From 17a652017a0243c57c954662e08a7976b9990fee Mon Sep 17 00:00:00 2001
From: jbroman <jbroman@chromium.org>
Date: Mon, 21 Mar 2016 08:38:58 -0700
Subject: Make SkComposeImageFilter::onFilterImage filter the bounds given to
 the inner filter.

Previously, the bounds requested by the caller would be passed to both the
inner and outer filter, but since the outer filter may move pixels, this is not
necessarily sufficient to supply the pixels required by the outer filter to fill
the bounds.

Unit test included.

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1813373002

Review URL: https://codereview.chromium.org/1813373002
---
 tests/ImageFilterTest.cpp | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

(limited to 'tests')

diff --git a/tests/ImageFilterTest.cpp b/tests/ImageFilterTest.cpp
index 6a2f942658..b9b0028f2d 100644
--- a/tests/ImageFilterTest.cpp
+++ b/tests/ImageFilterTest.cpp
@@ -1369,6 +1369,51 @@ DEF_GPUTEST_FOR_NATIVE_CONTEXT(ComposedImageFilterOffset_Gpu, reporter, context)
 }
 #endif
 
+static void test_composed_imagefilter_bounds(SkImageFilter::Proxy* proxy,
+                                             skiatest::Reporter* reporter,
+                                             GrContext* context) {
+    // The bounds passed to the inner filter must be filtered by the outer
+    // filter, so that the inner filter produces the pixels that the outer
+    // filter requires as input. This matters if the outer filter moves pixels.
+    // Here, accounting for the outer offset is necessary so that the green
+    // pixels of the picture are not clipped.
+
+    SkPictureRecorder recorder;
+    SkCanvas* recordingCanvas = recorder.beginRecording(SkRect::MakeWH(200, 100));
+    recordingCanvas->clipRect(SkRect::MakeXYWH(100, 0, 100, 100));
+    recordingCanvas->clear(SK_ColorGREEN);
+    sk_sp<SkPicture> picture = recorder.finishRecordingAsPicture();
+    sk_sp<SkImageFilter> pictureFilter(
+        SkPictureImageFilter::Create(picture.get()));
+    SkImageFilter::CropRect cropRect(SkRect::MakeWH(100, 100));
+    sk_sp<SkImageFilter> offsetFilter(SkOffsetImageFilter::Create(-100, 0, nullptr, &cropRect));
+    sk_sp<SkImageFilter> composedFilter(
+        SkComposeImageFilter::Create(offsetFilter.get(), pictureFilter.get()));
+
+    sk_sp<SkSpecialImage> sourceImage(create_empty_special_image(context, proxy, 100));
+    SkImageFilter::Context ctx(SkMatrix::I(), SkIRect::MakeWH(100, 100), nullptr);
+    SkIPoint offset;
+    sk_sp<SkSpecialImage> result(composedFilter->filterImage(sourceImage.get(), ctx, &offset));
+    REPORTER_ASSERT(reporter, offset.isZero());
+    REPORTER_ASSERT(reporter, result);
+    REPORTER_ASSERT(reporter, result->subset().size() == SkISize::Make(100, 100));
+
+    SkBitmap resultBM;
+    TestingSpecialImageAccess::GetROPixels(result.get(), &resultBM);
+    SkAutoLockPixels lock(resultBM);
+    REPORTER_ASSERT(reporter, resultBM.getColor(50, 50) == SK_ColorGREEN);
+}
+
+DEF_TEST(ComposedImageFilterBounds, reporter) {
+    run_raster_test(reporter, 100, test_composed_imagefilter_bounds);
+}
+
+#if SK_SUPPORT_GPU
+DEF_GPUTEST_FOR_NATIVE_CONTEXT(ComposedImageFilterBounds_Gpu, reporter, context) {
+    run_gpu_test(reporter, context, 100, test_composed_imagefilter_bounds);
+}
+#endif
+
 static void test_partial_crop_rect(SkImageFilter::Proxy* proxy,
                                    skiatest::Reporter* reporter,
                                    GrContext* context) {
-- 
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