gd_gif_out.c

来自「Linux/Unix下的绘图函数库（Graphic Drawing Librar」· C语言 代码 · 共 1,194 行 · 第 1/3 页

				     max_x-min_x+1, max_y-min_y+1);
			if (pim)
				gdImageDestroy (pim);
			tim = pim = pim2;
		}

		/* now let's compare pixels for transparent
		   optimization.  But only if transparent is set. */
		if (transparent >= 0) {
			for (y = 0; y < tim->sy; ++y)
				for (x = 0; x < tim->sx; ++x)
					if (comparewithmap
					    (prev_tim, tim,
					     prev_tim->pixels[min_y+y][min_x+x],
					     tim->pixels[y][x], 0)) {
						gdImageSetPixel (tim, x, y,
								 transparent);
						break;
					}
		}
		if (prev_pim)
			gdImageDestroy (prev_pim);
	}
	BitsPerPixel = colorstobpp(tim->colorsTotal);
	/* All set, let's do it. */
	GIFAnimEncode(
		out, tim->sx, tim->sy, LeftOfs, TopOfs, interlace, transparent,
		Delay, Disposal, BitsPerPixel,
		LocalCM ? tim->red : 0, tim->green, tim->blue, tim);
 fail_end:
	if (pim) {
		/* Destroy palette based temporary image. */
		gdImageDestroy(	pim);
	}
}

BGD_DECLARE(void) gdImageGifAnimEnd(FILE *outFile)
{
#if 1
  putc (';', outFile);
#else
  gdIOCtx *out = gdNewFileCtx (outFile);
  gdImageGifAnimEndCtx (out);
  out->gd_free (out);
#endif
}

BGD_DECLARE(void *) gdImageGifAnimEndPtr (int *size)
{
  char *rv = (char *) gdMalloc (1);
  *rv = ';';
  *size = 1;
  return (void *)rv;
}

BGD_DECLARE(void) gdImageGifAnimEndCtx(gdIOCtx *out)
{
	/*
	 * Write the GIF file terminator
	 */
	gdPutC( ';', out );
}

static int
colorstobpp(int colors)
{
    int bpp = 0;

    if ( colors <= 2 )
        bpp = 1;
    else if ( colors <= 4 )
        bpp = 2;
    else if ( colors <= 8 )
        bpp = 3;
    else if ( colors <= 16 )
        bpp = 4;
    else if ( colors <= 32 )
        bpp = 5;
    else if ( colors <= 64 )
        bpp = 6;
    else if ( colors <= 128 )
        bpp = 7;
    else if ( colors <= 256 )
        bpp = 8;
    return bpp;
    }

/*****************************************************************************
 *
 * GIFENCODE.C    - GIF Image compression interface
 *
 * GIFEncode( FName, GHeight, GWidth, GInterlace, Background, Transparent,
 *            BitsPerPixel, Red, Green, Blue, gdImagePtr )
 *
 *****************************************************************************/

#define TRUE 1
#define FALSE 0
/*
 * Bump the 'curx' and 'cury' to point to the next pixel
 */
static void
BumpPixel(GifCtx *ctx)
{
        /*
         * Bump the current X position
         */
        ++(ctx->curx);

        /*
         * If we are at the end of a scan line, set curx back to the beginning
         * If we are interlaced, bump the cury to the appropriate spot,
         * otherwise, just increment it.
         */
        if( ctx->curx == ctx->Width ) {
                ctx->curx = 0;

                if( !ctx->Interlace )
                        ++(ctx->cury);
                else {
                     switch( ctx->Pass ) {

                       case 0:
                          ctx->cury += 8;
                          if( ctx->cury >= ctx->Height ) {
                                ++(ctx->Pass);
                                ctx->cury = 4;
                          }
                          break;

                       case 1:
                          ctx->cury += 8;
                          if( ctx->cury >= ctx->Height ) {
                                ++(ctx->Pass);
                                ctx->cury = 2;
                          }
                          break;

                       case 2:
                          ctx->cury += 4;
                          if( ctx->cury >= ctx->Height ) {
                             ++(ctx->Pass);
                             ctx->cury = 1;
                          }
                          break;

                       case 3:
                          ctx->cury += 2;
                          break;
                        }
                }
        }
}

/*
 * Return the next pixel from the image
 */
static int
GIFNextPixel(gdImagePtr im, GifCtx *ctx)
{
        int r;

        if( ctx->CountDown == 0 )
                return EOF;

        --(ctx->CountDown);

        r = gdImageGetPixel(im, ctx->curx, ctx->cury);

        BumpPixel(ctx);

        return r;
}

/* public */

static void
GIFEncode(gdIOCtxPtr fp, int GWidth, int GHeight, int GInterlace, int Background, int Transparent, int BitsPerPixel, int *Red, int *Green, int *Blue, gdImagePtr im)
{
        int B;
        int RWidth, RHeight;
        int LeftOfs, TopOfs;
        int Resolution;
        int ColorMapSize;
        int InitCodeSize;
        int i;
	GifCtx ctx;
        ctx.Interlace = GInterlace;
	ctx.in_count = 1;
	memset(&ctx, 0, sizeof(ctx));
        ColorMapSize = 1 << BitsPerPixel;

