Fix blurred underlines on Win32 (#332656):pango-1-10

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

	Fix blurred underlines on Win32 (#332656):

	* pango/pangocairo-win32font.c (quantize_position): New function,
	copy from pangofc-font.c.
	(create_metrics_for_context): Call quantize_position() for
	underline and strikethrough position and thickness.

2 files changed, 34 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 4831f4c9..0c783ee2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2006-03-30  Tor Lillqvist  <tml@novell.com>
+
+	Fix blurred underlines on Win32 (#332656):
+
+	* pango/pangocairo-win32font.c (quantize_position): New function,
+	copy from pangofc-font.c.
+	(create_metrics_for_context): Call quantize_position() for
+	underline and strikethrough position and thickness.
+	
 2006-02-26  Behdad Esfahbod  <behdad@gnome.org>
 
 	* === Released 1.10.4 ===
diff --git a/pango/pangocairo-win32font.c b/pango/pangocairo-win32font.c
index e5d8dc0d..69a7f4b6 100644
--- a/pango/pangocairo-win32font.c
+++ b/pango/pangocairo-win32font.c
@@ -264,6 +264,28 @@ pango_cairo_win32_font_get_glyph_extents (PangoFont        *font,
     *logical_rect = info->logical_rect;
 }
 
+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;
+}
+
 static PangoFontMetrics *
 create_metrics_for_context (PangoFont    *font,
 			    PangoContext *context)
@@ -298,6 +320,9 @@ create_metrics_for_context (PangoFont    *font,
   metrics->strikethrough_thickness = metrics->underline_thickness;
   metrics->strikethrough_position = height / 4;
 
+  quantize_position (&metrics->underline_thickness, &metrics->underline_position);
+  quantize_position (&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);