Flutter PIP 插件 ---- 新增PipActivity，Android 11以下支持自动进入PIP Mode

接上文 Flutter PIP 插件 ---- Android

项目地址 PIP， pub.dev也已经同步发布 pip 0.0.3，你的加星和点赞，将是我继续改进最大的动力

开发文档 Add videos using picture-in-picture (PiP)介绍PIP功能从 Android 8.0 (API level 26) 引入，但是autoEnter功能从 Android 12 才开始支持，那么不支持的版本呢就需要通过监听 onUserLeaveHint 主动调用 enterPictureInPictureMode 才能进入 PIP Mode，在之前的版本中因为 FlutterActivity 没有转发 onUserLeaveHint，导致我们只能在 dart 中通过 flutter 的 didChangeAppLifecycleState 事件，在应用进入后台是主动调用的方式进入PIP Mode，但实际测下来，似乎无法区分通知栏下滑的通知，这导致即使应用在前台，当用户下滑通知栏的时候依然会自动进入PIP Mode, 这显然不是我们想要的，优化后的效果如下：

修改PIP插件

• 新增PipActivity

  package org.opentraa.pip;import android.app.PictureInPictureUiState;
  import android.content.res.Configuration;
  import android.os.Build;
  import androidx.annotation.NonNull;
  import androidx.annotation.RequiresApi;
  import io.flutter.embedding.android.FlutterActivity;@RequiresApi(Build.VERSION_CODES.O)
  public class PipActivity extends FlutterActivity {public interface PipActivityListener {void onPictureInPictureModeChanged(boolean isInPictureInPictureMode,Configuration newConfig);void onPictureInPictureUiStateChanged(PictureInPictureUiState state);boolean onPictureInPictureRequested();void onUserLeaveHint();}private PipActivityListener mListener;public void setPipActivityListener(PipActivityListener listener) {mListener = listener;}// only available in API level 26 and above@RequiresApi(26)@Overridepublic void onPictureInPictureModeChanged(boolean isInPictureInPictureMode,Configuration newConfig) {super.onPictureInPictureModeChanged(isInPictureInPictureMode, newConfig);if (mListener != null) {mListener.onPictureInPictureModeChanged(isInPictureInPictureMode,newConfig);}}// only available in API level 30 and above@RequiresApi(30)@Overridepublic boolean onPictureInPictureRequested() {if (mListener != null) {return mListener.onPictureInPictureRequested();}return super.onPictureInPictureRequested();}// only available in API level 31 and above@RequiresApi(31)@Overridepublic voidonPictureInPictureUiStateChanged(@NonNull PictureInPictureUiState state) {super.onPictureInPictureUiStateChanged(state);if (mListener != null) {mListener.onPictureInPictureUiStateChanged(state);}}@Overridepublic void onUserLeaveHint() {super.onUserLeaveHint();if (mListener != null) {mListener.onUserLeaveHint();}}
  }
  

  主要思路就是如果PIP 插件的用户想要在 Android 12 以下支持应用进入后台自动进入 PIP Mode 的话，可以将自己 MainActivity 的父类修改为 PipActivity ，这样在 PIP 插件被注册时，可以通过判断传入的 Activity 是否是 PipActivity 来决定是否启用相关的功能。

• 绑定 Activity 到 PipController
  PipPlugin 在 onAttachedToActivity 和 onReattachedToActivityForConfigChanges 的时候去初始化 PipController

  private void initPipController(@NonNull ActivityPluginBinding binding) {if (pipController == null) {pipController = new PipController(binding.getActivity(), new PipController.PipStateChangedListener() {@Overridepublic void onPipStateChangedListener(PipController.PipState state) {// put state into a json objectchannel.invokeMethod("stateChanged",new HashMap<String, Object>() {{ put("state", state.getValue()); }});}});} else {pipController.attachToActivity(binding.getActivity());}
  }@Override
  public void onAttachedToActivity(@NonNull ActivityPluginBinding binding) {initPipController(binding);
  }@Override
  public void onReattachedToActivityForConfigChanges(@NonNull ActivityPluginBinding binding) {initPipController(binding);
  }
  

• 在 PipController 构造函数和 attachToActivity 方法中去综合当前的系统版本和绑定的 Activity 进行检查是否支持 autoEnter

  public PipController(@NonNull Activity activity,@Nullable PipStateChangedListener listener) {setActivity(activity);//  ... Other code ...
  }private boolean checkAutoEnterSupport() {// Android 12 and above support to set auto enter enabled directlyif (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {return true;}// For android 11 and below, we need to check if the activity is kind of// PipActivity since we can enter pip mode when the onUserLeaveHint is// called to enter pip mode as a workaroundActivity activity = mActivity.get();return activity instanceof PipActivity;
  }private void setActivity(Activity activity) {mActivity = new WeakReference<>(activity);if (activity instanceof PipActivity) {((PipActivity)activity).setPipActivityListener(this);}mIsSupported = checkPipSupport();mIsAutoEnterSupported = checkAutoEnterSupport();
  }public void attachToActivity(@NonNull Activity activity) {setActivity(activity);
  }
  

修改Example项目中的MainActivity

• 孤伶伶的MainActivity

  package org.opentraa.pip_example;import io.flutter.embedding.android.FlutterActivity;
  import org.opentraa.pip.PipActivity;public class MainActivity extends PipActivity {
  }
  

如上，至此我们已经支持了全部版本的 PIP Mode autoEnter 功能。