相机预览未重新初始化 => 一个好的安卓相机实现？

Question

我的相机实现有一个小问题。目前，当我打开相机预览，我锁定手机，然后在回来时解锁它时，预览是可以的，仍然在运行。

问题是，当我按下手机的主页按钮时，返回应用程序时预览不再显示，只有黑屏，没有崩溃，也没有预览。

这是我的密码。我猜错误应该在方法onResume()、onPause()、onStop()的某个地方，但我无法准确地弄清楚。

这是我的更新版本：：：：

package ro.gebs.captoom.activities;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.RelativeLayout;
import android.widget.Toast;
import java.io.File;
import java.io.IOException;
import java.util.List;
import ro.gebs.captoom.R;
import ro.gebs.captoom.asynctasks.SavePictAsync;
import ro.gebs.captoom.interfaces.FinishTakePictureCallback;
import ro.gebs.captoom.utils.Utils;
import ro.gebs.captoom.utils.fonts.CustomFontButton;
import ro.gebs.captoom.utils.fonts.TopMenu;
@SuppressLint("SimpleDateFormat")
public class TakePicture extends Activity implements FinishTakePictureCallback {

    private SurfaceView surfaceView = null;
    private Camera camera = null;
    private Button buttonTakePicture;
    private boolean isFlashOn = false;
    private long the_folder_id;
    private boolean inPreview = true;
    Camera.AutoFocusCallback myAutoFocusCallback = new Camera.AutoFocusCallback() {
        @Override
        public void onAutoFocus(boolean success, Camera arg1) {
            if (success) {
                camera.takePicture(null, null, myPictureCallback_JPG);
            } else {
                Utils.showToast(TakePicture.this, "Not focused, try again", Toast.LENGTH_SHORT);
                buttonTakePicture.setEnabled(true);
            }
        }
    };
    final Camera.PictureCallback myPictureCallback_JPG = new Camera.PictureCallback() {
        @Override
        public void onPictureTaken(byte[] arg0, Camera arg1) {
            new SavePictAsync(arg0, TakePicture.this, camera, the_folder_id, buttonTakePicture).execute();
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.camera_control);
        surfaceView = (SurfaceView) findViewById(R.id.preview);
        surfaceView.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                System.out.println("------------ surf Created");
                if (camera == null) {
                    camera = Camera.open();
                    Camera.Parameters params = camera.getParameters();
                    params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
                    camera.setParameters(params);
                    try {
                        System.out.println("------------ 1");
                        camera.setPreviewDisplay(holder);
                        Camera.Parameters parameters = camera.getParameters();
                        List<Size> sizes = parameters.getSupportedPreviewSizes();
                        for (Size size : sizes) {
                            Log.d("TakePicture", size.height + "X" + size.width + "height" + surfaceView.getHeight() + "width" + surfaceView.getWidth());
                        }
                        Size optimalSize = getOptimalPreviewSize(sizes, surfaceView.getHeight(), surfaceView.getWidth());
                        parameters.setPreviewSize(optimalSize.width, optimalSize.height);
                        camera.setDisplayOrientation(90);
                        camera.setParameters(parameters);
                        camera.startPreview();
                        inPreview = true;
                    } catch (IOException e) {
                        Log.e("Take Picture", "Error", e);
                    }
                }
            }
            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                System.out.println("------------ surf Destroyed");
                if (inPreview) {
                    try {
                        if (camera != null) {
                            camera.cancelAutoFocus();
                            camera.stopPreview();
                        }
                        inPreview = false;
                    } catch (RuntimeException e) {
                        e.printStackTrace();
                    } finally {
                        if (camera != null) {
                            camera.release();
                            camera = null;
                        }
                    }
                }
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                if (!inPreview) {
                    try {
                        System.out.println("------------ surf Changed");
                        camera = Camera.open();
                        camera.setPreviewDisplay(surfaceView.getHolder());
                        camera.setDisplayOrientation(90);
                        camera.startPreview();
                        inPreview = true;
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }

