diff --git a/services/surfaceflinger/RegionSamplingThread.cpp b/services/surfaceflinger/RegionSamplingThread.cpp
new file mode 100644
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--- /dev/null
+++ b/services/surfaceflinger/RegionSamplingThread.cpp
@@ -0,0 +1,252 @@
+/*
+ * 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.
+ */
+
+//#define LOG_NDEBUG 0
+#define ATRACE_TAG ATRACE_TAG_GRAPHICS
+#undef LOG_TAG
+#define LOG_TAG "RegionSamplingThread"
+
+#include "RegionSamplingThread.h"
+
+#include <gui/IRegionSamplingListener.h>
+#include <utils/Trace.h>
+
+#include "DisplayDevice.h"
+#include "Layer.h"
+#include "SurfaceFlinger.h"
+
+namespace android {
+
+template <typename T>
+struct SpHash {
+    size_t operator()(const sp<T>& p) const { return std::hash<T*>()(p.get()); }
+};
+
+RegionSamplingThread::RegionSamplingThread(SurfaceFlinger& flinger) : mFlinger(flinger) {
+    std::lock_guard threadLock(mThreadMutex);
+    mThread = std::thread([this]() { threadMain(); });
+    pthread_setname_np(mThread.native_handle(), "RegionSamplingThread");
+}
+
+RegionSamplingThread::~RegionSamplingThread() {
+    {
+        std::lock_guard lock(mMutex);
+        mRunning = false;
+        mCondition.notify_one();
+    }
+
+    std::lock_guard threadLock(mThreadMutex);
+    if (mThread.joinable()) {
+        mThread.join();
+    }
+}
+
+void RegionSamplingThread::addListener(const Rect& samplingArea, const sp<IBinder>& stopLayerHandle,
+                                       const sp<IRegionSamplingListener>& listener) {
+    wp<Layer> stopLayer = stopLayerHandle != nullptr
+            ? static_cast<Layer::Handle*>(stopLayerHandle.get())->owner
+            : nullptr;
+
+    sp<IBinder> asBinder = IInterface::asBinder(listener);
+    asBinder->linkToDeath(this);
+    std::lock_guard lock(mMutex);
+    mDescriptors.emplace(wp<IBinder>(asBinder), Descriptor{samplingArea, stopLayer, listener});
+}
+
+void RegionSamplingThread::removeListener(const sp<IRegionSamplingListener>& listener) {
+    std::lock_guard lock(mMutex);
+    mDescriptors.erase(wp<IBinder>(IInterface::asBinder(listener)));
+}
+
+void RegionSamplingThread::sampleNow() {
+    std::lock_guard lock(mMutex);
+    mSampleRequested = true;
+    mCondition.notify_one();
+}
+
+void RegionSamplingThread::binderDied(const wp<IBinder>& who) {
+    std::lock_guard lock(mMutex);
+    mDescriptors.erase(who);
+}
+
+namespace {
+// Using Rec. 709 primaries
+float getLuma(float r, float g, float b) {
+    constexpr auto rec709_red_primary = 0.2126f;
+    constexpr auto rec709_green_primary = 0.7152f;
+    constexpr auto rec709_blue_primary = 0.0722f;
+    return rec709_red_primary * r + rec709_green_primary * g + rec709_blue_primary * b;
+}
+
+float sampleArea(const uint32_t* data, int32_t stride, const Rect& area) {
+    std::array<int32_t, 256> brightnessBuckets = {};
+    const int32_t majoritySampleNum = area.getWidth() * area.getHeight() / 2;
+
+    for (int32_t row = area.top; row < area.bottom; ++row) {
+        const uint32_t* rowBase = data + row * stride;
+        for (int32_t column = area.left; column < area.right; ++column) {
+            uint32_t pixel = rowBase[column];
+            const float r = (pixel & 0xFF) / 255.0f;
+            const float g = ((pixel >> 8) & 0xFF) / 255.0f;
+            const float b = ((pixel >> 16) & 0xFF) / 255.0f;
+            const uint8_t luma = std::round(getLuma(r, g, b) * 255.0f);
+            ++brightnessBuckets[luma];
+            if (brightnessBuckets[luma] > majoritySampleNum) return luma / 255.0f;
+        }
+    }
+
+    int32_t accumulated = 0;
+    size_t bucket = 0;
+    while (bucket++ < brightnessBuckets.size()) {
+        accumulated += brightnessBuckets[bucket];
+        if (accumulated > majoritySampleNum) break;
+    }
+
+    return bucket / 255.0f;
+}
+} // anonymous namespace
+
+std::vector<float> sampleBuffer(const sp<GraphicBuffer>& buffer, const Point& leftTop,
+                                const std::vector<RegionSamplingThread::Descriptor>& descriptors) {
+    void* data_raw = nullptr;
+    buffer->lock(GRALLOC_USAGE_SW_READ_OFTEN, &data_raw);
+    std::shared_ptr<uint32_t> data(reinterpret_cast<uint32_t*>(data_raw),
+                                   [&buffer](auto) { buffer->unlock(); });
+    if (!data) return {};
+
+    const int32_t stride = buffer->getStride();
+    std::vector<float> lumas(descriptors.size());
+    std::transform(descriptors.begin(), descriptors.end(), lumas.begin(),
+                   [&](auto const& descriptor) {
+                       return sampleArea(data.get(), stride, descriptor.area - leftTop);
