Dr. Ramkumar Lakshminarayanan article published in Tamil Computer Magazine. The content is about creating Android Application - Live Wallpaper.

1. Þ‰î ð°FJ™ ºîL™
¬ôš õ£™«ðŠðK¬ù
(Livewallpaper) à¼õ£‚°õ¶
âšõ£Á â¡ð¬îŠ 𣘂è
«ð£A«ø£‹.
݇†ó£Œ®¡ «ý£‹
vWKQ™ (Home screen) ÜQ
¬ôš õ£™«ðŠð˜!
<?xml version="1.0" encoding="UTF-8"?>
<wallpaper
xmlns:android="http://schemas.android.com/apk/res/andro
id"
android:thumbnail="@drawable/icon"
android:description="@string/wallpaper_description"
android:settingsActivity="ram.android.wallpaper.MyPreference
<?xml version="1.0" encoding="utf-8"?>
<manifest
xmlns:android="http://schemas.android.com/apk/res/andro
id"
package="ram.android.wallpaper"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon"
android:label="@string/app_name">
<service android:name="MyWallpaperService"
android:enabled="true"
android:permission="android.permission.BIND_WALLPAPER"
android:label="Wallpaper Example ">
<intent-filter>
<action
android:name="android.service.wallpaper.WallpaperService"
></action>
</intent-filter>
<meta-data
android:name="android.service.wallpaper"
android:resource="@xml/mywallpaper"></meta-data>
</service>
<activity android:label="@string/app_name"
android:name=".MyPreferencesActivity"
android:theme="@android:style/Theme.Light.WallpaperSetti
ngs"
android:exported="true">
</activity>
</application>
<uses-sdk android:minSdkVersion="10" />
<uses-feature
android:name="android.software.live_wallpaper"
android:required="true"></uses-feature>
</manifest>
Gó™-1
Gó™-2
ðì‹-2
ðì‹-1

2. «ñûÂì¡ ÜŠO«è û¬ù
à¼õ£‚°õ«î Þî¡ «ï£‚è
񣰋.
¬ôš õ£™ «ðŠðK¬ù
à¼õ£‚°õ õ£™«ðŠð˜
îèõL¬ù ªè£‡´œ÷ xml
ç¬ðL¬ù ºîL™ à¼õ£‚è
Ý¡†ó£Œ´ -2
Þ󣋰ñ£˜ ªô†²Iï£ó£òí¡
22
package
ram.android.wallpaper;
public class MyPoint {
String text;
private int x;
private int y;
public MyPoint(String
text, int x, int y) {
this.text = text;
this.x = x;
this.y = y;
}
}
package ram.android.wallpaper;
import android.os.Bundle;
import android.preference.Preference;
import
android.preference.Preference.OnPreferenceChangeListener;
import android.preference.PreferenceActivity;
import android.widget.Toast;
public class MyPreferencesActivity extends PreferenceActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.prefs);
// We want to add a validator to the number of circles
so that it only
// accepts numbers
Preference circlePreference =
getPreferenceScreen().findPreference("numberOfCircles");
// Add the validator
circlePreference.setOnPreferenceChangeListener(numberCheckL
istener);
}
/**
* Checks that a preference is a valid numerical value
*/
Preference.OnPreferenceChangeListener
numberCheckListener = new OnPreferenceChangeListener() {
@Override
public boolean onPreferenceChange(Preference
preference, Object newValue) {
// Check that the string is an integer
if (newValue != null &&
newValue.toString().length() > 0
&& newValue.toString().matches("d*")) {
return true;
}
// If now create a message to the user
Toast.makeText(MyPreferencesActivity.this,
"Invalid Input",
Toast.LENGTH_SHORT).show();
return false;
}
};
}
<?xml version="1.0"
encoding="utf-8"?>
<PreferenceScreen
xmlns:android="http://sche
mas.android.com/apk/res/an
droid">
<CheckBoxPreference
android:key="touch"
android:title="Enable
Touch"></CheckBoxPreferen
ce>
<EditTextPreference
android:key="numberOfCircl
es"
android:title="Number of
Circles"></EditTextPreferen
ce>
</PreferenceScreen>
«õ‡´‹. xml
ç¬ðL™ ÜŠO
«èû¡ ðŸPò
îèõ™è¬÷»‹
ñŸÁ‹ ñ£Ÿøƒ
è¬÷ ÜÂñF‚
°‹ ªêò™è¬÷
Gó™-3
Gó™-4
Gó™-5
ðì‹-3

