diff --git a/libs/gui/tests/Android.bp b/libs/gui/tests/Android.bp
index a5b87ec..ab6dcaa 100644
--- a/libs/gui/tests/Android.bp
+++ b/libs/gui/tests/Android.bp
@@ -23,6 +23,7 @@
         "IGraphicBufferProducer_test.cpp",
         "Malicious.cpp",
         "MultiTextureConsumer_test.cpp",
+        "RegionSampling_test.cpp",
         "StreamSplitter_test.cpp",
         "SurfaceTextureClient_test.cpp",
         "SurfaceTextureFBO_test.cpp",
diff --git a/libs/gui/tests/RegionSampling_test.cpp b/libs/gui/tests/RegionSampling_test.cpp
new file mode 100644
index 0000000..5652c0c
--- /dev/null
+++ b/libs/gui/tests/RegionSampling_test.cpp
@@ -0,0 +1,300 @@
+/*
+ * Copyright 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+#include <thread>
+
+#include <binder/ProcessState.h>
+#include <gui/DisplayEventReceiver.h>
+#include <gui/IRegionSamplingListener.h>
+#include <gui/ISurfaceComposer.h>
+#include <gui/Surface.h>
+#include <gui/SurfaceComposerClient.h>
+#include <private/gui/ComposerService.h>
+#include <utils/Looper.h>
+
+using namespace std::chrono_literals;
+
+namespace android::test {
+
+struct ChoreographerSync {
+    ChoreographerSync(DisplayEventReceiver& receiver) : receiver_(receiver) {}
+    ~ChoreographerSync() = default;
+
+    void notify() const {
+        std::unique_lock<decltype(mutex_)> lk(mutex_);
+
+        auto check_event = [](auto const& ev) -> bool {
+            return ev.header.type == DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
+        };
+        DisplayEventReceiver::Event ev_;
+        int evs = receiver_.getEvents(&ev_, 1);
+        auto vsync_event_found = check_event(ev_);
+        while (evs) {
+            evs = receiver_.getEvents(&ev_, 1);
+            vsync_event_found |= check_event(ev_);
+        }
+
+        if (vsync_event_found) {
+            notification_arrived_ = true;
+            cv_.notify_all();
+        }
+    }
+
+    void wait_vsync_notify() const {
+        std::unique_lock<decltype(mutex_)> lk(mutex_);
+        cv_.wait(lk, [this] { return notification_arrived_; });
+        notification_arrived_ = false;
+    }
+
+private:
+    ChoreographerSync(ChoreographerSync const&) = delete;
+    ChoreographerSync& operator=(ChoreographerSync const&) = delete;
+
+    std::mutex mutable mutex_;
+    std::condition_variable mutable cv_;
+    bool mutable notification_arrived_ = false;
+    DisplayEventReceiver& receiver_;
+};
+
+struct ChoreographerSim {
+    static std::unique_ptr<ChoreographerSim> make() {
+        auto receiver = std::make_unique<DisplayEventReceiver>();
+        if (!receiver || receiver->initCheck() == NO_INIT) {
+            ALOGE("No display reciever");
+            return nullptr;
+        }
+        return std::unique_ptr<ChoreographerSim>(new ChoreographerSim(std::move(receiver)));
+    }
+
+    ~ChoreographerSim() {
+        poll_ = false;
+        looper->wake();
+        choreographer_thread_.join();
+    }
+
+    void request_render_wait(std::function<void()> const& render_fn) {
+        display_event_receiver_->requestNextVsync();
+        choreographer_.wait_vsync_notify();
+        render_fn();
+
+        // Purpose is to make sure that the content is latched by the time we sample.
+        // Waiting one vsync after queueing could still race with vsync, so wait for two, after
+        // which the content is pretty reliably on screen.
