相机拍摄时如何对焦？

Question

我可以运行代码来拍照，但生成的图像不理想。在下图中，Google 徽标应位于中心，但事实并非如此。

我正在使用以下代码：

CameraView.java

package com.pictures;

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


import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.PixelFormat;
import android.graphics.Bitmap.CompressFormat;
import android.hardware.Camera;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;

public class CamaraView extends Activity implements SurfaceHolder.Callback,
        OnClickListener {
    static final int FOTO_MODE = 0;
    private static final String TAG = "CameraTest";
    Camera mCamera;
    boolean mPreviewRunning = false;
    private Context mContext = this;

    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);

        Log.e(TAG, "onCreate");

        Bundle extras = getIntent().getExtras();

        getWindow().setFormat(PixelFormat.TRANSLUCENT);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.main);
        mSurfaceView = (SurfaceView) findViewById(R.id.surface_camera);
        mSurfaceView.setOnClickListener(this);
        mSurfaceHolder = mSurfaceView.getHolder();
        mSurfaceHolder.addCallback(this);
        mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
    }

    Camera.PictureCallback mPictureCallback = new Camera.PictureCallback() {
        public void onPictureTaken(byte[] imageData, Camera c) {

            if (imageData != null) {

                Intent mIntent = new Intent();

                StoreByteImage(mContext, imageData, 50,
                        "ImageName");
                mCamera.startPreview();

                setResult(FOTO_MODE, mIntent);
                finish();

            }
        }
    };

    protected void onResume() {
        Log.e(TAG, "onResume");
        super.onResume();
    }

    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
    }

    protected void onStop() {
        Log.e(TAG, "onStop");
        super.onStop();
    }

    public void surfaceCreated(SurfaceHolder holder) {
        Log.e(TAG, "surfaceCreated");
        mCamera = Camera.open();

    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        Log.e(TAG, "surfaceChanged");

        // XXX stopPreview() will crash if preview is not running
        if (mPreviewRunning) {
            mCamera.stopPreview();
        }

        Camera.Parameters p = mCamera.getParameters();
        p.setPreviewSize(w, h);
        mCamera.setParameters(p);
        try {
            mCamera.setPreviewDisplay(holder);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        mCamera.startPreview();
        mPreviewRunning = true;
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        Log.e(TAG, "surfaceDestroyed");
        mCamera.stopPreview();
        mPreviewRunning = false;
        mCamera.release();
    }

    private SurfaceView mSurfaceView;
    private SurfaceHolder mSurfaceHolder;

    public void onClick(View arg0) {

        mCamera.takePicture(null, mPictureCallback, mPictureCallback);

    }

    public static boolean StoreByteImage(Context mContext, byte[] imageData,
            int quality, String expName) {

        File sdImageMainDirectory = new File( Environment.getExternalStorageDirectory() + "/Engagia");
        FileOutputStream fileOutputStream = null;
        String nameFile;
        try {


            BitmapFactory.Options options=new BitmapFactory.Options();
            options.inSampleSize = 1;

            Bitmap myImage = BitmapFactory.decodeByteArray(imageData, 0,
                    imageData.length,options);


            fileOutputStream = new FileOutputStream(
                    sdImageMainDirectory.toString() +"/image.jpg");


            BufferedOutputStream bos = new BufferedOutputStream(
                    fileOutputStream);

            myImage.compress(CompressFormat.JPEG, quality, bos);

            bos.flush();
            bos.close();

        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return true;
    }

}

AndroidManifest .xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.pictures"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".CamaraView"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

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

</manifest> 

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" android:layout_height="fill_parent"
    android:orientation="vertical">
    <SurfaceView android:id="@+id/surface_camera"
        android:layout_width="fill_parent" android:layout_height="10dip"
        android:layout_weight="1">      
    </SurfaceView>  
</LinearLayout>

有人知道这个问题的解决方案吗？非常感谢您的帮助！ :)

Answer 1

我相信，该手机不会将图像置于取景器的中心。用户应该通过移动手机来完成此操作。

要实现自动对焦，请查看 autoFocus() API。