (char *) buf + 3, 3);
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version[3] = '\0';
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if ((strcmp(version, "87a") != 0) && (strcmp(version, "89a") != 0)) {
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RWSetMsg("bad version number, not '87a' or '89a'");
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goto done;
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}
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Gif89.transparent = -1;
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Gif89.delayTime = -1;
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Gif89.inputFlag = -1;
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Gif89.disposal = 0;
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if (!ReadOK(src, buf, 7)) {
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RWSetMsg("failed to read screen descriptor");
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goto done;
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}
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GifScreen.Width = LM_to_uint(buf[0], buf[1]);
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GifScreen.Height = LM_to_uint(buf[2], buf[3]);
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GifScreen.BitPixel = 2 << (buf[4] & 0x07);
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GifScreen.ColorResolution = (((buf[4] & 0x70) >> 3) + 1);
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GifScreen.Background = buf[5];
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GifScreen.AspectRatio = buf[6];
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if (BitSet(buf[4], LOCALCOLORMAP)) { /* Global Colormap */
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if (ReadColorMap(src, GifScreen.BitPixel, GifScreen.ColorMap,
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&GifScreen.GrayScale)) {
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RWSetMsg("error reading global colormap");
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goto done;
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}
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}
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do {
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if (!ReadOK(src, &c, 1)) {
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RWSetMsg("EOF / read error on image data");
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goto done;
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}
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if (c == ';') { /* GIF terminator */
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if (imageCount < imageNumber) {
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RWSetMsg("only %d image%s found in file",
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imageCount, imageCount > 1 ? "s" : "");
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goto done;
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}
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}
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if (c == '!') { /* Extension */
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if (!ReadOK(src, &c, 1)) {
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RWSetMsg("EOF / read error on extention function code");
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goto done;
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}
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DoExtension(src, c);
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continue;
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}
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if (c != ',') { /* Not a valid start character */
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continue;
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}
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++imageCount;
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if (!ReadOK(src, buf, 9)) {
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RWSetMsg("couldn't read left/top/width/height");
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goto done;
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}
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useGlobalColormap = !BitSet(buf[8], LOCALCOLORMAP);
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bitPixel = 1 << ((buf[8] & 0x07) + 1);
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if (!useGlobalColormap) {
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if (ReadColorMap(src, bitPixel, localColorMap, &grayScale)) {
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RWSetMsg("error reading local colormap");
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goto done;
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}
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image = ReadImage(src, LM_to_uint(buf[4], buf[5]),
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LM_to_uint(buf[6], buf[7]),
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bitPixel, localColorMap, grayScale,
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BitSet(buf[8], INTERLACE),
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imageCount != imageNumber);
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} else {
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image = ReadImage(src, LM_to_uint(buf[4], buf[5]),
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LM_to_uint(buf[6], buf[7]),
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GifScreen.BitPixel, GifScreen.ColorMap,
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GifScreen.GrayScale, BitSet(buf[8], INTERLACE),
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imageCount != imageNumber);
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}
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} while (image == NULL);
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#ifdef USED_BY_SDL
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if ( Gif89.transparent > 0 ) {
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SDL_SetColorKey(image, SDL_SRCCOLORKEY, Gif89.transparent);
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}
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#endif
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done:
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return image;
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}
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static int
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ReadColorMap(SDL_RWops *src, int number,
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unsigned char buffer[3][MAXCOLORMAPSIZE], int *gray)
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{
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int i;
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unsigned char rgb[3];
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int flag;
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flag = TRUE;
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for (i = 0; i < number; ++i) {
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if (!ReadOK(src, rgb, sizeof(rgb))) {
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RWSetMsg("bad colormap");
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return 1;
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}
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buffer[CM_RED][i] = rgb[0];
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buffer[CM_GREEN][i] = rgb[1];
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buffer[CM_BLUE][i] = rgb[2];
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flag &= (rgb[0] == rgb[1] && rgb[1] == rgb[2]);
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}
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#if 0
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if (flag)
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*gray = (number == 2) ? PBM_TYPE : PGM_TYPE;
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else
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*gray = PPM_TYPE;
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#else
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*gray = 0;
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#endif
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return FALSE;
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}