        RWidth = ctx.Width = GWidth;
        RHeight = ctx.Height = GHeight;
        LeftOfs = TopOfs = 0;

        Resolution = BitsPerPixel;

        /*
         * Calculate number of bits we are expecting
         */
        ctx.CountDown = (long)ctx.Width * (long)ctx.Height;

        /*
         * Indicate which pass we are on (if interlace)
         */
        ctx.Pass = 0;

        /*
         * The initial code size
         */
        if( BitsPerPixel <= 1 )
                InitCodeSize = 2;
        else
                InitCodeSize = BitsPerPixel;

        /*
         * Set up the current x and y position
         */
        ctx.curx = ctx.cury = 0;

        /*
         * Write the Magic header
         */
        gdPutBuf(Transparent < 0 ? "GIF87a" : "GIF89a", 6, fp );

        /*
         * Write out the screen width and height
         */
        gifPutWord( RWidth, fp );
        gifPutWord( RHeight, fp );

        /*
         * Indicate that there is a global colour map
         */
        B = 0x80;       /* Yes, there is a color map */

        /*
         * OR in the resolution
         */
        B |= (Resolution - 1) << 5;

        /*
         * OR in the Bits per Pixel
         */
        B |= (BitsPerPixel - 1);

        /*
         * Write it out
         */
        gdPutC( B, fp );

        /*
         * Write out the Background colour
         */
        gdPutC( Background, fp );

        /*
         * Byte of 0's (future expansion)
         */
        gdPutC( 0, fp );

        /*
         * Write out the Global Colour Map
         */
        for( i=0; i<ColorMapSize; ++i ) {
                gdPutC( Red[i], fp );
                gdPutC( Green[i], fp );
                gdPutC( Blue[i], fp );
        }

	/*
	 * Write out extension for transparent colour index, if necessary.
	 */
	if ( Transparent >= 0 ) {
	    gdPutC( '!', fp );
	    gdPutC( 0xf9, fp );
	    gdPutC( 4, fp );
	    gdPutC( 1, fp );
	    gdPutC( 0, fp );
	    gdPutC( 0, fp );
	    gdPutC( (unsigned char) Transparent, fp );
	    gdPutC( 0, fp );
	}

        /*
         * Write an Image separator
         */
        gdPutC( ',', fp );

        /*
         * Write the Image header
         */

        gifPutWord( LeftOfs, fp );
        gifPutWord( TopOfs, fp );
        gifPutWord( ctx.Width, fp );
        gifPutWord( ctx.Height, fp );

        /*
         * Write out whether or not the image is interlaced
         */
        if( ctx.Interlace )
                gdPutC( 0x40, fp );
        else
                gdPutC( 0x00, fp );

        /*
         * Write out the initial code size
         */
        gdPutC( InitCodeSize, fp );

        /*
         * Go and actually compress the data
         */
        compress( InitCodeSize+1, fp, im, &ctx );

        /*
         * Write out a Zero-length packet (to end the series)
         */
        gdPutC( 0, fp );

        /*
         * Write the GIF file terminator
         */
        gdPutC( ';', fp );
}

static void
GIFAnimEncode(gdIOCtxPtr fp, int IWidth, int IHeight, int LeftOfs, int TopOfs, int GInterlace, int Transparent, int Delay, int Disposal, int BitsPerPixel, int *Red, int *Green, int *Blue, gdImagePtr im)
{
	int B;
        int ColorMapSize;
        int InitCodeSize;
        int i;
	GifCtx ctx;
        ctx.Interlace = GInterlace;
	ctx.in_count = 1;
	memset(&ctx, 0, sizeof(ctx));
        ColorMapSize = 1 << BitsPerPixel;

	if (LeftOfs < 0) LeftOfs = 0;
	if (TopOfs < 0) TopOfs = 0;
	if (Delay < 0) Delay = 100;
	if (Disposal < 0) Disposal = 1;

	ctx.Width = IWidth;
        ctx.Height = IHeight;

        /*
         * Calculate number of bits we are expecting
         */
        ctx.CountDown = (long)ctx.Width * (long)ctx.Height;

        /*
         * Indicate which pass we are on (if interlace)
         */
        ctx.Pass = 0;

        /*
         * The initial code size
         */
        if( BitsPerPixel <= 1 )
                InitCodeSize = 2;
        else
                InitCodeSize = BitsPerPixel;

        /*
         * Set up the current x and y position
         */
        ctx.curx = ctx.cury = 0;

	/*
	 * Write out extension for image animation and looping
	 */
	gdPutC( '!', fp );
	gdPutC( 0xf9, fp );
	gdPutC( 4, fp );
	gdPutC( (Transparent >= 0 ? 1 : 0)
		| (Disposal << 2), fp );
	gdPutC( (unsigned char)(Delay & 255), fp );
	gdPutC( (unsigned char)((Delay >> 8) & 255), fp );
	gdPutC( (unsigned char) Transparent, fp );
	gdPutC( 0, fp );

	/*
	 * Write an Image separator
	 */
	gdPutC( ',', fp );

        /*
         * Write out the Image header
         */
        gifPutWord( LeftOfs, fp );
        gifPutWord( TopOfs, fp );
        gifPutWord( ctx.Width, fp );
        gifPutWord( ctx.Height, fp );