1 files changed, 96 insertions, 0 deletions
diff --git a/tests/skbug6653.cpp b/tests/skbug6653.cpp
new file mode 100644
index 0000000000..eaf166c3e3
--- /dev/null
+++ b/tests/skbug6653.cpp
@@ -0,0 +1,96 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkTypes.h"
+
+#include "SkCanvas.h"
+#include "SkSurface.h"
+
+#if SK_SUPPORT_GPU
+
+#include "GrContext.h"
+#include "GrTest.h"
+#include "Test.h"
+
+static SkBitmap read_pixels(sk_sp<SkSurface> surface) {
+    SkBitmap bmp;
+    bmp.allocN32Pixels(surface->width(), surface->height());
+    if (!surface->getCanvas()->readPixels(bmp, 0, 0)) {
+        SkDebugf("readPixels failed\n");
+    }
+    return bmp;
+}
+
+static sk_sp<SkSurface> make_surface(GrContext* context) {
+    SkImageInfo info = SkImageInfo::Make(50, 50, kRGBA_8888_SkColorType, kPremul_SkAlphaType);
+    return SkSurface::MakeRenderTarget(context, SkBudgeted::kNo, info, 4,
+                                       kBottomLeft_GrSurfaceOrigin, nullptr);
+}
+
+// Tests that readPixels returns up-to-date results. Demonstrates a bug on Galaxy S6
+// (Mali T760), in MSAA mode.
+DEF_GPUTEST_FOR_RENDERING_CONTEXTS(skbug6653, reporter, ctxInfo) {
+    GrContext* ctx = ctxInfo.grContext();
+    SkRect rect = SkRect::MakeWH(50, 50);
+
+    SkPaint paint;
+    paint.setColor(SK_ColorWHITE);
+    paint.setStrokeWidth(5);
+    paint.setStyle(SkPaint::kStroke_Style);
+
+    // The one device that fails this test (Galaxy S6) does so in a flaky fashion. Trying many
+    // times makes it more likely to fail. Also, interacting with the phone (eg swiping between
+    // different home screens) while the test is running makes it fail close to 100%.
+    static const int kNumIterations = 50;
+
+    for (int i = 0; i < kNumIterations; ++i) {
+        auto s0 = make_surface(ctx);
+
+        auto s1 = make_surface(ctx);
+        s1->getCanvas()->clear(SK_ColorBLACK);
+        s1->getCanvas()->drawOval(rect, paint);
+        SkBitmap b1 = read_pixels(s1);
+        s1 = nullptr;
+
+        // The bug requires that all three of the following surfaces are cleared to the same color
+        auto s2 = make_surface(ctx);
+        s2->getCanvas()->clear(SK_ColorBLUE);
+        SkBitmap b2 = read_pixels(s2);
+        s2 = nullptr;
+
+        auto s3 = make_surface(ctx);
+        s3->getCanvas()->clear(SK_ColorBLUE);
+        SkBitmap b3 = read_pixels(s3);
+        s0->getCanvas()->drawBitmap(b3, 0, 0);
+        s3 = nullptr;
+
+        auto s4 = make_surface(ctx);
+        s4->getCanvas()->clear(SK_ColorBLUE);
+        s4->getCanvas()->drawOval(rect, paint);
+
+        // When this fails, b4 will "succeed", but return an empty bitmap (containing just the
+        // clear color). Regardless, b5 will contain the oval that was just drawn, so diffing the
+        // two bitmaps tests for the failure case.
+        SkBitmap b4 = read_pixels(s4);
+        SkBitmap b5 = read_pixels(s4);
+
+        bool match = true;
+        for (int y = 0; y < b4.height() && match; ++y) {
+            for (int x = 0; x < b4.width() && match; ++x) {
+                uint32_t pixelA = *b4.getAddr32(x, y);
+                uint32_t pixelB = *b5.getAddr32(x, y);
+                if (pixelA != pixelB) {
+                    match = false;
+                }
+            }
+        }
+
+        REPORTER_ASSERT(reporter, match);
+    }
+}
+
+#endif