ebgif.c

基于minigui开发的一套图形控件系统

/*********************************************
*功能:读取GIF文件的全局变量
*
*
***********************************************/
static int EbReadGIFGlobal ( FILE *src, GIFSCREEN* GifScreen)
{
	unsigned char buf[9];
	unsigned char version[4];
	
    fseek(src, 0L, 0);
	//GIF署名(Signature)和版本号(Version)
	
    if (!ReadOK (src, buf, 6))
        return -1;                
    if (strncmp((char *) buf, "GIF", 3) != 0)/* not gif image*/
    {
    	fprintf(stderr, "Err: File is not GIF \n");
        return -1;
    }
    strncpy (GifScreen->version, (char *) buf + 3, 3);
    GifScreen->version[3] = '\0';

    if (strcmp(GifScreen->version, "87a") != 0 && strcmp(GifScreen->version, "89a") != 0)
    {
    	fprintf(stderr, "Err:GIF's version is not know \n");
        return -1;  /* image loading error*/
    }
    GifScreen->transparent = -1;
    GifScreen->delayTime = -1;
    GifScreen->inputFlag = -1;
    GifScreen->disposal = 0;

    if (!ReadOK (src, buf, 7)) 
        return -1; /* image loading error*/

    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->gColorTable = BitSet(buf[4], LOCALCOLORMAP);
    GifScreen->Background = buf[5];
    GifScreen->AspectRatio = buf[6];
	
    if (GifScreen->gColorTable) //全局颜色列表标志/* Global Colormap */
	{        
        if (EbReadColorMap (src, GifScreen->BitPixel, GifScreen->ColorMap)) 
        {
        	fprintf(stderr, "Err: GIF read global colormap failed\n");
            return -1;     /* image loading error*/
        }
    }

	return 0;
}

/*********************************************
*功能:读取GIF文件的图形标识
*
*
***********************************************/
static int EbReadImageDesc (FILE *src, IMAGEDESC* ImageDesc, GIFSCREEN* GifScreen)
{
	unsigned char buf[16];
	
	if (!ReadOK (src, buf, 9)) 
		return -1;
	
	ImageDesc->Left= LM_to_uint (buf[0], buf[1]);				//X方向偏移量
	ImageDesc->Top= LM_to_uint (buf[2], buf[3]);				//Y方向偏移量
	ImageDesc->Width = LM_to_uint (buf[4], buf[5]);				//图象宽度
	ImageDesc->Height = LM_to_uint (buf[6], buf[7]);			//图象高度
	ImageDesc->haveColorMap = BitSet (buf[8], LOCALCOLORMAP);	//局部颜色列表标志

	ImageDesc->bitPixel = 1 << ((buf[8] & 0x07) + 1);			//局部颜色列表大小

    ImageDesc->interlace = BitSet(buf[8], INTERLACE);			// 交织标志
	ImageDesc->sortFlag = BitSet(buf[8], 0x20);	//分类标志，如果置位表示紧跟着的局部颜色列表分类排列
	
	if (ImageDesc->haveColorMap)
	{
		if (EbReadColorMap(src, ImageDesc->bitPixel, ImageDesc->ColorMap) < 0) 
			return -1;
	} 
	else 
	{
		memcpy (ImageDesc->ColorMap, GifScreen->ColorMap, MAXCOLORMAPSIZE*3);
	}

	return 0;
}


static int EbReadImage (FILE* src, MYBITMAP* bmp, IMAGEDESC* ImageDesc, ControlExtension * ctrl, int ignore)
{

    unsigned char c;
    int v;
    int xpos = 0, ypos = 0, pass = 0;

    /*initialize the compression routines*/
    if (!ReadOK(src, &c, 1)) 
	{
        fprintf (stderr,"load_gif: eof on image data\n");
        return -1;
    }
    if (EbLWZReadByte(src, TRUE, c) < 0) 
	{
        fprintf (stderr,"load_gif: error reading image\n");
        return -1;
    }
    /*if this is an "uninteresting picture" ignore it.*/
    if (ignore) 
	{
        while (EbLWZReadByte(src, FALSE, c) >= 0);
        return -0;
    }
    /*image = imagenewcmap(len, height, cmapsize);*/

    bmp->w = ImageDesc->Width;
    bmp->h = ImageDesc->Height;

    bmp->flags = MYBMP_FLOW_DOWN;
    if (ctrl->trsFlag)
	{
        bmp->flags |= MYBMP_TRANSPARENT;
        bmp->transparent = ctrl->trsColorIndex;
    }
    bmp->frames = 1;
    bmp->depth = 8;
    EbbmpComputePitch (bmp->depth, bmp->w, &bmp->pitch, TRUE);
    bmp->bits = malloc (bmp->h * bmp->pitch);

    if(!bmp->bits)
        return -1;

