下面是我的代码，但是当我打开相机出现并立即消失时出现一些错误。如何在相机视图上保持更长时间。？

Question

1.MainActivity.java 文件我认为错误发生在这一行

 public void surfaceDestroyed(SurfaceHolder holder) {
                cameraSource.stop()

我正在尝试使用 SurfaceView 打开相机和显示。这会延迟 activity 的加载很长时间。所以我想知道打开相机的最佳做法是什么。

package com.example.software2.ocrhy;
public class MainActivity extends AppCompatActivity {
    private TextView textView;
    private SurfaceView surfaceView;
    private CameraSource cameraSource;
    private TextRecognizer textRecognizer;
    private TextToSpeech textToSpeech;
    private String stringResult = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ActivityCompat.requestPermissions(this, new String[]{CAMERA}, PackageManager.PERMISSION_GRANTED);
        textToSpeech = new TextToSpeech(this, new TextToSpeech.OnInitListener() {
            @Override
            public void onInit(int status) {
            }
        });
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        cameraSource.release();
    }
    private void textRecognizer(){
        textRecognizer = new TextRecognizer.Builder(getApplicationContext()).build();
        cameraSource = new CameraSource.Builder(getApplicationContext(), textRecognizer)
                .setRequestedPreviewSize(1280, 1024)
                .build();

        surfaceView = findViewById(R.id.surfaceView);
        surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
            @SuppressLint("MissingPermission")
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                try {
                    cameraSource.start(surfaceView.getHolder());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                cameraSource.stop();
            }
        });
        textRecognizer.setProcessor(new Detector.Processor<TextBlock>() {
            @Override
            public void release() {
            }

            @Override
            public void receiveDetections(Detector.Detections<TextBlock> detections) {

                SparseArray<TextBlock> sparseArray = detections.getDetectedItems();
                StringBuilder stringBuilder = new StringBuilder();

                for (int i = 0; i<sparseArray.size(); ++i){
                    TextBlock textBlock = sparseArray.valueAt(i);
                    if (textBlock != null && textBlock.getValue() !=null){
                        stringBuilder.append(textBlock.getValue() + " ");
                    }
                }

                final String stringText = stringBuilder.toString();

                Handler handler = new Handler(Looper.getMainLooper());
                handler.post(() -> {
                    stringResult = stringText;
                    resultObtained();
                });
            }
        });
    }
    private void resultObtained(){
        setContentView(R.layout.activity_main);
        textView = findViewById(R.id.textView);
        textView.setText(stringResult);
        textToSpeech.speak(stringResult, TextToSpeech.QUEUE_FLUSH, null, null);
    }
    public void buttonStart(View view){
        setContentView(R.layout.surface);
        textRecognizer();
    }
}

I got full code from this link

java文件
相机出错activity

Answer 1

根据您的源代码，您的摄像头会立即开始读取文本。如果您想先在相机上看到您的文字，然后才开始阅读它，我们可以将其分解为以下步骤：

打开相机
导航到特定文本
终于当你通过相机看到你想读的文字时

我建议你对你的代码做一些小的修改

在您的 surfaceview.xml 上添加 Capture 按钮（例如在下面的代码中）

<?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">

   <SurfaceView
       android:id="@+id/surfaceView"
       android:layout_width="308dp"
       android:layout_height="503dp"
       android:layout_marginStart="64dp"
       android:layout_marginTop="32dp"
       app:layout_constraintStart_toStartOf="parent"
       app:layout_constraintTop_toTopOf="parent" />

   <Button
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       app:layout_constraintBottom_toBottomOf="parent"
       app:layout_constraintStart_toStartOf="parent"
       android:id="@+id/capture"
       android:layout_marginHorizontal="32dp"
       android:layout_marginBottom="32dp"
       android:text="Capture"
       app:layout_constraintEnd_toEndOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

将文本处理移出到单独的函数中

private void capture() {
        textRecognizer.setProcessor(new Detector.Processor<TextBlock>() {
            @Override
            public void release() {
            }

            @Override
            public void receiveDetections(Detector.Detections<TextBlock> detections) {

