webRTC（二十一）：android 录屏功能

• 效果
  
  录屏和截屏的思路基本一致，请看详细代码

• 布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".RecordScreenActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:orientation="vertical">

        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <ImageView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:src="@mipmap/ic_launcher" />
    </LinearLayout>

    <SurfaceView
        android:id="@+id/surface_view"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />
</LinearLayout>

将SurfaceView设置为录屏所需要的Surface

• 详细代码

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.graphics.PixelFormat;
import android.hardware.display.DisplayManager;
import android.hardware.display.VirtualDisplay;
import android.media.ImageReader;
import android.media.projection.MediaProjection;
import android.media.projection.MediaProjectionManager;
import android.os.Bundle;
import android.os.SystemClock;
import android.view.SurfaceView;
import android.view.View;
import android.widget.ImageView;

import com.example.webrtcdemo.utils.UIUtils;

/**
 * 录屏
 */
public class RecordScreenActivity extends AppCompatActivity {

    private static final int REQUEST_CODE = 102;
    private MediaProjectionManager projectionManager;
    private MediaProjection mediaProjection;
    private VirtualDisplay mVirtualDisplay;
    private SurfaceView mSurfaceView;

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mVirtualDisplay == null) {
            return;
        }
        mVirtualDisplay.release();
        mVirtualDisplay = null;

        if (mediaProjection != null) {
            mediaProjection.stop();
            mediaProjection = null;
        }
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_record_screen);
        mSurfaceView = findViewById(R.id.surface_view);
        projectionManager = (MediaProjectionManager) getSystemService(MEDIA_PROJECTION_SERVICE);
    }

    @Override
    public void onAttachedToWindow() {
        super.onAttachedToWindow();
        Intent captureIntent = projectionManager.createScreenCaptureIntent();
        startActivityForResult(captureIntent, REQUEST_CODE);
    }
    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_CODE && resultCode == RESULT_OK) {
            mediaProjection = projectionManager.getMediaProjection(resultCode, data);

            mVirtualDisplay = createVirtualDisplay();

        }
    }


    /**
     * name: 是生成的VirtualDisplay实例的名称；
     * width, height: 分别是生成实例的宽高，必须大于0；
     * dpi: 生成实例的像素密度，必须大于0，一般都取1；
     * surface: 这个比较重要，是你生成的VirtualDisplay的载体，
     * 我的理解是，VirtualDisplay的内容是一帧帧的屏幕截图（所以你看到是有宽高，像素密度等设置），
     * 所以MediaProjection获取到的其实是一帧帧的图，然后通过          surface（surface你可以理解成是android的一个画布，
     * 默认它会以每秒60帧来刷新，这里我们不再展开细说），来顺序播放这些图片，形成视频。
     *
     * @return
     */
    private VirtualDisplay createVirtualDisplay() {
        return mediaProjection.createVirtualDisplay("RecordScreen",
                UIUtils.getScreenWidth(this), UIUtils.getScreenHeight(this),
                UIUtils.getScreenDpi(this),
                DisplayManager.VIRTUAL_DISPLAY_FLAG_AUTO_MIRROR,
                mSurfaceView.getHolder().getSurface(), null /*Callbacks*/, null /*Handler*/);
    }
}

    <uses-feature android:name="android.hardware.camera" />
    <uses-feature android:name="android.hardware.camera.autofocus" />
    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
    <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
    <uses-permission android:name="android.permission.RECORD_AUDIO" />
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />