Remove SkLerpXfermode

This relies on the Chromium CL https://codereview.chromium.org/1610573004/ (Replace use of SkLerpXfermode with SkArithmeticMode)

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1611633002

Review URL: https://codereview.chromium.org/1611633002

10 files changed, 11 insertions, 226 deletions

diff --git a/gm/lerpmode.cpp b/gm/lerpmode.cpp
deleted file mode 100644
index ea30b6b5a4..0000000000
--- a/gm/lerpmode.cpp
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
- * Copyright 2013 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#include "gm.h"
-#include "SkCanvas.h"
-#include "SkLerpXfermode.h"
-
-static void show_circlelayers(SkCanvas* canvas, SkXfermode* mode) {
-    SkPaint paint;
-    paint.setAntiAlias(true);
-    SkRect r, bounds = { 10, 10, 110, 110 };
-
-    r = bounds;
-    r.fRight = bounds.centerX();
-    canvas->drawRect(r, paint);
-
-    canvas->saveLayer(&bounds, nullptr);
-
-    paint.setColor(0x80FF0000);
-    r = bounds;
-    r.inset(20, 0);
-    canvas->drawOval(r, paint);
-
-    paint.setColor(0x800000FF);
-    r = bounds;
-    r.inset(0, 20);
-    paint.setXfermode(mode);
-    canvas->drawOval(r, paint);
-
-    canvas->restore();
-}
-
-DEF_SIMPLE_GM(lerpmode, canvas, 240, 120) {
-        show_circlelayers(canvas, nullptr);
-        canvas->translate(150, 0);
-        SkAutoTUnref<SkXfermode> mode(SkLerpXfermode::Create(0.5f));
-        show_circlelayers(canvas, mode.get());
-}
diff --git a/gyp/effects.gypi b/gyp/effects.gypi
index 1c9e6fd8c6..0ab3cf5fc1 100644
--- a/gyp/effects.gypi
+++ b/gyp/effects.gypi
@@ -45,7 +45,6 @@
     '<(skia_src_path)/effects/SkGpuBlurUtils.cpp',
     '<(skia_src_path)/effects/SkLayerDrawLooper.cpp',
     '<(skia_src_path)/effects/SkLayerRasterizer.cpp',
-    '<(skia_src_path)/effects/SkLerpXfermode.cpp',
     '<(skia_src_path)/effects/SkLightingImageFilter.cpp',
     '<(skia_src_path)/effects/SkLumaColorFilter.cpp',
     '<(skia_src_path)/effects/SkMagnifierImageFilter.cpp',
@@ -104,7 +103,6 @@
     '<(skia_include_path)/effects/SkImageSource.h',
     '<(skia_include_path)/effects/SkLayerDrawLooper.h',
     '<(skia_include_path)/effects/SkLayerRasterizer.h',
-    '<(skia_include_path)/effects/SkLerpXfermode.h',
     '<(skia_include_path)/effects/SkLightingImageFilter.h',
     '<(skia_include_path)/effects/SkLumaColorFilter.h',
     '<(skia_include_path)/effects/SkMagnifierImageFilter.h',
diff --git a/include/core/SkScalar.h b/include/core/SkScalar.h
index 4efa8417af..84b53c8575 100644
--- a/include/core/SkScalar.h
+++ b/include/core/SkScalar.h
@@ -218,7 +218,7 @@ static inline SkScalar SkScalarSignAsScalar(SkScalar x) {
 #define SK_ScalarNearlyZero         (SK_Scalar1 / (1 << 12))
 
 static inline bool SkScalarNearlyZero(SkScalar x,
-                                    SkScalar tolerance = SK_ScalarNearlyZero) {
+                                      SkScalar tolerance = SK_ScalarNearlyZero) {
     SkASSERT(tolerance >= 0);
     return SkScalarAbs(x) <= tolerance;
 }
diff --git a/include/effects/SkLerpXfermode.h b/include/effects/SkLerpXfermode.h
deleted file mode 100644
index 27daf78982..0000000000
--- a/include/effects/SkLerpXfermode.h
+++ /dev/null
@@ -1,47 +0,0 @@
-/*
- * Copyright 2013 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#ifndef SkLerpXfermode_DEFINED
-#define SkLerpXfermode_DEFINED
-
-#include "SkXfermode.h"
-
-class SK_API SkLerpXfermode : public SkXfermode {
-public:
-    /**
-     *  result = scale * src + (1 - scale) * dst
-     *
-     *  When scale == 1, this is the same as kSrc_Mode
-     *  When scale == 0, this is the same as kDst_Mode
-     */
-    static SkXfermode* Create(SkScalar scale);
-
-    // overrides from SkXfermode
-    virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
-                        const SkAlpha aa[]) const override;
-    virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count,
-                        const SkAlpha aa[]) const override;
-    virtual void xferA8(SkAlpha dst[], const SkPMColor src[], int count,
-                        const SkAlpha aa[]) const override;
-
-    SK_TO_STRING_OVERRIDE()
-    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkLerpXfermode)
-
-protected:
-    void flatten(SkWriteBuffer&) const override;
-
-private:
-    SkLerpXfermode(unsigned scale256);
-
-    unsigned fScale256;  // 0..256
-
-    SkValue asValue() const override;
-
-    typedef SkXfermode INHERITED;
-};
-
-#endif
diff --git a/samplecode/SamplePathEffects.cpp b/samplecode/SamplePathEffects.cpp
index e194793f36..a162cf33ad 100644
--- a/samplecode/SamplePathEffects.cpp
+++ b/samplecode/SamplePathEffects.cpp
@@ -19,7 +19,6 @@
 #include "SkPathMeasure.h"
 #include "SkRandom.h"
 #include "SkColorPriv.h"
-#include "SkPixelXorXfermode.h"
 
