gd.c

下载来的一个看图软件的源代码

	  /* Refuse to draw if no style is set. */
	  return;
	}
      p = im->style[im->stylePos++];
      if ((p != gdTransparent) && (p != 0))
	{
	  gdImageSetPixel (im, x, y, gdBrushed);
	}
      im->stylePos = im->stylePos % im->styleLength;
      break;
    case gdBrushed:
      gdImageBrushApply (im, x, y);
      break;
    case gdTiled:
      gdImageTileApply (im, x, y);
      break;
    default:
      if (gdImageBoundsSafe (im, x, y))
	{
	  if (im->trueColor)
	    {
	      if (im->alphaBlendingFlag)
		{
		  im->tpixels[y][x] =
		    gdAlphaBlend (im->tpixels[y][x],
				  color);
		}
	      else
		{
		  im->tpixels[y][x] = color;
		}
	    }
	  else
	    {
	      im->pixels[y][x] = color;
	    }
	}
      break;
    }
}

static void
gdImageBrushApply (gdImagePtr im, int x, int y)
{
  int lx, ly;
  int hy;
  int hx;
  int x1, y1, x2, y2;
  int srcx, srcy;
  if (!im->brush)
    {
      return;
    }
  hy = gdImageSY (im->brush) / 2;
  y1 = y - hy;
  y2 = y1 + gdImageSY (im->brush);
  hx = gdImageSX (im->brush) / 2;
  x1 = x - hx;
  x2 = x1 + gdImageSX (im->brush);
  srcy = 0;
  if (im->trueColor)
    {
      for (ly = y1; (ly < y2); ly++)
	{
	  srcx = 0;
	  for (lx = x1; (lx < x2); lx++)
	    {
	      int p;
	      p = gdImageGetTrueColorPixel (
					     im->brush, srcx, srcy);
	      gdImageSetPixel (im, lx, ly,
			       p);
	      srcx++;
	    }
	  srcy++;
	}
    }
  else
    {
      for (ly = y1; (ly < y2); ly++)
	{
	  srcx = 0;
	  for (lx = x1; (lx < x2); lx++)
	    {
	      int p;
	      p = gdImageGetPixel (im->brush, srcx, srcy);
	      /* Allow for non-square brushes! */
	      if (p != gdImageGetTransparent (im->brush))
		{
		  /* Truecolor brush. Very slow
		     on a palette destination. */
		  if (im->brush->trueColor)
		    {
		      gdImageSetPixel (im, lx, ly,
				       gdImageColorResolveAlpha (
								  im,
						      gdTrueColorGetRed (p),
						    gdTrueColorGetGreen (p),
						     gdTrueColorGetBlue (p),
						  gdTrueColorGetAlpha (p)));
		    }
		  else
		    {
		      gdImageSetPixel (im, lx, ly,
				       im->brushColorMap[p]);
		    }
		}
	      srcx++;
	    }
	  srcy++;
	}
    }
}

static void
gdImageTileApply (gdImagePtr im, int x, int y)
{
  int srcx, srcy;
  int p;
  if (!im->tile)
    {
      return;
    }
  srcx = x % gdImageSX (im->tile);
  srcy = y % gdImageSY (im->tile);
  if (im->trueColor)
    {
      p = gdImageGetTrueColorPixel (im->tile, srcx, srcy);
      gdImageSetPixel (im, x, y, p);
    }
  else
    {
      /* Allow for transparency */
      if (p != gdImageGetTransparent (im->tile))
	{
	  if (im->tile->trueColor)
	    {
	      /* Truecolor tile. Very slow
	         on a palette destination. */
	      gdImageSetPixel (im, x, y,
			       gdImageColorResolveAlpha (
							  im,
						      gdTrueColorGetRed (p),
						    gdTrueColorGetGreen (p),
						     gdTrueColorGetBlue (p),
						  gdTrueColorGetAlpha (p)));
	    }
	  else
	    {
	      gdImageSetPixel (im, x, y,
			       im->tileColorMap[p]);
	    }
	}
    }
}

int
gdImageGetPixel (gdImagePtr im, int x, int y)
{
  if (gdImageBoundsSafe (im, x, y))
    {
      if (im->trueColor)
	{
	  return im->tpixels[y][x];
	}
      else
	{
	  return im->pixels[y][x];
	}
    }
  else
    {
      return 0;
    }
}

int
gdImageGetTrueColorPixel (gdImagePtr im, int x, int y)
{
  int p = gdImageGetPixel (im, x, y);
  if (!im->trueColor)
    {
      return gdTrueColorAlpha (im->red[p], im->green[p], im->blue[p],
			       (im->transparent == p) ? gdAlphaTransparent :
			       gdAlphaOpaque);
    }
  else
    {
      return p;
    }
}