+        display_event_receiver_->requestNextVsync();
+        choreographer_.wait_vsync_notify();
+        display_event_receiver_->requestNextVsync();
+        choreographer_.wait_vsync_notify();
+    }
+
+private:
+    ChoreographerSim(std::unique_ptr<DisplayEventReceiver> receiver)
+          : display_event_receiver_{std::move(receiver)},
+            choreographer_{*display_event_receiver_},
+            looper{new Looper(false)} {
+        choreographer_thread_ = std::thread([this] {
+            auto vsync_notify_fd = display_event_receiver_->getFd();
+            looper->addFd(vsync_notify_fd, 0, Looper::EVENT_INPUT,
+                          [](int /*fd*/, int /*events*/, void* data) -> int {
+                              if (!data) return 0;
+                              reinterpret_cast<ChoreographerSync*>(data)->notify();
+                              return 1;
+                          },
+                          const_cast<void*>(reinterpret_cast<void const*>(&choreographer_)));
+
+            while (poll_) {
+                auto const poll_interval =
+                        std::chrono::duration_cast<std::chrono::milliseconds>(1s).count();
+                auto rc = looper->pollOnce(poll_interval);
+                if ((rc != Looper::POLL_CALLBACK) && (rc != Looper::POLL_WAKE))
+                    ALOGW("Vsync Looper returned: %i\n", rc);
+            }
+        });
+    }
+
+    ChoreographerSim(ChoreographerSim const&) = delete;
+    ChoreographerSim& operator=(ChoreographerSim const&) = delete;
+
+    std::unique_ptr<DisplayEventReceiver> const display_event_receiver_;
+    ChoreographerSync const choreographer_;
+    sp<Looper> looper;
+    std::thread choreographer_thread_;
+    std::atomic<bool> poll_{true};
+};
+
+struct Listener : BnRegionSamplingListener {
+    void onSampleCollected(float medianLuma) override {
+        std::unique_lock<decltype(mutex)> lk(mutex);
+        received = true;
+        mLuma = medianLuma;
+        cv.notify_all();
+    };
+    bool wait_event(std::chrono::milliseconds timeout) {
+        std::unique_lock<decltype(mutex)> lk(mutex);
+        return cv.wait_for(lk, timeout, [this] { return received; });
+    }
+
+    float luma() {
+        std::unique_lock<decltype(mutex)> lk(mutex);
+        return mLuma;
+    }
+
+    void reset() {
+        std::unique_lock<decltype(mutex)> lk(mutex);
+        received = false;
+    }
+
+private:
+    std::condition_variable cv;
+    std::mutex mutex;
+    bool received = false;
+    float mLuma = -0.0f;
+};
+
+// Hoisted to TestSuite setup to avoid flake in test (b/124675919)
+std::unique_ptr<ChoreographerSim> gChoreographerSim = nullptr;
+
+struct RegionSamplingTest : ::testing::Test {
+protected:
+    RegionSamplingTest() { ProcessState::self()->startThreadPool(); }
+
+    static void SetUpTestSuite() {
+        gChoreographerSim = ChoreographerSim::make();
+        ASSERT_NE(gChoreographerSim, nullptr);
+    }
+
+    void SetUp() override {
+        mSurfaceComposerClient = new SurfaceComposerClient;
+        ASSERT_EQ(NO_ERROR, mSurfaceComposerClient->initCheck());
+
+        mBackgroundLayer =
+                mSurfaceComposerClient->createSurface(String8("Background RegionSamplingTest"), 0,
+                                                      0, PIXEL_FORMAT_RGBA_8888,
+                                                      ISurfaceComposerClient::eFXSurfaceColor);
+        uint32_t layerPositionBottom = 0x7E000000;
+        SurfaceComposerClient::Transaction{}
+                .setLayer(mBackgroundLayer, layerPositionBottom)
+                .setPosition(mBackgroundLayer, 100, 100)
+                .setColor(mBackgroundLayer, half3{0.5, 0.5, 0.5})
+                .show(mBackgroundLayer)
+                .apply();
+
+        mContentLayer = mSurfaceComposerClient->createSurface(String8("Content RegionSamplingTest"),
+                                                              300, 300, PIXEL_FORMAT_RGBA_8888, 0);
+
+        SurfaceComposerClient::Transaction{}
+                .setLayer(mContentLayer, layerPositionBottom + 1)
