Android Livewallpaper

Livewallpaper

From Android 2.1, Livewallpaper is supported. Livewallpaper is home screen, and lock screen wallpaper app?, umm… it’s difficult to say app, maybe service.

Let’s start No Activity template

When we create Livewallpaper, we don’t need to create Activity. So, we can select No Activity from Android Studio template.

Sample

Let’s start development.

In this time, I just explain basic sample. (Support 1 image in local to show)

This is step

Import image
Develop Service
Prepare wallpaper configuration xml
Change AndroidManifest.xml to support wallpaper service

Sample

LiveWallSample.kt

class LiveWallSample : WallpaperService() {

    override fun onCreateEngine(): Engine {
        return WallPaperEngine()
    }

    private inner class WallPaperEngine : Engine() {

        private var visible : Boolean = true

        private val handler : Handler = Handler()

        private val runner : Runnable = Runnable {
            drawFrame()
        }

        private var width : Int = 0

        private var height : Int = 0

        override fun onCreate(surfaceHolder: SurfaceHolder?) {
            super.onCreate(surfaceHolder)
        }

        override fun onSurfaceChanged(
            holder: SurfaceHolder?,
            format: Int,
            width: Int,
            height: Int
        ) {
            super.onSurfaceChanged(holder, format, width, height)
            this.width = width
            this.height = height
        }

        override fun onSurfaceDestroyed(holder: SurfaceHolder?) {
            super.onSurfaceDestroyed(holder)
            this.visible = false
            handler.removeCallbacks(runner)
        }

        override fun onVisibilityChanged(visible: Boolean) {
            this.visible = visible
            if (visible) {
                handler.post(runner)
            } else {
                handler.removeCallbacks(runner)
            }
        }

        override fun onTouchEvent(event: MotionEvent?) {
            super.onTouchEvent(event)
        }

        /* Helper Methods */
        private fun drawFrame() {
            var canvas : Canvas? = null
            try {
                canvas = surfaceHolder.lockCanvas()
                canvas?.let {
                    // Draw something
                    drawImage(it)
                }
            } finally {
                canvas?.let {
                    surfaceHolder.unlockCanvasAndPost(it)
                }
            }
        }

        private fun drawImage(canvas: Canvas) {
            val bitmap : Bitmap = BitmapFactory.decodeResource(resources, R.drawable.lion)
            canvas.drawBitmap(bitmap, null, Rect(0, 0, width, height), null)
        }


        // onSurfaceChanged
        // onVisibilityChanged
        // onSurfaceDestroyed
        // onCreate
    }
}

This is main service code. Extends WallpaperService class and implement

onCreateEngine, and Prepare Engine to draw something in canvas.

xml/live_wallpaper.xml

Livewall paper definition XML.

<?xml version="1.0" encoding="utf-8"?>
<wallpaper xmlns:android="http://schemas.android.com/apk/res/android"
    android:thumbnail="@drawable/logo">
</wallpaper>

AndroidManifest.xml

Set service as application layer (No Activity)

Also support above XML wallpaper definition.

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.daiji110.wallpapersample">

    <uses-feature android:name="android.software.live_wallpaper" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <service android:name=".LiveWallSample"
            android:label="@string/app_name"
            android:permission="android.permission.BIND_WALLPAPER">

            <intent-filter>
                <action android:name="android.service.wallpaper.WallpaperService" />
            </intent-filter>
            <meta-data
                android:name="android.service.wallpaper"
                android:resource="@xml/live_wallpaper" />
        </service>

    </application>
</manifest>