[raster] Make bbox handling the same as with Microsoft's rasterizer.

Right before B/W rasterizing, the bbox gets simply rounded to
integers.  This fixes, for example, glyph `three' in font `Helvetica
Neue LT Com 65 Medium' at 11ppem.

Thanks to Greg Hitchcock who explained this behaviour.

* src/raster/ftrend1.c (ft_raster1_render): Implement it.

ChangeLog

@@ -1,3 +1,15 @@
+2011-01-15  Werner Lemberg  <wl@gnu.org>
+
+	[raster] Make bbox handling the same as with Microsoft's rasterizer.
+
+	Right before B/W rasterizing, the bbox gets simply rounded to
+	integers.  This fixes, for example, glyph `three' in font `Helvetica
+	Neue LT Com 65 Medium' at 11ppem.
+
+	Thanks to Greg Hitchcock who explained this behaviour.
+
+	* src/raster/ftrend1.c (ft_raster1_render): Implement it.
+
 2011-01-15  suzuki toshiya  <mpsuzuki@hiroshima-u.ac.jp>
 
 	Copy -mcpu=* & -march=* options from CFLAGS to LDFLAGS.

src/raster/ftrend1.c

@@ -161,10 +161,18 @@
     /* compute the control box, and grid fit it */
     FT_Outline_Get_CBox( outline, &cbox );
 
+    /* undocumented but confirmed: bbox values get rounded */
+#if 1
+    cbox.xMin = FT_PIX_ROUND( cbox.xMin );
+    cbox.yMin = FT_PIX_ROUND( cbox.yMin );
+    cbox.xMax = FT_PIX_ROUND( cbox.xMax );
+    cbox.yMax = FT_PIX_ROUND( cbox.yMax );
+#else
     cbox.xMin = FT_PIX_FLOOR( cbox.xMin );
     cbox.yMin = FT_PIX_FLOOR( cbox.yMin );
     cbox.xMax = FT_PIX_CEIL( cbox.xMax );
     cbox.yMax = FT_PIX_CEIL( cbox.yMax );
+#endif
 
     width  = (FT_UInt)( ( cbox.xMax - cbox.xMin ) >> 6 );
     height = (FT_UInt)( ( cbox.yMax - cbox.yMin ) >> 6 );