gd.c

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

      vert = 1;

      d = 2 * dy - dx;
      incr1 = 2 * dy;
      incr2 = 2 * (dy - dx);
      if (x1 > x2)
	{
	  x = x2;
	  y = y2;
	  ydirflag = (-1);
	  xend = x1;
	}
      else
	{
	  x = x1;
	  y = y1;
	  ydirflag = 1;
	  xend = x2;
	}
      dashedSet (im, x, y, color, &on, &dashStep, wid, vert);
      if (((y2 - y1) * ydirflag) > 0)
	{
	  while (x < xend)
	    {
	      x++;
	      if (d < 0)
		{
		  d += incr1;
		}
	      else
		{
		  y++;
		  d += incr2;
		}
	      dashedSet (im, x, y, color, &on, &dashStep, wid, vert);
	    }
	}
      else
	{
	  while (x < xend)
	    {
	      x++;
	      if (d < 0)
		{
		  d += incr1;
		}
	      else
		{
		  y--;
		  d += incr2;
		}
	      dashedSet (im, x, y, color, &on, &dashStep, wid, vert);
	    }
	}
    }
  else
    {
      /* 2.0.12: Michael Schwartz: divide rather than multiply;
         TBB: but watch out for /0! */
      double as = sin (atan2 (dy, dx));
      if (as != 0)
	{
	  wid = thick / as;
	}
      else
	{
	  wid = 1;
	}
      vert = 0;

      d = 2 * dx - dy;
      incr1 = 2 * dx;
      incr2 = 2 * (dx - dy);
      if (y1 > y2)
	{
	  y = y2;
	  x = x2;
	  yend = y1;
	  xdirflag = (-1);
	}
      else
	{
	  y = y1;
	  x = x1;
	  yend = y2;
	  xdirflag = 1;
	}
      dashedSet (im, x, y, color, &on, &dashStep, wid, vert);
      if (((x2 - x1) * xdirflag) > 0)
	{
	  while (y < yend)
	    {
	      y++;
	      if (d < 0)
		{
		  d += incr1;
		}
	      else
		{
		  x++;
		  d += incr2;
		}
	      dashedSet (im, x, y, color, &on, &dashStep, wid, vert);
	    }
	}
      else
	{
	  while (y < yend)
	    {
	      y++;
	      if (d < 0)
		{
		  d += incr1;
		}
	      else
		{
		  x--;
		  d += incr2;
		}
	      dashedSet (im, x, y, color, &on, &dashStep, wid, vert);
	    }
	}
    }
}

static void
dashedSet (gdImagePtr im, int x, int y, int color,
	   int *onP, int *dashStepP, int wid, int vert)
{
  int dashStep = *dashStepP;
  int on = *onP;
  int w, wstart;

  dashStep++;
  if (dashStep == gdDashSize)
    {
      dashStep = 0;
      on = !on;
    }
  if (on)
    {
      if (vert)
	{
	  wstart = y - wid / 2;
	  for (w = wstart; w < wstart + wid; w++)
	    gdImageSetPixel (im, x, w, color);
	}
      else
	{
	  wstart = x - wid / 2;
	  for (w = wstart; w < wstart + wid; w++)
	    gdImageSetPixel (im, w, y, color);
	}
    }
  *dashStepP = dashStep;
  *onP = on;
}

BGD_DECLARE(int) gdImageBoundsSafe (gdImagePtr im, int x, int y)
{
  return gdImageBoundsSafeMacro (im, x, y);
}

BGD_DECLARE(void) gdImageChar (gdImagePtr im, gdFontPtr f, int x, int y, int c, int color)
{
  int cx, cy;
  int px, py;
  int fline;
  cx = 0;
  cy = 0;
#ifdef CHARSET_EBCDIC
  c = ASC (c);
#endif /*CHARSET_EBCDIC */
  if ((c < f->offset) || (c >= (f->offset + f->nchars)))
    {
      return;
    }
  fline = (c - f->offset) * f->h * f->w;
  for (py = y; (py < (y + f->h)); py++)
    {
      for (px = x; (px < (x + f->w)); px++)
	{
	  if (f->data[fline + cy * f->w + cx])
	    {
	      gdImageSetPixel (im, px, py, color);
	    }
	  cx++;
	}
      cx = 0;
      cy++;
    }
}