3. package ram.android.wallpaper;
import java.util.ArrayList;
import java.util.List;
import android.content.SharedPreferences;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import
android.preference.PreferenceManager;
import
android.service.wallpaper.WallpaperService;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
public class MyWallpaperService extends
WallpaperService {
@Override
public Engine onCreateEngine() {
return new MyWallpaperEngine();
}
private class MyWallpaperEngine
extends Engine {
private final Handler handler = new
Handler();
private final Runnable drawRunner
= new Runnable() {
@Override
public void run() {
draw();
}
};
private List<MyPoint> circles;
private Paint paint = new Paint();
private int width;
int height;
private boolean visible = true;
private int maxNumber;
private boolean touchEnabled;
public MyWallpaperEngine() {
SharedPreferences prefs =
PreferenceManager
.getDefaultSharedPreferences(MyWallpaperSer
vice.this);
maxNumber = Integer
.valueOf(prefs.getString("numberOfCircles",
"4"));
touchEnabled =
prefs.getBoolean("touch", false);
circles = new
ArrayList<MyPoint>();
paint.setAntiAlias(true);
paint.setColor(Color.WHITE);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeWidth(10f);
handler.post(drawRunner);
}
@Override
public void
onVisibilityChanged(boolean visible) {
this.visible = visible;
if (visible) {
handler.post(drawRunner);
} else {
handler.removeCallbacks(drawRunner);
}
}
}
Gó™-6
ðì‹-4
»‹ ªè£‡®¼‚è «õ‡
´‹.
õ£™«ðŠð˜ ê˜iv â¡ø
A÷£vC¬ù Ü®Šð¬ìò£è
ªè£‡´ ¬ôš õ£™«ðŠð˜
èœ Ý‡†ó£Œ´ ªê™«ðC
J™ ªêò™ð´Aø¶.
Þ‰î º¬øJ™ on create
engine â¡ø º¬øJ¬ù
implement ªêŒ¶ F¼‹ð
ªðÁ‹ return object õ¬èò£è
'engine' â¡ðî¬ù ªðø «õ‡
´‹.
android.permission.BIND.WA
LLPAPER â¡ø ð‡H¬ù
ÜÂñF ªè£´Šðî¡ Íô‹
android.wallpaper.wallpaperser

4. @Override
public void onSurfaceDestroyed(SurfaceHolder holder) {
super.onSurfaceDestroyed(holder);
this.visible = false;
handler.removeCallbacks(drawRunner);
}
@Override
public void onSurfaceChanged(SurfaceHolder holder, int format,
int width, int height) {
this.width = width;
this.height = height;
super.onSurfaceChanged(holder, format, width, height);
}
@Override
public void onTouchEvent(MotionEvent event) {
if (touchEnabled) {
float x = event.getX();
float y = event.getY();
SurfaceHolder holder = getSurfaceHolder();
Canvas canvas = null;
try {
canvas = holder.lockCanvas();
if (canvas != null) {
canvas.drawColor(Color.BLACK);
circles.clear();
circles.add(new MyPoint(String.valueOf(circles.size() + 1), x, y));
drawCircles(canvas, circles);
}
} finally {
if (canvas != null)
holder.unlockCanvasAndPost(canvas);
}
super.onTouchEvent(event);
}
}
private void draw() {
SurfaceHolder holder = getSurfaceHolder();
Canvas canvas = null;
try {
canvas = holder.lockCanvas();
if (canvas != null) {
if (circles.size() >= maxNumber) {
circles.clear();
}
int x = (int) (width * Math.random());
int y = (int) (height * Math.random());
circles.add(new MyPoint(String.valueOf(circles.size() + 1),
x, y));
drawCircles(canvas, circles);
}
} finally {
if (canvas != null)
holder.unlockCanvasAndPost(canvas);
}
handler.removeCallbacks(drawRunner);
if (visible) {
handler.postDelayed(drawRunner, 5000);
}
}
// Surface view requires that all elements are drawn completely
private void drawCircles(Canvas canvas, List<MyPoint> circles) {
canvas.drawColor(Color.BLACK);
for (MyPoint point : circles) {
canvas.drawCircle(point.x, point.y, 20.0f, paint);
}
}
}
Gó™-7

