Implement an SkPaint-based image filter

This implements SkPaintImageFilter, and is intended to replace
SkRectShaderImageFilter. By allowing a paint and not just a
shader as input, this allows consumers to control dithering.

BUG=skia:4780
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1556553002

Review URL: https://codereview.chromium.org/1556553002

4 files changed, 95 insertions, 2 deletions

diff --git a/src/core/SkPathEffect.cpp b/src/core/SkPathEffect.cpp
index 2403ffcb30..293bb53b2c 100644
--- a/src/core/SkPathEffect.cpp
+++ b/src/core/SkPathEffect.cpp
@@ -67,7 +67,11 @@ void SkPairPathEffect::toString(SkString* str) const {
 SkFlattenable* SkComposePathEffect::CreateProc(SkReadBuffer& buffer) {
     SkAutoTUnref<SkPathEffect> pe0(buffer.readPathEffect());
     SkAutoTUnref<SkPathEffect> pe1(buffer.readPathEffect());
-    return SkComposePathEffect::Create(pe0, pe1);
+    if (pe0 && pe1) {
+        return SkComposePathEffect::Create(pe0, pe1);
+    } else {
+        return nullptr;
+    }
 }
 
 bool SkComposePathEffect::filterPath(SkPath* dst, const SkPath& src,
@@ -100,7 +104,11 @@ void SkComposePathEffect::toString(SkString* str) const {
 SkFlattenable* SkSumPathEffect::CreateProc(SkReadBuffer& buffer) {
     SkAutoTUnref<SkPathEffect> pe0(buffer.readPathEffect());
     SkAutoTUnref<SkPathEffect> pe1(buffer.readPathEffect());
-    return SkSumPathEffect::Create(pe0, pe1);
+    if (pe0 && pe1) {
+        return SkSumPathEffect::Create(pe0, pe1);
+    } else {
+        return nullptr;
+    }
 }
 
 bool SkSumPathEffect::filterPath(SkPath* dst, const SkPath& src,
diff --git a/src/effects/SkPaintImageFilter.cpp b/src/effects/SkPaintImageFilter.cpp
new file mode 100644
index 0000000000..d141f34dfb
--- /dev/null
+++ b/src/effects/SkPaintImageFilter.cpp
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkPaintImageFilter.h"
+#include "SkBitmap.h"
+#include "SkCanvas.h"
+#include "SkDevice.h"
+#include "SkReadBuffer.h"
+#include "SkWriteBuffer.h"
+
+SkImageFilter* SkPaintImageFilter::Create(const SkPaint& paint, const CropRect* cropRect) {
+    return new SkPaintImageFilter(paint, cropRect);
+}
+
+SkPaintImageFilter::SkPaintImageFilter(const SkPaint& paint, const CropRect* cropRect)
+  : INHERITED(0, nullptr, cropRect)
+  , fPaint(paint) {
+}
+
+SkFlattenable* SkPaintImageFilter::CreateProc(SkReadBuffer& buffer) {
+    SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 0);
+    SkPaint paint;
+    buffer.readPaint(&paint);
+    return Create(paint, &common.cropRect());
+}
+
+void SkPaintImageFilter::flatten(SkWriteBuffer& buffer) const {
+    this->INHERITED::flatten(buffer);
+    buffer.writePaint(fPaint);
+}
+
+bool SkPaintImageFilter::onFilterImage(Proxy* proxy,
+                                            const SkBitmap& source,
+                                            const Context& ctx,
+                                            SkBitmap* result,
+                                            SkIPoint* offset) const {
+    SkIRect bounds;
+    if (!this->applyCropRect(ctx, source, SkIPoint::Make(0, 0), &bounds)) {
+        return false;
+    }
+
+    SkAutoTUnref<SkBaseDevice> device(proxy->createDevice(bounds.width(),
+                                                          bounds.height()));
+    if (nullptr == device.get()) {
+        return false;
+    }
+    SkCanvas canvas(device.get());
+
+    SkMatrix matrix(ctx.ctm());
+    matrix.postTranslate(SkIntToScalar(-bounds.left()), SkIntToScalar(-bounds.top()));
+    SkRect rect = SkRect::MakeWH(SkIntToScalar(bounds.width()), SkIntToScalar(bounds.height()));
+    SkMatrix inverse;
+    if (matrix.invert(&inverse)) {
+        inverse.mapRect(&rect);
+    }
+    canvas.setMatrix(matrix);
+    canvas.drawRect(rect, fPaint);
+
+    *result = device.get()->accessBitmap(false);
+    offset->fX = bounds.fLeft;
+    offset->fY = bounds.fTop;
+    return true;
+}
+
+bool SkPaintImageFilter::canComputeFastBounds() const {
+    // http:skbug.com/4627: "make computeFastBounds and onFilterBounds() CropRect-aware"
+    // computeFastBounds() doesn't currently take the crop rect into account,
+    // so we can't compute it. If a full crop rect is set, we should return true here.
+    return false;
+}
+
+#ifndef SK_IGNORE_TO_STRING
+void SkPaintImageFilter::toString(SkString* str) const {
+    str->appendf("SkPaintImageFilter: (");
+    str->append(")");
+}
+#endif
diff --git a/src/ports/SkGlobalInitialization_chromium.cpp b/src/ports/SkGlobalInitialization_chromium.cpp
index f86fdedf43..a756743d1f 100644
--- a/src/ports/SkGlobalInitialization_chromium.cpp
+++ b/src/ports/SkGlobalInitialization_chromium.cpp
@@ -55,6 +55,7 @@
 #include "SkMorphologyImageFilter.h"
 #include "SkOffsetImageFilter.h"
 #include "SkOnce.h"
+#include "SkPaintImageFilter.h"
 #include "SkPerlinNoiseShader.h"
 #include "SkPictureImageFilter.h"
 #include "SkPictureShader.h"
@@ -116,6 +117,7 @@ public:
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPath1DPathEffect)
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkLine2DPathEffect)
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkModeColorFilter)
+        SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPaintImageFilter)
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPath2DPathEffect)
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPerlinNoiseShader)
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPictureImageFilter)
diff --git a/src/ports/SkGlobalInitialization_default.cpp b/src/ports/SkGlobalInitialization_default.cpp
index e710806698..2b7fda021c 100644
--- a/src/ports/SkGlobalInitialization_default.cpp
+++ b/src/ports/SkGlobalInitialization_default.cpp
@@ -51,6 +51,7 @@
 #include "SkMorphologyImageFilter.h"
 #include "SkOffsetImageFilter.h"
 #include "SkOnce.h"
+#include "SkPaintImageFilter.h"
 #include "SkPerlinNoiseShader.h"
 #include "SkPictureImageFilter.h"
 #include "SkPictureShader.h"
@@ -95,6 +96,7 @@ public:
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPath1DPathEffect)
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkLine2DPathEffect)
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkModeColorFilter)
+        SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPaintImageFilter)
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPath2DPathEffect)
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPerlinNoiseShader)
         SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPictureImageFilter)