package com.example.camerbatterytest;

 import java.io.IOException;

 import java.util.List;

 import android.app.Activity;

 import android.graphics.PixelFormat;

 import android.hardware.Camera;

 import android.hardware.Camera.Size;

 import android.os.Bundle;

 import android.util.Log;

 import android.view.Menu;

 import android.view.MenuItem;

 import android.view.SurfaceHolder;

 import android.view.SurfaceView;

 import android.widget.Button;

 public class CamerActivity extends Activity implements SurfaceHolder.Callback{

     Button takephoto;//未实现

     private SurfaceView mySurfaceView;

     private SurfaceHolder mysurfaceHolder;

     Camera camera;//5.0以后这个camera已经不推荐使用

     @Override

     protected void onCreate(Bundle savedInstanceState) {

         super.onCreate(savedInstanceState);

         setContentView(R.layout.activity_camer);

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

         mySurfaceView = (SurfaceView) findViewById(R.id.surfaceView1);

         mysurfaceHolder=mySurfaceView.getHolder();

         mysurfaceHolder.addCallback(this);

     }

     @Override

     public void surfaceCreated(SurfaceHolder holder) {

         Log.d("huang","surfaceCreated");

         camera = Camera.open();  

     }

     @Override

     public void surfaceChanged(SurfaceHolder holder, int format, int width,

             int height) {

         Log.d("huang","surfaceview width="+width+" and height="+height);

         Camera.Parameters parameters = camera.getParameters();

         Camera.Size bestSize=getBestPreviewSize(width,height,parameters);

         parameters.setPreviewSize(bestSize.width, bestSize.height);
         camera.setParameters(parameters);

         try {

             camera.setPreviewDisplay(mysurfaceHolder);

         } catch (IOException e) {

             e.printStackTrace();

         }

         camera.setDisplayOrientation(90);//显示的方向旋转角度

         camera.startPreview();

     }

     @Override

     public void surfaceDestroyed(SurfaceHolder holder)

     {

         Log.d("huang","surfaceDestroyed");

             if (camera != null)

             {

                 camera.stopPreview();

                 camera.release();

             }

     }

       private Camera.Size getBestPreviewSize(int surfaceViewWidth, int surfaceViewHeight, Camera.Parameters parameters) {

             Camera.Size bestSize=null;

 　　　　　　　　//不同机器 尺寸大小排序方式不一样  有的从小到大有的从大到小

             for (Camera.Size size : parameters.getSupportedPreviewSizes())

             {

               if (size.width <= surfaceViewWidth && size.height <= surfaceViewHeight)

               {

                 if (bestSize == null) //初始化一个值

                     bestSize=size;

                 else

                 {

                   int tempArea=bestSize.width * bestSize.height;

                   int newArea=size.width * size.height;

                   if (newArea > tempArea) //取满足条件里面最大的

                       bestSize=size;

                 }

               }

             }

             return bestSize;

           }

 }