Android 以雙擊亮屏為例，上層控制驅動節點的流程

1、雙擊螢屏時，tp報上來的事件設定為KeyEvent.KEYCODE_U，則在PhoneWindowManager中可以增加監聽，只要正常上報該事件，按以下的執行則能實作雙擊亮屏的功能，

ALPS_R0MP1/frameworks / base/services/core/java/com/android/server/policy/PhoneWindowManager.java
 
    @Override
    public int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags) {
 
 
    ......//省略大量代碼
    case KeyEvent.KEYCODE_U:{
                if (SystemProperties.getBoolean("ro.hct_double_click_brighten_screen_support", false)) {
                    result &= ~ACTION_PASS_TO_USER;
                    if (down) {
                        isWakeKey = true;
                    }
                }
                break;
            }
}

2、實作功能后則需要添加按鈕控制，以達到不需要時關閉該功能后節省點的目的，UI具體實作代碼如下：

ALPS_R0MP1/vendor/mediatek/proprietary/packages / apps/MtkSettings/src/com/android/settings/gestures/WakeUpSwitchController.java
 
package com.android.settings.gestures;
import android.content.Context;
import android.os.SystemProperties;
import android.os.UserHandle;
import android.provider.Settings;
 
import androidx.preference.Preference;
import androidx.preference.PreferenceScreen;
import androidx.preference.SwitchPreference;
import com.android.settings.core.TogglePreferenceController;
 
public class WakeUpSwitchController extends TogglePreferenceController {
    private final Context mContext;
    private static final int MY_USER_ID = UserHandle.myUserId();
    private final String WAKE_UP_SWITHCH_MOD = "wake_up_switch_mod";
    public WakeUpSwitchController(Context context, String preferenceKey) {
        super(context, preferenceKey);
        mContext = context;
    }
    @Override
    public boolean isChecked() {
        return Settings.System.getIntForUser(mContext.getContentResolver(),
                WAKE_UP_SWITHCH_MOD,
                0, MY_USER_ID) != 0;
    }
    @Override
    public boolean setChecked(boolean isChecked) {
        Settings.System.putIntForUser(mContext.getContentResolver(), WAKE_UP_SWITHCH_MOD,
                isChecked ? 1 : 0, MY_USER_ID);
        //通過這只prop值，來控制驅動節點
        SystemProperties.set("persist.vendor.hct.gesturewake", isChecked ? "1" : "0");
        return true;
    }
    @Override
    public int getAvailabilityStatus() {
        return SystemProperties.getBoolean("ro.hct_double_click_brighten_screen_support", false) ? AVAILABLE : UNSUPPORTED_ON_DEVICE;
    }
}

3、通過對目標prop值的監聽來控制tp的節點，具體實作如下：

ALPS_R0MP1/device / mediatek/mt6779/init.mt6779.rc
 
 
#gesturewake
    chown root system /sys/bus/i2c/devices/0-0038/fts_gesture_mode  //修改節點檔案所有型別
    chmod 0777 /sys/bus/i2c/devices/0-0038/fts_gesture_mode         //修改節點檔案讀寫權限
on property:persist.vendor.hct.gesturewake=*                        //監聽prop并將其寫入節點(類似ContentProvider功能)
    write /sys/bus/i2c/devices/0-0038/fts_gesture_mode ${persist.vendor.hct.gesturewake}
 
 
----------
ALPS_R0MP1/device / mediatek/sepolicy/basic/non_plat/file.te
 
#gesturewake
type hct_gesture_mode, fs_type, sysfs_type;         //定義節點檔案屬性
 
----------
ALPS_R0MP1/device / mediatek/sepolicy/basic/non_plat/file_contexts
 
#gesturewake
/sys/bus/i2c/devices/0-0038/fts_gesture_mode u:object_r:hct_gesture_mode:s0     //定義節點檔案
 
----------
ALPS_R0MP1/device / mediatek/sepolicy/basic/non_plat/property_contexts
 
#=============gesture wake==============
persist.vendor.hct.gesturewake u:object_r:system_prop:s0            //定義prop屬性
 
 
----------
ALPS_R0MP1/device / mediatek/sepolicy/basic/non_plat/system_app.te
 
#gesturewake
allow system_app system_prop:property_service set;
allow system_app hct_gesture_mode:file { write read getattr open };     //允許系統app讀寫該prop