Add 'blank_screen' util.

//

// Copyright (C) 2017 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.

//

// Turns off the screen.

// Canonical usage is for init (which can't talk to hals directly).

cc_binary {

    name: "blank_screen",

    init_rc: ["blank_screen.rc"],

    srcs: ["main.cpp"],

    shared_libs: [

        "android.hardware.light@2.0",

        "libbase",

        "libhidlbase",

        "libhidltransport",

        "libutils",

    ],

}

service blank_screen /system/bin/blank_screen

    user system

    oneshot

    group system readproc

    shutdown critical

/*

 * Copyright (C) 2017 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 <iostream>

#include <string>

#include <android-base/logging.h>

#include <android/hardware/light/2.0/ILight.h>

void error(const std::string& msg) {

    LOG(ERROR) << msg;

    std::cerr << msg << std::endl;

}

int main() {

    using ::android::hardware::light::V2_0::Brightness;

    using ::android::hardware::light::V2_0::Flash;

    using ::android::hardware::light::V2_0::ILight;

    using ::android::hardware::light::V2_0::LightState;

    using ::android::hardware::light::V2_0::Status;

    using ::android::hardware::light::V2_0::Type;

    using ::android::sp;

    sp<ILight> service = ILight::getService();

    if (service == nullptr) {

        error("Could not retrieve light service.");

        return -1;

    }

    const static LightState off = {

        .color = 0u, .flashMode = Flash::NONE, .brightnessMode = Brightness::USER,

    };

    Status ret = service->setLight(Type::BACKLIGHT, off).withDefault(Status::UNKNOWN);

    if (ret != Status::SUCCESS) {

        error("Failed to shut off screen");

    }

    return 0;

}