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static int
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DoExtension(SDL_RWops *src, int label)
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{
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static unsigned char buf[256];
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char *str;
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switch (label) {
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case 0x01: /* Plain Text Extension */
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str = "Plain Text Extension";
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break;
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case 0xff: /* Application Extension */
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str = "Application Extension";
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break;
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case 0xfe: /* Comment Extension */
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str = "Comment Extension";
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while (GetDataBlock(src, (unsigned char *) buf) != 0);
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return FALSE;
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case 0xf9: /* Graphic Control Extension */
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str = "Graphic Control Extension";
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(void) GetDataBlock(src, (unsigned char *) buf);
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Gif89.disposal = (buf[0] >> 2) & 0x7;
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Gif89.inputFlag = (buf[0] >> 1) & 0x1;
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Gif89.delayTime = LM_to_uint(buf[1], buf[2]);
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if ((buf[0] & 0x1) != 0)
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Gif89.transparent = buf[3];
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while (GetDataBlock(src, (unsigned char *) buf) != 0);
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return FALSE;
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default:
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str = (char *)buf;
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sprintf(str, "UNKNOWN (0x%02x)", label);
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break;
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}
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while (GetDataBlock(src, (unsigned char *) buf) != 0);
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return FALSE;
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}
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static int ZeroDataBlock = FALSE;
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static int
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GetDataBlock(SDL_RWops *src, unsigned char *buf)
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{
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unsigned char count;
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if (!ReadOK(src, &count, 1)) {
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/* pm_message("error in getting DataBlock size" ); */
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return -1;
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}
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ZeroDataBlock = count == 0;
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if ((count != 0) && (!ReadOK(src, buf, count))) {
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/* pm_message("error in reading DataBlock" ); */
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return -1;
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}
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return count;
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}
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static int
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GetCode(SDL_RWops *src, int code_size, int flag)
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{
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static unsigned char buf[280];
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static int curbit, lastbit, done, last_byte;
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int i, j, ret;
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unsigned char count;
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if (flag) {
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curbit = 0;
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lastbit = 0;
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done = FALSE;
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return 0;
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}
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if ((curbit + code_size) >= lastbit) {
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if (done) {
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if (curbit >= lastbit)
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RWSetMsg("ran off the end of my bits");
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return -1;
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}
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buf[0] = buf[last_byte - 2];
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buf[1] = buf[last_byte - 1];
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if ((count = GetDataBlock(src, &buf[2])) == 0)
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done = TRUE;
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last_byte = 2 + count;
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curbit = (curbit - lastbit) + 16;
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lastbit = (2 + count) * 8;
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}
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ret = 0;
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for (i = curbit, j = 0; j < code_size; ++i, ++j)
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ret |= ((buf[i / 8] & (1 << (i % 8))) != 0) << j;
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curbit += code_size;
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return ret;
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}
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static int
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LWZReadByte(SDL_RWops *src, int flag, int input_code_size)
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{
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static int fresh = FALSE;
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int code, incode;
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static int code_size, set_code_size;
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static int max_code, max_code_size;
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static int firstcode, oldcode;
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static int clear_code, end_code;
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static int table[2][(1 << MAX_LWZ_BITS)];
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static int stack[(1 << (MAX_LWZ_BITS)) * 2], *sp;
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register int i;
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if (flag) {
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set_code_size = input_code_size;
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code_size = set_code_size + 1;
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clear_code = 1 << set_code_size;
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end_code = clear_code + 1;
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max_code_size = 2 * clear_code;
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max_code = clear_code + 2;
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GetCode(src, 0, TRUE);
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fresh = TRUE;
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for (i = 0; i < clear_code; ++i) {
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table[0][i] = 0;
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table[1][i] = i;
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}
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for (; i < (1 << MAX_LWZ_BITS); ++i)
