Determine the best camera preview size

It'a example to determine the best supported camera preview size, to have the biggest preview area.

package com.example.androidcamera;

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

import android.hardware.Camera;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.widget.Toast;
import android.app.Activity;

public class MainActivity extends Activity {
 
 Camera myCamera;
 SurfaceView mySurfaceView;
 SurfaceHolder mySurfaceHolder;
 boolean isPreview;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        isPreview = false;
        mySurfaceView = (SurfaceView)findViewById(R.id.mypreview);
        mySurfaceHolder = mySurfaceView.getHolder();
        mySurfaceHolder.addCallback(mySurfaceCallback);
        
    }
    
    SurfaceHolder.Callback mySurfaceCallback
    = new SurfaceHolder.Callback(){

  @Override
  public void surfaceChanged(SurfaceHolder holder, int format, int width,
    int height) {
   Camera.Parameters myParameters = myCamera.getParameters();
   Camera.Size myBestSize = getBestPreviewSize(width, height, myParameters);
   
   if(myBestSize != null){
    myParameters.setPreviewSize(myBestSize.width, myBestSize.height);
    myCamera.setParameters(myParameters);
    myCamera.startPreview();
    isPreview = true;
    
    Toast.makeText(getApplicationContext(), 
      "Best Size:\n" +
      String.valueOf(myBestSize.width) + " : " + String.valueOf(myBestSize.height), 
      Toast.LENGTH_LONG).show();
   }
  }

  @Override
  public void surfaceCreated(SurfaceHolder holder) {
   try {
    myCamera.setPreviewDisplay(mySurfaceHolder);
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
   
  }

  @Override
  public void surfaceDestroyed(SurfaceHolder holder) {
   // TODO Auto-generated method stub
   
  }
     
    };
    
    private Camera.Size getBestPreviewSize(int width, int height, Camera.Parameters parameters){
     Camera.Size bestSize = null;
     List<Camera.Size> sizeList = parameters.getSupportedPreviewSizes();
     
     bestSize = sizeList.get(0);
     
     for(int i = 1; i < sizeList.size(); i++){
      if((sizeList.get(i).width * sizeList.get(i).height) >
        (bestSize.width * bestSize.height)){
       bestSize = sizeList.get(i);
      }
     }

     return bestSize;
    }
    
 @Override
 protected void onResume() {
  super.onResume();
  myCamera = Camera.open();
 }

 @Override
 protected void onPause() {
  
  if(isPreview){
   myCamera.stopPreview();
  }
  
  myCamera.release();
  myCamera = null;
  isPreview = false;
  
  super.onPause();
 }

}

Modify the layout to have a SurfaceView for preview.

<RelativeLayout 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" >

    <SurfaceView
        android:id="@+id/mypreview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

Modify AndroidManifest.xml to add permission of "android.permission.CAMERA", and set android:screenOrientation="landscape".

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.androidcamera"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="15" />
    <uses-permission android:name="android.permission.CAMERA"/>

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

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

</manifest>

Download the files.