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.

1 files changed, 34 insertions, 0 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;
+}