    while ((v = EbLWZReadByte(src, FALSE, c)) >= 0) 
	{
#if 0
		int index = (ypos) * bmp->pitch + (xpos)*3;
		bmp->bits[index + 0 ] = ImageDesc->ColorMap[CM_RED][v]; 
		bmp->bits[index + 1 ] = ImageDesc->ColorMap[CM_GREEN][v];
		bmp->bits[index + 2 ] = ImageDesc->ColorMap[CM_BLUE][v];
#else		
    	 bmp->bits[ypos * bmp->pitch + xpos] = v;
#endif
        ++xpos;
        if (xpos == ImageDesc->Width) 
		{
            xpos = 0;
            if (ImageDesc->interlace) 
			{
                switch (pass) 
				{
                case 0:
                case 1:
                    ypos += 8;
                    break;
                case 2:
                    ypos += 4;
                    break;
                case 3:
                    ypos += 2;
                    break;
                }

                if (ypos >= ImageDesc->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 >= ImageDesc->Height)
            break;
    }

fini:
    return 0;
}


int EbReadGIF(FILE *src, GIFBITMAP *gifbmp, HDC hdc)
{
    unsigned char c;
    int ok = 0;
	MYBITMAP mybmp;
	PBITMAP pbmp;
	IMAGEDESC ImageDesc;
	GIFBITMAPELEMENT* pgifel=NULL;
	
	if ( EbReadGIFGlobal(src, &(gifbmp->screen)) < 0 ) 
		return -1;

    if ( (ok = ReadOK(src, &c, 1)) == 0) 
        return -1;

	while ( c != ';' && ok>0 )
	{
		switch (c) 
		{
		case '!'://0x21-扩展块
		{	
    		if ((ok = ReadOK (src, &c, 1)) == 0) 
      			  return -1;
			if ( c == 0xF9)
			{
				pgifel = (GIFBITMAPELEMENT*) malloc (sizeof (GIFBITMAPELEMENT));
				if (pgifel == NULL)
					return -1;
				memset(pgifel, 0 , sizeof(GIFBITMAPELEMENT));
			}
			EbDoExtension(src, c, pgifel);
			break;
		}
		case ','://0x2C-图象标识符
		{
			if (EbReadImageDesc (src, &ImageDesc, &(gifbmp->screen)) < 0)
				return -1;
			if(EbReadImage(src, &mybmp, &ImageDesc, &(pgifel->ctrl), 0 ) < 0)
				return -1;
			if (pgifel == NULL)
			{
				pgifel = (GIFBITMAPELEMENT*) malloc (sizeof (GIFBITMAPELEMENT));
				if (pgifel == NULL)
					return -1;
				memset(pgifel, 0 , sizeof(GIFBITMAPELEMENT));
			}
			else 
			{
				pgifel->prev = pgifel->next = NULL;
				pgifel->top = ImageDesc.Top;
				pgifel->left = ImageDesc.Left;
				
				pbmp = &(pgifel->Bitmap);
#ifdef _USE_NEWGAL
                if (ExpandMyBitmap (hdc, pbmp, &mybmp, ImageDesc.ColorMap, 0) < 0)
#else
                if (ExpandMyBitmap (hdc, &mybmp, ImageDesc.ColorMap, pbmp) < 0) 
#endif
				{
                    free (mybmp.bits);
					goto error;
                }
                free (mybmp.bits);
				
				if (gifbmp->first == NULL)
				{
					gifbmp->first = gifbmp->current = pgifel;
				} 
				else 
				{
					pgifel->prev = gifbmp->current;
					gifbmp->current->next = pgifel;
					gifbmp->current = gifbmp->current->next;
				}
				gifbmp->count ++ ;
				pgifel = NULL;
				
			}
			break;
		}
		default:
			break;
		}

		ok = ReadOK (src, &c, 1);
	
	}
	
	EbRewindGIF(gifbmp);
	return 0;

error:
    EbCleanGIF (gifbmp);
    return -1;
}

void EbInitGIF (GIFBITMAP* gifbmp)
{
	memset((void *)gifbmp, 0, sizeof(GIFBITMAP));
	gifbmp->first = gifbmp->current = NULL;	
	return;
}

void EbCleanGIF (GIFBITMAP* gifbmp)
{
	GIFBITMAPELEMENT *tmpel, *pel;
		
	pel = gifbmp->first;
	while (pel) 
	{
		tmpel= pel->next;
		if (pel->Bitmap.bmBits)
			free (pel->Bitmap.bmBits);
		free (pel);

		pel = tmpel;
	}
	return;
}

void EbRewindGIF (GIFBITMAP* gifbmp)
{
	gifbmp->current = gifbmp->first;
}

PBITMAP EbGetCurrentGIFBmp (GIFBITMAP* gifbmp)
{
	if(gifbmp->current)
		return &(gifbmp->current->Bitmap);
	else
		return 0;
}

PBITMAP EbGetNextGIFBmp (GIFBITMAP* gifbmp)
{
	gifbmp->current = gifbmp->current->next;
	return EbGetCurrentGIFBmp (gifbmp);
}

PGIFBITMAPELEMENT EbGetCurrentGIFItem(GIFBITMAP* gifbmp)
{
	if (gifbmp->current)
		return gifbmp->current;
	else
		return NULL;
}

PGIFBITMAPELEMENT EbGetNextGIFItem(GIFBITMAP* gifbmp)
{
	gifbmp->current = gifbmp->current->next;
	
	if (gifbmp->current == NULL)
		gifbmp->current = gifbmp->first;
	
	return gifbmp->current;
}