gd.c

Linux/Unix下的绘图函数库（Graphic Drawing Library）

  /* Below */
  if (y < ((im->sy) - 1))
    {
      lastBorder = 1;
      for (i = leftLimit; (i <= rightLimit); i++)
	{
	  int c;
	  c = gdImageGetPixel (im, i, y + 1);
	  if (lastBorder)
	    {
	      if (c == old)
		{
		  gdImageFill (im, i, y + 1, color);
		  lastBorder = 0;
		}
	    }
	  else if (c != old)
	    {
	      lastBorder = 1;
	    }
	}
    }
}

BGD_DECLARE(void) gdImageRectangle (gdImagePtr im, int x1, int y1, int x2, int y2, int color)
{
  int x1h = x1, x1v = x1, y1h = y1, y1v = y1, x2h = x2, x2v = x2, y2h = y2,
    y2v = y2;
  int thick = im->thick;
  if (thick > 1)
    {
      int half = thick / 2;
      int half1 = thick - half;

      if (y1 < y2)
	{
	  y1v = y1h - half;
	  y2v = y2h + half1 - 1;
	}
      else
	{
	  y1v = y1h + half1 - 1;
	  y2v = y2h - half;
	}
    }

  gdImageLine (im, x1h, y1h, x2h, y1h, color);
  gdImageLine (im, x1h, y2h, x2h, y2h, color);
  gdImageLine (im, x1v, y1v, x1v, y2v, color);
  gdImageLine (im, x2v, y1v, x2v, y2v, color);
}

BGD_DECLARE(void) gdImageFilledRectangle (gdImagePtr im, int x1, int y1, int x2, int y2,
			int color)
{
  int x, y;
  /* Nick Atty: limit the points at the edge.  Note that this also
     nicely kills any plotting for rectangles completely outside the
     window as it makes the tests in the for loops fail */
  if (x1 < 0)
    x1 = 0;
  if (x1 > gdImageSX (im))
    x1 = gdImageSX (im);
  if (y1 < 0)
    y1 = 0;
  if (y1 > gdImageSY (im))
    y1 = gdImageSY (im);

  for (y = y1; (y <= y2); y++)
    {
      for (x = x1; (x <= x2); x++)
	{
	  gdImageSetPixel (im, x, y, color);
	}
    }
}

BGD_DECLARE(void) gdImageCopy (gdImagePtr dst, gdImagePtr src, int dstX, int dstY, int srcX,
	     int srcY, int w, int h)
{
  int c;
  int x, y;
  int tox, toy;
  int i;
  int colorMap[gdMaxColors];
  if (dst->trueColor)
    {
      /* 2.0: much easier when the destination is truecolor. */
      /* 2.0.10: needs a transparent-index check that is still valid if
         the source is not truecolor. Thanks to Frank Warmerdam. */
      for (y = 0; (y < h); y++)
	{
	  for (x = 0; (x < w); x++)
	    {
	      int p = gdImageGetPixel (src, srcX + x, srcY + y);
	      if (p != src->transparent)
		{
		  int c = gdImageGetTrueColorPixel (src, srcX + x,
						    srcY + y);
		  gdImageSetPixel (dst, dstX + x, dstY + y, c);
		}
	    }
	}
      return;
    }
  for (i = 0; (i < gdMaxColors); i++)
    {
      colorMap[i] = (-1);
    }
  toy = dstY;
  for (y = srcY; (y < (srcY + h)); y++)
    {
      tox = dstX;
      for (x = srcX; (x < (srcX + w)); x++)
	{
	  int nc;
	  int mapTo;
	  c = gdImageGetPixel (src, x, y);
	  /* Added 7/24/95: support transparent copies */
	  if (gdImageGetTransparent (src) == c)
	    {
	      tox++;
	      continue;
	    }
	  /* Have we established a mapping for this color? */
	  if (src->trueColor)
	    {
	      /* 2.05: remap to the palette available in the
	         destination image. This is slow and
	         works badly, but it beats crashing! Thanks 
	         to Padhrig McCarthy. */
	      mapTo = gdImageColorResolveAlpha (dst,
						gdTrueColorGetRed (c),
						gdTrueColorGetGreen (c),
						gdTrueColorGetBlue (c),
						gdTrueColorGetAlpha (c));
	    }
	  else if (colorMap[c] == (-1))
	    {
	      /* If it's the same image, mapping is trivial */
	      if (dst == src)
		{
		  nc = c;
		}
	      else
		{
		  /* Get best match possible. This
		     function never returns error. */
		  nc = gdImageColorResolveAlpha (dst,
						 src->red[c], src->green[c],
						 src->blue[c], src->alpha[c]);
		}
	      colorMap[c] = nc;
	      mapTo = colorMap[c];
	    }
	  else
	    {
	      mapTo = colorMap[c];
	    }
	  gdImageSetPixel (dst, tox, toy, mapTo);
	  tox++;
	}
      toy++;
    }
}

