安卓开发之多进程弹窗

背景

有时在弹窗绘图时，需要弹窗在新的进程中，以保证在弹窗绘图的过程中不会占用过多的内存导致主进程被关。

代码实现子进程弹窗

首先我们需要一个透明的activity来作为弹窗展示，并且这个透明activity就存在于子进程中，这一切都可以在清单文件中实现：

使用到的主题定义在res/values/themes.xml中：


    @android:color/transparent 
    true 
    false 
    @android:style/Animation.Translucent

而后设置activity的位置和尺寸：

public class ProcessActivity extends Activity {
    ...

    @SuppressLint("ClickableViewAccessibility")
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_process);

        ...

        WindowManager.LayoutParams lp = getWindow().getAttributes();
        lp.width = 950;
        lp.height = 1700;
        lp.gravity = Gravity.START;
        getWindow().setAttributes(lp);

        ...
    }
    ...
}

使用到的布局文件activity_process.xml如下所示：

背景色为青色，两个button，一个负责展示toast，一个负责结束这个弹窗，我们在onCreate()中为它们添加点击事件监听：

Button button_process = findViewById(R.id.btn_process);
Button button_finish = findViewById(R.id.btn_finish);

button_process.setonClickListener(v -> {
    Toast.makeText(this, "onCreate: Button in sub process has been clicked.", Toast.LENGTH_SHORT).show();
});
button_finish.setonClickListener(v -> {
    ProcessActivity.this.finish();
});

接下来要实现的是事件透传：因为子进程窗口是一个弹窗，当没有触摸到弹窗中可点击组件时，应该由下面的activity去承接触摸事件，这部分逻辑的实现如下所示：

public class ProcessActivity extends Activity {
    private View mRootView;

    @SuppressLint("ClickableViewAccessibility")
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        mRootView = LayoutInflater.from(this).inflate(R.layout.activity_process, null);
        setContentView(mRootView);
        ...

        Button button_process = findViewById(R.id.btn_process);
        Button button_finish = findViewById(R.id.btn_finish);

        ...
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            View target = Utils.getViewTouchedByEvent(mRootView, event);
            if (target != null) {
                target.dispatchTouchEvent(event);
                return true;
            }
        }

        Intent intent = new Intent();
        intent.setAction("TouchEvent");
        intent.putExtra("event", event);
        sendBroadcast(intent);
        return super.dispatchTouchEvent(event);
    }
}

因为弹窗窗口和主窗口位于两个进程中，因此触摸事件的传递需要用IPC方式，这里采用的是广播。Utils.isDebugWindowValidTouched()负责判断当前点击事件是否点到了某个可点击的控件，方法代码如下：

public static View getViewTouchedByEvent(View view, MotionEvent event) {
    if (view == null || event == null) {
        return null;
    }

    if (!(view instanceof ViewGroup)) {
        return isDebugWindowValidTouched(view, event) ? view : null;
    }

    ViewGroup parent = ((ViewGroup) view);
    int childrenCount = parent.getChildCount();
    for (int i = 0; i < childrenCount; i++) {
        View target = getViewTouchedByEvent(parent.getChildAt(i), event);
        if (target != null) {
            return target;
        }
    }
    return null;
}

private static boolean isDebugWindowValidTouched(View view, MotionEvent event) {
    if (event == null || view == null) {
        return false;
    }

    if (view.getVisibility() != View.VISIBLE) {
        return false;
    }

    final float eventRawX = event.getRawX(); // 获取event在屏幕上的坐标
    final float eventRawY = event.getRawY();

    RectF rect = new RectF();
    int[] location = new int[2];
    view.getLocationOnScreen(location); // 获取view在屏幕上的坐标位置

    float x = location[0];
    float y = location[1];
    rect.left = x;
    rect.right = x + view.getWidth();
    rect.top = y;
    rect.bottom = y + view.getHeight();


    return rect.contains(eventRawX, eventRawY);
}

子进程弹窗窗口ProcessActivity的完整代码如下所示：

package com.example.testrxjava;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Process;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.CompoundButton;
import android.widget.Switch;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ToggleButton;

import androidx.annotation.Nullable;

import java.util.ArrayList;
import java.util.List;

public class ProcessActivity extends Activity {
    public static final String TAG = "ProcessActivity";
    private View mRootView;

    @SuppressLint("ClickableViewAccessibility")
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mRootView = LayoutInflater.from(this).inflate(R.layout.activity_process, null);
        setContentView(mRootView);
        Log.i(TAG, "onCreate: pid = " + Process.myPid());

        Button button_process = findViewById(R.id.btn_process);
        TextView button_finish = findViewById(R.id.btn_finish);

        button_process.setonClickListener(v -> {
            Toast.makeText(this, "onCreate: Button in sub process has been clicked.", Toast.LENGTH_SHORT).show();
        });
        button_finish.setonClickListener(v -> {
            ProcessActivity.this.finish();
        });

        ToggleButton toggleButton = findViewById(R.id.toggle);
        toggleButton.setonCheckedChangeListener((buttonView, isChecked) -> Toast.makeText(ProcessActivity.this,
                "Toggle button in sub process has been clicked, current state of checking is: " + isChecked,
                Toast.LENGTH_SHORT).show());

