Android系統全域觸摸事件監聽

Android觸摸全域監聽指的是呼叫監聽后在任何界面都能獲取到觸摸事件，

要實作這個功能必須要修改原始碼添加新的介面，因為系統默認是不暴露這個方法的，

監聽系統全域觸摸事件的類和相關代碼：

frameworks\base\services\core\java\com\android\server\wm\WindowManagerService.java
    @Override
    public void registerPointerEventListener(PointerEventListener listener, int displayId) {
        Slog.i(TAG, "registerPointerEventListener PointerEventListener = " + listener);
        synchronized (mGlobalLock) {
            final DisplayContent displayContent = mRoot.getDisplayContent(displayId);
            if (displayContent != null) {
                displayContent.registerPointerEventListener(listener);
            }
        }
    }

    @Override
    public void unregisterPointerEventListener(PointerEventListener listener, int displayId) {
        synchronized (mGlobalLock) {
            final DisplayContent displayContent = mRoot.getDisplayContent(displayId);
            if (displayContent != null) {
                displayContent.unregisterPointerEventListener(listener);
            }
        }
    }

第一個引數：是中PointerEventListener介面，

里面有MotionEvent物件含有點擊事件，比如DOWN、UP、MOVING等其他資訊，

    package android.view;
    public interface WindowManagerPolicyConstants {
        interface PointerEventListener {
            void onPointerEvent(MotionEvent motionEvent);
        }
    }

第二個引數，螢屏id，正常用0 ，表示主螢屏id，有些設備有投屏或者第二屏才需要關注這個，

下面介紹如何注冊這個服務

1、系結這個系統服務，這個方法行不通

因為這個服務的aidl介面IWindowManager，并沒有暴露這個方法
registerPointerEventListener方法定義在另一個內部介面 WindowManagerFuncs 中

public interface WindowManagerPolicy extends WindowManagerPolicyConstants {
    public interface WindowManagerFuncs {
            /** Register a system listener for touch events */
            void registerPointerEventListener(PointerEventListener listener, int displayId);

            /** Unregister a system listener for touch events */
            void unregisterPointerEventListener(PointerEventListener listener, int displayId);
    }
}

2、獲取WindowManagerFuncs物件,該物件獲取的方式在原始碼中有多種

參考：

frameworks\base\services\core\java\com\android\server\policy\PhoneWindowManager.java
public PhoneWindowManager extends AbsPhoneWindowManager implements WindowManagerPolicy, IHwPhoneWindowManagerInner{
    public WindowManagerFuncs getWindowManagerFuncs(){
        return mWindowManagerFuncs; 
    }
}

WindowManagerFuncs在原始碼中是可以直接new的，使用如下：

PhoneWindowManager phoneWindowManager = new PhoneWindowManager();
WindowManagerFuncs windowManagerFuncs = phoneWindowManager.getWindowManagerFuncs();
windowManagerFuncsEx.registerPointerEventListener(listener, Display.DEFAULT_DISPLAY);

3、在華為Emui原始碼添加aidl回呼

WindowManagerEx有通道直接發送資料到WindowManagerService并可以進行資料監聽

（1）添加aidl介面

vendor\huawei\Emui\frameworks\hwCommInterface\base\core\java\com\huawei\android\app\IHwPointEventCallback.aidl
package com.huawei.android.app;
    import android.view.MotionEvent;
    oneway interface IHwPointEventCallback {
        void onPointerEvent(in MotionEvent motionEvent);
    }

（2）WindowManagerEx的修改

vendor\huawei\Emui\frameworks\hwext\hwext\framework\src\com\huawei\android\app\WindowManagerEx.java
    private final int TRANSACTION_SET_POINTER_EVENT_LISTENER = android.os.IBinder.FIRST_CALL_TRANSACTION + 2100;
    //給WindowManagerService傳遞監聽物件
    public static void setPointerEventListener(IHwPointEventCallback listener) {
        Log.i(LOG_TAG, "setPointerEventListener listener = " + listener);
        IBinder windowManagerBinder = WindowManagerGlobal.getWindowManagerService().asBinder();
        if (windowManagerBinder != null) {
            Parcel data = Parcel.obtain();
            Parcel reply = Parcel.obtain();
            try {
                data.writeInterfaceToken("android.view.IWindowManager");
                //傳遞aidl監聽物件
                data.writeStrongBinder(listener != null ? listener.asBinder() : null);
               //發送
                windowManagerBinder.transact(TRANSACTION_SET_POINTER_EVENT_LISTENER, data, reply, 0);
            } catch (RemoteException e){
                Log.e(LOG_TAG, "setPointerEventListener exception is " + e.getMessage());
            } finally {
                data.recycle();
                reply.recycle();
            }
        } else {
            Log.w(LOG_TAG, "setPointerEventListener windowManagerBinder is null");
        }
    }

（3）在WindowManagerService中接收資料并做實際監聽

基于盡量不修改原始碼的理念，Emui中有WindowManagerService的子類HwWindowManagerService，在子類中修改代碼即可，

vendor\huawei\Emui\frameworks\base\services\java\huawei\com\android\server\wm\HwWindowManagerService.java
    HwWindowManagerService extends WindowManagerService
    private final int TRANSACTION_SET_POINTER_EVENT_LISTENER = android.os.IBinder.FIRST_CALL_TRANSACTION + 2100;
    private IHwPointEventCallback mIHwPointEventCallback = null;
    
    //接收WindowManagerEx傳遞過來的資料
    public boolean onTransact(int code, Parcel data, Parcel reply, int flags)
        throws RemoteException {
            switch (code) {
                case TRANSACTION_SET_POINTER_EVENT_LISTENER:
                    data.enforceInterface("android.view.IWindowManager");
                    IHwPointEventCallback observer = IHwPointEventCallback.Stub.asInterface(data.readStrongBinder());
                    setPointerEventListener(observer);
                    reply.writeNoException();
                    return true;

        }
    }
    
    //在Service中創建唯一的監聽物件
    private PointerEventListener mPointerEventListener = new PointerEventListener() {
        @Override
        public void onPointerEvent(MotionEvent motionEvent) {
            if(mIHwPointEventCallback != null) {
                try {
                    mIHwPointEventCallback.onPointerEvent(motionEvent);
                } catch (RemoteException e) {
                    Slog.e(TAG, "mIHwPointEventCallback error = " + e.getMessage());
                }
            }
        }
    };

    //添加設定觸摸監聽方法
    private void setPointerEventListener(IHwPointEventCallback listener) {
        Slog.i(TAG, "setPointerEventListener PointerEventListener = " + listener);
        int uid = Binder.getCallingUid();
        if(uid != Process.SYSTEM_UID){
            Slog.e(TAG, "setPointerEventListener uid must be "+ Process.SYSTEM_UID +",but now uid = " + uid);
            return;
        }
        mIHwPointEventCallback = listener;
        if(listener != null) {
            //實際調到父類的注冊觸摸事件的方法
            registerPointerEventListener(mPointerEventListener, Display.DEFAULT_DISPLAY);
        }
        else {
            //實際調到父類的反注冊觸摸事件的方法
            unregisterPointerEventListener(mPointerEventListener, Display.DEFAULT_DISPLAY);
        }
    }

方法3可以實作在普通app中監聽到系統的全域觸摸事件，

因為app可以依賴Emui的emui_addons.jar，
呼叫到里面的部分類，比如WindowManagerEx，就可以監聽全域觸摸事件，

其他系統環境可以根據實際情況參考上面的實作，

共勉：看得更多才知道還有更多還沒看過，