/* This function is a substitute for real alpha channel operations,
   so it doesn't pay attention to the alpha channel. */
BGD_DECLARE(void) gdImageCopyMerge (gdImagePtr dst, gdImagePtr src, int dstX, int dstY,
		  int srcX, int srcY, int w, int h, int pct)
{

  int c, dc;
  int x, y;
  int tox, toy;
  int ncR, ncG, ncB;
  toy = dstY;
  for (y = srcY; (y < (srcY + h)); y++)
    {
      tox = dstX;
      for (x = srcX; (x < (srcX + w)); x++)
	{
	  int nc;
	  c = gdImageGetPixel (src, x, y);
	  /* Added 7/24/95: support transparent copies */
	  if (gdImageGetTransparent (src) == c)
	    {
	      tox++;
	      continue;
	    }
	  /* If it's the same image, mapping is trivial */
	  if (dst == src)
	    {
	      nc = c;
	    }
	  else
	    {
	      dc = gdImageGetPixel (dst, tox, toy);

	      ncR = gdImageRed (src, c) * (pct / 100.0)
		+ gdImageRed (dst, dc) * ((100 - pct) / 100.0);
	      ncG = gdImageGreen (src, c) * (pct / 100.0)
		+ gdImageGreen (dst, dc) * ((100 - pct) / 100.0);
	      ncB = gdImageBlue (src, c) * (pct / 100.0)
		+ gdImageBlue (dst, dc) * ((100 - pct) / 100.0);

	      /* Find a reasonable color */
	      nc = gdImageColorResolve (dst, ncR, ncG, ncB);
	    }
	  gdImageSetPixel (dst, tox, toy, nc);
	  tox++;
	}
      toy++;
    }
}

/* This function is a substitute for real alpha channel operations,
   so it doesn't pay attention to the alpha channel. */
BGD_DECLARE(void) gdImageCopyMergeGray (gdImagePtr dst, gdImagePtr src, int dstX, int dstY,
		      int srcX, int srcY, int w, int h, int pct)
{

  int c, dc;
  int x, y;
  int tox, toy;
  int ncR, ncG, ncB;
  float g;
  toy = dstY;
  for (y = srcY; (y < (srcY + h)); y++)
    {
      tox = dstX;
      for (x = srcX; (x < (srcX + w)); x++)
	{
	  int nc;
	  c = gdImageGetPixel (src, x, y);
	  /* Added 7/24/95: support transparent copies */
	  if (gdImageGetTransparent (src) == c)
	    {
	      tox++;
	      continue;
	    }
	  /* 
	   * If it's the same image, mapping is NOT trivial since we 
	   * merge with greyscale target, but if pct is 100, the grey 
	   * value is not used, so it becomes trivial. pjw 2.0.12. 
	   */
	  if (dst == src && pct == 100)
	    {
	      nc = c;
	    }
	  else
	    {
	      dc = gdImageGetPixel (dst, tox, toy);
	      g = 0.29900 * dst->red[dc]
		+ 0.58700 * dst->green[dc] + 0.11400 * dst->blue[dc];

	      ncR = gdImageRed (src, c) * (pct / 100.0)
		+ g * ((100 - pct) / 100.0);
	      ncG = gdImageGreen (src, c) * (pct / 100.0)
		+ g * ((100 - pct) / 100.0);
	      ncB = gdImageBlue (src, c) * (pct / 100.0)
		+ g * ((100 - pct) / 100.0);

	      /* First look for an exact match */
	      nc = gdImageColorExact (dst, ncR, ncG, ncB);
	      if (nc == (-1))
		{
		  /* No, so try to allocate it */
		  nc = gdImageColorAllocate (dst, ncR, ncG, ncB);
		  /* If we're out of colors, go for the
		     closest color */
		  if (nc == (-1))
		    {
		      nc = gdImageColorClosest (dst, ncR, ncG, ncB);
		    }
		}
	    }
	  gdImageSetPixel (dst, tox, toy, nc);
	  tox++;
	}
      toy++;
    }
}