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table[0][i] = table[1][0] = 0;
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sp = stack;
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return 0;
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} else if (fresh) {
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fresh = FALSE;
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do {
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firstcode = oldcode = GetCode(src, code_size, FALSE);
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} while (firstcode == clear_code);
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return firstcode;
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}
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if (sp > stack)
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return *--sp;
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while ((code = GetCode(src, code_size, FALSE)) >= 0) {
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if (code == clear_code) {
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for (i = 0; i < clear_code; ++i) {
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table[0][i] = 0;
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table[1][i] = i;
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}
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for (; i < (1 << MAX_LWZ_BITS); ++i)
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table[0][i] = table[1][i] = 0;
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code_size = set_code_size + 1;
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max_code_size = 2 * clear_code;
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max_code = clear_code + 2;
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sp = stack;
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firstcode = oldcode = GetCode(src, code_size, FALSE);
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return firstcode;
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} else if (code == end_code) {
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int count;
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unsigned char buf[260];
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if (ZeroDataBlock)
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return -2;
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while ((count = GetDataBlock(src, buf)) > 0);
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if (count != 0) {
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/*
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* pm_message("missing EOD in data stream (common occurence)");
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*/
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}
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return -2;
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}
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incode = code;
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if (code >= max_code) {
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*sp++ = firstcode;
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code = oldcode;
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}
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while (code >= clear_code) {
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*sp++ = table[1][code];
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if (code == table[0][code])
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RWSetMsg("circular table entry BIG ERROR");
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code = table[0][code];
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}
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*sp++ = firstcode = table[1][code];
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if ((code = max_code) < (1 << MAX_LWZ_BITS)) {
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table[0][code] = oldcode;
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table[1][code] = firstcode;
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++max_code;
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if ((max_code >= max_code_size) &&
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(max_code_size < (1 << MAX_LWZ_BITS))) {
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max_code_size *= 2;
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++code_size;
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}
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}
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oldcode = incode;
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if (sp > stack)
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return *--sp;
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}
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return code;
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}
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static Image *
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ReadImage(SDL_RWops * src, int len, int height, int cmapSize,
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unsigned char cmap[3][MAXCOLORMAPSIZE],
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int gray, int interlace, int ignore)
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{
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Image *image;
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unsigned char c;
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int i, v;
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int xpos = 0, ypos = 0, pass = 0;
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/*
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** Initialize the compression routines
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*/
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if (!ReadOK(src, &c, 1)) {
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RWSetMsg("EOF / read error on image data");
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return NULL;
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}
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if (LWZReadByte(src, TRUE, c) < 0) {
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RWSetMsg("error reading image");
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return NULL;
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}
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/*
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** If this is an "uninteresting picture" ignore it.
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*/
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if (ignore) {
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while (LWZReadByte(src, FALSE, c) >= 0);
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return NULL;
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}
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image = ImageNewCmap(len, height, cmapSize);
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for (i = 0; i < cmapSize; i++)
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ImageSetCmap(image, i, cmap[CM_RED][i],
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cmap[CM_GREEN][i], cmap[CM_BLUE][i]);
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while ((v = LWZReadByte(src, FALSE, c)) >= 0) {
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#ifdef USED_BY_SDL
|
|
((Uint8 *)image->pixels)[xpos + ypos * image->pitch] = v;
|
|
#else
|
|
image->data[xpos + ypos * len] = v;
|
|
#endif
|
|
++xpos;
|
|
if (xpos == len) {
|
|
xpos = 0;
|
|
if (interlace) {
|
|
switch (pass) {
|
|
case 0:
|
|
case 1:
|
|
ypos += 8;
|
|
break;
|
|
case 2:
|
|
ypos += 4;
|
|
break;
|
|
case 3:
|
|
ypos += 2;
|
|
break;
|
|
}
|
|
|
|
if (ypos >= height) {
|
|
++pass;
|
|
switch (pass) {
|
|
case 1:
|
|
ypos = 4;
|
|
break;
|
|
case 2:
|
|
ypos = 2;
|
|
break;
|
|
case 3:
|
|
ypos = 1;
|
|
break;
|
|
default:
|
|
goto fini;
|
|
}
|
|
}
|
|
} else {
|
|
++ypos;
|
|
}
|
|
}
|
|
if (ypos >= height)
|
|
break;
|
|
}
|
|
|
|
fini:
|
|
|
|
return image;
|
|
}
|
|
|
|
#else
|
|
|
|
/* See if an image is contained in a data source */
|
|
int IMG_isGIF(SDL_RWops *src)
|
|
{
|
|
return(0);
|
|
}
|
|
|
|
/* Load a GIF type image from an SDL datasource */
|
|
SDL_Surface *IMG_LoadGIF_RW(SDL_RWops *src)
|
|
{
|
|
return(NULL);
|
|
}
|
|
|
|
#endif /* LOAD_GIF */
|