[sf] Implement addSamplingListener

Implements ISurfaceComposer::addSamplingListener, which allows a client
to receive streaming median luma updates for a given region of the
screen.

Bug: 119639245
Test: Manual using SamplingDemo in libgui
Test: Automated libgui_test in Ic85a97f475a3414a79d3719bbd0b2b648bbccfb0
Change-Id: Ic52359aeab884e734a806372be0eb4e327c45298
diff --git a/libs/gui/tests/SamplingDemo.cpp b/libs/gui/tests/SamplingDemo.cpp
new file mode 100644
index 0000000..9891587
--- /dev/null
+++ b/libs/gui/tests/SamplingDemo.cpp
@@ -0,0 +1,135 @@
+/*
+ * 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 ATRACE_TAG ATRACE_TAG_GRAPHICS
+#define LOG_TAG "SamplingTest"
+
+#include <chrono>
+#include <thread>
+
+#include <binder/IPCThreadState.h>
+#include <binder/ProcessState.h>
+#include <gui/IRegionSamplingListener.h>
+#include <gui/ISurfaceComposer.h>
+#include <gui/SurfaceComposerClient.h>
+#include <gui/SurfaceControl.h>
+#include <private/gui/ComposerService.h>
+#include <utils/Trace.h>
+
+using namespace std::chrono_literals;
+
+namespace android {
+
+class Button : public BnRegionSamplingListener {
+public:
+    Button(const char* name, const Rect& samplingArea) {
+        sp<SurfaceComposerClient> client = new SurfaceComposerClient;
+
+        mButton = client->createSurface(String8(name), 0, 0, PIXEL_FORMAT_RGBA_8888,
+                                        ISurfaceComposerClient::eFXSurfaceColor);
+
+        const int32_t width = samplingArea.getWidth();
+        const int32_t height = samplingArea.getHeight();
+
+        SurfaceComposerClient::Transaction{}
+                .setLayer(mButton, 0x7fffffff)
+                .setCrop_legacy(mButton,
+                                {0, 0, width - 2 * BUTTON_PADDING, height - 2 * BUTTON_PADDING})
+                .setPosition(mButton, samplingArea.left + BUTTON_PADDING,
+                             samplingArea.top + BUTTON_PADDING)
+                .setColor(mButton, half3{1, 1, 1})
+                .show(mButton)
+                .apply();
+
+        mButtonBlend = client->createSurface(String8(name) + "Blend", 0, 0, PIXEL_FORMAT_RGBA_8888,
+                                             ISurfaceComposerClient::eFXSurfaceColor);
+
+        SurfaceComposerClient::Transaction{}
+                .setLayer(mButtonBlend, 0x7ffffffe)
+                .setCrop_legacy(mButtonBlend,
+                                {0, 0, width - 2 * SAMPLE_AREA_PADDING,
+                                 height - 2 * SAMPLE_AREA_PADDING})
+                .setPosition(mButtonBlend, samplingArea.left + SAMPLE_AREA_PADDING,
+                             samplingArea.top + SAMPLE_AREA_PADDING)
+                .setColor(mButtonBlend, half3{1, 1, 1})
+                .setAlpha(mButtonBlend, 0.2)
+                .show(mButtonBlend)
+                .apply(true);
+
+        const bool HIGHLIGHT_SAMPLING_AREA = false;
+        if (HIGHLIGHT_SAMPLING_AREA) {
+            mSamplingArea =
+                    client->createSurface(String8("SamplingArea"), 0, 0, PIXEL_FORMAT_RGBA_8888,
+                                          ISurfaceComposerClient::eFXSurfaceColor);
+
+            SurfaceComposerClient::Transaction{}
+                    .setLayer(mSamplingArea, 0x7ffffffd)
+                    .setCrop_legacy(mSamplingArea, {0, 0, 100, 32})
+                    .setPosition(mSamplingArea, 490, 1606)
+                    .setColor(mSamplingArea, half3{0, 1, 0})
+                    .setAlpha(mSamplingArea, 0.1)
+                    .show(mSamplingArea)
+                    .apply();
+        }
+    }
+
+    sp<IBinder> getStopLayerHandle() { return mButtonBlend->getHandle(); }
+
+private:
+    static const int32_t BLEND_WIDTH = 2;
+    static const int32_t SAMPLE_AREA_PADDING = 8;
+    static const int32_t BUTTON_PADDING = BLEND_WIDTH + SAMPLE_AREA_PADDING;
+
+    void setColor(float color) {
+        const float complement = std::fmod(color + 0.5f, 1.0f);
+        SurfaceComposerClient::Transaction{}
+                .setColor(mButton, half3{complement, complement, complement})
+                .setColor(mButtonBlend, half3{color, color, color})
+                .apply();
+    }
+
+    void onSampleCollected(float medianLuma) override {
+        ATRACE_CALL();
+        setColor(medianLuma);
+    }
+
+    sp<SurfaceComposerClient> mClient;
+    sp<SurfaceControl> mButton;
+    sp<SurfaceControl> mButtonBlend;
+    sp<SurfaceControl> mSamplingArea;
+};
+
+} // namespace android
+
+using namespace android;
+
+int main(int, const char**) {
+    const Rect homeButtonArea{490, 1606, 590, 1654};
+    sp<android::Button> homeButton = new android::Button("HomeButton", homeButtonArea);
+    const Rect backButtonArea{200, 1606, 248, 1654};
+    sp<android::Button> backButton = new android::Button("BackButton", backButtonArea);
+
+    sp<ISurfaceComposer> composer = ComposerService::getComposerService();
+    composer->addRegionSamplingListener(homeButtonArea, homeButton->getStopLayerHandle(),
+                                        homeButton);
+    composer->addRegionSamplingListener(backButtonArea, backButton->getStopLayerHandle(),
+                                        backButton);
+
+    ProcessState::self()->startThreadPool();
+    IPCThreadState::self()->joinThreadPool();
+
+    return 0;
+}