BGD_DECLARE(void) gdImageCopyResized (gdImagePtr dst, gdImagePtr src, int dstX, int dstY,
		    int srcX, int srcY, int dstW, int dstH, int srcW,
		    int srcH)
{
  int c;
  int x, y;
  int tox, toy;
  int ydest;
  int i;
  int colorMap[gdMaxColors];
  /* Stretch vectors */
  int *stx;
  int *sty;
  /* We only need to use floating point to determine the correct
     stretch vector for one line's worth. */
  if (overflow2(sizeof (int), srcW)) {
    return;
  }
  if (overflow2(sizeof (int), srcH)) {
    return;
  }
  stx = (int *) gdMalloc (sizeof (int) * srcW);
  sty = (int *) gdMalloc (sizeof (int) * srcH);
  /* Fixed by Mao Morimoto 2.0.16 */
  for (i = 0; (i < srcW); i++)
    {
      stx[i] = dstW * (i + 1) / srcW - dstW * i / srcW;
    }
  for (i = 0; (i < srcH); i++)
    {
      sty[i] = dstH * (i + 1) / srcH - dstH * i / srcH;
    }
  for (i = 0; (i < gdMaxColors); i++)
    {
      colorMap[i] = (-1);
    }
  toy = dstY;
  for (y = srcY; (y < (srcY + srcH)); y++)
    {
      for (ydest = 0; (ydest < sty[y - srcY]); ydest++)
	{
	  tox = dstX;
	  for (x = srcX; (x < (srcX + srcW)); x++)
	    {
	      int nc = 0;
	      int mapTo;
	      if (!stx[x - srcX])
		{
		  continue;
		}
	      if (dst->trueColor)
		{
		  /* 2.0.9: Thorben Kundinger: Maybe the source image is not 
		     a truecolor image */
		  if (!src->trueColor)
		    {
		      int tmp = gdImageGetPixel (src, x, y);
		      mapTo = gdImageGetTrueColorPixel (src, x, y);
		      if (gdImageGetTransparent (src) == tmp)
			{
			  /* 2.0.21, TK: not tox++ */
			  tox += stx[x - srcX];
			  continue;
			}
		    }
		  else
		    {
		      /* TK: old code follows */
		      mapTo = gdImageGetTrueColorPixel (src, x, y);
		      /* Added 7/24/95: support transparent copies */
		      if (gdImageGetTransparent (src) == mapTo)
			{
			  /* 2.0.21, TK: not tox++ */
			  tox += stx[x - srcX];
			  continue;
			}
		    }
		}
	      else
		{
		  c = gdImageGetPixel (src, x, y);
		  /* Added 7/24/95: support transparent copies */
		  if (gdImageGetTransparent (src) == c)
		    {
		      tox += stx[x - srcX];
		      continue;
		    }
		  if (src->trueColor)
		    {
		      /* Remap to the palette available in the
		         destination image. This is slow and
		         works badly. */
		      mapTo = gdImageColorResolveAlpha (dst,
							gdTrueColorGetRed (c),
							gdTrueColorGetGreen
							(c),
							gdTrueColorGetBlue
							(c),
							gdTrueColorGetAlpha
							(c));
		    }
		  else
		    {
		      /* Have we established a mapping for this color? */
		      if (colorMap[c] == (-1))
			{
			  /* If it's the same image, mapping is trivial */
			  if (dst == src)
			    {
			      nc = c;
			    }
			  else
			    {
			      /* Find or create the best match */
			      /* 2.0.5: can't use gdTrueColorGetRed, etc with palette */
			      nc = gdImageColorResolveAlpha (dst,
							     gdImageRed (src,
									 c),
							     gdImageGreen
							     (src, c),
							     gdImageBlue (src,
									  c),
							     gdImageAlpha
							     (src, c));
			    }
			  colorMap[c] = nc;
			}
		      mapTo = colorMap[c];
		    }
		}
	      for (i = 0; (i < stx[x - srcX]); i++)
		{
		  gdImageSetPixel (dst, tox, toy, mapTo);
		  tox++;
		}
	    }
	  toy++;
	}
    }
  gdFree (stx);
  gdFree (sty);
}

/* gd 2.0.8: gdImageCopyRotated is added. Source 
	is a rectangle, with its upper left corner at
	srcX and srcY. Destination is the *center* of
        the rotated copy. Angle is in degrees, same as
        gdImageArc. Floating point destination center
	coordinates allow accurate rotation of 
	objects of odd-numbered width or height. */

