Android系统移植与调试之------->增加一个双击物理按键打开和关闭闪光灯并将闪光灯状态同步到下拉菜单中

最近有一个客户有这样的需求：

1、在【设置】--->【无障碍】中添加一个开关按钮。

如果打开开关的话，双击某个物理按键的时候，打开闪光灯，再双击该物理按键的时候，关闭闪光灯。

如果关闭开关的话，双击该物理按键的时候，不做任何处理。

2、打开关闭闪光灯的状态，在下拉菜单中也要同步。

如下图所示的效果：

当打开上面添加的开关后，如果双击POC键（POC键是我们公司自定义的一个物理按键）的时候，就打开闪光灯，并将下拉菜单中的闪光灯图标点亮，如下图所示

如果再次双击POC键（POC键是我们公司自定义的一个物理按键）的时候，就关闭闪光灯，并将下拉菜单中的闪光灯图标熄灭，如下图所示

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下面来具体说说怎么实现该功能：

第一步：添加开关按钮布局

在packages/apps/Settings/res/xml/accessibility_settings.xml 文件中添加一个开关，开关位置放在【按电源按钮结束通话】和【自动选择屏幕】中间，代码如下

        <SwitchPreference
                android:key="toggle_power_button_ends_call_preference"
                android:title="@string/accessibility_power_button_ends_call_prerefence_title"
                android:persistent="false"/>
        <!-- added by ouyang start [2015-11-3] -->
        <SwitchPreference
                android:key="toggle_camera_button__start_flashlight_preference"
                android:title="@string/accessibility_camera_button_start_flashlight_preference_title"
                android:summary="@string/accessibility_camera_button_start_flashlight_preference_subtitle"
                android:persistent="false"/>
 		<!-- added by ouyang end   [2015-11-3] -->

        <SwitchPreference
                android:key="toggle_lock_screen_rotation_preference"
                android:title="@string/accelerometer_title"
                android:persistent="false"/>

在packages/apps/Settings/res/values-zh-rCN/strings.xml文件中添加相应的字符串

    <!-- added by ouyang start [2015-11-3] -->
    <string name="accessibility_camera_button_start_flashlight_preference_title">"双击[相机键]打开闪光灯"</string>
    <string name="accessibility_camera_button_start_flashlight_preference_title_E580">"双击[POC键]打开闪光灯"</string>
    <string name="accessibility_camera_button_start_flashlight_preference_subtitle">"开启此功能后，摄像机暂时无法使用"</string>
    <!-- added by ouyang end [2015-11-3] -->

packages/apps/Settings/res/values/strings.xml文件中添加相应的字符串

    <!-- added by ouyang start [2015-11-3] -->
    <string name="accessibility_camera_button_start_flashlight_preference_title">"Camera button twice,open flash light"</string>
    <string name="accessibility_camera_button_start_flashlight_preference_title_E580">"POC button twice,open flash light"</string>
    <string name="accessibility_camera_button_start_flashlight_preference_subtitle">"After open this feature, the camera can not be used"</string>
    <!-- added by ouyang end [2015-11-3] -->

第二步：对该开关按钮做逻辑处理，在packages/apps/Settings/src/com/android/settings/accessibility/AccessibilitySettings.java文件中

先定义一个字符串常量，该常量为添加的开关的key，定义该按钮开关常量和SharedPreences常量，用来保存该按钮打开关闭状态值

    // added by ouyang start [2015-11-3]
    private static final String TOGGLE_CAMER_BUTTON_START_FLASHLIGHT_PREFERENCE =
            "toggle_camera_button__start_flashlight_preference";
    // added by ouyang end [2015-11-3] 

    // added by ouyang start [2015-11-3]
	private SwitchPreference mToggleCameraButtonStartFlashlightPreference;
	private SharedPreferences preferences;
	private SharedPreferences.Editor editor;
	// added by ouyang end   [2015-11-3] 

通过该字符串找到定义的开关，并做些处理，如从保存好的Perference中读取开关打开关闭状态并显示，在initializeAllPreferences方法中，添加如下代码

