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

2 files changed, 121 insertions, 7 deletions

diff --git a/tests/ImageFilterTest.cpp b/tests/ImageFilterTest.cpp
index fa1569d89a..c6991cd052 100644
--- a/tests/ImageFilterTest.cpp
+++ b/tests/ImageFilterTest.cpp
@@ -23,6 +23,7 @@
 #include "SkMergeImageFilter.h"
 #include "SkMorphologyImageFilter.h"
 #include "SkOffsetImageFilter.h"
+#include "SkPaintImageFilter.h"
 #include "SkPerlinNoiseShader.h"
 #include "SkPicture.h"
 #include "SkPictureImageFilter.h"
@@ -30,7 +31,6 @@
 #include "SkPoint3.h"
 #include "SkReadBuffer.h"
 #include "SkRect.h"
-#include "SkRectShaderImageFilter.h"
 #include "SkSurface.h"
 #include "SkTableColorFilter.h"
 #include "SkTileImageFilter.h"
@@ -439,14 +439,15 @@ DEF_TEST(ImageFilterDrawTiled, reporter) {
     SkAutoTUnref<SkPicture> picture(recorder.endRecording());
     SkAutoTUnref<SkImageFilter> pictureFilter(SkPictureImageFilter::Create(picture.get()));
     SkAutoTUnref<SkShader> shader(SkPerlinNoiseShader::CreateTurbulence(SK_Scalar1, SK_Scalar1, 1, 0));
+    SkPaint noisePaint;
+    noisePaint.setShader(shader);
 
-    SkAutoTUnref<SkImageFilter> rectShaderFilter(SkRectShaderImageFilter::Create(shader.get()));
+    SkAutoTUnref<SkImageFilter> paintFilter(SkPaintImageFilter::Create(noisePaint));
 
-    SkAutoTUnref<SkShader> greenColorShader(SkShader::CreateColorShader(SK_ColorGREEN));
     SkImageFilter::CropRect leftSideCropRect(SkRect::MakeXYWH(0, 0, 32, 64));
-    SkAutoTUnref<SkImageFilter> rectShaderFilterLeft(SkRectShaderImageFilter::Create(greenColorShader.get(), &leftSideCropRect));
+    SkAutoTUnref<SkImageFilter> paintFilterLeft(SkPaintImageFilter::Create(greenPaint, &leftSideCropRect));
     SkImageFilter::CropRect rightSideCropRect(SkRect::MakeXYWH(32, 0, 32, 64));
-    SkAutoTUnref<SkImageFilter> rectShaderFilterRight(SkRectShaderImageFilter::Create(greenColorShader.get(), &rightSideCropRect));
+    SkAutoTUnref<SkImageFilter> paintFilterRight(SkPaintImageFilter::Create(greenPaint, &rightSideCropRect));
 
     struct {
         const char*    fName;
@@ -471,7 +472,7 @@ DEF_TEST(ImageFilterDrawTiled, reporter) {
                   SkMatrixConvolutionImageFilter::kRepeat_TileMode, false) },
         { "merge", SkMergeImageFilter::Create(nullptr, nullptr, SkXfermode::kSrcOver_Mode) },
         { "merge with disjoint inputs", SkMergeImageFilter::Create(
-              rectShaderFilterLeft, rectShaderFilterRight, SkXfermode::kSrcOver_Mode) },
+              paintFilterLeft, paintFilterRight, SkXfermode::kSrcOver_Mode) },
         { "offset", SkOffsetImageFilter::Create(SK_Scalar1, SK_Scalar1) },
         { "dilate", SkDilateImageFilter::Create(3, 2) },
         { "erode", SkErodeImageFilter::Create(2, 3) },
@@ -480,7 +481,7 @@ DEF_TEST(ImageFilterDrawTiled, reporter) {
         { "matrix", SkImageFilter::CreateMatrixFilter(matrix, kLow_SkFilterQuality) },
         { "blur and offset", SkOffsetImageFilter::Create(five, five, blur.get()) },
         { "picture and blur", SkBlurImageFilter::Create(five, five, pictureFilter.get()) },
-        { "rect shader and blur", SkBlurImageFilter::Create(five, five, rectShaderFilter.get()) },
+        { "paint and blur", SkBlurImageFilter::Create(five, five, paintFilter.get()) },
     };
 
