Add gdImageAAline (antialiased line)

Add AA support for gdImagePolygon

diff --git a/ext/gd/libgd/gd.c b/ext/gd/libgd/gd.c
index 661eca738c2f73cceb5f5aa0a68eac1bd81fa42a..db1d9ffe22d8fd4aa5296bc72e57d0a042c360fe 100644 (file)
--- a/ext/gd/libgd/gd.c
+++ b/ext/gd/libgd/gd.c
@@ -1037,6 +1037,134 @@ gdImageLine (gdImagePtr im, int x1, int y1, int x2, int y2, int color)
        }
     }
 }
+
+
+#define BLEND_COLOR(a, nc, c, cc) \
+nc = (cc) + (((((c) - (cc)) * (a)) + ((((c) - (cc)) * (a)) >> 8) + 0x80) >> 8);
+
+inline static void gdImageSetAAPixelColor(gdImagePtr im, int x, int y, int color, int t)
+{
+       int dr,dg,db,p,r,g,b;
+       dr = gdTrueColorGetRed(color);
+       dg = gdTrueColorGetGreen(color);
+       db = gdTrueColorGetBlue(color);
+
+       p = gdImageGetPixel(im,x,y);
+       r = gdTrueColorGetRed(p);
+       g = gdTrueColorGetGreen(p);
+       b = gdTrueColorGetBlue(p);
+
+       BLEND_COLOR(t, dr, r, dr);
+       BLEND_COLOR(t, dg, g, dg);
+       BLEND_COLOR(t, db, b, db);
+       im->tpixels[y][x]=gdTrueColorAlpha(dr, dg, db,  gdAlphaOpaque);
+}  
+
+void gdImageAALine (gdImagePtr im, int x1, int y1, int x2, int y2, int col)
+{
+/* keep them as 32bits */
+long x, y, inc;
+       long dx, dy,tmp;
+
+       if (y1 < 0 && y2 < 0) {
+               return;
+       }
+       if (y1 < 0) {
+       x1 += (y1 * (x1 - x2)) / (y2 - y1);
+               y1 = 0;
+       }
+       if (y2 < 0) {
+               x2 += (y2 * (x1 - x2)) / (y2 - y1);
+       y2 = 0;
+       }
+
+       /* bottom edge */
+       if (y1 >= im->sy && y2 >= im->sy) {
+               return;
+       }
+       if (y1 >= im->sy) {
+               x1 -= ((im->sy - y1) * (x1 - x2)) / (y2 - y1);
+               y1 = im->sy - 1;
+       }
+       if (y2 >= im->sy) {
+               x2 -= ((im->sy - y2) * (x1 - x2)) / (y2 - y1);
+               y2 = im->sy - 1;
+       }
+
+       /* left edge */
+       if (x1 < 0 && x2 < 0) {
+               return;
+       }
+       if (x1 < 0) {
+               y1 += (x1 * (y1 - y2)) / (x2 - x1);
+               x1 = 0;
+       }
+       if (x2 < 0) {
+               y2 += (x2 * (y1 - y2)) / (x2 - x1);
+               x2 = 0;
+       }
+       /* right edge */
+       if (x1 >= im->sx && x2 >= im->sx) {
+               return;
+       }
+       if (x1 >= im->sx) {
+               y1 -= ((im->sx - x1) * (y1 - y2)) / (x2 - x1);
+               x1 = im->sx - 1;
+       }
+       if (x2 >= im->sx) {
+               y2 -= ((im->sx - x2) * (y1 - y2)) / (x2 - x1);
+               x2 = im->sx - 1;
+       }
+
+       dx = x2 - x1;
+       dy = y2 - y1;
+
+       if (dx == 0 && dy == 0) {
+               return;
+       }
+       if (abs(dx) > abs(dy)) {
+               if (dx < 0) {
+                       tmp = x1;
+                       x1 = x2;
+                       x2 = tmp;
+                       tmp = y1;
+                       y1 = y2;
+                       y2 = tmp;
+                       dx = x2 - x1;
+                       dy = y2 - y1;
+               }
+               x = x1 << 16;
+               y = y1 << 16;
+               inc = (dy * 65536) / dx;
+               while ((x >> 16) < x2) {
+                       gdImageSetAAPixelColor(im, x >> 16, y >> 16, col, (y >> 8) & 0xFF);
+                       gdImageSetAAPixelColor(im, x >> 16, (y >> 16) + 1,col, (~y >> 8) & 0xFF);
+                       x += (1 << 16);
+                       y += inc;
+               }
+       } else {
+               if (dy < 0) {
+                       tmp = x1;
+                       x1 = x2;
+                       x2 = tmp;
+                       tmp = y1;
+                       y1 = y2;
+                       y2 = tmp;
+                       dx = x2 - x1;
+                       dy = y2 - y1;
+               }
+               x = x1 << 16;
+               y = y1 << 16;
+               inc = (dx * 65536) / dy;
+               while ((y>>16) < y2) {
+                       gdImageSetAAPixelColor(im, x >> 16, y >> 16, col, (x >> 8) & 0xFF);
+                       gdImageSetAAPixelColor(im, (x >> 16) + 1, (y >> 16),col, (~x >> 8) & 0xFF);
+                       x += inc;
+                       y += (1<<16);
+               }
+       }
+}
+
 static void dashedSet (gdImagePtr im, int x, int y, int color,
                       int *onP, int *dashStepP, int wid, int vert);
 
@@ -2776,22 +2904,28 @@ fail:
 void
 gdImagePolygon (gdImagePtr im, gdPointPtr p, int n, int c)
 {
-  int i;
-  int lx, ly;
-  if (!n)
-    {
-      return;
-    }
-  lx = p->x;
-  ly = p->y;
-  gdImageLine (im, lx, ly, p[n - 1].x, p[n - 1].y, c);
-  for (i = 1; (i < n); i++)
-    {
-      p++;
-      gdImageLine (im, lx, ly, p->x, p->y, c);
-      lx = p->x;
-      ly = p->y;
-    }
+       int i;
+       int lx, ly;
+       typedef void (*image_line)(gdImagePtr im, int x1, int y1, int x2, int y2, int color);
+       image_line draw_line;
+
+       if (!n) {
+               return;
+       }
+       if ( im->antialias) {
+               draw_line = gdImageAALine;
+       } else {
+               draw_line = gdImageLine;
+       }
+       lx = p->x;
+       ly = p->y;
+       draw_line(im, lx, ly, p[n - 1].x, p[n - 1].y, c);
+       for (i = 1; (i < n); i++) {
+               p++;
+               draw_line(im, lx, ly, p->x, p->y, c);
+               lx = p->x;
+               ly = p->y;
+       }
 }
 
 int gdCompareInt (const void *a, const void *b);
@@ -3082,6 +3216,12 @@ gdImageAlphaBlending (gdImagePtr im, int alphaBlendingArg)
   im->alphaBlendingFlag = alphaBlendingArg;
 }
 
+void
+gdImageAntialias (gdImagePtr im, int antialias)
+{
+       im->antialias = antialias;
+}
+
 void
 gdImageSaveAlpha (gdImagePtr im, int saveAlphaArg)
 {