Android Application Development Cookbook: 93 Recipes for Building Winning Apps

Recipe 9.6 Switching on the Flashlight

Android Versions

Level 1 and above

Permissions

CAMERA

FLASHLIGHT

Source Code to Download from Wrox.com

Flashlight.zip

Along with the built-in cameras that most Android devices offer, a flashlight is usually included next to the camera on the back of the device. This recipe shows you how to activate the flashlight of your camera.

Solution

To activate the flashlight on your Android device, you first need to declare two permissions:

    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.FLASHLIGHT"/>

You also need to have a SurfaceView in your UI to display the preview of images taken with the camera:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/button1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Turn On Flash" 
        android:onClick="TurnOn"/>

    <Button
        android:id="@+id/button2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Turn Off Flash" 
        android:onClick="TurnOff"/>
    <SurfaceView 
        android:id="@+id/surface1"
        android:layout_width="match_parent"
        android:layout_height="200dp"/>

</LinearLayout>

The SurfaceView view provides a dedicated drawing surface to display the images captured by your camera.

In your activity, you also need to implement ...