BGD_DECLARE(void) gdImageCopyRotated (gdImagePtr dst,
		    gdImagePtr src,
		    double dstX, double dstY,
		    int srcX, int srcY,
		    int srcWidth, int srcHeight, int angle)
{
  double dx, dy;
  double radius = sqrt (srcWidth * srcWidth + srcHeight * srcHeight);
  double aCos = cos (angle * .0174532925);
  double aSin = sin (angle * .0174532925);
  double scX = srcX + ((double) srcWidth) / 2;
  double scY = srcY + ((double) srcHeight) / 2;
  int cmap[gdMaxColors];
  int i;
  for (i = 0; (i < gdMaxColors); i++)
    {
      cmap[i] = (-1);
    }
  for (dy = dstY - radius; (dy <= dstY + radius); dy++)
    {
      for (dx = dstX - radius; (dx <= dstX + radius); dx++)
	{
	  double sxd = (dx - dstX) * aCos - (dy - dstY) * aSin;
	  double syd = (dy - dstY) * aCos + (dx - dstX) * aSin;
	  int sx = sxd + scX;
	  int sy = syd + scY;
	  if ((sx >= srcX) && (sx < srcX + srcWidth) &&
	      (sy >= srcY) && (sy < srcY + srcHeight))
	    {
	      int c = gdImageGetPixel (src, sx, sy);
	      if (!src->trueColor)
		{
		  /* Use a table to avoid an expensive
		     lookup on every single pixel */
		  if (cmap[c] == -1)
		    {
		      cmap[c] = gdImageColorResolveAlpha (dst,
							  gdImageRed (src, c),
							  gdImageGreen (src,
									c),
							  gdImageBlue (src,
								       c),
							  gdImageAlpha (src,
									c));
		    }
		  gdImageSetPixel (dst, dx, dy, cmap[c]);
		}
	      else
		{
		  gdImageSetPixel (dst,
				   dx, dy,
				   gdImageColorResolveAlpha (dst,
							     gdImageRed (src,
									 c),
							     gdImageGreen
							     (src, c),
							     gdImageBlue (src,
									  c),
							     gdImageAlpha
							     (src, c)));
		}
	    }
	}
    }
}

/* When gd 1.x was first created, floating point was to be avoided.
   These days it is often faster than table lookups or integer
   arithmetic. The routine below is shamelessly, gloriously
   floating point. TBB */

/* 2.0.10: cast instead of floor() yields 35% performance improvement. 
	Thanks to John Buckman. */

#define floor2(exp) ((long) exp)
/*#define floor2(exp) floor(exp)*/

BGD_DECLARE(void) gdImageCopyResampled (gdImagePtr dst,
		      gdImagePtr src,
		      int dstX, int dstY,
		      int srcX, int srcY,
		      int dstW, int dstH, int srcW, int srcH)
{
  int x, y;
  double sy1, sy2, sx1, sx2;
  if (!dst->trueColor)
    {
      gdImageCopyResized (dst, src, dstX, dstY, srcX, srcY, dstW, dstH,
			  srcW, srcH);
      return;
    }
  for (y = dstY; (y < dstY + dstH); y++)
    {
      sy1 = ((double) y - (double) dstY) * (double) srcH / (double) dstH;
      sy2 = ((double) (y + 1) - (double) dstY) * (double) srcH /
	(double) dstH;
      for (x = dstX; (x < dstX + dstW); x++)
	{
	  double sx, sy;
	  double spixels = 0;
	  double red = 0.0, green = 0.0, blue = 0.0, alpha = 0.0;
	  sx1 = ((double) x - (double) dstX) * (double) srcW / dstW;
	  sx2 = ((double) (x + 1) - (double) dstX) * (double) srcW / dstW;
	  sy = sy1;
	  do
	    {
	      double yportion;
	      if (floor2 (sy) == floor2 (sy1))
		{
		  yportion = 1.0 - (sy - floor2 (sy));
		  if (yportion > sy2 - sy1)
		    {
		      yportion = sy2 - sy1;
		    }
		  sy = floor2 (sy);
		}
	      else if (sy == floor2 (sy2))
		{
		  yportion = sy2 - floor2 (sy2);
		}
	      else
		{
		  yportion = 1.0;
		}
	      sx = sx1;
	      do
		{
		  double xportion;
		  double pcontribution;
		  int p;
		  if (floor2 (sx) == floor2 (sx1))
		    {
		      xportion = 1.0 - (sx - floor2 (sx));
		      if (xportion > sx2 - sx1)
			{
			  xportion = sx2 - sx1;
			}
		      sx = floor2 (sx);
		    }
		  else if (sx == floor2 (sx2))
		    {
		      xportion = sx2 - floor2 (sx2);
		    }
		  else
		    {
		      xportion = 1.0;
		    }
		  pcontribution = xportion * yportion;
		  /* 2.08: previously srcX and srcY were ignored. 
		     Andrew Pattison */
		  p = gdImageGetTrueColorPixel (src,
						(int) sx + srcX,
						(int) sy + srcY);
		  red += gdTrueColorGetRed (p) * pcontribution;