android WindowManagerService addFakeWindow 研究

首先，该方法起源于：

FakeWindow com.android.server.wm.WindowManagerService.addFakeWindow(Looper looper, Factory inputEventReceiverFactory, String name, int windowType, int layoutParamsFlags, int layoutParamsPrivateFlags, boolean canReceiveKeys, boolean hasFocus, boolean touchFullscreen)
           

定义位置：

<span style="font-family: Arial, Helvetica, sans-serif;">FakeWindow android.view.WindowManagerPolicy.WindowManagerFuncs.addFakeWindow(Looper looper, Factory inputEventReceiverFactory, String name, int windowType, int layoutParamsFlags, int layoutParamsPrivateFlags, boolean canReceiveKeys, boolean hasFocus, boolean touchFullscreen)</span>
           

实现：

synchronized (mWindowMap) {
            FakeWindowImpl fw = new FakeWindowImpl(this, looper, inputEventReceiverFactory,
                    name, windowType,
                    layoutParamsFlags, layoutParamsPrivateFlags, canReceiveKeys,
                    hasFocus, touchFullscreen);
            int i=0;
            while (i<mFakeWindows.size()) {
                if (mFakeWindows.get(i).mWindowLayer <= fw.mWindowLayer) {
                    break;
                }
            }
            mFakeWindows.add(i, fw);
            mInputMonitor.updateInputWindowsLw(true);
           

好，接下来该看 FakeWindowImpl ，位置：

com.android.server.wm.FakeWindowImpl
           

到这里我先讲讲我为什么要研究这个方法，因为我发现这个方法有一个功能是可以添加一个虚拟窗口，监听全屏触摸事件，我想实现的就是监听全局触摸事件，所以可以以此方法为切入点！

我们来看看他的构造函数：

public FakeWindowImpl(WindowManagerService service,
            Looper looper, InputEventReceiver.Factory inputEventReceiverFactory,
            String name, int windowType, int layoutParamsFlags, int layoutParamsPrivateFlags,
            boolean canReceiveKeys, boolean hasFocus, boolean touchFullscreen) 
           

InputEventReceiver.Factory inputEventReceiverFactory, 这个参数才是我的重点，因为他才是接收 InputEvent 的实体，那好我们看看构造函数如何使用此参数咯，

重点来啦，

InputChannel[] channels = InputChannel.openInputChannelPair(name);
        mServerChannel = channels[0];
        mClientChannel = channels[1];
        mService.mInputManager.registerInputChannel(mServerChannel, null);

        mInputEventReceiver = inputEventReceiverFactory.createInputEventReceiver(
                mClientChannel, looper);
           

重点在于 InputChannel ，看来我得先搞懂他是什么咯，

关于 InputChannel 可以移步到这里： Android入门之在客户进程中注册InputChannel  Android入门之创建InputChannel

再看 InputEventReceiver 的创建，

 mInputEventReceiver = inputEventReceiverFactory.createInputEventReceiver(mClientChannel, looper);

这个对象在这里：

com.android.internal.policy.impl.PhoneWindowManager.mHideNavInputEventReceiverFactory
           

final InputEventReceiver.Factory mHideNavInputEventReceiverFactory =
            new InputEventReceiver.Factory() {
        @Override
        public InputEventReceiver createInputEventReceiver(
                InputChannel inputChannel, Looper looper) {
            return new HideNavInputEventReceiver(inputChannel, looper);
        }
    };
           

InputEventReceiver 的实现是：

/**
     * Input handler used while nav bar is hidden.  Captures any touch on the screen,
     * to determine when the nav bar should be shown and prevent applications from
     * receiving those touches.
     */
    final class HideNavInputEventReceiver extends InputEventReceiver {
        public HideNavInputEventReceiver(InputChannel inputChannel, Looper looper) {
            super(inputChannel, looper);
        }
           

他这个对象是干嘛用的呢，我们知道从 Android 4.2 开始，开发者可以将导航栏 和 状态栏隐藏来使屏幕显示更多内容，这个对象就是用来监听导航栏隐藏掉的时候，如何呼唤出来，要不然就得重启手机了

，不过就此吐槽几点，Android 框架过于复杂， 以至于一个导航栏处理起来都是很麻烦，废话不多说，

来看 InputEventReceiver 如何使用 InputChannel：

/**
     * Creates an input event receiver bound to the specified input channel.
     *
     * @param inputChannel The input channel.
     * @param looper The looper to use when invoking callbacks.
     */
    public InputEventReceiver(InputChannel inputChannel, Looper looper) {
        if (inputChannel == null) {
            throw new IllegalArgumentException("inputChannel must not be null");
        }
        if (looper == null) {
            throw new IllegalArgumentException("looper must not be null");
        }

        mInputChannel = inputChannel;
        mMessageQueue = looper.getQueue();
        mReceiverPtr = nativeInit(new WeakReference<InputEventReceiver>(this),
                inputChannel, mMessageQueue);

        mCloseGuard.open("dispose");
    }
           

我们看到他的工作赚到了 native 层，nativeInit，这我就不深究了，我已经知道我该怎么做了！

重点就是先使用：

InputChannel[] channels = InputChannel.openInputChannelPair(name); 

创建一对输入接收器，然后向 InputManagerService 注册 channel ：

void com.android.server.input.InputManagerService.registerInputChannel(InputChannel inputChannel, InputWindowHandle inputWindowHandle)
           

Android输入输出机制之来龙去脉之前生后世

然后我开始测试代码。。。