Settings: add a new developer menu entry to show hdr/sdr ratio overlay.

- The hdr/sdr ratio overlay will be shown on screen if the option is
  selected from the developer option.
- This option is hidden on non-HDR-supported devices.
- Add flags: com.android.settings.flags.development_hdr_sdr_ratio

Test: enable show hdr/sdr ratio from developer menu; com.android.settings.development.ShowHdrSdrRatioPreferenceControllerTest
Bug: 291863102
Change-Id: Idd72f95c67c95cd8127f9b94e031b3d87b18e307

src/com/android/settings/development/ShowHdrSdrRatioPreferenceController.java

@@ -0,0 +1,144 @@
+/**
+ * Copyright (C) 2023 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.
+ */
+
+package com.android.settings.development;
+
+import android.content.Context;
+import android.hardware.display.DisplayManager;
+import android.os.IBinder;
+import android.os.Parcel;
+import android.os.RemoteException;
+import android.os.ServiceManager;
+import android.view.Display;
+
+import androidx.annotation.VisibleForTesting;
+import androidx.preference.Preference;
+import androidx.preference.TwoStatePreference;
+
+import com.android.settings.core.PreferenceControllerMixin;
+import com.android.settings.flags.Flags;
+import com.android.settingslib.development.DeveloperOptionsPreferenceController;
+
+/**
+ * Controller class for controlling the hdr/sdr ratio on SurfaceFlinger
+ */
+public class ShowHdrSdrRatioPreferenceController extends DeveloperOptionsPreferenceController
+        implements Preference.OnPreferenceChangeListener, PreferenceControllerMixin {
+
+    private static final String SHOW_REFRESH_RATE_KEY = "show_hdr_sdr_ratio";
+
+    private static final int SETTING_VALUE_QUERY = 2;
+    private static final int SETTING_VALUE_ON = 1;
+    private static final int SETTING_VALUE_OFF = 0;
+
+    private static final String SURFACE_FLINGER_SERVICE_KEY = "SurfaceFlinger";
+
+    private static final int SURFACE_FLINGER_CODE = 1043;
+
+    private static final String SURFACE_COMPOSER_INTERFACE_KEY = "android.ui.ISurfaceComposer";
+
+    private final IBinder mSurfaceFlinger;
+
+    private final boolean mIsHdrSdrRatioAvailable;
+
+    public ShowHdrSdrRatioPreferenceController(Context context) {
+        super(context);
+        mSurfaceFlinger = ServiceManager.getService(SURFACE_FLINGER_SERVICE_KEY);
+        DisplayManager displayManager = context.getSystemService(DisplayManager.class);
+        Display display = displayManager.getDisplay(Display.DEFAULT_DISPLAY);
+        mIsHdrSdrRatioAvailable = display != null && display.isHdrSdrRatioAvailable();
+    }
+
+    @VisibleForTesting
+    ShowHdrSdrRatioPreferenceController(Context context, IBinder surfaceFlinger,
+                                        boolean isHdrSdrRatioAvailable) {
+        super(context);
+        mSurfaceFlinger = surfaceFlinger;
+        mIsHdrSdrRatioAvailable = isHdrSdrRatioAvailable;
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return SHOW_REFRESH_RATE_KEY;
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        final boolean isEnabled = (Boolean) newValue;
+        writeShowHdrSdrRatioSetting(isEnabled);
+        return true;
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        super.updateState(preference);
+        updateShowHdrSdrRatioSetting();
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return Flags.developmentHdrSdrRatio() && mIsHdrSdrRatioAvailable;
+    }
+
+    @Override
+    protected void onDeveloperOptionsSwitchDisabled() {
+        super.onDeveloperOptionsSwitchDisabled();
+        final TwoStatePreference preference = (TwoStatePreference) mPreference;
+        if (preference.isChecked()) {
+            // Writing false to the preference when the setting is already off will have a
+            // side effect of turning on the preference that we wish to avoid
+            writeShowHdrSdrRatioSetting(false);
+            preference.setChecked(false);
+        }
+    }
+
+    private void updateShowHdrSdrRatioSetting() {
+        // magic communication with surface flinger.
+        try {
+            if (mSurfaceFlinger != null) {
+                final Parcel data = Parcel.obtain();
+                final Parcel reply = Parcel.obtain();
+                data.writeInterfaceToken(SURFACE_COMPOSER_INTERFACE_KEY);
+                data.writeInt(SETTING_VALUE_QUERY);
+                mSurfaceFlinger.transact(SURFACE_FLINGER_CODE, data, reply, 0 /* flags */);
+                final boolean enabled = reply.readBoolean();
+                ((TwoStatePreference) mPreference).setChecked(enabled);
+                reply.recycle();
+                data.recycle();
+            }
+        } catch (RemoteException ex) {
+            // intentional no-op
+        }
+    }
+
+    @VisibleForTesting
+    void writeShowHdrSdrRatioSetting(boolean isEnabled) {
+        try {
+            if (mSurfaceFlinger != null) {
+                final Parcel data = Parcel.obtain();
+                data.writeInterfaceToken(SURFACE_COMPOSER_INTERFACE_KEY);
+                final int showHdrSdrRatio = isEnabled ? SETTING_VALUE_ON : SETTING_VALUE_OFF;
+                data.writeInt(showHdrSdrRatio);
+                mSurfaceFlinger.transact(SURFACE_FLINGER_CODE, data,
+                        null /* reply */, 0 /* flags */);
+                data.recycle();
+            }
+        } catch (RemoteException ex) {
+            // intentional no-op
+        }
+        updateShowHdrSdrRatioSetting();
+    }
+}