android - 第二次自动对焦后拍照失败

Question

我正在开发一个使用自动对焦的安卓相机应用。

这个问题，我第一次可以捕获，但是当我第二次 try catch 时，出现以下异常。

4-19 11:28:32.509: E/AndroidRuntime(4409): FATAL EXCEPTION: main
04-19 11:28:32.509: E/AndroidRuntime(4409): java.lang.RuntimeException: takePicture failed
04-19 11:28:32.509: E/AndroidRuntime(4409):     at android.hardware.Camera.native_takePicture(Native Method)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at android.hardware.Camera.takePicture(Camera.java:878)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at android.hardware.Camera.takePicture(Camera.java:842)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at com.example.camerasample.MainActivity$4.onClick(MainActivity.java:60)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at android.view.View.performClick(View.java:2485)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at android.view.View$PerformClick.run(View.java:9080)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at android.os.Handler.handleCallback(Handler.java:587)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at android.os.Handler.dispatchMessage(Handler.java:92)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at android.os.Looper.loop(Looper.java:130)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at android.app.ActivityThread.main(ActivityThread.java:3687)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at java.lang.reflect.Method.invokeNative(Native Method)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at java.lang.reflect.Method.invoke(Method.java:507)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
04-19 11:28:32.509: E/AndroidRuntime(4409):     at dalvik.system.NativeStart.main(Native Method)

但在没有自动对焦功能的相机中拍摄时工作正常。

下面附上我的代码

主 Activity .java

package com.example.camerasample;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import com.example.camerasample.R;

import android.app.Activity;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.AutoFocusCallback;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnLongClickListener;
import android.view.ViewGroup.LayoutParams;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.FrameLayout;

public class MainActivity extends Activity {
    private static final String TAG = "CamTestActivity";
    Preview preview;
    Button buttonClick;
    Camera camera;
    String fileName;
    Activity act;
    Context ctx;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ctx = this;
        act = this;
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);

        setContentView(R.layout.activity_main);

        preview = new Preview(this, (SurfaceView)findViewById(R.id.surfaceView));
        preview.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
        ((FrameLayout) findViewById(R.id.preview)).addView(preview);
        preview.setKeepScreenOn(true);

        buttonClick = (Button) findViewById(R.id.buttonClick);

        buttonClick.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                camera.takePicture(shutterCallback, rawCallback, jpegCallback);
            }
        });

        buttonClick.setOnLongClickListener(new OnLongClickListener(){
            @Override
            public boolean onLongClick(View arg0) {
                camera.autoFocus(new AutoFocusCallback(){
                    @Override
                    public void onAutoFocus(boolean arg0, Camera arg1) {
                    }
                });
                return true;
            }
        });
    }

    @Override
    protected void onResume() {
        super.onResume();
        camera = Camera.open();
        camera.startPreview();
        preview.setCamera(camera);
    }

    @Override
    protected void onPause() {
        if(camera != null) {
            camera.stopPreview();
            preview.setCamera(null);
            camera.release();
            camera = null;
        }
        super.onPause();
    }

    private void resetCam() {
        camera.startPreview();
        preview.setCamera(camera);
    }

    ShutterCallback shutterCallback = new ShutterCallback() {
        public void onShutter() {
            // Log.d(TAG, "onShutter'd");
        }
    };

    PictureCallback rawCallback = new PictureCallback() {
        public void onPictureTaken(byte[] data, Camera camera) {
            // Log.d(TAG, "onPictureTaken - raw");
        }
    };

    PictureCallback jpegCallback = new PictureCallback() {
        public void onPictureTaken(byte[] data, Camera camera) {
            FileOutputStream outStream = null;
            try {
                // Write to SD Card
                fileName = String.format("/sdcard/camtest/%d.jpg", System.currentTimeMillis());
                outStream = new FileOutputStream(fileName);
                outStream.write(data);
                outStream.close();
                Log.d(TAG, "onPictureTaken - wrote bytes: " + data.length);

                resetCam();

            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
            }
            Log.d(TAG, "onPictureTaken - jpeg");
        }
    };
}

预览.java

package com.example.camerasample;

import java.io.IOException;
import java.util.List;

import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;

class Preview extends ViewGroup implements SurfaceHolder.Callback {
    private final String TAG = "Preview";

    SurfaceView mSurfaceView;
    SurfaceHolder mHolder;
    Size mPreviewSize;
    List<Size> mSupportedPreviewSizes;
    Camera mCamera;

    @SuppressWarnings("deprecation")
    Preview(Context context, SurfaceView sv) {
        super(context);

        mSurfaceView = sv;

        mHolder = mSurfaceView.getHolder();
        mHolder.addCallback(this);
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    public void setCamera(Camera camera) {
        mCamera = camera;
        if (mCamera != null) {
            mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes();
            requestLayout();

