Android摄像头编程及注意事项

做了Android摄像头编程的测试，自己总结一下代码和其中的注意事项。

CameraTestActivity.java：

package test.cameratest;

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

import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.res.Configuration;
import android.util.Log;
import android.view.Display;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;
import android.widget.LinearLayout;

public class MainActivity extends Activity implements SurfaceHolder.Callback {

    private String Tag = "CameraTest";
    private SurfaceView mSurfaceView;
    private SurfaceHolder mSurfaceHolder;
    private Camera mCamera;
    private Size previewSize;
    private int screenWidth;
    private int screenHeight;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //全屏
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
        WindowManager.LayoutParams.FLAG_FULLSCREEN);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        setContentView(R.layout.activity_main);
        
        WindowManager wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
        Display display = wm.getDefaultDisplay();
        //获取屏幕的宽和高
        screenWidth = display.getWidth();
        screenHeight = display.getHeight();
        
        mSurfaceView = (SurfaceView) findViewById(R.id.surfaceview);
        mSurfaceHolder = mSurfaceView.getHolder();
        mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        mSurfaceHolder.addCallback(this);
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.d(Tag, "resume");
    }
    
    @Override
    protected void onPause() {
        super.onPause();
        Log.d(Tag, "pause");
    }
    
    @Override
    protected void onStop() {
        super.onStop();
        Log.d(Tag, "stop");
    }
    
    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.d(Tag, "destroy");
    }
    
    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        Log.d(Tag, "surface created");
        mCamera = Camera.open();
        if (mCamera == null) {
            Log.d(Tag, "camera null");
        }
        try {
            mCamera.setPreviewDisplay(holder);
        } catch (IOException e) {
            Log.e(Tag, "IOException caused by setPreviewDisplay");
        }
        mCamera.setPreviewCallback(mPreviewCallback);
        Camera.Parameters parameters = mCamera.getParameters();
        //Log.d(Tag, parameters.flatten());
        if (this.getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT) {
            parameters.set("orientation", "portrait");
            mCamera.setDisplayOrientation(90);
        } else {
            parameters.set("orientation", "landscape");
            mCamera.setDisplayOrientation(0);
        }
        int previewWidth = 0;
        int previewHeight = 0;
        List<Camera.Size> previewSizes = parameters.getSupportedPreviewSizes();
        Iterator<Camera.Size> iter = previewSizes.iterator();
        while (iter.hasNext()) {
            Camera.Size size = iter.next();
            Log.d(Tag, "" + size.width + " by " + size.height);
            if (size.width >= previewWidth && size.width <= screenHeight &&
                    size.height >= previewHeight && size.height <= screenWidth) {//640
                previewWidth = size.width;
                previewHeight = size.height;
            }
        }
        parameters.setPreviewSize(previewWidth, previewHeight);
        Log.d(Tag, "preivewWidth: " + previewWidth + " preivewHeight: " + previewHeight);
        List<String> focusModes = parameters.getSupportedFocusModes();
        if (focusModes != null && focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
            parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
        }
        mCamera.setParameters(parameters);
        previewSize = mCamera.getParameters().getPreviewSize();
    }
    
    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        Log.d(Tag, "surface changed");
        //Log.d(Tag, "surface size: " + width + " by " + height);
        //Log.d(Tag, "preview size: " + previewSize.width + " by " + previewSize.height);
        //使SurfaceView大小和预览大小比例相同
        mSurfaceView.setLayoutParams(new LinearLayout.LayoutParams(width, (int)(width * previewSize.width / previewSize.height)));
        //Log.d(Tag, "surface size2: " + width + " by " + (int)(width * previewSize.width / previewSize.height));
        mCamera.startPreview();
        mCamera.autoFocus(mAutoFocusCallback);
    }
    
    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        Log.d(Tag, "surface destroyed");
        if (mCamera != null) {
            mCamera.autoFocus(null);
            mCamera.stopPreview();
            mCamera.setPreviewCallback(null);
            mCamera.release();
            mCamera = null;
        }
    }
    
    Camera.AutoFocusCallback mAutoFocusCallback = new Camera.AutoFocusCallback() {
        @Override
        public void onAutoFocus(boolean success, Camera camera) {
            Log.d(Tag, "AutoFocus: " + success);
            if (success) {
                //自动对焦成功
                // ...
            } else {
                //自动对焦失败，再次对焦
                mCamera.autoFocus(mAutoFocusCallback);
            }
        }
    };
    
    Camera.PreviewCallback mPreviewCallback = new Camera.PreviewCallback() {
        @Override
        public void onPreviewFrame(byte[] data, Camera camera)
        {
            
        }
    };
    
}

 

布局文件activity_camera_test.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <SurfaceView  
        android:layout_width="fill_parent" 
           android:layout_height="wrap_content" 
        android:id="@+id/surfaceview"/>

</LinearLayout>

注意事项：（新发现的会再补充上）

1，在surfaceChanged函数里面，mCamera.autoFocus(mAutoFocusCallback)，如果写成autoFocus(null)的话，程序安装后第一次打开时预览会很亮很模糊。