replace SkXfermode obj with SkBlendMode enum in paints

BUG=skia:5814

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2714

Change-Id: I4fb489ba6b3f77b458f7e4a99f79c7ad10859135
Reviewed-on: https://skia-review.googlesource.com/2714
Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Mike Reed <reed@google.com>

6 files changed, 112 insertions, 8 deletions

diff --git a/include/core/SkBlendMode.h b/include/core/SkBlendMode.h
new file mode 100644
index 0000000000..eb3469f256
--- /dev/null
+++ b/include/core/SkBlendMode.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkBlendMode_DEFINED
+#define SkBlendMode_DEFINED
+
+enum class SkBlendMode {
+    kClear,    //!< [0, 0]
+    kSrc,      //!< [Sa, Sc]
+    kDst,      //!< [Da, Dc]
+    kSrcOver,  //!< [Sa + Da * (1 - Sa), Sc + Dc * (1 - Sa)]
+    kDstOver,  //!< [Da + Sa * (1 - Da), Dc + Sc * (1 - Da)]
+    kSrcIn,    //!< [Sa * Da, Sc * Da]
+    kDstIn,    //!< [Da * Sa, Dc * Sa]
+    kSrcOut,   //!< [Sa * (1 - Da), Sc * (1 - Da)]
+    kDstOut,   //!< [Da * (1 - Sa), Dc * (1 - Sa)]
+    kSrcATop,  //!< [Da, Sc * Da + Dc * (1 - Sa)]
+    kDstATop,  //!< [Sa, Dc * Sa + Sc * (1 - Da)]
+    kXor,      //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + Dc * (1 - Sa)]
+    kPlus,     //!< [Sa + Da, Sc + Dc]
+    kModulate, // multiplies all components (= alpha and color)
+
+    // Following blend modes are defined in the CSS Compositing standard:
+    // https://dvcs.w3.org/hg/FXTF/rawfile/tip/compositing/index.html#blending
+    kScreen,
+    kLastCoeffMode = kScreen,
+
+    kOverlay,
+    kDarken,
+    kLighten,
+    kColorDodge,
+    kColorBurn,
+    kHardLight,
+    kSoftLight,
+    kDifference,
+    kExclusion,
+    kMultiply,
+    kLastSeparableMode = kMultiply,
+
+    kHue,
+    kSaturation,
+    kColor,
+    kLuminosity,
+    kLastMode = kLuminosity
+};
+
+#endif
diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index 8d98e5024f..5078f4255c 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -9,6 +9,7 @@
 #define SkCanvas_DEFINED
 
 #include "SkTypes.h"
+#include "SkBlendMode.h"
 #include "SkBitmap.h"
 #include "SkClipOp.h"
 #include "SkDeque.h"
@@ -595,22 +596,31 @@ public:
         @param b    the blue component (0..255) of the color to fill the canvas
         @param mode the mode to apply the color in (defaults to SrcOver)
     */
-    void drawARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b,
-                  SkXfermode::Mode mode = SkXfermode::kSrcOver_Mode);
+    void drawARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b, SkBlendMode mode = SkBlendMode::kSrcOver);
+#ifdef SK_SUPPORT_LEGACY_XFERMODE_OBJECT
+    void drawARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b, SkXfermode::Mode mode) {
+        this->drawARGB(a, r, g, b, (SkBlendMode)mode);
+    }
+#endif
 
     /** Fill the entire canvas' bitmap (restricted to the current clip) with the
         specified color and mode.
         @param color    the color to draw with
         @param mode the mode to apply the color in (defaults to SrcOver)
     */
-    void drawColor(SkColor color, SkXfermode::Mode mode = SkXfermode::kSrcOver_Mode);
+    void drawColor(SkColor color, SkBlendMode mode = SkBlendMode::kSrcOver);
+#ifdef SK_SUPPORT_LEGACY_XFERMODE_OBJECT
+    void drawColor(SkColor color, SkXfermode::Mode mode) {
+        this->drawColor(color, (SkBlendMode)mode);
+    }
+#endif
 
     /**
      *  Helper method for drawing a color in SRC mode, completely replacing all the pixels
      *  in the current clip with this color.
      */
     void clear(SkColor color) {
-        this->drawColor(color, SkXfermode::kSrc_Mode);
+        this->drawColor(color, SkBlendMode::kSrc);
     }
 
     /**
diff --git a/include/core/SkColorFilter.h b/include/core/SkColorFilter.h
index 609550f676..5a23a343a2 100644
--- a/include/core/SkColorFilter.h
+++ b/include/core/SkColorFilter.h
@@ -115,6 +115,9 @@ public:
                     or NULL if the mode will have no effect.
     */
     static sk_sp<SkColorFilter> MakeModeFilter(SkColor c, SkXfermode::Mode mode);
+    static sk_sp<SkColorFilter> MakeModeFilter(SkColor c, SkBlendMode mode) {
+        return MakeModeFilter(c, (SkXfermode::Mode)mode);
+    }
 
     /** Construct a colorfilter whose effect is to first apply the inner filter and then apply
      *  the outer filter to the result of the inner's.
diff --git a/include/core/SkPaint.h b/include/core/SkPaint.h
index e28d2fc92d..ddc90ae19c 100644
--- a/include/core/SkPaint.h
+++ b/include/core/SkPaint.h
@@ -8,11 +8,14 @@
 #ifndef SkPaint_DEFINED
 #define SkPaint_DEFINED
 
