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

1 files changed, 113 insertions, 0 deletions

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);
+}