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

java 复制代码

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)
 @Override
 public 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)
 @Override
 public boolean onPictureInPictureRequested() {
   if (mListener != null) {
     return mListener.onPictureInPictureRequested();
   }
   return super.onPictureInPictureRequested();
 }

 // only available in API level 31 and above
 @RequiresApi(31)
 @Override
 public void
 onPictureInPictureUiStateChanged(@NonNull PictureInPictureUiState state) {
   super.onPictureInPictureUiStateChanged(state);
   if (mListener != null) {
     mListener.onPictureInPictureUiStateChanged(state);
   }
 }

 @Override
 public 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

java 复制代码

private void initPipController(@NonNull ActivityPluginBinding binding) {
  if (pipController == null) {
    pipController = new PipController(
        binding.getActivity(), new PipController.PipStateChangedListener() {
          @Override
          public void onPipStateChangedListener(
              PipController.PipState state) {
            // put state into a json object
            channel.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

java 复制代码

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 directly
  if (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 workaround
  Activity 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

java 复制代码

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。