From: Benjamin Otte <otte@gnome.org>
Date: Thu, 16 Jul 2009 13:33:43 +0000 (+0200)
Subject: Clarify color burn code - no semantical changes
X-Git-Tag: pixman-0.15.18~29
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=12e829a8de1e45708b5dfeaa8137af6eeaf0f662;p=platform%2Fupstream%2Fpixman.git

Clarify color burn code - no semantical changes

- Improve documentation to be equal to Proposed ISO32000 Extension
- Simplify code in default case
---

diff --git a/pixman/pixman-combine.c.template b/pixman/pixman-combine.c.template
index 935b7b5..2cbdb64 100644
--- a/pixman/pixman-combine.c.template
+++ b/pixman/pixman-combine.c.template
@@ -646,8 +646,10 @@ PDF_SEPARABLE_BLEND_MODE (color_dodge)
 /*
  * Color burn
  * B(Dca, Da, Sca, Sa) =
- *   if Sca. == 0
- *     (Da == Dca).Sa.Da
+ *   if Dca == Da
+ *     Sa.Da
+ *   if Sca == 0
+ *     0
  *   otherwise
  *     Sa.Da.(1 - min (1, (1 - Dca/Da).Sa / Sca))
  */
@@ -660,9 +662,8 @@ blend_color_burn (comp4_t dca, comp4_t da, comp4_t sca, comp4_t sa)
     }
     else
     {
-	comp4_t sada = sa * da;
-	comp4_t rca = (da - dca) * sa * sa / sca;
-	return DIV_ONE_UNc (rca > sada ? 0 : sada - rca);
+	comp4_t rca = (da - dca) * sa / sca;
+	return DIV_ONE_UNc (sa * (MAX (rca, da) - rca));
     }
 }