                SparseArray<TextBlock> sparseArray = detections.getDetectedItems();
                StringBuilder stringBuilder = new StringBuilder();

                for (int i = 0; i<sparseArray.size(); ++i){
                    TextBlock textBlock = sparseArray.valueAt(i);
                    if (textBlock != null && textBlock.getValue() !=null){
                        stringBuilder.append(textBlock.getValue() + " ");
                    }
                }

                final String stringText = stringBuilder.toString();

                Handler handler = new Handler(Looper.getMainLooper());
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                   stringResult = stringText;
                   resultObtained();
                    }
                });
            }
        });
}

点击 capture 按钮捕获您的文字

public void buttonStart(View view){
        setContentView(R.layout.surfaceview);
        Button capture = findViewById(R.id.capture);
        capture.setOnClickListener(v -> capture());
        textRecognizer();
}

结果整个 MainActivity



import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.speech.tts.TextToSpeech;
import android.util.SparseArray;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import com.google.android.gms.vision.CameraSource;
import com.google.android.gms.vision.Detector;
import com.google.android.gms.vision.text.TextBlock;
import com.google.android.gms.vision.text.TextRecognizer;

import java.io.IOException;

import static android.Manifest.permission.CAMERA;

public class MainActivity extends AppCompatActivity {

    private TextView textView;
    private SurfaceView surfaceView;

    private CameraSource cameraSource;
    private TextRecognizer textRecognizer;

    private TextToSpeech textToSpeech;
    private String stringResult = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ActivityCompat.requestPermissions(this, new String[]{CAMERA}, PackageManager.PERMISSION_GRANTED);
        textToSpeech = new TextToSpeech(this, new TextToSpeech.OnInitListener() {
            @Override
            public void onInit(int status) {
            }
        });
    }

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

    private void textRecognizer() {
        textRecognizer = new TextRecognizer.Builder(getApplicationContext()).build();
        cameraSource = new CameraSource.Builder(getApplicationContext(), textRecognizer)
                .setRequestedPreviewSize(1280, 1024)
                .setAutoFocusEnabled(true)
                .build();

        surfaceView = findViewById(R.id.surfaceView);
        Context context = this;
        surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                try {
                    if (ActivityCompat.checkSelfPermission(context, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                        // TODO: Consider calling
                        //    ActivityCompat#requestPermissions
                        // here to request the missing permissions, and then overriding
                        //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                        //                                          int[] grantResults)
                        // to handle the case where the user grants the permission. See the documentation
                        // for ActivityCompat#requestPermissions for more details.
                        return;
                    }
                    cameraSource.start(surfaceView.getHolder());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                cameraSource.stop();
            }
        });
    }
    private void capture() {
        textRecognizer.setProcessor(new Detector.Processor<TextBlock>() {
            @Override
            public void release() {
            }

            @Override
            public void receiveDetections(Detector.Detections<TextBlock> detections) {

                SparseArray<TextBlock> sparseArray = detections.getDetectedItems();
                StringBuilder stringBuilder = new StringBuilder();

                for (int i = 0; i<sparseArray.size(); ++i){
                    TextBlock textBlock = sparseArray.valueAt(i);
                    if (textBlock != null && textBlock.getValue() !=null){
                        stringBuilder.append(textBlock.getValue() + " ");
                    }
                }

                final String stringText = stringBuilder.toString();

                Handler handler = new Handler(Looper.getMainLooper());
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                        stringResult = stringText;
                        resultObtained();
                    }
                });
            }
        });
    }

    private void resultObtained(){
        setContentView(R.layout.activity_main);
        textView = findViewById(R.id.textView);
        textView.setText(stringResult);
        textToSpeech.speak(stringResult, TextToSpeech.QUEUE_FLUSH, null, null);
    }

    public void buttonStart(View view){
        setContentView(R.layout.surfaceview);
        Button capture = findViewById(R.id.capture);
        capture.setOnClickListener(v -> capture());
        textRecognizer();
    }
}

下面是我的代码，但是当我打开相机出现并立即消失时出现一些错误。如何在相机视图上保持更长时间。？

Below is my code but there is some error when i open camera appear and immediately disappear. How to hold on the camera view for a bit longer.?

java

android

camera