[LIBART] Full-width filling patch

[James Turner <james turner crocodile-clips com>]

This patch addresses a problem we have encountered from the Mozilla SVG 
implementation; when using the art_render calls, rows which completely 
span the update area are not drawn at all. A comparisom with the 
relevant paths in art_rgb_svp.c (notably the alpha tests at line 270 for 
example) should make it apparent what's missing from the _render case.

Feedback  appreciated, especially that my alpha values are correct. Note 
this code has been tested on four machines every day for several weeks, 
without any apparent problems. (But only by the Mozilla SVG code)

Assuming it looks good, checkin to the Gnome tree would be appreciated 
too :-)

James Turner

Index: art_render_svp.c
===================================================================
RCS file: /cvs/gnome/libart_lgpl/art_render_svp.c,v
retrieving revision 1.2
diff -u -r1.2 art_render_svp.c
--- art_render_svp.c	2000/05/29 21:58:00	1.2
+++ art_render_svp.c	2001/09/12 15:51:20
@@ -105,7 +105,17 @@
 	  run[n_run].alpha = 0x8000;
 	  n_run++;
 	}
-    }
+  }  else {
+  
+  	if (running_sum > 0x80ff) {
+  		run[0].x = x0;
+  		run[0].alpha = running_sum;
+  		
+  		run[1].x = x1;
+	  	run[1].alpha = 0x8000;
+	 	n_run = 2;
+  	}
+  }
 
   render->n_run = n_run;
 
@@ -172,7 +182,22 @@
 	  n_run++;
 	  span_x[n_span++] = x1;
 	}
-    }
+  }  else {
+  
+  	if (running_sum > 0x80ff) {
+  		run[0].x = x0;
+  		run[0].alpha = running_sum;
+  		
+  		run[1].x = x1;
+	  	run[1].alpha = 0x8000;
+	 	n_run = 2;
+	 	
+	 	/* fix the spans too */
+	 	span_x[0] = x0;
+	 	span_x[1] = x1;
+	 	n_span = 2;
+  	}
+  }
 
   render->n_run = n_run;
   render->n_span = n_span;
@@ -238,7 +263,18 @@
 	  run[n_run].alpha = 0x8000;
 	  n_run++;
 	}
-    }
+   }  else {
+  	alpha = (running_sum >> 16) & 0xff;
+  	if (alpha) {
+  		run[0].x = x0;
+  		alpha = ((running_sum >> 8) * opacity + 0x80080) >> 8;
+  		run[0].alpha = alpha;
+  		
+  		run[1].x = x1;
+	  	run[1].alpha = 0x8000;
+	 	n_run = 2;
+  	}
+  }
 
   render->n_run = n_run;
 
@@ -312,7 +348,23 @@
 	  n_run++;
 	  span_x[n_span++] = x1;
 	}
-    }
+   }  else {
+  	alpha = (running_sum >> 16) & 0xff;
+  	if (alpha) {
+  		run[0].x = x0;
+  		alpha = ((running_sum >> 8) * opacity + 0x80080) >> 8;
+  		run[0].alpha = alpha;
+  		
+  		run[1].x = x1;
+	  	run[1].alpha = 0x8000;
+	 	n_run = 2;
+	 	
+	 	/* fix the spans too */
+	 	span_x[0] = x0;
+	 	span_x[1] = x1;
+	 	n_span = 2;
+  	}
+  }
 
   render->n_run = n_run;
   render->n_span = n_span;