// added by ouyang start [2015-11-3]
        mToggleCameraButtonStartFlashlightPreference =
                (SwitchPreference) findPreference(TOGGLE_CAMER_BUTTON_START_FLASHLIGHT_PREFERENCE);
        if (android.os.SystemProperties.isHanbangVersion()) {
        	Log.e(TAG, "is HanbangVersion()");
            mToggleCameraButtonStartFlashlightPreference.setEnabled(false);
        }else{
        	Log.e(TAG, "is not HanbangVersion()");
            mToggleCameraButtonStartFlashlightPreference.setEnabled(true);
        }
        Log.e(TAG, "mToggleCameraButtonStartFlashlightPreference.isEbable="+  mToggleCameraButtonStartFlashlightPreference.isEnabled());
        if (android.os.SystemProperties.isDT800Project()) {
        	mToggleCameraButtonStartFlashlightPreference.setTitle(R.string.accessibility_camera_button_start_flashlight_preference_title);
		}else if (android.os.SystemProperties.isE580Project()) {
			mToggleCameraButtonStartFlashlightPreference.setTitle(R.string.accessibility_camera_button_start_flashlight_preference_title_E580);
		}
        preferences= getActivity().getApplicationContext().getSharedPreferences("FlashLight",
                            Context.MODE_MULTI_PROCESS
                           +Context.MODE_WORLD_READABLE
                           +Context.MODE_WORLD_WRITEABLE);
        editor=preferences.edit();
        boolean flashChecked=preferences.getBoolean("flashChecked", false);
        mToggleCameraButtonStartFlashlightPreference.setChecked(flashChecked);
        Log.e(TAG, "flashChecked="+flashChecked);
        // added by ouyang end [2015-11-3] 

这段代码主要是对该开关进行初始化，并对不同的项目进行判断，DT800项目和E580项目加载不同的字符串来描述开关。这些方法可以在/frameworks/base/core/java/android/os/SystemProperties.java文件中自己添加，代码如下：

       public static boolean isDT800Project() {
		return SystemProperties.get("ro.custom.build.version").contains("DT800");
       }   

        public static boolean isE580Project() {
		return SystemProperties.get("ro.custom.build.version").contains("E580");
        }

        public static boolean isHanbangVersion(){
		return SystemProperties.get("ro.product.model").contains("Hanbang");
        }

在packages/apps/Settings/src/com/android/settings/accessibility/AccessibilitySettings.java文件中的onPreferenceTreeClick方法中，要添加对该开关的点击事件处理。

代码如下，添加几行代码：

else if (mTogglePowerButtonEndsCallPreference == preference) {
            handleTogglePowerButtonEndsCallPreferenceClick();
            return true;
        }
        // added by ouyang start [2015-11-3]
        else if (mToggleCameraButtonStartFlashlightPreference == preference) {
            handleToggleCameraButtonStartFlashlightPreferenceClick();
            return true;
        }
        // added by ouyang end [2015-11-3]
        else if (mToggleLockScreenRotationPreference == preference) {
            handleLockScreenRotationPreferenceClick();
            return true;
        } 

其中handleToggleCameraButtonStartFlashlightPreferenceClick()方法自己自定义的，代码如下：

   // added by ouyang start [2015-11-3]
    private void handleToggleCameraButtonStartFlashlightPreferenceClick(){
    	if (mToggleCameraButtonStartFlashlightPreference.isChecked()) {
            editor.putBoolean("flashChecked", true);
            editor.commit();
	}else{
	   editor.putBoolean("flashChecked", false);
	   editor.commit();
	}
    }
    // added by ouyang end [2015-11-3] 

该方法主要功能是保存该开关是打开状态还是关闭状态，这个状态值可以让其他的进程读取。

第三步：定义一个BroadcastReceiver，并动态注册该广播。代码文件在frameworks/base/packages/SystemUI/src/com/android/systemui/qs/tiles/FlashlightTile.java