BGD_DECLARE(void) gdImageCharUp (gdImagePtr im, gdFontPtr f, int x, int y, int c, int color)
{
  int cx, cy;
  int px, py;
  int fline;
  cx = 0;
  cy = 0;
#ifdef CHARSET_EBCDIC
  c = ASC (c);
#endif /*CHARSET_EBCDIC */
  if ((c < f->offset) || (c >= (f->offset + f->nchars)))
    {
      return;
    }
  fline = (c - f->offset) * f->h * f->w;
  for (py = y; (py > (y - f->w)); py--)
    {
      for (px = x; (px < (x + f->h)); px++)
	{
	  if (f->data[fline + cy * f->w + cx])
	    {
	      gdImageSetPixel (im, px, py, color);
	    }
	  cy++;
	}
      cy = 0;
      cx++;
    }
}

BGD_DECLARE(void) gdImageString (gdImagePtr im, gdFontPtr f,
	       int x, int y, unsigned char *s, int color)
{
  int i;
  int l;
  l = strlen ((char *) s);
  for (i = 0; (i < l); i++)
    {
      gdImageChar (im, f, x, y, s[i], color);
      x += f->w;
    }
}

BGD_DECLARE(void) gdImageStringUp (gdImagePtr im, gdFontPtr f,
		 int x, int y, unsigned char *s, int color)
{
  int i;
  int l;
  l = strlen ((char *) s);
  for (i = 0; (i < l); i++)
    {
      gdImageCharUp (im, f, x, y, s[i], color);
      y -= f->w;
    }
}

static int strlen16 (unsigned short *s);

BGD_DECLARE(void) gdImageString16 (gdImagePtr im, gdFontPtr f,
		 int x, int y, unsigned short *s, int color)
{
  int i;
  int l;
  l = strlen16 (s);
  for (i = 0; (i < l); i++)
    {
      gdImageChar (im, f, x, y, s[i], color);
      x += f->w;
    }
}

BGD_DECLARE(void) gdImageStringUp16 (gdImagePtr im, gdFontPtr f,
		   int x, int y, unsigned short *s, int color)
{
  int i;
  int l;
  l = strlen16 (s);
  for (i = 0; (i < l); i++)
    {
      gdImageCharUp (im, f, x, y, s[i], color);
      y -= f->w;
    }
}

static int
strlen16 (unsigned short *s)
{
  int len = 0;
  while (*s)
    {
      s++;
      len++;
    }
  return len;
}

#ifndef HAVE_LSQRT
/* If you don't have a nice square root function for longs, you can use
   ** this hack
 */
long
lsqrt (long n)
{
  long result = (long) sqrt ((double) n);
  return result;
}
#endif

/* s and e are integers modulo 360 (degrees), with 0 degrees
   being the rightmost extreme and degrees changing clockwise.
   cx and cy are the center in pixels; w and h are the horizontal 
   and vertical diameter in pixels. Nice interface, but slow.
   See gd_arc_f_buggy.c for a better version that doesn't 
   seem to be bug-free yet. */

BGD_DECLARE(void) gdImageArc (gdImagePtr im, int cx, int cy, int w, int h, int s, int e,
	    int color)
{
  gdImageFilledArc (im, cx, cy, w, h, s, e, color, gdNoFill);
}

BGD_DECLARE(void) gdImageFilledArc (gdImagePtr im, int cx, int cy, int w, int h, int s, int e,
		  int color, int style)
{
  gdPoint pts[3];
  int i;
  int lx = 0, ly = 0;
  int fx = 0, fy = 0;
  while (e < s)
    {
      e += 360;
    }
  for (i = s; (i <= e); i++)
    {
      int x, y;
      x = ((long) gdCosT[i % 360] * (long) w / (2 * 1024)) + cx;
      y = ((long) gdSinT[i % 360] * (long) h / (2 * 1024)) + cy;
      if (i != s)
	{
	  if (!(style & gdChord))
	    {
	      if (style & gdNoFill)
		{
		  gdImageLine (im, lx, ly, x, y, color);
		}
	      else
		{
		  /* This is expensive! */
		  pts[0].x = lx;
		  pts[0].y = ly;
		  pts[1].x = x;
		  pts[1].y = y;
		  pts[2].x = cx;
		  pts[2].y = cy;
		  gdImageFilledPolygon (im, pts, 3, color);
		}
	    }
	}
      else
	{
	  fx = x;
	  fy = y;
	}
      lx = x;
      ly = y;
    }
  if (style & gdChord)
    {
      if (style & gdNoFill)
	{
	  if (style & gdEdged)
	    {
	      gdImageLine (im, cx, cy, lx, ly, color);
	      gdImageLine (im, cx, cy, fx, fy, color);
	    }
	  gdImageLine (im, fx, fy, lx, ly, color);
	}
      else
	{
	  pts[0].x = fx;
	  pts[0].y = fy;
	  pts[1].x = lx;
	  pts[1].y = ly;
	  pts[2].x = cx;
	  pts[2].y = cy;
	  gdImageFilledPolygon (im, pts, 3, color);
	}
    }
  else
    {
      if (style & gdNoFill)
	{
	  if (style & gdEdged)
	    {
	      gdImageLine (im, cx, cy, lx, ly, color);
	      gdImageLine (im, cx, cy, fx, fy, color);
	    }
	}
    }
}

