Implement SkBlurDrawLooper with SkLayerDrawLooper

This allows us to delete SkBlurDrawLooper (and leave only one draw
looper implementation).

BUG=skia:

Change-Id: I549af86b81babf19e3649bdffffe2fdb0b308d5a
Reviewed-on: https://skia-review.googlesource.com/10101
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Derek Sollenberger <djsollen@google.com>

5 files changed, 42 insertions, 197 deletions

diff --git a/gn/effects.gni b/gn/effects.gni
index cc2b8ed146..df8e75b144 100644
--- a/gn/effects.gni
+++ b/gn/effects.gni
@@ -21,7 +21,6 @@ skia_effects_sources = [
   "$_src/effects/SkArcToPathEffect.cpp",
   "$_src/effects/SkArithmeticImageFilter.cpp",
   "$_src/effects/SkArithmeticMode.cpp",
-  "$_src/effects/SkBlurDrawLooper.cpp",
   "$_src/effects/SkBlurMask.cpp",
   "$_src/effects/SkBlurMask.h",
   "$_src/effects/SkBlurMaskFilter.cpp",
diff --git a/include/effects/SkBlurDrawLooper.h b/include/effects/SkBlurDrawLooper.h
index 415018a2ad..45289c8941 100644
--- a/include/effects/SkBlurDrawLooper.h
+++ b/include/effects/SkBlurDrawLooper.h
@@ -10,61 +10,13 @@
 #define SkBlurDrawLooper_DEFINED
 
 #include "SkDrawLooper.h"
-#include "SkColor.h"
 
-class SkArenaAlloc;
-class SkMaskFilter;
-class SkColorFilter;
-
-/** \class SkBlurDrawLooper
-    This class draws a shadow of the object (possibly offset), and then draws
-    the original object in its original position.
-    should there be an option to just draw the shadow/blur layer? webkit?
-*/
-class SK_API SkBlurDrawLooper : public SkDrawLooper {
-public:
-    static sk_sp<SkDrawLooper> Make(SkColor color, SkScalar sigma, SkScalar dx, SkScalar dy) {
-        return sk_sp<SkDrawLooper>(new SkBlurDrawLooper(color, sigma, dx, dy));
-    }
-
-    SkDrawLooper::Context* makeContext(SkCanvas*, SkArenaAlloc*) const override;
-
-    SK_TO_STRING_OVERRIDE()
-    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkBlurDrawLooper)
-
-protected:
-    SkBlurDrawLooper(SkColor color, SkScalar sigma, SkScalar dx, SkScalar dy);
-
-    void flatten(SkWriteBuffer&) const override;
-
-    bool asABlurShadow(BlurShadowRec*) const override;
-
-private:
-    sk_sp<SkMaskFilter>  fBlur;
-    SkScalar        fDx, fDy, fSigma;
-    SkColor         fBlurColor;
-
-    enum State {
-        kBeforeEdge,
-        kAfterEdge,
-        kDone
-    };
-
-    class BlurDrawLooperContext : public SkDrawLooper::Context {
-    public:
-        explicit BlurDrawLooperContext(const SkBlurDrawLooper* looper);
-
-        bool next(SkCanvas* canvas, SkPaint* paint) override;
-
-    private:
-        const SkBlurDrawLooper* fLooper;
-        State fState;
-    };
-
-    void init(SkScalar sigma, SkScalar dx, SkScalar dy, SkColor color);
-    void initEffects();
-
-    typedef SkDrawLooper INHERITED;
+/**
+ *  Draws a shadow of the object (possibly offset), and then draws the original object in
+ *  its original position.
+ */
+namespace SkBlurDrawLooper {
+    sk_sp<SkDrawLooper> Make(SkColor color, SkScalar sigma, SkScalar dx, SkScalar dy);
 };
 