，在该文件中添加一个BroadcastReceiver

 //added by ouyang
    private final BroadcastReceiver mFlashBroadcastReceiver =new BroadcastReceiver(){
    	boolean isDoublePress = false;
    	@Override
    	public void onReceive(Context context, Intent intent) {
    		String action = intent.getAction();
    		Log.d(TAG, "action= " + action);
    		Log.d(TAG, "isDoublePress= " + isDoublePress);
    		Log.d(TAG, "now time = " + new SimpleDateFormat("yyyy-MM-dd hh:mm:ss.SSS").format(new Date()));
    		if ((action == "com.runbo.camera.key.up") || (action == "com.runbo.poc.key.up")) {
    			Handler checkHandler = new Handler();
    			if (!isDoublePress) {
    				isDoublePress = true;
    				Log.i(TAG, "<----===============Single Press the Camera Key---->");
    				Runnable CheckDoubleRunnable = new Runnable() {
    					@Override
    					public void run() {
    						isDoublePress = false;
    					}
    				};
    				checkHandler.postDelayed(CheckDoubleRunnable, 500);
    			} else {
    				isDoublePress = false;
    				Log.i(TAG, "<----============Double Press the Camera Key ---->");
    				boolean handlerReceiver = false;
    				boolean flashChecked=false;
    				try {
    					Context myContext= context.createPackageContext("com.android.settings",
    							Context.CONTEXT_IGNORE_SECURITY);
    					SharedPreferences sharedPreferences = myContext.getSharedPreferences("FlashLight",
    							Context.MODE_WORLD_READABLE | Context.MODE_MULTI_PROCESS);
        				flashChecked = sharedPreferences.getBoolean("flashChecked", false);
					} catch (Exception e) {
						Log.d(TAG, Log.getStackTraceString(e));
					}
    				if (action == "com.runbo.camera.key.up") {
    					if (android.os.SystemProperties.isDT800Project()
    							&& !android.os.SystemProperties.isHanbangVersion()) {
    						handlerReceiver = true;
    					}
    				} else if (action == "com.runbo.poc.key.up") {
    					if (android.os.SystemProperties.isE580Project()) {
    						handlerReceiver = true;
    					}
    				}
    				Log.d(TAG, "handlerReceiver= " + handlerReceiver);
    				Log.d(TAG, "flashChecked= " + flashChecked);
    				if (handlerReceiver && flashChecked) {
    					Log.i(TAG, "============mState.value="+mState.value);
    					if (!mState.value) {
    						boolean newState = !mState.value;
    						mFlashlightController.setFlashlight(newState);
    					    refreshState(newState ? UserBoolean.USER_TRUE : UserBoolean.USER_FALSE);
    						Log.i(TAG, "============setFlashlight(true);============");
						}else{
							boolean newState = !mState.value;
    						mFlashlightController.setFlashlight(newState);
    					    refreshState(newState ? UserBoolean.USER_TRUE : UserBoolean.USER_FALSE);
							Log.i(TAG, "============setFlashlight(false);============");
						}
    				}
    			}
    		}
    	}
    };

在FlashlightTile的构造方法中进行注册，代码如下：

  public FlashlightTile(Host host) {
        super(host);
        mFlashlightController = host.getFlashlightController();
        mFlashlightController.addListener(this);

        //added by ouyang start
        IntentFilter pocFilter = new IntentFilter();
        pocFilter.addAction("com.runbo.poc.key.up");
        pocFilter.addAction("com.runbo.camera.key.up");
        this.mContext.registerReceiver(mFlashBroadcastReceiver, pocFilter);
        Log.d(TAG, "registerReceiver(mFlashBroadcastReceiver, pocFilter)");
        //added by ouyang end
    }

该BroadcastReceiver接收通过按POC键后释放而发送的广播“com.runbo.poc.key.up”和通过按Camera键后释放而发送的广播“com.runbo.camera.key.up”，这两个广播是自定义的广播。然后判断是单击还是双击，当双击后再通过读取SharedPreferences的值来判断定义的开关是否是打开的，如果开关是打开的再判断闪光灯是打开还是关闭，如果是打开的，双击后就关闭闪光灯。如果是关闭的，就打开闪光灯。并更新下拉菜单的图标和相应的状态。如果开关是关闭的，不进行打开关闭闪光灯的操作。

这两个广播是在frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java文件中的interceptKeyBeforeQueueing(KeyEvent event, int policyFlags)方法中额外添加的代码，发送广播出来的。

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  作者：欧阳鹏  欢迎转载，与人分享是进步的源泉！

  转载请保留原文地址：http://blog.csdn.net/ouyang_peng

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