/* Bresenham as presented in Foley & Van Dam */
void
gdImageLine (gdImagePtr im, int x1, int y1, int x2, int y2, int color)
{
  int dx, dy, incr1, incr2, d, x, y, xend, yend, xdirflag, ydirflag;
  int wid;
  int w, wstart;
  int thick = im->thick;
  dx = abs (x2 - x1);
  dy = abs (y2 - y1);
  if (dy <= dx)
    {
      /* More-or-less horizontal. use wid for vertical stroke */
      wid = thick * cos (atan2 (dy, dx));
      if (wid == 0)
	wid = 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;
	}

      /* Set up line thickness */
      wstart = y - wid / 2;
      for (w = wstart; w < wstart + wid; w++)
	gdImageSetPixel (im, x, w, color);

      if (((y2 - y1) * ydirflag) > 0)
	{
	  while (x < xend)
	    {
	      x++;
	      if (d < 0)
		{
		  d += incr1;
		}
	      else
		{
		  y++;
		  d += incr2;
		}
	      wstart = y - wid / 2;
	      for (w = wstart; w < wstart + wid; w++)
		gdImageSetPixel (im, x, w, color);
	    }
	}
      else
	{
	  while (x < xend)
	    {
	      x++;
	      if (d < 0)
		{
		  d += incr1;
		}
	      else
		{
		  y--;
		  d += incr2;
		}
	      wstart = y - wid / 2;
	      for (w = wstart; w < wstart + wid; w++)
		gdImageSetPixel (im, x, w, color);
	    }
	}
    }
  else
    {
      /* More-or-less vertical. use wid for horizontal stroke */
      wid = thick * sin (atan2 (dy, dx));
      if (wid == 0)
	wid = 1;

      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;
	}

      /* Set up line thickness */
      wstart = x - wid / 2;
      for (w = wstart; w < wstart + wid; w++)
	gdImageSetPixel (im, w, y, color);

      if (((x2 - x1) * xdirflag) > 0)
	{
	  while (y < yend)
	    {
	      y++;
	      if (d < 0)
		{
		  d += incr1;
		}
	      else
		{
		  x++;
		  d += incr2;
		}
	      wstart = x - wid / 2;
	      for (w = wstart; w < wstart + wid; w++)
		gdImageSetPixel (im, w, y, color);
	    }
	}
      else
	{
	  while (y < yend)
	    {
	      y++;
	      if (d < 0)
		{
		  d += incr1;
		}
	      else
		{
		  x--;
		  d += incr2;
		}
	      wstart = x - wid / 2;
	      for (w = wstart; w < wstart + wid; w++)
		gdImageSetPixel (im, w, y, color);
	    }
	}
    }
}
static void dashedSet (gdImagePtr im, int x, int y, int color,
		       int *onP, int *dashStepP, int wid, int vert);

void
gdImageDashedLine (gdImagePtr im, int x1, int y1, int x2, int y2, int color)
{
  int dx, dy, incr1, incr2, d, x, y, xend, yend, xdirflag, ydirflag;
  int dashStep = 0;
  int on = 1;
  int wid;
  int w, wstart, vert;
  int thick = im->thick;

  dx = abs (x2 - x1);
  dy = abs (y2 - y1);
  if (dy <= dx)
    {
      /* More-or-less horizontal. use wid for vertical stroke */
      wid = thick * sin (atan2 (dy, dx));
      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
    {
      /* More-or-less vertical. use wid for horizontal stroke */
      wid = thick * sin (atan2 (dy, dx));
      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;
}
#ifdef ORIGINAL_BOUNDS_SAFE
int
gdImageBoundsSafe (gdImagePtr im, int x, int y)
{
  return (!(((y < 0) || (y >= im->sy)) ||
	    ((x < 0) || (x >= im->sx))));
}
#endif /* ORIGINAL_BOUNDS_SAFE */
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++;
    }
}

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++;
    }
}

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;
    }
}

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);

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;
    }
}

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;
    }
}