Revert[4] "replace SkXfermode obj with SkBlendMode enum in paints"

This reverts commit 2cbcd12281ee807214df094964c584c78932e10b.

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2924

Change-Id: I0fa5c58af428f3da8565465d1219a34ef8417d9a
Reviewed-on: https://skia-review.googlesource.com/2924
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/src/core/SkXfermode.cpp b/src/core/SkXfermode.cpp
index 58c557805b..38a160870e 100644
--- a/src/core/SkXfermode.cpp
+++ b/src/core/SkXfermode.cpp
@@ -1472,3 +1472,64 @@ bool SkProcCoeffXfermode::onAppendStages(SkRasterPipeline* p) const {
     }
     return false;
 }
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool SkBlendMode_SupportsCoverageAsAlpha(SkBlendMode mode) {
+    switch (mode) {
+        case SkBlendMode::kDst:
+        case SkBlendMode::kSrcOver:
+        case SkBlendMode::kDstOver:
+        case SkBlendMode::kDstOut:
+        case SkBlendMode::kSrcATop:
+        case SkBlendMode::kXor:
+        case SkBlendMode::kPlus:
+            return true;
+        default:
+            break;
+    }
+    return false;
+}
+
+bool SkXfermode::IsOpaque(SkBlendMode mode, SrcColorOpacity opacityType) {
+    const ProcCoeff rec = gProcCoeffs[(int)mode];
+
+    switch (rec.fSC) {
+        case kDA_Coeff:
+        case kDC_Coeff:
+        case kIDA_Coeff:
+        case kIDC_Coeff:
+            return false;
+        default:
+            break;
+    }
+
+    switch (rec.fDC) {
+        case kZero_Coeff:
+            return true;
+        case kISA_Coeff:
+            return kOpaque_SrcColorOpacity == opacityType;
+        case kSA_Coeff:
+            return kTransparentBlack_SrcColorOpacity == opacityType ||
+            kTransparentAlpha_SrcColorOpacity == opacityType;
+        case kSC_Coeff:
+            return kTransparentBlack_SrcColorOpacity == opacityType;
+        default:
+            return false;
+    }
+    return false;
+}
+
+#if SK_SUPPORT_GPU
+sk_sp<GrXPFactory> SkBlendMode_AsXPFactory(SkBlendMode mode) {
+    const ProcCoeff rec = gProcCoeffs[(int)mode];
+    if (CANNOT_USE_COEFF != rec.fSC) {
+        sk_sp<GrXPFactory> result(GrPorterDuffXPFactory::Make(mode));
+        SkASSERT(result);
+        return result;
+    }
+
+    SkASSERT(GrCustomXfermode::IsSupportedMode((SkXfermode::Mode)mode));
+    return GrCustomXfermode::MakeXPFactory((SkXfermode::Mode)mode);
+}
+#endif