Android实现画中画功能（图片）

简介： Android 8.0（API 级别 26）允许以画中画 (PIP) 模式启动 Activity。画中画是一种特殊类型的多窗口模式，最常用于视频播放。使用该模式，用户可以通过固定到屏幕一角的小窗口观看视频，同时在应用之间进行导航或浏览主屏幕上的内容。

画中画窗口会显示在屏幕的最上层，位于系统选择的一角。您可以将画中画窗口拖动到其他位置（会自动贴边）。当您点按该窗口时，会看到两个特殊的控件：全屏切换开关（位于窗口的中心）和关闭按钮（右上角的“X”）。

效果图：

1、声明对画中画的支持：

默认情况下，系统不会自动为应用提供画中画支持。如果您想在应用中支持画中画，可以通过将 android:supportsPictureInPicture 设置为 true，在清单中注册视频 Activity。此外，指定您的 Activity 处理布局配置更改，这样一来，在画中画模式转换期间发生布局更改时，您的 Activity 就不会重新启动。

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.csu.pictureinpicture">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme"
        tools:ignore="GoogleAppIndexingWarning">
        <activity
            android:name=".TestPipActivity"
            android:configChanges="screenSize|smallestScreenSize|screenLayout|orientation"
            android:resizeableActivity="true"
            android:supportsPictureInPicture="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>

2、将 Activity 切换到画中画模式：

如要进入画中画模式，Activity 必须调用enterPictureInPictureMode() 。

ivPip.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        int ivWidth = imageViewPip.getWidth();
        int ivHeight = imageViewPip.getHeight();
        if (ivWidth != 0 && ivHeight != 0) {
            // 设置宽高比例值，第一个参数表示分子，第二个参数表示分母
            // 10/5=2，表示画中画窗口的宽度是高度的两倍
            Rational rational = new Rational(ivWidth, ivHeight);
            mBuilder.setAspectRatio(rational).build();
        }
        enterPictureInPictureMode(mBuilder.build());
    }
});

3、处理画中画模式下的界面元素

当 Activity 进入或退出画中画模式时，系统会调用 Activity.onPictureInPictureModeChanged() 或 Fragment.onPictureInPictureModeChanged() 。在画中画模式下，Activity 会在一个小窗口中显示。在画中画模式下，用户无法与界面元素互动，并且可能很难看清小界面元素的详细信息。在 Activity 进入画中画模式之前移除其他界面元素，并在 Activity 再次变为全屏时恢复这些元素：

@Override
public void onPictureInPictureModeChanged(boolean isInPictureInPictureMode, Configuration newConfig) {
    super.onPictureInPictureModeChanged(isInPictureInPictureMode, newConfig);
    Log.i(TAG, "onPictureInPictureModeChanged: " + isInPictureInPictureMode);
    if (isInPictureInPictureMode) {
        // hide some ui
        tvTitle.setVisibility(View.INVISIBLE);
        tvDetail.setVisibility(View.INVISIBLE);
        tvInfo.setVisibility(View.INVISIBLE);
        ivPip.setVisibility(View.INVISIBLE);
        imageView.setVisibility(View.INVISIBLE);
        imageViewPip.setVisibility(View.VISIBLE);
    } else {
        // Restore the full-screen UI
        tvTitle.setVisibility(View.VISIBLE);
        tvDetail.setVisibility(View.VISIBLE);
        tvInfo.setVisibility(View.VISIBLE);
        ivPip.setVisibility(View.VISIBLE);
        imageView.setVisibility(View.VISIBLE);
        imageViewPip.setVisibility(View.INVISIBLE);
    }
}

完整代码：

页面布局文件：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.csu.pictureinpicture.TestPipActivity">

    <ImageView
        android:id="@+id/image_view_pip"
        android:layout_width="300dp"
        android:layout_height="200dp"
        android:src="@mipmap/image"
        android:scaleType="centerCrop"
        android:visibility="invisible"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"/>

    <TextView
        android:id="@+id/tv_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="图片画中画演示"
        android:textSize="24sp"
        android:textColor="#353535"
        android:layout_marginTop="50dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>

