[ftsmooth] Improve rendering.

* src/smooth/ftsmooth.c (gray_render_conic): Since version 2.4.3,
cubic deviations have been estimated _after_ UPSCALE, whereas
conic ones have been evaluated _before_ UPSCALE, which produces
inferior rendering results.  Fix this.
Partially undo change from 2010-10-15 by using ONE_PIXEL/4; this has
been tested with demo images sent to the mailing list.  See

  http://lists.gnu.org/archive/html/freetype-devel/2010-10/msg00055.html

and later mails in this thread.

ChangeLog

@@ -1,3 +1,18 @@
+2010-11-01  Alexei Podtelezhnikov  <apodtele@gmail.com>
+
+	[ftsmooth] Improve rendering.
+
+	* src/smooth/ftsmooth.c (gray_render_conic): Since version 2.4.3,
+	cubic deviations have been estimated _after_ UPSCALE, whereas
+	conic ones have been evaluated _before_ UPSCALE, which produces
+	inferior rendering results.  Fix this.
+	Partially undo change from 2010-10-15 by using ONE_PIXEL/4; this has
+	been tested with demo images sent to the mailing list.  See
+
+	  http://lists.gnu.org/archive/html/freetype-devel/2010-10/msg00055.html
+
+	and later mails in this thread.
+
 2010-10-28  Werner Lemberg  <wl@gnu.org>
 
 	[ftraster] Minor fixes.

src/smooth/ftgrays.c

@@ -877,40 +877,35 @@ typedef ptrdiff_t  FT_PtrDist;
     FT_Vector*  arc;
 
 
-    dx = DOWNSCALE( ras.x ) + to->x - ( control->x << 1 );
-    if ( dx < 0 )
-      dx = -dx;
-    dy = DOWNSCALE( ras.y ) + to->y - ( control->y << 1 );
-    if ( dy < 0 )
-      dy = -dy;
+    arc      = ras.bez_stack;
+    arc[0].x = UPSCALE( to->x );
+    arc[0].y = UPSCALE( to->y );
+    arc[1].x = UPSCALE( control->x );
+    arc[1].y = UPSCALE( control->y );
+    arc[2].x = ras.x;
+    arc[2].y = ras.y;
+
+    dx = FT_ABS( arc[2].x + arc[0].x - 2 * arc[1].x );
+    dy = FT_ABS( arc[2].y + arc[0].y - 2 * arc[1].y );
     if ( dx < dy )
       dx = dy;
 
-    if ( dx <= ONE_PIXEL / 8 )
+    if ( dx <= ONE_PIXEL / 4 )
     {
-      gray_render_line( RAS_VAR_ UPSCALE( to->x ), UPSCALE( to->y ) );
+      gray_render_line( RAS_VAR_ arc[0].x, arc[0].y );
       return;
     }
 
-    level = 1;
-    dx /= ONE_PIXEL / 8;
-    while ( dx > 1 )
+    level = 0;
+    while ( dx > ONE_PIXEL / 4 )
     {
       dx >>= 2;
       level++;
     }
 
-    arc       = ras.bez_stack;
     levels    = ras.lev_stack;
-    top       = 0;
     levels[0] = level;
-
-    arc[0].x = UPSCALE( to->x );
-    arc[0].y = UPSCALE( to->y );
-    arc[1].x = UPSCALE( control->x );
-    arc[1].y = UPSCALE( control->y );
-    arc[2].x = ras.x;
-    arc[2].y = ras.y;
+    top       = 0;
 
     while ( top >= 0 )
     {