GIF图片/动画解码程序

#include "define.h" #include "malloc.h" #include "stdio.h" #include "alj.h" #include "lzw.h" #include "stream.h" #define FILENAME "d:\\1.gif" int file_load(uint8_t ** buf) { FILE * fp; long len; fp=fopen(FILENAME,"rb+"); if(fp==NULL) { printf("The file is not exeict!\n"); getch(); return -1; } fseek(fp,0L,SEEK_END); len=ftell(fp)-1; *buf=(uint8_t *)malloc(len); if(*buf==NULL) { printf("Ram is out!\n"); getch(); return -1; } fseek(fp,0L,SEEK_SET); fread(*buf,1L,len,fp); fclose(fp); #ifdef debug printf("The file is copied to Ram!\n"); getch(); #endif return len; } #undef FILENAME void file_close(GifState * s) { free(s->bytestream); free(s->outdata); } int gif_head(GifState * s) { char sig[6]; uint8_t gif87a_sig[6] = "GIF87a"; uint8_t gif89a_sig[6] = "GIF89a"; bytestream_get_buffer(&s->bytestream, sig, 6); if(*sig==*gif87a_sig|*sig==*gif89a_sig) return 0; return -1; } int far gif_init(GifState *s) { uint8_t tmp; int n; unsigned int len; ff_lzw_decode_open(&s->lzw); s->transparent_color_index=0; s->gce_delay=0; s->gce_disposal=0; s->screen_width=bytestream_get_2byte(&s->bytestream); s->screen_height=bytestream_get_2byte(&s->bytestream); tmp=bytestream_get_1byte(&s->bytestream); s->background_color_index=bytestream_get_1byte(&s->bytestream); bytestream_get_1byte(&s->bytestream); len=s->screen_width * s->screen_height; s->outdata=(uint8_t *)malloc(len); if(s->outdata==NULL) { printf("RAM is out!\n"); getch(); return -1; } s->color_resolution=((tmp&0x70)>>4)+1; s->bits_per_pixel=(tmp&0x7)+1; if((tmp&0x80)==0x80) { n=1<<s->bits_per_pixel; bytestream_get_buffer(&s->bytestream,s->global_palette,3*n); } return 0; } int far gif_read_extension(GifState *s) { int ext_code,ext_len,i, gce_flags, gce_transparent_index; ext_code=bytestream_get_1byte(&s->bytestream); ext_len=bytestream_get_1byte(&s->bytestream); switch(ext_code) { case 0xf9: if (ext_len != 4) goto discard_ext; s->transparent_color_index = -1; gce_flags = bytestream_get_1byte(&s->bytestream); s->gce_delay = bytestream_get_2byte(&s->bytestream); gce_transparent_index = bytestream_get_1byte(&s->bytestream); if (gce_flags & 0x01) s->transparent_color_index = gce_transparent_index; else s->transparent_color_index = -1; s->gce_disposal = (gce_flags >> 2) & 0x7; #ifdef DEBUG dprintf(s->avctx, "gif: gce_flags=%x delay=%d tcolor=%d disposal=%d\n", gce_flags, s->gce_delay, s->transparent_color_index, s->gce_disposal); #endif ext_len = bytestream_get_1byte(&s->bytestream); break; } /* NOTE: many extension blocks can come after */ discard_ext: while (ext_len != 0) { for (i = 0; i < ext_len; i++) bytestream_get_1byte(&s->bytestream); ext_len = bytestream_get_1byte(&s->bytestream); #ifdef DEBUG dprintf(s->avctx, "gif: ext_len1=%d\n", ext_len); #endif } return 0; } #define RL24(x) ((((const uint8_t*)(x))[0] << 16) | \ (((const uint8_t*)(x))[1] << 8) | \ ((const uint8_t*)(x))[2]) int far gif_read_image(GifState *s) { uint16_t left, top, height, width; uint8_t tmp,has_local_palette, is_interleaved; uint8_t bits_per_pixel,linesize; uint8_t * palette,*ptr,*ptr1; int n,i,code_size, y, y1, pass; left=bytestream_get_2byte(&s->bytestream); top=bytestream_get_2byte(&s->bytestream); width=bytestream_get_2byte(&s->bytestream); height=bytestream_get_2byte(&s->bytestream); tmp=bytestream_get_1byte(&s->bytestream); bits_per_pixel=(tmp&0x7)+1; is_interleaved=tmp&0x40; has_local_palette=tmp&0x80; if(has_local_palette==0x80) { bytestream_get_buffer(&s->bytestream,s->local_palette,3*(1<<bits_per_pixel)); palette=s->local_palette; } else { palette=s->global_palette; bits_per_pixel = s->bits_per_pixel; } if((top+height)>s->screen_height||(l<input type="image" src="">eft+width)>s->screen_width) { printf("The image is wrong!\n"); return -1; } s->image_palette1=s->global_palette; n=(1<<bits_per_pixel); for (i=0;i<n;i++) { s->image_palette[i]=(0xff<<24)|RL24(palette); palette+=3; } for(;i<255;i++) { s->image_palette[i]=(0xff<<24); } if(s->transparent_color_index>=0) s->image_palette[s->transparent_color_index]=0; code_size=bytestream_get_1byte(&s->bytestream); ff_lzw_decode_init(s->lzw, code_size, s->bytestream,s->bytestream_end - s->bytestream, FF_LZW_GIF); linesize=s->screen_width; ptr1=s->outdata +top*linesize+ left; ptr=ptr1; y1=0; pass=0; for(y=0;y<height;y++) { ff_lzw_decode(s->lzw, ptr, width); if (is_interleaved) { switch(pass) { default: case 0: case 1: y1 += 8; ptr += linesize * 8; if (y1 >= height) { y1 = pass ? 2 : 4; ptr = ptr1 + linesize * y1; pass++; } break; case 2: y1 += 4; ptr += linesize * 4; if (y1 >= height) { y1 = 1; ptr = ptr1 + linesize; pass++; } break; case 3: y1 += 2; ptr += linesize * 2; break; } } else { ptr += linesize; } } ff_lzw_decode_tail(s->lzw); s->bytestream = ff_lzw_cur_ptr(s->lzw); return 2; }