Android利用WindowManager实现悬浮窗

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

Settings.canDrawOverlays(this)

Intent intent = new Intent();
intent.setAction(Settings.ACTION_MANAGE_OVERLAY_PERMISSION);
intent.setData(Uri.parse("package:"+getPackageName()));
startActivity(intent);

mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);

public interface ViewManager
{
  /**
   * Assign the passed LayoutParams to the passed View and add the view to the window.
   * <p>Throws {@link android.view.WindowManager.BadTokenException} for certain programming
   * errors, such as adding a second view to a window without removing the first view.
   * <p>Throws {@link android.view.WindowManager.InvalidDisplayException} if the window is on a
   * secondary {@link Display} and the specified display can't be found
   * (see {@link android.app.Presentation}).
   * @param view The view to be added to this window.
   * @param params The LayoutParams to assign to view.
   */
  public void addView(View view, ViewGroup.LayoutParams params);
  public void updateViewLayout(View view, ViewGroup.LayoutParams params);
  public void removeView(View view);
}

wParamsTop = new WindowManager.LayoutParams();
wParamsTop.width = WindowManager.LayoutParams.WRAP_CONTENT;
wParamsTop.height = WindowManager.LayoutParams.WRAP_CONTENT;
//初始化坐标
wParamsTop.x = 0;
wParamsTop.y = 0;
//弹窗类型为系统Window
wParamsTop.type = WindowManager.LayoutParams.TYPE_PHONE;
//以左上角为基准
wParamsTop.gravity = Gravity.START | Gravity.TOP;
wParamsTop.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;
//如果不加,背景会是一片黑色。
wParamsTop.format = PixelFormat.RGBA_8888;