        }
        );
        LayoutInflater controlInflater = LayoutInflater.from(getBaseContext());
        ViewGroup viewControl = (ViewGroup) controlInflater.inflate(R.layout.camera_control, null);
        assert viewControl != null;
        final CustomFontButton cancel_btn = (CustomFontButton) findViewById(R.id.cancel_btn);
        cancel_btn.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v) {
                finish();
            }
        }
        );
        buttonTakePicture = (Button) findViewById(R.id.take_picture);
        buttonTakePicture.setOnClickListener(new Button.OnClickListener()
        {
            @Override
            public void onClick(View arg0) {
                try {
                    Utils.showToast(TakePicture.this, "Focusing...", Toast.LENGTH_SHORT);
                    camera.autoFocus(myAutoFocusCallback);
                    buttonTakePicture.setEnabled(false);
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        }
        );
        RelativeLayout headerView = (RelativeLayout) findViewById(R.id.top_header_green);
        ImageButton menu_btn = (ImageButton) findViewById(R.id.menu_btn);
        new
                TopMenu(this, this, headerView, menu_btn);

        ImageButton flashBtn = (ImageButton) findViewById(R.id.flash_btn);
        flashBtn.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View view) {
                Context context = getApplicationContext();
                if (context.getPackageManager().hasSystemFeature(getPackageManager().FEATURE_CAMERA_FLASH)) {
                    Camera.Parameters params = camera.getParameters();
                    if (isFlashOn) {
                        params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
                        camera.setParameters(params);
                        isFlashOn = false;
                        Utils.showToast(context, getString(R.string.FlashOff), Toast.LENGTH_SHORT);
                    } else {
                        params.setFlashMode(Camera.Parameters.FLASH_MODE_AUTO);
                        camera.setParameters(params);
                        isFlashOn = true;
                        Utils.showToast(context, getString(R.string.FlashAuto), Toast.LENGTH_SHORT);
                    }
                }
            }
        }
        );
    }
    @Override
    public void finishTakePicture() {
        finish();
    }
    @Override
    protected void onResume() {
        the_folder_id = getIntent().getLongExtra("the_folder_id", 0);
        buttonTakePicture.setEnabled(true);
        super.onResume();
    }
    @Override
    public void onBackPressed() {
        super.onBackPressed();
        if (PreviewPhoto.photos != null) {
            for (String image : PreviewPhoto.photos) {
                File file = new File(image);
                file.delete();
            }
            PreviewPhoto.photos.clear();
        }
    }
    private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
        final double ASPECT_TOLERANCE = 0.1;
        double targetRatio = (double) w / h;
        if (sizes == null)
            return null;
        Log.d("TakePicture", "TargetRatio: " + targetRatio);
        Size optimalSize = null;
        double minDiff = Double.MAX_VALUE;
        for (Size size : sizes) {
            double ratio = (double) size.width / size.height;
            if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)
                continue;
            if (Math.abs(size.height - h) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - h);
            }
        }
        if (optimalSize == null) {
            minDiff = Double.MAX_VALUE;
            for (Size size : sizes) {
                if (Math.abs(size.height - h) < minDiff) {
                    optimalSize = size;
                    minDiff = Math.abs(size.height - h);
                }
            }
        }
        Log.d("TakePicture", "The optimal size is:" + optimalSize.height + "X" + optimalSize.width);
        return optimalSize;
    }
}

由于我已经覆盖了surfaceDestroyed、surfaceCreated，所以在onPause、onResume方法中没有太多可做的事情。

希望这个问题能帮助很多人，因为它被证明是一个很好的android相机实现。

你怎么看

既然这是一个有效的解决方案，我想知道你们是否认为这是一种有效的实现？我之所以这么问，是因为我只在一些设备上测试过。。。

Answer 1

在onPause和onResume方法中设置一些断点，看看会发生什么。你发生的事情有点奇怪。当预览为黑色时，也可以尝试拍照或录制视频，看看会发生什么。张贴logcat