Android MediaProjection acquisitionLatestImage始终为ImageReader返回Null

问题描述

我正在编写简单的Screenshot应用程序，并为此使用MediaProjection + ImageReader。我使用some sample解决此任务。
当我单击“捕获”按钮时，我总是在日志消息中得到"image: NULL"。

在ImageReader.newInstance中，我将格式设置为ImageFormat.RGB_565。默认值为0x1，但是当我使用此值时，会显示警告消息：

必须是以下之一：ImageFormat.UNKNowN，ImageFormat.RGB_565， ImageFormat.YV12，ImageFormat.Y8，ImageFormat.NV16，ImageFormat.NV21， ImageFormat.YUY2，ImageFormat.JPEG，ImageFormat.DEPTH_JPEG， ImageFormat.YUV_420_888，ImageFormat.YUV_422_888， ImageFormat.YUV_444_888，ImageFormat.FLEX_RGB_888， ImageFormat.FLEX_RGBA_8888，ImageFormat.RAW_SENSOR， ImageFormat.RAW_PRIVATE，ImageFormat.RAW10，ImageFormat.RAW12， ImageFormat.DEPTH16，ImageFormat.DEPTH_POINT_CLOUD， ImageFormat.PRIVATE，ImageFormat.HEIC

我的问题：为什么 ImageReader 中的 Image 总是 Null ？以及如何正确解决？谢谢

我的代码：

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.ImageFormat;
import android.hardware.display.displayManager;
import android.hardware.display.Virtualdisplay;
import android.media.Image;
import android.media.ImageReader;
import android.media.projection.MediaProjection;
import android.media.projection.mediaprojectionmanager;
import android.os.Bundle;
import android.os.Environment;
import android.util.displayMetrics;
import android.util.Log;
import android.view.View;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private static final String TAG = "test_t";

    private ImageReader mImageReader;
    private mediaprojectionmanager mmediaprojectionmanager;
    private Intent mCreateScreenCaptureIntent;
    private MediaProjection mMediaProjection;
    private Virtualdisplay mVirtualdisplay;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        View mBtnCapture = findViewById(R.id.btn_capture);
        mBtnCapture.setonClickListener(this);

        init();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        tearDownMediaProjection();
    }

    @Override
    protected void onActivityResult(int requestCode,int resultCode,Intent data) {
        super.onActivityResult(requestCode,resultCode,data);
        mMediaProjection = mmediaprojectionmanager.getMediaProjection(resultCode,data);
        if (mMediaProjection != null) {
            startScreenCapture();
            takeCapture();
            stopScreenCapture();
        }
    }

    @Override
    public void onClick(View v) {
        startActivityForResult(mCreateScreenCaptureIntent,777);
    }

    private void init() {
        displayMetrics displayMetrics = getResources().getdisplayMetrics();
        mImageReader = ImageReader.newInstance(displayMetrics.widthPixels,displayMetrics.heightPixels,ImageFormat.RGB_565,2); // format 0x1

        mmediaprojectionmanager = (mediaprojectionmanager) getSystemService(MEDIA_PROJECTION_SERVICE);
        mCreateScreenCaptureIntent = mmediaprojectionmanager.createScreenCaptureIntent();
    }

    private void startScreenCapture() {
        if (mMediaProjection == null)
            return;

        displayMetrics displayMetrics = getResources().getdisplayMetrics();
        mVirtualdisplay = mMediaProjection.createVirtualdisplay(
                "ScreenCapture",displayMetrics.widthPixels,displayMetrics.densityDpi,displayManager.VIRTUAL_disPLAY_FLAG_AUTO_MIRROR,mImageReader.getSurface(),null,null);
    }

    private void stopScreenCapture() {
        if (mVirtualdisplay == null) {
            return;
        }
        mVirtualdisplay.release();
        mVirtualdisplay = null;
    }

    private void takeCapture() {
        Image image = mImageReader.acquireLatestimage();
        if (image == null) {
            Log.d(TAG,"image: NULL");
            return;
        }

        int width = image.getWidth();
        int height = image.getHeight();
        final Image.Plane[] planes = image.getPlanes();
        final ByteBuffer buffer = planes[0].getBuffer();
        int pixelStride = planes[0].getPixelStride();
        int rowStride = planes[0].getRowStride();
        int rowPadding = rowStride - pixelStride * width;
        Bitmap mBitmap = Bitmap.createBitmap(width + rowPadding / pixelStride,height,Bitmap.Config.ARGB_8888);
        mBitmap.copyPixelsFromBuffer(buffer);
        mBitmap = Bitmap.createBitmap(mBitmap,width,height);
        image.close();
        saveBitmapToFile(mBitmap);
    }

    private void saveBitmapToFile(Bitmap bitmap) {
        File directory = new File(Environment.getExternalStorageDirectory(),"SCREEN_TEMP");
        if (!directory.exists())
            directory.mkdirs();
        String name = "shot" + new SimpleDateFormat("yyyyMMddHHmmsss").format(new Date()) + "." + Bitmap.CompressFormat.PNG.toString();
        File file = new File(directory,name);
        try {
            if (!file.exists()) {
                file.createNewFile();
            }
            FileOutputStream out = new FileOutputStream(file);
            bitmap.compress(Bitmap.CompressFormat.PNG,100,out);
            out.flush();
            out.close();
        } catch (IOException e) {
            e.printstacktrace();
        }
    }

    private void tearDownMediaProjection() {
        if (mMediaProjection != null) {
            mMediaProjection.stop();
            mMediaProjection = null;
        }
    }
}

解决方法

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