<uses-permission android:name="android.permission.SYSTEM_OVERLAY_WINDOW" />
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />

<--! 說明一下，第一個權限是8.0之后懸浮窗窗口類型設置需要，第二個權限假如不加的話，我oppo手機跳轉懸浮窗設置時，找不到這個app -->

package com.zh.pullrefresh;
 
import android.content.Context;
import android.graphics.PixelFormat;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.FrameLayout;
import android.widget.ImageView;
 
import androidx.annotation.NonNull;
 
public class SmallWindowsView extends FrameLayout {
 
  private int mSlop;//觸發(fā)移動事件的最小距離
  private float downX;//手指放下去的x坐標
  private float downY;//手指放下去的Y坐標
  /**
   * 下面四個數(shù)據(jù)都為像素
   */
  private int screenWidth;//屏幕寬度
  private int screenHeight;//屏幕高度
  private int viewWidth;//小窗的寬度
  private int viewHeight;//小窗的高度
 
  private WindowManager wm;//窗口管理器，用來把view添加進窗口層
  private WindowManager.LayoutParams wmParams;
 
  public SmallWindowsView(@NonNull Context context) {
    super(context);
    init();
  }
 
  private void init() {
    ViewConfiguration vc = ViewConfiguration.get(getContext());
    mSlop = vc.getScaledTouchSlop();
    screenWidth = getContext().getResources().getDisplayMetrics().widthPixels;
    screenHeight = getContext().getResources().getDisplayMetrics().heightPixels;
    viewWidth = dp2px(getContext(), 130);
    viewHeight = dp2px(getContext(), 130);
 
    //可以根據(jù)你的實際情況在這個FrameLayout里添加界面控件之類的，
    // 我之前是用的實時音視頻，把相關業(yè)務代碼去掉了，直接放一個圖標
    // 實際上就是拿到一個View從WindowManager給addView進去
    ImageView imageView = new ImageView(getContext());
    imageView.setImageResource(R.mipmap.ic_launcher);
    LayoutParams params = new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
        ViewGroup.LayoutParams.MATCH_PARENT);
    addView(imageView, params);
  }
 
  //dp轉px
  public int dp2px(Context context, int dp) {
    return (int) (getDensity(context) * dp + 0.5);
  }
  public float getDensity(Context context) {
    return context.getResources().getDisplayMetrics().density;
  }
 
  public void show() {
    wm = (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);
    wmParams = new WindowManager.LayoutParams(
        viewWidth, viewHeight,
        WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY,//8.0以上需要用這個權限
        WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
            | WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL,
        PixelFormat.TRANSLUCENT);
    wmParams.gravity = Gravity.NO_GRAVITY;
    wmParams.x = screenWidth/2 - viewWidth/2;
    wmParams.y = screenHeight/2 - viewHeight/2;
    wm.addView(this, wmParams);
  }
 
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    //本來想在這邊直接設置寬高，但是有問題
//    setMeasuredDimension(QMUIDisplayHelper.dp2px(getContext(), 130), QMUIDisplayHelper.dp2px(getContext(), 130));
  }
  //攔截觸摸事件自己消費
  @Override
  public boolean onInterceptTouchEvent(MotionEvent ev) {
    return true;
  }
  private long downTime;
  private float lastMoveX;
  private float lastMoveY;
  //消費觸摸事件
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()) {
      case MotionEvent.ACTION_DOWN:
        downX = event.getRawX();
        downY = event.getRawY();
        lastMoveX = downX;
        lastMoveY = downY;
        downTime = System.currentTimeMillis();
        break;
      case MotionEvent.ACTION_MOVE:
        float moveX = event.getRawX();
        float moveY = event.getRawY();
        //就兩個坐標算他們距離要大于觸發(fā)移動事件的最小距離
        //這里也可以減去lastMoveX lastMoveY 但是移動會有卡頓感 因此這里使用的還是downX downY
        if (Math.pow(Math.abs(moveX - downX), 2) + Math.pow(Math.abs(moveY - downY), 2) > Math.pow(mSlop, 2)) {
          updateViewPosition(moveX - lastMoveX, moveY - lastMoveY);
          lastMoveX = moveX;
          lastMoveY = moveY;
        }
 
        break;
      case MotionEvent.ACTION_UP:
        float upX = event.getRawX();
        float upY = event.getRawY();
        long upTime = System.currentTimeMillis();
        long time = upTime - downTime;
        //點擊事件實現(xiàn) 點擊小窗口消失
        //這里加了時間判斷，是因為假如移動到原來的地方，也會觸發(fā)成點擊事件
        if (Math.pow(Math.abs(upX - downX), 2) + Math.pow(Math.abs(upY - downY), 2) < Math.pow(mSlop, 2) && time < 1000) {
          showRtcVideo();
        } else {
 
        }
        break;
    }
    return true;
  }
  private void showRtcVideo() {
    dismiss();
//    Toast.makeText(getContext(), "aaaaaaaaa", Toast.LENGTH_SHORT).show();
  }
 
  public void dismiss() {
    wm.removeView(this);
  }
 
  private void updateViewPosition(float moveX, float moveY) {
    wmParams.gravity = Gravity.NO_GRAVITY;
    //更新浮動窗口位置參數(shù)
    //    Log.d("moveX, moveY", moveX + "--" + moveY);
    wmParams.x = (int) (wmParams.x + moveX);
    wmParams.y = (int) (wmParams.y + moveY);
    //    刷新顯示
    wm.updateViewLayout(this, wmParams);
 
  }
}

@Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
 
    final SmallWindowsView smallWindowsView = new SmallWindowsView(getApplicationContext());
 
    Button btShowWindow = findViewById(R.id.bt_show_window);
    btShowWindow.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        if (Build.VERSION.SDK_INT >= 23) {
          if (!(Settings.canDrawOverlays(MainActivity.this))) {
            Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION);
            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            startActivity(intent);
            return;
          }
        } else {
          if (!EasyPermissions.hasPermissions(MainActivity.this, Manifest.permission.SYSTEM_ALERT_WINDOW)) {
            EasyPermissions.requestPermissions(MainActivity.this, "需要權限用以展示懸浮窗",
                2048, Manifest.permission.SYSTEM_ALERT_WINDOW);
            return;
          }
        }
        smallWindowsView.show();
      }
    });
  }