Android Live Wallpaper，这篇教程讲解android透明屏幕的实现方式。它以eclipse4.2、java 1.6、android4.1位基础。
1. 提前预习
下面的教程假设您已经掌握了android开发的基本知识 Android development。Android开发教程，学习基本知识，可以参考这个教程：http://www.vogella.com/tutorials/Android/article.html
2.概述
2.1. Live Wallpapers
Live Wallpapers是为Android主屏幕提供动画的、交互式的背景。live墙纸与其他Android应用程序相似，可以使用大多数相同的功能。
2.2. 这样创建live wallpaper
要创建一个活墙纸，您需要创建一个描述您的墙纸的XML文件。这个文件应该包含应用程序的描述，并且可以包含一个预览和一个连接到一个允许自定义live墙纸的偏好活动活动的链接。
您还创建了一个必须扩展WallpaperService类的服务。这个类是系统中所有活墙纸的基类。您必须实现onCreateEngine()方法并返回一个android.service.wallpaper.WallpaperService.Engine类型的对象。这个对象处理生命周期事件、动画和墙纸的图画。引擎类定义了生命周期方法，例如onCreate()、onSurfaceCreated()、onVisibilityChanged()、onOffsetsChanged()、onTouchEvent()和onCommand()。
该服务需要允许使用android。权限。BIND_WALLPAPER注册,必须通过一个android.service.wallpaper意图过滤器。WallpaperService行动。
2.3. Intent to set the wallpaper
您可以使用意图来设置墙纸。
// Button to set the Wallpaper
public void onClick(View view) {
Intent intent = new Intent(
WallpaperManager.ACTION_CHANGE_LIVE_WALLPAPER);
intent.putExtra(WallpaperManager.EXTRA_LIVE_WALLPAPER_COMPONENT,
new ComponentName(this, MyWallpaperService.class));
startActivity(intent);
}3. Android Wallpaper 例子
创建一个名为de.vogella.android.wallpaper的新项目。不要创建Activity。
创建/ res/ xml文件夹并创建my墙纸的xml文件。
<?xml version="1.0" encoding="UTF-8"?>
<wallpaper
xmlns:android="http://schemas.android.com/apk/res/android"
android:thumbnail="@drawable/icon"
android:description="@string/wallpaper_description"
android:settingsActivity="de.vogella.android.wallpaper.MyPreferencesActivity"/>这个文件包含你的墙纸和预览图。您还可以输入一个活动的链接，该活动允许配置墙纸。这个资源文件将与androidmanifest . xml链接起来。您还可以包括“android:thumbnail属性”，它可以指向一个可绘制的，它可以提供一个较小的运行墙纸的图像。
改变你的AndroidManifest。xml到下面来定义您的MyWallpaperService服务。也定义uses-feature。
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="de.vogella.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:label="Wallpaper Example "
android:permission="android.permission.BIND_WALLPAPER" >
<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:name=".MyPreferencesActivity"
android:exported="true"
android:label="@string/app_name"
android:theme="@android:style/Theme.Light.WallpaperSettings" >
</activity>
<activity
android:name=".SetWallpaperActivity"
android:label="@string/app_name"
android:theme="@android:style/Theme.Light.WallpaperSettings" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-sdk android:minSdkVersion="10" />
<uses-feature
android:name="android.software.live_wallpaper"
android:required="true" >
</uses-feature>
</manifest>我们创建MyPoint类来保存所绘制的元素。
package de.vogella.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;
}
}创建一个新的activity，在 res/xml文件夹下创建prefs.xml文件。
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<CheckBoxPreference android:key="touch"
android:title="Enable Touch"></CheckBoxPreference>
<EditTextPreference android:key="numberOfCircles"
android:title="Number of Circles"></EditTextPreference>
</PreferenceScreen>package de.vogella.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);
// add a validator to the "numberofCircles" preference so that it only
// accepts numbers
Preference circlePreference = getPreferenceScreen().findPreference(
"numberOfCircles");
// add the validator
circlePreference.setOnPreferenceChangeListener(numberCheckListener);
}
/**
* 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;
}
};
}创建一个Wallpaper 的服务
package de.vogella.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(MyWallpaperService.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);
}
}
}@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);
}
}
}创建下列activity，该activity应该使用包含一个按钮的布局。这个按钮应该使用onClick属性来指向onClick方法。
package de.vogella.android.wallpaper;
import android.app.Activity;
import android.app.WallpaperManager;
import android.content.ComponentName;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
public class SetWallpaperActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void onClick(View view) {
Intent intent = new Intent(
WallpaperManager.ACTION_CHANGE_LIVE_WALLPAPER);
intent.putExtra(WallpaperManager.EXTRA_LIVE_WALLPAPER_COMPONENT,
new ComponentName(this, MyWallpaperService.class));
startActivity(intent);
}
}如果您开始应用程序，您的应用程序应该允许设置壁纸。你的背景应该类似下面的截图。如果您通过首选项启用了触摸功能，您可以单击屏幕来删除现有的圆圈，也可以通过设置来定义应该显示的圆圈的数量。
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作者：gsg8709 发表于2017/9/12 18:53:14 原文链接
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