 #define CORNER_RADIUS   12
 
diff --git a/src/core/SkValue.h b/src/core/SkValue.h
index 5a6453f908..5200842228 100644
--- a/src/core/SkValue.h
+++ b/src/core/SkValue.h
@@ -29,7 +29,6 @@ public:
 
         ArithmeticXfermode,
         DefaultXfermode,
-        LerpXfermode,
         PixelXorXfermode,
         ProcCoeffXfermode,
 
diff --git a/src/effects/SkArithmeticMode.cpp b/src/effects/SkArithmeticMode.cpp
index 9eb7dd2198..33783a52f8 100644
--- a/src/effects/SkArithmeticMode.cpp
+++ b/src/effects/SkArithmeticMode.cpp
@@ -21,8 +21,16 @@ static const bool gUseUnpremul = false;
 
 class SkArithmeticMode_scalar : public SkXfermode {
 public:
-    static SkArithmeticMode_scalar* Create(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4,
-                                           bool enforcePMColor) {
+    static SkXfermode* Create(SkScalar k1, SkScalar k2, SkScalar k3, SkScalar k4,
+                              bool enforcePMColor) {
+        if (SkScalarNearlyZero(k1) && SkScalarNearlyEqual(k2, SK_Scalar1) &&
+            SkScalarNearlyZero(k3) && SkScalarNearlyZero(k4)) {
+            return SkXfermode::Create(SkXfermode::kSrc_Mode);
+        } else if (SkScalarNearlyZero(k1) && SkScalarNearlyZero(k2) && 
+                   SkScalarNearlyEqual(k3, SK_Scalar1) && SkScalarNearlyZero(k4)) {
+            return SkXfermode::Create(SkXfermode::kDst_Mode);
+        }
+
         return new SkArithmeticMode_scalar(k1, k2, k3, k4, enforcePMColor);
     }
 
