giftobmp.c

IP网络语音通讯软件源代码. 不可多得的语音源代码

			   if (sp > LZWstack)
					   return *--sp;
	   }
	   return code;
}

//	DOEXTENSION  --  Process extension items

static int DoExtension(int label)
{
	   char buf[256];
#ifdef GIF_DEBUG	   
	   char *str;
#endif	   

	   switch (label) {
	   case 0x01:			   /* Plain Text Extension */
#ifdef GIF_DEBUG	   
               str = "Plain Text Extension";
#endif	   
			   break; 
			   
	   case 0xff:			   /* Application Extension */
#ifdef GIF_DEBUG	   
               str = "Application Extension";
#endif	   
			   break;
			   
	   case 0xfe:			   /* Comment Extension */
#ifdef GIF_DEBUG	   
               str = "Comment Extension";
#endif
         // This line should fix many crashes because John Walker was
         // originally checking for a zero return, which would never
         // occur because if the block is zero length, GetDataBlock()
         // returns -1, never 0.
			   while (GetDataBlock((unsigned char *) buf) != -1) {
			   }
			   return FALSE;
			   
	   case 0xf9:			   /* Graphic Control Extension */
#ifdef GIF_DEBUG	   
               str = "Graphic Control Extension";
#endif	   
			   (void) GetDataBlock((unsigned char *) buf);
			   Gif89.disposal = (buf[0] >> 2) & 0x7;
			   Gif89.inputFlag = (buf[0] >> 1) & 0x1;
			   Gif89.delayTime = LM_to_uint(buf[1],buf[2]);
			   if ((buf[0] & 0x1) != 0)
					   Gif89.transparent = buf[3];

         // This line should fix many crashes because John Walker was
         // originally checking for a zero return, which would never
         // occur because if the block is zero length, GetDataBlock()
         // returns -1, never 0.
			   while (GetDataBlock((unsigned char *) buf) != -1) ;
			   return FALSE;
			   
	   default:
			   break;
	   }

     // This line should fix many crashes because John Walker was
     // originally checking for a zero return, which would never
     // occur because if the block is zero length, GetDataBlock()
     // returns -1, never 0.
	   while (GetDataBlock((unsigned char *) buf) != -1) ;

	   return FALSE;
}

/*	READIMAGE  --  Read all components of image and, if successful,
				   create the in-memory .BMP file.  */

static int ReadImage(int len, int height,
					 int ncolours, unsigned char FAR cmap[3][MAXCOLORMAPSIZE],
					 int interlace, int ignore)
{
	   unsigned char c;	   
	   int v, linelen;
	   int xpos = 0, ypos = 0, pass = 0;
	   DWORD bfsize;
	   BYTE _huge *pixels;
	   LPBITMAPFILEHEADER bfh;
	   LPBITMAPINFO bi;
	   LPBITMAPINFOHEADER bh;

	   //  Initialize the Compression routines
	   
	   ReadOK(fd, &c, 1);

	   if (LWZReadByte(TRUE, c) < 0)
               return FALSE;

       //  If this is an "uninteresting picture" ignore it.

	   if (ignore) {
			   while (LWZReadByte(FALSE, c) >= 0) ;
			   return FALSE;
	   }
	   
	   //  Allocate the in-memory bitmap file.
	   
	   linelen = (len + 3) & (~3);
	   bmpFile = (LPBYTE) GlobalAllocPtr(GPTR, bfsize =
	   				sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) +
	   				256 * sizeof(RGBQUAD) + (linelen * ((DWORD) height)));
	   bfh = (LPBITMAPFILEHEADER) bmpFile;
	   bi = (LPBITMAPINFO) (bmpFile + sizeof(BITMAPFILEHEADER));
	   bh = &(bi->bmiHeader); 
	   pixels = bmpFile + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) +
	   				256 * sizeof(RGBQUAD);
	   				
	   //	Build file header
	   
	   _fmemcpy(&bfh->bfType, "BM", 2);
	   bfh->bfSize = bfsize;
	   bfh->bfOffBits = ((LPBYTE) pixels) - bmpFile;
	   
