add SkXfermode::IsMode() and use that in SkDevice

git-svn-id: http://skia.googlecode.com/svn/trunk@2703 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 9 insertions, 0 deletions

diff --git a/src/core/SkXfermode.cpp b/src/core/SkXfermode.cpp
index e4d34e1ada..3ddacad60a 100644
--- a/src/core/SkXfermode.cpp
+++ b/src/core/SkXfermode.cpp
@@ -1033,6 +1033,15 @@ bool SkXfermode::AsCoeff(SkXfermode* xfer, Coeff* src, Coeff* dst) {
     return xfer->asCoeff(src, dst);
 }
 
+bool SkXfermode::IsMode(SkXfermode* xfer, Mode mode) {
+    // if xfer==null then the mode is srcover
+    Mode m = kSrcOver_Mode;
+    if (xfer && !xfer->asMode(&m)) {
+        return false;
+    }
+    return mode == m;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 //////////// 16bit xfermode procs