Control Flash Light, function as a torch.

The method Camera.setParameters() was introduced since Android API level 5. Using this method with parameters.setFlashMode(Parameters.FLASH_MODE_TORCH), we can control the build-in flash light of Android device as a torch.



Modify main.xml to have a button to toggle torch on/off.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<Button
    android:id="@+id/flashcontrol"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    />
</LinearLayout>

main code

package com.exercise.AndroidFlashLight;

import android.app.Activity;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class AndroidFlashLight extends Activity {

 Camera camera = null;
 Parameters parameters;
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        final Button FlashLightControl = (Button)findViewById(R.id.flashcontrol);
        FlashLightControl.setText("Set FLASH_MODE_TORCH");
        
        FlashLightControl.setOnClickListener(new Button.OnClickListener(){

   @Override
   public void onClick(View arg0) {
    // TODO Auto-generated method stub
    if(camera == null){
     camera = Camera.open();
     parameters = camera.getParameters();
     parameters.setFlashMode(Parameters.FLASH_MODE_TORCH);
     camera.setParameters(parameters);
     FlashLightControl.setText("Set FLASH_MODE_OFF");
    }else{
     parameters.setFlashMode(Parameters.FLASH_MODE_OFF);
     camera.setParameters(parameters);
     camera.release();
     camera = null;
     FlashLightControl.setText("Set FLASH_MODE_TORCH");
    }
    
   }});
    }
}

Modify AndroidManifest.xml to grant permission of "android.permission.CAMERA".

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.exercise.AndroidFlashLight"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".AndroidFlashLight"
                  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-sdk android:minSdkVersion="7" />
    <uses-permission android:name="android.permission.CAMERA"/>
</manifest> 

Download the files.