Improve b/w rasterizer.

Problem reported by Krzysztof Kotlenga <pocek@users.sf.net>.

* src/raster/raster.c (Vertical_Sweep_Drop, Horizontal_Sweep_Drop,
Horizontal_Gray_Sweep_Drop): For smart drop-out mode, if
intersections are equally distant relative to next pixel center,
select the left pixel, not the right one.

ChangeLog

@@ -1,3 +1,13 @@
+2009-05-22  Werner Lemberg  <wl@gnu.org>
+
+	Improve b/w rasterizer.
+	Problem reported by Krzysztof Kotlenga <pocek@users.sf.net>.
+
+	* src/raster/raster.c (Vertical_Sweep_Drop, Horizontal_Sweep_Drop,
+	Horizontal_Gray_Sweep_Drop): For smart drop-out mode, if
+	intersections are equally distant relative to next pixel center,
+	select the left pixel, not the right one.
+
 2009-05-19  Werner Lemberg  <wl@gnu.org>
 
 	Fix Savannah bug #26600.

src/raster/ftraster.c

@@ -2230,7 +2230,7 @@ a  };
           break;
 
         case 4: /* smart drop-outs including stubs */
-          pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half );
+          pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
           break;
 
         case 1: /* simple drop-outs excluding stubs */
@@ -2276,7 +2276,7 @@ a  };
           if ( ras.dropOutControl == 1 )
             pxl = e2;
           else
-            pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half );
+            pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
           break;
 
         default: /* modes 2, 3, 6, 7 */
@@ -2425,7 +2425,7 @@ a  };
           break;
 
         case 4: /* smart drop-outs including stubs */
-          pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half );
+          pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
           break;
 
         case 1: /* simple drop-outs excluding stubs */
@@ -2443,7 +2443,7 @@ a  };
           if ( ras.dropOutControl == 1 )
             pxl = e2;
           else
-            pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half );
+            pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
           break;
 
         default: /* modes 2, 3, 6, 7 */
@@ -2675,7 +2675,7 @@ a  };
           break;
 
         case 4: /* smart drop-outs including stubs */
-          e1 = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half );
+          e1 = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
           break;
 
         case 1: /* simple drop-outs excluding stubs */
@@ -2693,7 +2693,7 @@ a  };
           if ( ras.dropOutControl == 1 )
             e1 = e2;
           else
-            e1 = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half );
+            e1 = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
 
           break;