Added premulFourChannelColor to GrInvariantOutput

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2148273002

Review-Url: https://codereview.chromium.org/2148273002

1 files changed, 12 insertions, 0 deletions

diff --git a/include/gpu/GrInvariantOutput.h b/include/gpu/GrInvariantOutput.h
index 8cf4bf59c3..6e2cbe84f9 100644
--- a/include/gpu/GrInvariantOutput.h
+++ b/include/gpu/GrInvariantOutput.h
@@ -197,6 +197,18 @@ public:
         SkDEBUGCODE(this->validate());
     }
 
+    void premulFourChannelColor() {
+        SkDEBUGCODE(this->validate());
+        SkASSERT(!fIsSingleComponent);
+        fNonMulStageFound = true;
+        if (!(fValidFlags & kA_GrColorComponentFlag)) {
+            fValidFlags = kNone_GrColorComponentFlags;
+        } else {
+            fColor = GrPremulColor(fColor);
+        }
+        SkDEBUGCODE(this->validate());
+    }
+
     void invalidateComponents(GrColorComponentFlags invalidateFlags, ReadInput readsInput) {
         SkDEBUGCODE(this->validate());
         fValidFlags = (fValidFlags & ~invalidateFlags);