    <ImageView
        android:id="@+id/image_view"
        android:layout_width="0dp"
        android:layout_height="300dp"
        android:src="@mipmap/image"
        android:scaleType="centerCrop"
        android:layout_marginTop="60dp"
        app:layout_constraintTop_toBottomOf="@id/tv_title"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"/>

    <ImageView
        android:id="@+id/iv_pip"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@mipmap/pip"
        android:layout_marginEnd="10dp"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="@id/image_view"
        app:layout_constraintBottom_toBottomOf="@id/image_view"/>

    <TextView
        android:id="@+id/tv_detail"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="detail"
        android:textSize="14sp"
        android:lineSpacingMultiplier="1.5"
        android:layout_marginStart="10dp"
        android:layout_marginTop="10dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toBottomOf="@id/image_view"/>

    <TextView
        android:id="@+id/tv_info"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="SDK Version"
        android:layout_marginBottom="10dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

Activity文件：

import androidx.appcompat.app.AppCompatActivity;
import androidx.constraintlayout.widget.ConstraintLayout;
import androidx.constraintlayout.widget.Constraints;

import android.app.PictureInPictureParams;
import android.content.res.Configuration;
import android.os.Bundle;
import android.os.Build;
import android.util.Log;
import android.util.Rational;
import android.view.View;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class TestPipActivity extends AppCompatActivity {

    private static final String TAG = "TestPipActivity";

    private TextView tvTitle, tvInfo, tvDetail;
    private ImageView imageView, imageViewPip, ivPip;

    private PictureInPictureParams.Builder mBuilder;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_test_pip);

        tvTitle = findViewById(R.id.tv_title);
        tvDetail = findViewById(R.id.tv_detail);
        tvInfo = findViewById(R.id.tv_info);
        imageView = findViewById(R.id.image_view);
        ivPip = findViewById(R.id.iv_pip);
        imageViewPip = findViewById(R.id.image_view_pip);

        tvDetail.setText("Name: kobe.png\r\nSize: 75.7KB(480px * 300px)\r\nDate: 2020/09/17 15:40");

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O
          && getPackageManager().hasSystemFeature(PackageManager.FEATURE_PICTURE_IN_PICTURE)) {
            mBuilder = new PictureInPictureParams.Builder();

            ivPip.setVisibility(View.VISIBLE);
            tvInfo.setText("SDK Version:" + Build.VERSION.SDK_INT + "(支持画中画模式)");

        } else {
            ivPip.setVisibility(View.INVISIBLE);
            tvInfo.setText("SDK Version:" + Build.VERSION.SDK_INT + "(不支持画中画模式)");
        }

        ivPip.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int ivWidth = imageViewPip.getWidth();
                int ivHeight = imageViewPip.getHeight();
                if (ivWidth != 0 && ivHeight != 0) {
                    // 设置宽高比例值，第一个参数表示分子，第二个参数表示分母
                    // 10/5=2，表示画中画窗口的宽度是高度的两倍
                    Rational rational = new Rational(ivWidth, ivHeight);
                    mBuilder.setAspectRatio(rational).build();
                }
                enterPictureInPictureMode(mBuilder.build());
            }
        });
    }

    @Override
    public void onPictureInPictureModeChanged(boolean isInPictureInPictureMode, Configuration newConfig) {
        super.onPictureInPictureModeChanged(isInPictureInPictureMode, newConfig);
        Log.i(TAG, "onPictureInPictureModeChanged: " + isInPictureInPictureMode);
        if (isInPictureInPictureMode) {
            // hide some ui
            tvTitle.setVisibility(View.INVISIBLE);
            tvDetail.setVisibility(View.INVISIBLE);
            tvInfo.setVisibility(View.INVISIBLE);
            ivPip.setVisibility(View.INVISIBLE);
            imageView.setVisibility(View.INVISIBLE);
            imageViewPip.setVisibility(View.VISIBLE);
        } else {
            // Restore the full-screen UI
            tvTitle.setVisibility(View.VISIBLE);
            tvDetail.setVisibility(View.VISIBLE);
            tvInfo.setVisibility(View.VISIBLE);
            ivPip.setVisibility(View.VISIBLE);
            imageView.setVisibility(View.VISIBLE);
            imageViewPip.setVisibility(View.INVISIBLE);
        }
    }
}

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