+                   });
+    return lumas;
+}
+
+void RegionSamplingThread::captureSample() {
+    ATRACE_CALL();
+
+    if (mDescriptors.empty()) {
+        return;
+    }
+
+    std::vector<RegionSamplingThread::Descriptor> descriptors;
+    Region sampleRegion;
+    for (const auto& [listener, descriptor] : mDescriptors) {
+        sampleRegion.orSelf(descriptor.area);
+        descriptors.emplace_back(descriptor);
+    }
+
+    Rect sampledArea = sampleRegion.bounds();
+
+    sp<const DisplayDevice> device = mFlinger.getDefaultDisplayDevice();
+    DisplayRenderArea renderArea(device, sampledArea, sampledArea.getWidth(),
+                                 sampledArea.getHeight(), ui::Dataspace::V0_SRGB,
+                                 ui::Transform::ROT_0);
+
+    std::unordered_set<sp<IRegionSamplingListener>, SpHash<IRegionSamplingListener>> listeners;
+
+    auto traverseLayers = [&](const LayerVector::Visitor& visitor) {
+        bool stopLayerFound = false;
+        auto filterVisitor = [&](Layer* layer) {
+            // We don't want to capture any layers beyond the stop layer
+            if (stopLayerFound) return;
+
+            // Likewise if we just found a stop layer, set the flag and abort
+            for (const auto& [area, stopLayer, listener] : descriptors) {
+                if (layer == stopLayer.promote().get()) {
+                    stopLayerFound = true;
+                    return;
+                }
+            }
+
+            // Compute the layer's position on the screen
+            Rect bounds = Rect(layer->getBounds());
+            ui::Transform transform = layer->getTransform();
+            constexpr bool roundOutwards = true;
+            Rect transformed = transform.transform(bounds, roundOutwards);
+
+            // If this layer doesn't intersect with the larger sampledArea, skip capturing it
+            Rect ignore;
+            if (!transformed.intersect(sampledArea, &ignore)) return;
+
+            // If the layer doesn't intersect a sampling area, skip capturing it
+            bool intersectsAnyArea = false;
+            for (const auto& [area, stopLayer, listener] : descriptors) {
+                if (transformed.intersect(area, &ignore)) {
+                    intersectsAnyArea = true;
+                    listeners.insert(listener);
+                }
+            }
+            if (!intersectsAnyArea) return;
+
+            ALOGV("Traversing [%s] [%d, %d, %d, %d]", layer->getName().string(), bounds.left,
+                  bounds.top, bounds.right, bounds.bottom);
+            visitor(layer);
+        };
+        mFlinger.traverseLayersInDisplay(device, filterVisitor);
+    };
+
+    const uint32_t usage = GRALLOC_USAGE_SW_READ_OFTEN | GRALLOC_USAGE_HW_RENDER;
+    sp<GraphicBuffer> buffer =
+            new GraphicBuffer(sampledArea.getWidth(), sampledArea.getHeight(),
+                              PIXEL_FORMAT_RGBA_8888, 1, usage, "RegionSamplingThread");
+
+    // When calling into SF, we post a message into the SF message queue (so the
+    // screen capture runs on the main thread). This message blocks until the
+    // screenshot is actually captured, but before the capture occurs, the main
+    // thread may perform a normal refresh cycle. At the end of this cycle, it
+    // can request another sample (because layers changed), which triggers a
+    // call into sampleNow. When sampleNow attempts to grab the mutex, we can
+    // deadlock.
+    //
+    // To avoid this, we drop the mutex while we call into SF.
+    mMutex.unlock();
+    mFlinger.captureScreenCore(renderArea, traverseLayers, buffer, false);
+    mMutex.lock();
+
+    std::vector<Descriptor> activeDescriptors;
+    for (const auto& descriptor : descriptors) {
+        if (listeners.count(descriptor.listener) != 0) {
+            activeDescriptors.emplace_back(descriptor);
+        }
+    }
+
+    ALOGV("Sampling %zu descriptors", activeDescriptors.size());
+    std::vector<float> lumas = sampleBuffer(buffer, sampledArea.leftTop(), activeDescriptors);
+
+    if (lumas.size() != activeDescriptors.size()) {
+        return;
+    }
+
+    for (size_t d = 0; d < activeDescriptors.size(); ++d) {
+        activeDescriptors[d].listener->onSampleCollected(lumas[d]);
+    }
+}
+
+void RegionSamplingThread::threadMain() {
+    std::lock_guard lock(mMutex);
+    while (mRunning) {
+        if (mSampleRequested) {
+            mSampleRequested = false;
+            captureSample();
+        }
+        mCondition.wait(mMutex,
+                        [this]() REQUIRES(mMutex) { return mSampleRequested || !mRunning; });
+    }
+}
+
+} // namespace android