5. <?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/a
pk/res/android"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:padding="30dip"
android:orientation="horizontal">
<LinearLayout android:orientation="vertical"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:layout_gravity="center">
<TextView android:text="My App"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_gravity="center"
android:layout_marginBottom="25dip"
android:textSize="24.5sp" />
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="one" />
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="two" />
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="three" />
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="four" />
</LinearLayout>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/
apk/res/android"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:padding="15dip"
android:orientation="horizontal">
<LinearLayout android:orientation="vertical"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:layout_gravity="center"
android:paddingLeft="20dip"
android:paddingRight="20dip">
<TextView android:text="My App"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_gravity="center"
android:layout_marginBottom="20dip"
android:textSize="24.5sp" />
<TableLayout
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_gravity="center"
android:stretchColumns="*">
<TableRow>
<Button android:text="one" />
<Button android:text="two" />
</TableRow>
<TableRow>
<Button android:text="three" />
<Button android:text="four" />
</TableRow>
</TableLayout>
</LinearLayout>
</LinearLayout>
Gó™-8 Gó™-9
vice â¡ø android ÜŠO
«èûQ™ ªêò™ð´‹. android.
service.wallpaper.wallpaperserv
ice engine â¡ø A÷£«ê ¬ôš
õ£™«ðŠðK¬ù ªêò™
𴈶õîŸè£ù A÷£ê£°‹.
Þî¬ù îMó ïñ¶ ÜŠO
«èûQ™ àœ÷ android mani
fest.xml -™ "android software.
live-wallpaper"ðò¡ð´ˆ¶
A«ø£‹ â¡ðî¬ù ÜŠO«è
ê‚°ˆ ªîKòŠð´ˆî «õ‡
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«ðŠð˜ ðò¡ð´ˆî£î ªê™
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𴋫𣶠ãŸð´‹ H¬ö¬ò
îM˜‚èô£‹.
¹Fò Šó£ªü‚† å¡P¬ù
ªî£ìƒA ram.android.wall
paper â¡Á ªðòK´ƒèœ.
Þƒ° Ý‚®M†®J¬ù à¼
õ£‚è£b˜èœ,
res/xml â¡ø ç«ð£™
ìK¬ù à¼õ£‚A ÜF™ my
wallpaper.xml ç¬ðL¬ù à¼
õ£‚°ƒèœ. mywallpaper. xml
ç¬ðL™ õ£™«ðŠð¼‚è£ù
îèõ½‹ ñŸÁ‹ Aó£çH‚
îèõ½‹ Þ¼‚°‹, ªêò™ð
´‹ õ£™«ðŠðK¡ CPò ðìˆ
F¬ù "android thumbnail" â¡
ðF™ ªè£´‚èô£‹.
¬ñ õ£™«ðŠð¼‚è£ù
Gó™èœ (Gó™-1)-™ ªè£´‚èŠ
ð†´œ÷¶.
Ü´ˆîî£è androidmain
fest.xmlL™ "mywallpaperservi
ce" ðŸPò îèõL¬ù ªîKòŠ
ð´ˆî «õ‡´‹. androidmain
fest.xml L¬ù Gó™-2™ àœ
÷¶ «ð£¡ø¶ ñ£Ÿøƒèœ
ªêŒFì «õ‡´‹.
¬ñ ð£J¡† (Mypoint)
â¡ø A÷£C¬ù Ü´ˆîî£è
à¼õ£‚è «õ‡´‹. õ¬ó‰î

6. - ªî£ì¼‹
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è£ù¬õ Gó™-3™ ªè£´‚èŠ
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getshared preference ðò¡
𴈶õî¡ Íô‹ ꣈Fòñ£‚
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res/xml ç«ð£™ìK™ prefs.
xml â¡ø ç¬ðL¬ù à¼õ£‚
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ference activity â¡ø ªðò
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