+                .setPosition(mContentLayer, 100, 100)
+                .setColor(mContentLayer, half3{0.5, 0.5, 0.5})
+                .show(mContentLayer)
+                .apply();
+
+        mTopLayer = mSurfaceComposerClient->createSurface(String8("TopLayer RegionSamplingTest"), 0,
+                                                          0, PIXEL_FORMAT_RGBA_8888, 0);
+        SurfaceComposerClient::Transaction{}
+                .setLayer(mTopLayer, layerPositionBottom + 2)
+                .setPosition(mTopLayer, 0, 0)
+                .show(mBackgroundLayer)
+                .apply();
+    }
+
+    void fill_render(uint32_t rgba_value) {
+        auto surface = mContentLayer->getSurface();
+        ANativeWindow_Buffer outBuffer;
+        status_t status = surface->lock(&outBuffer, NULL);
+        ASSERT_EQ(status, android::OK);
+        auto b = reinterpret_cast<uint32_t*>(outBuffer.bits);
+        for (auto i = 0; i < outBuffer.height; i++) {
+            for (auto j = 0; j < outBuffer.width; j++) {
+                b[j] = rgba_value;
+            }
+            b += outBuffer.stride;
+        }
+
+        gChoreographerSim->request_render_wait([&surface] { surface->unlockAndPost(); });
+    }
+
+    sp<SurfaceComposerClient> mSurfaceComposerClient;
+    sp<SurfaceControl> mBackgroundLayer;
+    sp<SurfaceControl> mContentLayer;
+    sp<SurfaceControl> mTopLayer;
+
+    uint32_t const rgba_green = 0xFF00FF00;
+    float const luma_green = 0.7152;
+    uint32_t const rgba_blue = 0xFFFF0000;
+    float const luma_blue = 0.0722;
+    float const error_margin = 0.01;
+    float const luma_gray = 0.50;
+};
+
+TEST_F(RegionSamplingTest, CollectsLuma) {
+    fill_render(rgba_green);
+
+    sp<ISurfaceComposer> composer = ComposerService::getComposerService();
+    sp<Listener> listener = new Listener();
+    const Rect sampleArea{100, 100, 200, 200};
+    composer->addRegionSamplingListener(sampleArea, mTopLayer->getHandle(), listener);
+
+    EXPECT_TRUE(listener->wait_event(300ms)) << "timed out waiting for luma event to be received";
+    EXPECT_NEAR(listener->luma(), luma_green, error_margin);
+
+    composer->removeRegionSamplingListener(listener);
+}
+
+TEST_F(RegionSamplingTest, CollectsChangingLuma) {
+    fill_render(rgba_green);
+
+    sp<ISurfaceComposer> composer = ComposerService::getComposerService();
+    sp<Listener> listener = new Listener();
+    const Rect sampleArea{100, 100, 200, 200};
+    composer->addRegionSamplingListener(sampleArea, mTopLayer->getHandle(), listener);
+
+    EXPECT_TRUE(listener->wait_event(300ms)) << "timed out waiting for luma event to be received";
+    EXPECT_NEAR(listener->luma(), luma_green, error_margin);
+
+    listener->reset();
+
+    fill_render(rgba_blue);
+    EXPECT_TRUE(listener->wait_event(300ms))
+            << "timed out waiting for 2nd luma event to be received";
+    EXPECT_NEAR(listener->luma(), luma_blue, error_margin);
+
+    composer->removeRegionSamplingListener(listener);
+}
+
+TEST_F(RegionSamplingTest, CollectsLumaFromTwoRegions) {
+    fill_render(rgba_green);
+    sp<ISurfaceComposer> composer = ComposerService::getComposerService();
+    sp<Listener> greenListener = new Listener();
+    const Rect greenSampleArea{100, 100, 200, 200};
+    composer->addRegionSamplingListener(greenSampleArea, mTopLayer->getHandle(), greenListener);
+
+    sp<Listener> grayListener = new Listener();
+    const Rect graySampleArea{500, 100, 600, 200};
+    composer->addRegionSamplingListener(graySampleArea, mTopLayer->getHandle(), grayListener);
+
+    EXPECT_TRUE(grayListener->wait_event(300ms))
+            << "timed out waiting for luma event to be received";
+    EXPECT_NEAR(grayListener->luma(), luma_gray, error_margin);
+    EXPECT_TRUE(greenListener->wait_event(300ms))
+            << "timed out waiting for luma event to be received";
+    EXPECT_NEAR(greenListener->luma(), luma_green, error_margin);
+
+    composer->removeRegionSamplingListener(greenListener);
+    composer->removeRegionSamplingListener(grayListener);
+}
+
+} // namespace android::test