+#include "SkBlendMode.h"
 #include "SkColor.h"
 #include "SkFilterQuality.h"
 #include "SkMatrix.h"
 #include "SkXfermode.h"
 
+//#define SK_SUPPORT_LEGACY_XFERMODE_OBJECT
+
 class SkAutoDescriptor;
 class SkAutoGlyphCache;
 class SkColorFilter;
@@ -525,12 +528,13 @@ public:
 #endif
     void setColorFilter(sk_sp<SkColorFilter>);
 
+#ifdef SK_SUPPORT_LEGACY_XFERMODE_OBJECT
     /** Get the paint's xfermode object.
         <p />
       The xfermode's reference count is not affected.
         @return the paint's xfermode (or NULL)
     */
-    SkXfermode* getXfermode() const { return fXfermode.get(); }
+    SkXfermode* getXfermode() const;
 
     /** Set or clear the xfermode object.
         <p />
@@ -552,6 +556,11 @@ public:
         the paint's xfermode is set to null.
      */
     SkXfermode* setXfermodeMode(SkXfermode::Mode);
+#endif
+
+    SkBlendMode getBlendMode() const { return (SkBlendMode)fBlendMode; }
+    bool isSrcOver() const { return (SkBlendMode)fBlendMode == SkBlendMode::kSrcOver; }
+    void setBlendMode(SkBlendMode mode) { fBlendMode = (unsigned)mode; }
 
     /** Get the paint's patheffect object.
         <p />
@@ -1090,7 +1099,6 @@ private:
     sk_sp<SkTypeface>     fTypeface;
     sk_sp<SkPathEffect>   fPathEffect;
     sk_sp<SkShader>       fShader;
-    sk_sp<SkXfermode>     fXfermode;
     sk_sp<SkMaskFilter>   fMaskFilter;
     sk_sp<SkColorFilter>  fColorFilter;
     sk_sp<SkRasterizer>   fRasterizer;
@@ -1103,6 +1111,7 @@ private:
     SkColor         fColor;
     SkScalar        fWidth;
     SkScalar        fMiterLimit;
+    uint32_t        fBlendMode; // just need 5-6 bits for SkXfermode::Mode
     union {
         struct {
             // all of these bitfields should add up to 32
diff --git a/include/core/SkPicture.h b/include/core/SkPicture.h
index c398d3a4ec..c2d05f9c41 100644
--- a/include/core/SkPicture.h
+++ b/include/core/SkPicture.h
@@ -224,10 +224,11 @@ private:
     // V47: Add occluder rect to SkBlurMaskFilter
     // V48: Read and write extended SkTextBlobs.
     // V49: Gradients serialized as SkColor4f + SkColorSpace
+    // V50: SkXfermode -> SkBlendMode
 
     // Only SKPs within the min/current picture version range (inclusive) can be read.
     static const uint32_t     MIN_PICTURE_VERSION = 35;     // Produced by Chrome M39.
-    static const uint32_t CURRENT_PICTURE_VERSION = 49;
+    static const uint32_t CURRENT_PICTURE_VERSION = 50;
 
     static_assert(MIN_PICTURE_VERSION <= 41,
                   "Remove kFontFileName and related code from SkFontDescriptor.cpp.");
diff --git a/include/core/SkXfermode.h b/include/core/SkXfermode.h
index 2d12b3c931..8319ad6882 100644
--- a/include/core/SkXfermode.h
+++ b/include/core/SkXfermode.h
@@ -8,8 +8,9 @@
 #ifndef SkXfermode_DEFINED
 #define SkXfermode_DEFINED
 
-#include "SkFlattenable.h"
+#include "SkBlendMode.h"
 #include "SkColor.h"
+#include "SkFlattenable.h"
 
 class GrFragmentProcessor;
 class GrTexture;
@@ -112,6 +113,9 @@ public:
      * Gets the name of the Mode as a string.
      */
     static const char* ModeName(Mode);
+    static const char* ModeName(SkBlendMode mode) {
+        return ModeName(Mode(mode));
+    }
 
     /**
      *  If the xfermode is one of the modes in the Mode enum, then asMode()
@@ -157,6 +161,31 @@ public:
     }
 #endif
 
+    /**
+     *  Skia maintains global xfermode objects corresponding to each BlendMode. This returns a
+     *  ptr to that global xfermode (or null if the mode is srcover). Thus the caller may use
+     *  the returned ptr, but it should leave its refcnt untouched.
+     */
+    static SkXfermode* Peek(SkBlendMode mode) {
+        sk_sp<SkXfermode> xfer = Make(mode);
+        if (!xfer) {
+            SkASSERT(SkBlendMode::kSrcOver == mode);
+            return nullptr;
+        }
+        SkASSERT(!xfer->unique());
+        return xfer.get();
+    }
+
+    static sk_sp<SkXfermode> Make(SkBlendMode bm) {
+        return Make((Mode)bm);
+    }
+
+    SkBlendMode blend() const {
+        Mode mode;
+        SkAssertResult(this->asMode(&mode));
+        return (SkBlendMode)mode;
+    }
+
     /** Return a function pointer to a routine that applies the specified
         porter-duff transfer mode.
      */
@@ -215,6 +244,7 @@ public:
     static bool IsOpaque(const sk_sp<SkXfermode>& xfer, SrcColorOpacity opacityType) {
         return IsOpaque(xfer.get(), opacityType);
     }
+    static bool IsOpaque(SkBlendMode, SrcColorOpacity);
 
 #if SK_SUPPORT_GPU
     /** Used by the SkXfermodeImageFilter to blend two colors via a GrFragmentProcessor.