Fix blurred underlines on Win32 (#332656):

2006-03-30  Tor Lillqvist  <tml@novell.com>

	Fix blurred underlines on Win32 (#332656):

	* pango/pango-utils.c (pango_quantize_line_geometry):
	New public function. Used to be the static quantize_position() in
	pangofc-font.c

	* pango/pango-utils.h: Declare it.

	* pango/pango.def: Here, too.

	* pango/pangofc-font.c (quantize_position): Remove.
	(get_face_metrics): Use pango_quantize_line_geometry() instead.

	* pango/pangocairo-win32font.c (create_metrics_for_context): Call
	pango_quantize_line_geometry() for underline and strikethrough
	geometries.

5 files changed, 47 insertions, 24 deletions

diff --git a/pango/pango-utils.c b/pango/pango-utils.c
index 7758c27f..5f7a206f 100644
--- a/pango/pango-utils.c
+++ b/pango/pango-utils.c
@@ -1806,3 +1806,37 @@ pango_is_zero_width (gunichar ch)
 		(ch >= 0x202A && ch <= 0x202E)
 	 )) || ch == 0xFEFF;
 }
+
+/**
+ * pango_quantize_line_geometry:
+ * @thickness: pointer to the thickness of a line, in Pango scaled units
+ * @position: corresponding position
+ *
+ * Quantizes the thickness and position of a line, typically an
+ * underline or strikethrough, to whole device pixels, that is
+ * multiplies of PANGO_SCALE. The purpose of this function is to avoid
+ * such lines looking blurry.
+ *
+ * Since: 1.12
+ */
+void
+pango_quantize_line_geometry (int *thickness,
+			      int *position)
+{
+  int thickness_pixels = (*thickness + PANGO_SCALE / 2) / PANGO_SCALE;
+  if (thickness_pixels == 0)
+    thickness_pixels = 1;
+  
+  if (thickness_pixels & 1)
+    {
+      int new_center = ((*position - *thickness / 2) & ~(PANGO_SCALE - 1)) + PANGO_SCALE / 2;
+      *position = new_center + (PANGO_SCALE * thickness_pixels) / 2;
+    }
+  else
+    {
+      int new_center = ((*position - *thickness / 2 + PANGO_SCALE / 2) & ~(PANGO_SCALE - 1));
+      *position = new_center + (PANGO_SCALE * thickness_pixels) / 2;
+    }
+
+  *thickness = thickness_pixels * PANGO_SCALE;
+}
diff --git a/pango/pango-utils.h b/pango/pango-utils.h
index 00d4889e..bc130532 100644
--- a/pango/pango-utils.h
+++ b/pango/pango-utils.h
@@ -102,6 +102,9 @@ gboolean pango_is_zero_width (gunichar ch) G_GNUC_CONST;
 /* String interning for static strings */
 #define I_(string) g_intern_static_string (string)
 
+void pango_quantize_line_geometry (int *thickness,
+				   int *position);
+
 G_END_DECLS
 
 #endif /* __PANGO_UTILS_H__ */
diff --git a/pango/pango.def b/pango/pango.def
index ee8c6856..cb88c903 100644
--- a/pango/pango.def
+++ b/pango/pango.def
@@ -278,6 +278,7 @@ EXPORTS
 	pango_parse_style
 	pango_parse_variant
 	pango_parse_weight
+	pango_quantize_line_geometry
 	pango_read_line
 	pango_render_part_get_type
 	pango_renderer_activate
diff --git a/pango/pangocairo-win32font.c b/pango/pangocairo-win32font.c
index 40e5be85..67c71202 100644
--- a/pango/pangocairo-win32font.c
+++ b/pango/pangocairo-win32font.c
@@ -302,6 +302,11 @@ create_metrics_for_context (PangoFont    *font,
   metrics->strikethrough_thickness = metrics->underline_thickness;
   metrics->strikethrough_position = height / 4;
 
+  pango_quantize_line_geometry (&metrics->underline_thickness,
+				&metrics->underline_position);
+  pango_quantize_line_geometry (&metrics->strikethrough_thickness,
+				&metrics->strikethrough_position);
+
   layout = pango_layout_new (context);
   font_desc = pango_font_describe (font);
   pango_layout_set_font_description (layout, font_desc);
diff --git a/pango/pangofc-font.c b/pango/pangofc-font.c
index d6e2d8fd..1724f12f 100644
--- a/pango/pangofc-font.c
+++ b/pango/pangofc-font.c
@@ -252,28 +252,6 @@ pango_fc_font_get_coverage (PangoFont     *font,
 					  fcfont);
 }
 
-static void
-quantize_position (int *thickness,
-		   int *position)
-{
-  int thickness_pixels = (*thickness + PANGO_SCALE / 2) / PANGO_SCALE;
-  if (thickness_pixels == 0)
-    thickness_pixels = 1;
-  
-  if (thickness_pixels & 1)
-    {
-      int new_center = ((*position - *thickness / 2) & ~(PANGO_SCALE - 1)) + PANGO_SCALE / 2;
-      *position = new_center + (PANGO_SCALE * thickness_pixels) / 2;
-    }
-  else
-    {
-      int new_center = ((*position - *thickness / 2 + PANGO_SCALE / 2) & ~(PANGO_SCALE - 1));
-      *position = new_center + (PANGO_SCALE * thickness_pixels) / 2;
-    }
-
-  *thickness = thickness_pixels * PANGO_SCALE;
-}
-
 /* For Xft, it would be slightly more efficient to simply to
  * call Xft, and also more robust against changes in Xft.
  * But for now, we simply use the same code for all backends.
@@ -386,8 +364,10 @@ get_face_metrics (PangoFcFont      *fcfont,
    */
   if (fcfont->is_hinted)
     {
-      quantize_position (&metrics->underline_thickness, &metrics->underline_position);
-      quantize_position (&metrics->strikethrough_thickness, &metrics->strikethrough_position);
+      pango_quantize_line_geometry (&metrics->underline_thickness,
+				    &metrics->underline_position);
+      pango_quantize_line_geometry (&metrics->strikethrough_thickness,
+				    &metrics->strikethrough_position);
     }
   
   PANGO_FC_FONT_UNLOCK_FACE (fcfont);