            // get Camera parameters
            Camera.Parameters params = mCamera.getParameters();

            List<String> focusModes = params.getSupportedFocusModes();
            if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
                // set the focus mode
                params.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
                // set Camera parameters
                mCamera.setParameters(params);
            }
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // We purposely disregard child measurements because act as a
        // wrapper to a SurfaceView that centers the camera preview instead
        // of stretching it.
        final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
        final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);
        setMeasuredDimension(width, height);

        if (mSupportedPreviewSizes != null) {
            mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height);
        }
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        if (changed && getChildCount() > 0) {
            final View child = getChildAt(0);

            final int width = r - l;
            final int height = b - t;

            int previewWidth = width;
            int previewHeight = height;
            if (mPreviewSize != null) {
                previewWidth = mPreviewSize.width;
                previewHeight = mPreviewSize.height;
            }

            // Center the child SurfaceView within the parent.
            if (width * previewHeight > height * previewWidth) {
                final int scaledChildWidth = previewWidth * height / previewHeight;
                child.layout((width - scaledChildWidth) / 2, 0,
                        (width + scaledChildWidth) / 2, height);
            } else {
                final int scaledChildHeight = previewHeight * width / previewWidth;
                child.layout(0, (height - scaledChildHeight) / 2,
                        width, (height + scaledChildHeight) / 2);
            }
        }
    }

    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, acquire the camera and tell it where
        // to draw.
        try {
            if (mCamera != null) {
                mCamera.setPreviewDisplay(holder);
            }
        } catch (IOException exception) {
            Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // Surface will be destroyed when we return, so stop the preview.
        if (mCamera != null) {
            mCamera.stopPreview();
        }
    }


    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;

        Size optimalSize = null;
        double minDiff = Double.MAX_VALUE;

        int targetHeight = h;

        // Try to find an size match aspect ratio and size
        for (Size size : sizes) {
            double ratio = (double) size.width / size.height;
            if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
            if (Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }

        // Cannot find the one match the aspect ratio, ignore the requirement
        if (optimalSize == null) {
            minDiff = Double.MAX_VALUE;
            for (Size size : sizes) {
                if (Math.abs(size.height - targetHeight) < minDiff) {
                    optimalSize = size;
                    minDiff = Math.abs(size.height - targetHeight);
                }
            }
        }
        return optimalSize;
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        if(mCamera != null) {
            Camera.Parameters parameters = mCamera.getParameters();
            parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
            requestLayout();

            mCamera.setParameters(parameters);
            mCamera.startPreview();
        }
    }

}

list :

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.camerasample"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="8" />

    <uses-feature android:name="android.hardware.camera" />

    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.hardware.camera.autofocus" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:label="@string/app_name"
            android:name=".MainActivity"
            android:screenOrientation="landscape" >
            <intent-filter >
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

我在任何地方都找不到确切的解决方案，请帮忙。

Answer 1

我提出了两个对我有用的解决方案。1)正确停止和恢复相机。我通过调用这些方法来做到这一点 onPause 和 onResume，也在相机预览的中间，我在我的应用程序中扫描二维码:

public void stopCamera(){
     mCamera.cancelAutoFocus();
     mCamera.setPreviewCallback(null);
     mCamera.stopPreview();  
     mPreviewing = false;
     }

public void rethrottleCamera(){
        updateViews(); //Updates my Layouts
        mPreviewing = true;
        mCamera.startPreview();
        mCamera.setPreviewCallback(previewCb);  
        mCamera.autoFocus(autoFocusCB); 
        }   

2) 非常棘手，但工作起来就像魔术一样!确保在创建预览表面后调用自动对焦。为此，延迟 200 毫秒运行自动对焦，为要创建的表面争取时间。通过在“CameraPreview”对象声明上按 ctrl+clic 来设置它，例如:

CameraPreview my_camera;

寻找“public void surfaceChanged”方法并进行以下更改:

//Add a delay to AUTOFOCUS after mCamera.startpreview();!!:
    mCamera.startPreview();                 
    final Handler handler = new Handler();
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {                    
            mCamera.autoFocus(autoFocusCallback);
            }
    }, 200); //<-200 millisecond delay

    //If you call autofocus right after startPreview, chances are,
    //that the previewSurface will have not been created yet,
    //and autofocus will fail:
    mCamera.startPreview();               //Bad idea!
    mCamera.autoFocus(autoFocusCallback); //Bad idea!

还有许多其他修复程序，但这两个可能会节省您的时间。