diff --git a/src/effects/SkLerpXfermode.cpp b/src/effects/SkLerpXfermode.cpp
deleted file mode 100644
index a069e8b367..0000000000
--- a/src/effects/SkLerpXfermode.cpp
+++ /dev/null
@@ -1,118 +0,0 @@
-/*
- * Copyright 2013 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#include "SkLerpXfermode.h"
-#include "SkColorPriv.h"
-#include "SkReadBuffer.h"
-#include "SkWriteBuffer.h"
-#include "SkString.h"
-#include "SkValue.h"
-#include "SkValueKeys.h"
-
-SkXfermode* SkLerpXfermode::Create(SkScalar scale) {
-    int scale256 = SkScalarRoundToInt(scale * 256);
-    if (scale256 >= 256) {
-        return SkXfermode::Create(SkXfermode::kSrc_Mode);
-    } else if (scale256 <= 0) {
-        return SkXfermode::Create(SkXfermode::kDst_Mode);
-    }
-    return new SkLerpXfermode(scale256);
-}
-
-SkLerpXfermode::SkLerpXfermode(unsigned scale256) : fScale256(scale256) {}
-
-void SkLerpXfermode::flatten(SkWriteBuffer& buffer) const {
-    buffer.writeUInt(fScale256);
-}
-
-SkFlattenable* SkLerpXfermode::CreateProc(SkReadBuffer& buffer) {
-    return new SkLerpXfermode(buffer.readUInt());
-}
-
-void SkLerpXfermode::xfer32(SkPMColor dst[], const SkPMColor src[], int count,
-                             const SkAlpha aa[]) const {
-    const int scale = fScale256;
-
-    if (aa) {
-        for (int i = 0; i < count; ++i) {
-            unsigned a = aa[i];
-            if (a) {
-                SkPMColor dstC = dst[i];
-                SkPMColor resC = SkFastFourByteInterp256(src[i], dstC, scale);
-                if (a < 255) {
-                    resC = SkFastFourByteInterp256(resC, dstC, a + (a >> 7));
-                }
-                dst[i] = resC;
-            }
-        }
-    } else {
-        for (int i = 0; i < count; ++i) {
-            dst[i] = SkFastFourByteInterp256(src[i], dst[i], scale);
-        }
-    }
-}
-
-void SkLerpXfermode::xfer16(uint16_t dst[], const SkPMColor src[], int count,
-                             const SkAlpha aa[]) const {
-    const int scale = fScale256;
-
-    if (aa) {
-        for (int i = 0; i < count; ++i) {
-            unsigned a = aa[i];
-            if (a) {
-                SkPMColor dstC = SkPixel16ToPixel32(dst[i]);
-                SkPMColor resC = SkFastFourByteInterp256(src[i], dstC, scale);
-                if (a < 255) {
-                    resC = SkFastFourByteInterp256(resC, dstC, a + (a >> 7));
-                }
-                dst[i] = SkPixel32ToPixel16(resC);
-            }
-        }
-    } else {
-        for (int i = 0; i < count; ++i) {
-            SkPMColor dstC = SkPixel16ToPixel32(dst[i]);
-            SkPMColor resC = SkFastFourByteInterp256(src[i], dstC, scale);
-            dst[i] = SkPixel32ToPixel16(resC);
-        }
-    }
-}
-
-void SkLerpXfermode::xferA8(SkAlpha dst[], const SkPMColor src[], int count,
-                             const SkAlpha aa[]) const {
-    const int scale = fScale256;
-
-    if (aa) {
-        for (int i = 0; i < count; ++i) {
-            unsigned a = aa[i];
-            if (a) {
-                unsigned dstA = dst[i];
-                unsigned resA = SkAlphaBlend(SkGetPackedA32(src[i]), dstA, scale);
-                if (a < 255) {
-                    resA = SkAlphaBlend(resA, dstA, a + (a >> 7));
-                }
-                dst[i] = resA;
-            }
-        }
-    } else {
-        for (int i = 0; i < count; ++i) {
-            dst[i] = SkAlphaBlend(SkGetPackedA32(src[i]), dst[i], scale);
-        }
-    }
-}
-
-#ifndef SK_IGNORE_TO_STRING
-void SkLerpXfermode::toString(SkString* str) const {
-    str->printf("SkLerpXfermode: scale: %g", fScale256 / 256.0);
-}
-#endif
-
-SkValue SkLerpXfermode::asValue() const {
-    auto value = SkValue::Object(SkValue::LerpXfermode);
-    value.set(SkValueKeys::LerpXfermode::kScale,
-              SkValue::FromF32(fScale256 / 256.0f));
-    return value;
-}
diff --git a/src/effects/SkToFromValue.cpp b/src/effects/SkToFromValue.cpp
index b981d1715e..cbb265b33f 100644
--- a/src/effects/SkToFromValue.cpp
+++ b/src/effects/SkToFromValue.cpp
@@ -6,7 +6,6 @@
  */
 
 #include "SkArithmeticMode.h"
-#include "SkLerpXfermode.h"
 #include "SkMatrix.h"
 #include "SkPixelXorXfermode.h"
 #include "SkToFromValue.h"
@@ -89,14 +88,6 @@ static bool from_value_ArithmeticXfermode(const SkValue& val,
     return true;
 }
 
-static bool from_value_LerpXfermode(const SkValue& val,
-                                    SkAutoTUnref<SkXfermode>* dst) {
-    float scale;
-    REQUIRE(getT(val, SkValueKeys::LerpXfermode::kScale, &scale));
-    dst->reset(SkLerpXfermode::Create(scale));
-    return true;
-}
-
 static bool from_value_PixelXorXfermode(const SkValue& val,
                                         SkAutoTUnref<SkXfermode>* dst) {
     uint32_t opColor;
@@ -118,7 +109,6 @@ template<> bool SkFromValue< SkAutoTUnref<SkXfermode> >(
     switch (val.type()) {
         case SkValue::DefaultXfermode:    return from_value_DefaultXfermode(val, dst);
         case SkValue::ArithmeticXfermode: return from_value_ArithmeticXfermode(val, dst);
-        case SkValue::LerpXfermode:       return from_value_LerpXfermode(val, dst);
         case SkValue::PixelXorXfermode:   return from_value_PixelXorXfermode(val, dst);
         case SkValue::ProcCoeffXfermode:  return from_value_ProcCoeffXfermode(val, dst);
         default:                          REQUIRE(false);
diff --git a/src/ports/SkGlobalInitialization_default.cpp b/src/ports/SkGlobalInitialization_default.cpp
index 9471f01c88..de5052760a 100644
--- a/src/ports/SkGlobalInitialization_default.cpp
+++ b/src/ports/SkGlobalInitialization_default.cpp
@@ -28,7 +28,6 @@
 #include "SkImageSource.h"
 #include "SkLayerDrawLooper.h"
 #include "SkLayerRasterizer.h"
-#include "SkLerpXfermode.h"
 #include "SkLightingImageFilter.h"
 #include "SkLightingShader.h"
 #include "SkLumaColorFilter.h"
@@ -82,7 +81,6 @@ void SkFlattenable::PrivateInitializer::InitEffects() {
     SkLightingShader::InitializeFlattenables();
 
     // Xfermode
-    SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkLerpXfermode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPixelXorXfermode)
 
     // PathEffect