	   //	Build BITMAPINFOHEADER
	   
	   bh->biSize = sizeof(BITMAPINFOHEADER);
	   bh->biWidth = len;
	   bh->biHeight = height;
	   bh->biPlanes = 1;
	   bh->biBitCount = 8;
	   bh->biCompression = BI_RGB;
	   bh->biSizeImage = 0;
	   bh->biClrUsed = bh->biClrImportant = ncolours;
	   
	   //	Transcribe colour table to the bmiColors list
	   
	   for (v = 0; v < ncolours; v++) {
	       bi->bmiColors[v].rgbRed = cmap[CM_RED][v];
	       bi->bmiColors[v].rgbGreen = cmap[CM_GREEN][v];
	       bi->bmiColors[v].rgbBlue = cmap[CM_BLUE][v];
	   }  

	   while ((v = LWZReadByte(FALSE, c)) >= 0 ) {
	   		   if (ypos > 0 && ypos < height) {
	               pixels[(linelen * ((DWORD) ((height - 1) - ypos))) + xpos] = v;
	           }

			   ++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 TRUE;
}

/*	GIFTOBMP  --  Convert an in-memory GIF file to an in-memory
				  .BMP file.  Returns NULL if anything went wrong
				  in the conversion process.  */

LPBYTE GIFtoBMP(LPBYTE gif, int imageNumber)
{
	   unsigned char buf[16];
	   unsigned char c;
	   int useGlobalColormap;
	   int bitPixel;
	   int imageCount = 0;
	   char version[4];
       
       gifFile = gif;
       gifAddr = 0;
       fatal = FALSE;
	   ReadOK(fd, buf, 6);

       if (strncmp((char *) buf,"GIF",3) != 0)
               pm_error("not a GIF file");

	   strncpy(version, (char *) buf + 3, 3);
       version[3] = '\0';

       if ((strcmp(version, "87a") != 0) && (strcmp(version, "89a") != 0))
               pm_error("bad version number, not '87a' or '89a'");
               
       GIFcontext = (struct context FAR *) GlobalAllocPtr(GPTR, sizeof(struct context));
       if (GIFcontext == NULL) {
           return NULL;
       }

	   ReadOK(fd,buf,7);

	   GifScreen.Width = LM_to_uint(buf[0], buf[1]);
	   GifScreen.Height = LM_to_uint(buf[2], buf[3]);
	   GifScreen.BitPixel = 2 << (buf[4] & 0x07);
	   GifScreen.ColorResolution = (((buf[4] & 0x70) >> 3) + 1);
	   GifScreen.Background = buf[5];
	   GifScreen.AspectRatio = buf[6];

	   if (BitSet(buf[4], LOCALCOLORMAP)) {    /* Global Colormap */
			   if (!ReadColorMap(GifScreen.BitPixel, GifScreen.ColorMap))
                       pm_error("error reading global colormap");
	   }

	   for (;;) {
			   ReadOK(fd, &c, 1);

               if (c == ';') {         /* GIF terminator */
					   if (imageCount < imageNumber)
                               pm_error("Too few images found in file");
                       if (GIFcontext != NULL) {
                       	   GlobalFreePtr(GIFcontext);
                       	   GIFcontext = NULL;
                       }
					   return bmpFile;
			   }

               if (c == '!') {         /* Extension */
					   ReadOK(fd, &c, 1);
					   DoExtension(c);
					   continue;
			   }

               if (c != ',') {         /* Not a valid start character */
					   continue;
			   }

			   ++imageCount;

			   ReadOK(fd, buf, 9);

			   useGlobalColormap = ! BitSet(buf[8], LOCALCOLORMAP);

			   bitPixel = 1 << ((buf[8] & 0x07) + 1);

			   if (!useGlobalColormap) {
					   if (!ReadColorMap(bitPixel, localColorMap))
                               pm_error("error reading local colormap");
					   ReadImage(LM_to_uint(buf[4], buf[5]),
								 LM_to_uint(buf[6], buf[7]), 
								 bitPixel, localColorMap,
								 BitSet(buf[8], INTERLACE), imageCount != imageNumber);
			   } else {
					   ReadImage(LM_to_uint(buf[4], buf[5]),
								 LM_to_uint(buf[6], buf[7]), 
								 GifScreen.BitPixel, GifScreen.ColorMap,
								 BitSet(buf[8], INTERLACE), imageCount != imageNumber);
			   }

	   }
}