     SkBitmap untiledResult, tiledResult;
diff --git a/tests/PaintImageFilterTest.cpp b/tests/PaintImageFilterTest.cpp
new file mode 100644
index 0000000000..b71fe47119
--- /dev/null
+++ b/tests/PaintImageFilterTest.cpp
@@ -0,0 +1,113 @@
+/*
+ * 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 "SkCanvas.h"
+#include "SkGradientShader.h"
+#include "SkPaintImageFilter.h"
+#include "SkShader.h"
+#include "Test.h"
+
+static void test_unscaled(skiatest::Reporter* reporter) {
+    int w = 10, h = 10;
+    SkRect r = SkRect::MakeWH(SkIntToScalar(w), SkIntToScalar(h));
+
+    SkBitmap filterResult, paintResult;
+
+    filterResult.allocN32Pixels(w, h);
+    SkCanvas canvasFilter(filterResult);
+    canvasFilter.clear(0x00000000);
+
+    paintResult.allocN32Pixels(w, h);
+    SkCanvas canvasPaint(paintResult);
+    canvasPaint.clear(0x00000000);
+
+    SkPoint center = SkPoint::Make(SkIntToScalar(5), SkIntToScalar(5));
+    SkColor colors[] = {SK_ColorBLUE, SK_ColorRED, SK_ColorGREEN};
+    SkScalar pos[] = {0, SK_ScalarHalf, SK_Scalar1};
+    SkScalar radius = SkIntToScalar(5);
+
+    SkAutoTUnref<SkShader> s(SkGradientShader::CreateRadial(
+        center, radius, colors, pos, SK_ARRAY_COUNT(colors), SkShader::kClamp_TileMode));
+    SkPaint gradientPaint;
+    gradientPaint.setShader(s);
+
+    // Test using the image filter
+    {
+        SkPaint paint;
+        SkImageFilter::CropRect cr(r);
+        paint.setImageFilter(SkPaintImageFilter::Create(gradientPaint, &cr))->unref();
+        canvasFilter.drawRect(r, paint);
+    }
+
+    // Test using the paint directly
+    {
+        canvasPaint.drawRect(r, gradientPaint);
+    }
+
+    // Assert that both paths yielded the same result
+    for (int y = 0; y < r.height(); ++y) {
+        const SkPMColor* filterPtr = filterResult.getAddr32(0, y);
+        const SkPMColor* paintPtr = paintResult.getAddr32(0, y);
+        for (int x = 0; x < r.width(); ++x, ++filterPtr, ++paintPtr) {
+            REPORTER_ASSERT(reporter, *filterPtr == *paintPtr);
+        }
+    }
+}
+
+static void test_scaled(skiatest::Reporter* reporter) {
+    int w = 10, h = 10;
+    SkRect r = SkRect::MakeWH(SkIntToScalar(w), SkIntToScalar(h));
+
+    SkBitmap filterResult, paintResult;
+
+    filterResult.allocN32Pixels(w, h);
+    SkCanvas canvasFilter(filterResult);
+    canvasFilter.clear(0x00000000);
+
+    paintResult.allocN32Pixels(w, h);
+    SkCanvas canvasPaint(paintResult);
+    canvasPaint.clear(0x00000000);
+
+    SkPoint center = SkPoint::Make(SkIntToScalar(5), SkIntToScalar(5));
+    SkColor colors[] = {SK_ColorBLUE, SK_ColorRED, SK_ColorGREEN};
+    SkScalar pos[] = {0, SK_ScalarHalf, SK_Scalar1};
+    SkScalar radius = SkIntToScalar(5);
+
+    SkAutoTUnref<SkShader> s(SkGradientShader::CreateRadial(
+        center, radius, colors, pos, SK_ARRAY_COUNT(colors), SkShader::kClamp_TileMode));
+    SkPaint gradientPaint;
+    gradientPaint.setShader(s);
+
+    // Test using the image filter
+    {
+        SkPaint paint;
+        SkImageFilter::CropRect cr(r);
+        paint.setImageFilter(SkPaintImageFilter::Create(gradientPaint, &cr))->unref();
+        canvasFilter.scale(SkIntToScalar(2), SkIntToScalar(2));
+        canvasFilter.drawRect(r, paint);
+    }
+
+    // Test using the paint directly
+    {
+        canvasPaint.scale(SkIntToScalar(2), SkIntToScalar(2));
+        canvasPaint.drawRect(r, gradientPaint);
+    }
+
+    // Assert that both paths yielded the same result
+    for (int y = 0; y < r.height(); ++y) {
+        const SkPMColor* filterPtr = filterResult.getAddr32(0, y);
+        const SkPMColor* paintPtr = paintResult.getAddr32(0, y);
+        for (int x = 0; x < r.width(); ++x, ++filterPtr, ++paintPtr) {
+            REPORTER_ASSERT(reporter, *filterPtr == *paintPtr);
+        }
+    }
+}
+
+DEF_TEST(PaintImageFilter, reporter) {
+    test_unscaled(reporter);
+    test_scaled(reporter);
+}