 #endif
diff --git a/src/effects/SkBlurDrawLooper.cpp b/src/effects/SkBlurDrawLooper.cpp
deleted file mode 100644
index 34ce093a9e..0000000000
--- a/src/effects/SkBlurDrawLooper.cpp
+++ /dev/null
@@ -1,138 +0,0 @@
-/*
- * Copyright 2011 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#include "SkArenaAlloc.h"
-#include "SkBlurDrawLooper.h"
-#include "SkBlurMask.h"     // just for SkBlurMask::ConvertRadiusToSigma
-#include "SkBlurMaskFilter.h"
-#include "SkCanvas.h"
-#include "SkColorFilter.h"
-#include "SkReadBuffer.h"
-#include "SkWriteBuffer.h"
-#include "SkMaskFilter.h"
-#include "SkPaint.h"
-#include "SkString.h"
-#include "SkStringUtils.h"
-
-SkBlurDrawLooper::SkBlurDrawLooper(SkColor color, SkScalar sigma,
-                                   SkScalar dx, SkScalar dy) {
-    this->init(sigma, dx, dy, color);
-}
-
-// only call from constructor
-void SkBlurDrawLooper::initEffects() {
-    if (fSigma > 0) {
-        fBlur = SkBlurMaskFilter::Make(kNormal_SkBlurStyle, fSigma,
-                                       SkBlurMaskFilter::kNone_BlurFlag);
-    } else {
-        fBlur = nullptr;
-    }
-}
-
-void SkBlurDrawLooper::init(SkScalar sigma, SkScalar dx, SkScalar dy, SkColor color) {
-    fSigma = sigma;
-    fDx = dx;
-    fDy = dy;
-    fBlurColor = color;
-
-    this->initEffects();
-}
-
-sk_sp<SkFlattenable> SkBlurDrawLooper::CreateProc(SkReadBuffer& buffer) {
-    const SkColor color = buffer.readColor();
-    const SkScalar sigma = buffer.readScalar();
-    const SkScalar dx = buffer.readScalar();
-    const SkScalar dy = buffer.readScalar();
-    return Make(color, sigma, dx, dy);
-}
-
-void SkBlurDrawLooper::flatten(SkWriteBuffer& buffer) const {
-    buffer.writeColor(fBlurColor);
-    buffer.writeScalar(fSigma);
-    buffer.writeScalar(fDx);
-    buffer.writeScalar(fDy);
-}
-
-bool SkBlurDrawLooper::asABlurShadow(BlurShadowRec* rec) const {
-    if (fSigma <= 0) {
-        return false;
-    }
-
-    if (rec) {
-        rec->fSigma = fSigma;
-        rec->fColor = fBlurColor;
-        rec->fOffset.set(fDx, fDy);
-        rec->fStyle = kNormal_SkBlurStyle;
-        rec->fQuality = kLow_SkBlurQuality;
-    }
-    return true;
-}
-
-////////////////////////////////////////////////////////////////////////////////////////
-
-
-SkDrawLooper::Context* SkBlurDrawLooper::makeContext(SkCanvas*, SkArenaAlloc* alloc) const {
-    return alloc->make<BlurDrawLooperContext>(this);
-}
-
-SkBlurDrawLooper::BlurDrawLooperContext::BlurDrawLooperContext(
-        const SkBlurDrawLooper* looper)
-    : fLooper(looper), fState(SkBlurDrawLooper::kBeforeEdge) {}
-
-bool SkBlurDrawLooper::BlurDrawLooperContext::next(SkCanvas* canvas,
-                                                   SkPaint* paint) {
-    switch (fState) {
-        case kBeforeEdge:
-            // we do nothing if a maskfilter is already installed
-            if (paint->getMaskFilter()) {
-                fState = kDone;
-                return false;
-            }
-#ifdef SK_BUILD_FOR_ANDROID
-            SkColor blurColor;
-            blurColor = fLooper->fBlurColor;
-            if (SkColorGetA(blurColor) == 255) {
-                blurColor = SkColorSetA(blurColor, paint->getAlpha());
-            }
-            paint->setColor(blurColor);
-#else
-            paint->setColor(fLooper->fBlurColor);
-#endif
-            paint->setMaskFilter(fLooper->fBlur);
-            canvas->save();
-            canvas->translate(fLooper->fDx, fLooper->fDy);
-            fState = kAfterEdge;
-            return true;
-        case kAfterEdge:
-            canvas->restore();
-            fState = kDone;
-            return true;
-        default:
-            SkASSERT(kDone == fState);
-            return false;
-    }
-}
-
-#ifndef SK_IGNORE_TO_STRING
-void SkBlurDrawLooper::toString(SkString* str) const {
-    str->append("SkBlurDrawLooper: ");
-
-    str->append("dx: ");
-    str->appendScalar(fDx);
-
-    str->append(" dy: ");
-    str->appendScalar(fDy);
-
-    str->append(" color: ");
-    str->appendHex(fBlurColor);
-
-    str->append(" flags: (None)");
-
-    // TODO: add optional "fBlurFilter->toString(str);" when SkMaskFilter::toString is added
-    // alternatively we could cache the radius in SkBlurDrawLooper and just add it here
-}
-#endif
diff --git a/src/effects/SkLayerDrawLooper.cpp b/src/effects/SkLayerDrawLooper.cpp
index 5c0cf6bf7b..a20638c005 100644
--- a/src/effects/SkLayerDrawLooper.cpp
+++ b/src/effects/SkLayerDrawLooper.cpp
@@ -5,6 +5,8 @@
  * found in the LICENSE file.
  */
 #include "SkArenaAlloc.h"
+#include "SkBlurDrawLooper.h"
+#include "SkBlurMaskFilter.h"
 #include "SkCanvas.h"
 #include "SkColor.h"
 #include "SkReadBuffer.h"
@@ -61,8 +63,15 @@ static SkColor xferColor(SkColor src, SkColor dst, SkBlendMode mode) {
 // text/length parameters of a draw[Pos]Text call.
 void SkLayerDrawLooper::LayerDrawLooperContext::ApplyInfo(
         SkPaint* dst, const SkPaint& src, const LayerInfo& info) {
-
-    dst->setColor(xferColor(src.getColor(), dst->getColor(), (SkBlendMode)info.fColorMode));
+    SkColor srcColor = src.getColor();
+#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
+    // The framework may respect the alpha value on the original paint.
+    // Match this legacy behavior.
+    if (SkColorGetA(srcColor) == 255) {
+        srcColor = SkColorSetA(srcColor, dst->getAlpha());
+    }
+#endif
+    dst->setColor(xferColor(srcColor, dst->getColor(), (SkBlendMode)info.fColorMode));
 
     BitFlags bits = info.fPaintBits;
     SkPaint::TextEncoding encoding = dst->getTextEncoding();
@@ -356,3 +365,28 @@ sk_sp<SkDrawLooper> SkLayerDrawLooper::Builder::detach() {
 
     return sk_sp<SkDrawLooper>(looper);
 }
+
+sk_sp<SkDrawLooper> SkBlurDrawLooper::Make(SkColor color, SkScalar sigma, SkScalar dx, SkScalar dy)
+{
+    sk_sp<SkMaskFilter> blur = nullptr;
+    if (sigma > 0.0f) {
+        blur = SkBlurMaskFilter::Make(kNormal_SkBlurStyle, sigma, SkBlurMaskFilter::kNone_BlurFlag);
+    }
+
+    SkLayerDrawLooper::Builder builder;
+
+    // First layer
+    SkLayerDrawLooper::LayerInfo defaultLayer;
+    builder.addLayer(defaultLayer);
+
+    // Blur layer
+    SkLayerDrawLooper::LayerInfo blurInfo;
+    blurInfo.fColorMode = SkBlendMode::kSrc;
+    blurInfo.fPaintBits = SkLayerDrawLooper::kMaskFilter_Bit;
+    blurInfo.fOffset = SkVector::Make(dx, dy);
+    SkPaint* paint = builder.addLayer(blurInfo);
+    paint->setMaskFilter(std::move(blur));
+    paint->setColor(color);
+
+    return builder.detach();
+}
diff --git a/src/ports/SkGlobalInitialization_default.cpp b/src/ports/SkGlobalInitialization_default.cpp
index df4dde30a6..608f5c8518 100644
--- a/src/ports/SkGlobalInitialization_default.cpp
+++ b/src/ports/SkGlobalInitialization_default.cpp
@@ -11,7 +11,6 @@
 #include "../../src/effects/SkArithmeticModePriv.h"
 #include "SkArcToPathEffect.h"
 #include "SkBitmapSourceDeserializer.h"
-#include "SkBlurDrawLooper.h"
 #include "SkBlurImageFilter.h"
 #include "SkBlurMaskFilter.h"
 #include "SkColorFilterImageFilter.h"
@@ -74,7 +73,6 @@ void SkFlattenable::PrivateInitializer::InitEffects() {
     SkRRectsGaussianEdgeMaskFilter::InitializeFlattenables();
 
     // DrawLooper
-    SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkBlurDrawLooper)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkLayerDrawLooper)
 
     // Rasterizer