Merge damage region when dropping an app buffer

When we decide to drop a buffer from a buffer queue, make sure to merge
the damage region from the dropped buffer into the current damage
region. Otherwise we'll pass the wrong damage region to hardware
composer and get broken rendering.

Bug: 136158117
Test: Wrote a new test in Transaction_test.cpp to repro the problem and
confirm the fix works.

Change-Id: Icdc61e1be3297450f2869c496dad1453fb6dca6d
diff --git a/services/surfaceflinger/tests/Transaction_test.cpp b/services/surfaceflinger/tests/Transaction_test.cpp
index d5f6534..c93e15e 100644
--- a/services/surfaceflinger/tests/Transaction_test.cpp
+++ b/services/surfaceflinger/tests/Transaction_test.cpp
@@ -28,6 +28,7 @@
 
 #include <binder/ProcessState.h>
 #include <gui/BufferItemConsumer.h>
+#include <gui/IProducerListener.h>
 #include <gui/ISurfaceComposer.h>
 #include <gui/LayerState.h>
 #include <gui/Surface.h>
@@ -6059,4 +6060,97 @@
     }
 }
 
+// This test ensures that when we drop an app buffer in SurfaceFlinger, we merge
+// the dropped buffer's damage region into the next buffer's damage region. If
+// we don't do this, we'll report an incorrect damage region to hardware
+// composer, resulting in broken rendering. This test checks the BufferQueue
+// case.
+//
+// Unfortunately, we don't currently have a way to inspect the damage region
+// SurfaceFlinger sends to hardware composer from a test, so this test requires
+// the dev to manually watch the device's screen during the test to spot broken
+// rendering. Because the results can't be automatically verified, this test is
+// marked disabled.
+TEST_F(LayerTransactionTest, DISABLED_BufferQueueLayerMergeDamageRegionWhenDroppingBuffers) {
+    const int width = mDisplayWidth;
+    const int height = mDisplayHeight;
+    sp<SurfaceControl> layer;
+    ASSERT_NO_FATAL_FAILURE(layer = createLayer("test", width, height));
+    const auto producer = layer->getIGraphicBufferProducer();
+    const sp<IProducerListener> dummyListener(new DummyProducerListener);
+    IGraphicBufferProducer::QueueBufferOutput queueBufferOutput;
+    ASSERT_EQ(OK,
+              producer->connect(dummyListener, NATIVE_WINDOW_API_CPU, true, &queueBufferOutput));
+
+    std::map<int, sp<GraphicBuffer>> slotMap;
+    auto slotToBuffer = [&](int slot, sp<GraphicBuffer>* buf) {
+        ASSERT_NE(nullptr, buf);
+        const auto iter = slotMap.find(slot);
+        ASSERT_NE(slotMap.end(), iter);
+        *buf = iter->second;
+    };
+
+    auto dequeue = [&](int* outSlot) {
+        ASSERT_NE(nullptr, outSlot);
+        *outSlot = -1;
+        int slot;
+        sp<Fence> fence;
+        uint64_t age;
+        FrameEventHistoryDelta timestamps;
+        const status_t dequeueResult =
+                producer->dequeueBuffer(&slot, &fence, width, height, PIXEL_FORMAT_RGBA_8888,
+                                        GRALLOC_USAGE_SW_READ_OFTEN | GRALLOC_USAGE_SW_WRITE_OFTEN,
+                                        &age, &timestamps);
+        if (dequeueResult == IGraphicBufferProducer::BUFFER_NEEDS_REALLOCATION) {
+            sp<GraphicBuffer> newBuf;
+            ASSERT_EQ(OK, producer->requestBuffer(slot, &newBuf));
+            ASSERT_NE(nullptr, newBuf.get());
+            slotMap[slot] = newBuf;
+        } else {
+            ASSERT_EQ(OK, dequeueResult);
+        }
+        *outSlot = slot;
+    };
+
+    auto queue = [&](int slot, const Region& damage, nsecs_t displayTime) {
+        IGraphicBufferProducer::QueueBufferInput input(
+                /*timestamp=*/displayTime, /*isAutoTimestamp=*/false, HAL_DATASPACE_UNKNOWN,
+                /*crop=*/Rect::EMPTY_RECT, NATIVE_WINDOW_SCALING_MODE_SCALE_TO_WINDOW,
+                /*transform=*/0, Fence::NO_FENCE);
+        input.setSurfaceDamage(damage);
+        IGraphicBufferProducer::QueueBufferOutput output;
+        ASSERT_EQ(OK, producer->queueBuffer(slot, input, &output));
+    };
+
+    auto fillAndPostBuffers = [&](const Color& color) {
+        int slot1;
+        ASSERT_NO_FATAL_FAILURE(dequeue(&slot1));
+        int slot2;
+        ASSERT_NO_FATAL_FAILURE(dequeue(&slot2));
+
+        sp<GraphicBuffer> buf1;
+        ASSERT_NO_FATAL_FAILURE(slotToBuffer(slot1, &buf1));
+        sp<GraphicBuffer> buf2;
+        ASSERT_NO_FATAL_FAILURE(slotToBuffer(slot2, &buf2));
+        fillGraphicBufferColor(buf1, Rect(width, height), color);
+        fillGraphicBufferColor(buf2, Rect(width, height), color);
+
+        const auto displayTime = systemTime() + milliseconds_to_nanoseconds(100);
+        ASSERT_NO_FATAL_FAILURE(queue(slot1, Region::INVALID_REGION, displayTime));
+        ASSERT_NO_FATAL_FAILURE(
+                queue(slot2, Region(Rect(width / 3, height / 3, 2 * width / 3, 2 * height / 3)),
+                      displayTime));
+    };
+
+    const auto startTime = systemTime();
+    const std::array<Color, 3> colors = {Color::RED, Color::GREEN, Color::BLUE};
+    int colorIndex = 0;
+    while (nanoseconds_to_seconds(systemTime() - startTime) < 10) {
+        ASSERT_NO_FATAL_FAILURE(fillAndPostBuffers(colors[colorIndex++ % colors.size()]));
+        std::this_thread::sleep_for(1s);
+    }
+
+    ASSERT_EQ(OK, producer->disconnect(NATIVE_WINDOW_API_CPU));
+}
+
 } // namespace android