BGD_DECLARE(void) gdImageFilledEllipse (gdImagePtr im, int cx, int cy, int w, int h, int color)
{
  gdImageFilledArc (im, cx, cy, w, h, 0, 360, color, gdPie);
}

BGD_DECLARE(void) gdImageFillToBorder (gdImagePtr im, int x, int y, int border, int color)
{
  int lastBorder;
  /* Seek left */
  int leftLimit, rightLimit;
  int i;
  leftLimit = (-1);
  if (border < 0)
    {
      /* Refuse to fill to a non-solid border */
      return;
    }
  for (i = x; (i >= 0); i--)
    {
      if (gdImageGetPixel (im, i, y) == border)
	{
	  break;
	}
      gdImageSetPixel (im, i, y, color);
      leftLimit = i;
    }
  if (leftLimit == (-1))
    {
      return;
    }
  /* Seek right */
  rightLimit = x;
  for (i = (x + 1); (i < im->sx); i++)
    {
      if (gdImageGetPixel (im, i, y) == border)
	{
	  break;
	}
      gdImageSetPixel (im, i, y, color);
      rightLimit = i;
    }
  /* Look at lines above and below and start paints */
  /* Above */
  if (y > 0)
    {
      lastBorder = 1;
      for (i = leftLimit; (i <= rightLimit); i++)
	{
	  int c;
	  c = gdImageGetPixel (im, i, y - 1);
	  if (lastBorder)
	    {
	      if ((c != border) && (c != color))
		{
		  gdImageFillToBorder (im, i, y - 1, border, color);
		  lastBorder = 0;
		}
	    }
	  else if ((c == border) || (c == color))
	    {
	      lastBorder = 1;
	    }
	}
    }
  /* 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 != border) && (c != color))
		{
		  gdImageFillToBorder (im, i, y + 1, border, color);
		  lastBorder = 0;
		}
	    }
	  else if ((c == border) || (c == color))
	    {
	      lastBorder = 1;
	    }
	}
    }
}

BGD_DECLARE(void) gdImageFill (gdImagePtr im, int x, int y, int color)
{
  int lastBorder;
  int old;
  int leftLimit, rightLimit;
  int i;
  old = gdImageGetPixel (im, x, y);
  if (color == gdTiled)
    {
      /* Tile fill -- got to watch out! */
      int p, tileColor;
      int srcx, srcy;
      if (!im->tile)
	{
	  return;
	}
      /* Refuse to flood-fill with a transparent pattern --
         I can't do it without allocating another image */
      if (gdImageGetTransparent (im->tile) != (-1))
	{
	  return;
	}
      srcx = x % gdImageSX (im->tile);
      srcy = y % gdImageSY (im->tile);
      p = gdImageGetPixel (im->tile, srcx, srcy);
      if (im->trueColor)
	{
	  tileColor = p;
	}
      else
	{
	  if (im->tile->trueColor)
	    {
	      tileColor = gdImageColorResolveAlpha (im,
						    gdTrueColorGetRed (p),
						    gdTrueColorGetGreen (p),
						    gdTrueColorGetBlue (p),
						    gdTrueColorGetAlpha (p));
	    }
	  else
	    {
	      tileColor = im->tileColorMap[p];
	    }
	}
      if (old == tileColor)
	{
	  /* Nothing to be done */
	  return;
	}
    }
  else
    {
      if (old == color)
	{
	  /* Nothing to be done */
	  return;
	}
    }
  /* Seek left */
  leftLimit = (-1);
  for (i = x; (i >= 0); i--)
    {
      if (gdImageGetPixel (im, i, y) != old)
	{
	  break;
	}
      gdImageSetPixel (im, i, y, color);
      leftLimit = i;
    }
  if (leftLimit == (-1))
    {
      return;
    }
  /* Seek right */
  rightLimit = x;
  for (i = (x + 1); (i < im->sx); i++)
    {
      if (gdImageGetPixel (im, i, y) != old)
	{
	  break;
	}
      gdImageSetPixel (im, i, y, color);
      rightLimit = i;
    }
  /* Look at lines above and below and start paints */
  /* Above */
  if (y > 0)
    {
      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;
	    }
	}
    }