        Switch switch_button = findViewById(R.id.switch_sub_process);
        switch_button.setonCheckedChangeListener((buttonView, isChecked) -> Toast.makeText(ProcessActivity.this,
                "Switch in sub process has been clicked, current state of checking is: " + isChecked,
                Toast.LENGTH_SHORT).show());


        WindowManager.LayoutParams lp = getWindow().getAttributes();
        lp.width = 950;
        lp.height = 1700;
        lp.gravity = Gravity.START;
        getWindow().setAttributes(lp);
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            View target = Utils.getViewTouchedByEvent(mRootView, event);
            if (target != null) {
                target.dispatchTouchEvent(event);
                return true;
            }
        }

        Intent intent = new Intent();
        intent.setAction("TouchEvent");
        intent.putExtra("event", event);
        sendBroadcast(intent);
        return super.dispatchTouchEvent(event);
    }
}

主界面

回到主界面，首先需要接收一下TouchEvent这个广播：

public class MainActivity extends AppCompatActivity {
    ...
    private BroadcastReceiver mReceiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ...
        mReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                if (intent.getAction().equals("TouchEvent")) {
                    MotionEvent event = intent.getParcelableExtra("event");
                    try {
                        Class popupClass = Class.forName("android.widget.PopupWindow");
                        Field decorViewField = popupClass.getDeclaredField("mDecorView");
                        decorViewField.setAccessible(true);
                        Object decorView = decorViewField.get(window);

                        Method dispatchTouchEvent = decorView.getClass().getDeclaredMethod("dispatchTouchEvent", MotionEvent.class);
                        dispatchTouchEvent.invoke(decorView, event);

                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        };

        IntentFilter filter = new IntentFilter("TouchEvent");
        registerReceiver(mReceiver, filter);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(mReceiver);
    }
}

因为主界面中也有一个弹窗，因此当触摸事件从子进程传过来的时候，需要主进程的弹窗去处理，因此在onReceive()方法中通过反射执行了主进程弹窗的mDecorView的dispatchTouchEvent()方法去传递触摸事件，MainActivity的完整代码如下所示：

package com.example.testrxjava;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.graphics.RectF;
import android.os.Bundle;
import android.os.Parcelable;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ListView;
import android.widget.PopupWindow;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private Button mButton;
    private Button mHide;
    private BroadcastReceiver mReceiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TextView textView = findViewById(R.id.text_view);
        ListView listView = findViewById(R.id.list);
        ArrayList list = new ArrayList<>();
        for (int i = 0; i < 200; i++) {
            list.add("No." + i);
        }
        MyAdapter adapter = new MyAdapter(list, this);

        listView.setAdapter(adapter);

        adapter.notifyDataSetChanged();

        PopupWindow window = new PopupWindow(this);
        View windowView = LayoutInflater.from(this).inflate(R.layout.window_layout, null);

        mButton = windowView.findViewById(R.id.btn_window);
        mButton.setonClickListener(view -> {
            startActivity(new Intent(MainActivity.this, ProcessActivity.class));
        });

        mHide = windowView.findViewById(R.id.btn_hide);
        mHide.setonClickListener(v -> {
            mButton.setVisibility(mButton.getVisibility() == View.VISIBLE ? View.GONE : View.VISIBLE);
        });

        window.setTouchInterceptor((view, motionEvent) -> {
            if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
                View target = Utils.getViewTouchedByEvent(windowView, motionEvent);
                if (target != null) {
                    target.dispatchTouchEvent(motionEvent);
                    return true;
                }
            }
            MainActivity.this.dispatchTouchEvent(motionEvent);
            return false;
        });

        View rootView = getWindow().getDecorView();
        window.setOutsideTouchable(false);
        window.setonDismissListener(() -> textView.post(() -> {
            window.showAtLocation(rootView, Gravity.BOTTOM, 0, 0);
        }));
        window.setContentView(windowView);
        window.setWidth(ViewGroup.LayoutParams.MATCH_PARENT);
        window.setHeight(ViewGroup.LayoutParams.WRAP_CONTENT);

        findViewById(R.id.root).setonClickListener(v -> {
            Log.i("MainActivity", "Touch event gets to text view!");
        });

        textView.post(() -> {
            window.showAtLocation(rootView, Gravity.BOTTOM, 0, 0);
        });

        mReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                if (intent.getAction().equals("TouchEvent")) {
                    MotionEvent event = intent.getParcelableExtra("event");
                    try {
                        Class popupClass = Class.forName("android.widget.PopupWindow");
                        Field decorViewField = popupClass.getDeclaredField("mDecorView");
                        decorViewField.setAccessible(true);
                        Object decorView = decorViewField.get(window);

                        Method dispatchTouchEvent = decorView.getClass().getDeclaredMethod("dispatchTouchEvent", MotionEvent.class);
                        dispatchTouchEvent.invoke(decorView, event);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        };

        IntentFilter filter = new IntentFilter("TouchEvent");
        registerReceiver(mReceiver, filter);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(mReceiver);
    }
}

效果

背景紫色的是主进程的弹窗，青色的是子进程的弹窗。从录像中可以看到，当按下事件按到位于上层的组件时，上层的组件会响应；如果按到了上层弹窗的空白处，触摸事件则会向下传递。

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