
源码地址
设置动态壁纸-TextClockWallpaperService
起源
填坑啦!填坑啦!
其实关于「设置动态壁纸的实操」我是弃坑了的,因为我单方面觉得只是壁纸相关API的使用,价值不大。但不久前有「掘友」留言说及这事,并表示期待更新「下篇」,于是我又单方面觉得价值还是有的,能帮一个是一个。
目录
以下是我列的本篇目录,将按顺序依次做解说
- 如何快速上手设置壁纸?
- 相关API说明
- 文字时钟动态壁纸实践
如何快速上手设置壁纸?
NOTE: 这里暂时不关心「为什么」,我们只按照既定的步骤,快速上手实现一个「Hong Kong is part of China!」静态壁纸
- 在
res -> xml
目录下新建一个壁纸描述文件,名字可自取(text_colck_wallpaper.xml),内容很简单<wallpaper xmlns:android="http://schemas.android.com/apk/res/android" />
- 继承
WallpaperService
在内部处理我们自己的绘制。(可以关注下onVisibilityChanged方法)class TextClockWallpaperService : WallpaperService() { override fun onCreateEngine(): Engine { return MyEngine() } inner class MyEngine : Engine() { /** * 准备画笔 */ private val mPaint = Paint().apply { this.color = Color.RED this.isAntiAlias = true this.textSize = 60f this.textAlign = Paint.Align.CENTER } /** * Called to inform you of the wallpaper becoming visible or * hidden. <em>It is very important that a wallpaper only use * CPU while it is visible.</em>. * * 当壁纸显示或隐藏时会回调该方法。 * 很重要的一点是,要只在壁纸显示的时候做绘制操作(占用CPU)。 */ override fun onVisibilityChanged(visible: Boolean) { super.onVisibilityChanged(visible) Log.d("clock", "onVisibilityChanged >>> $visible") //只在壁纸显示的做绘制操作,这很重要! if (visible) { surfaceHolder.lockCanvas()?.let { canvas -> //将原点移动到画布中心 canvas.save() canvas.translate((canvas.width / 2).toFloat(), (canvas.height / 2).toFloat()) //绘制文字 canvas.drawText("Hong Kong is part of China!", 0f, 0f, mPaint) canvas.restore() surfaceHolder.unlockCanvasAndPost(canvas) } } } } }
- 在
AndroidManifest.xml
文件中增加壁纸服务的声明<!--动态壁纸服务--> <service android:name=".view.TextClockWallpaperService" 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/text_clock_wallpaper" /> </service>
- 增加启动壁纸设置服务的方法
btnSet.setOnClickListener { val intent = Intent().apply { action = WallpaperManager.ACTION_CHANGE_LIVE_WALLPAPER putExtra( WallpaperManager.EXTRA_LIVE_WALLPAPER_COMPONENT, ComponentName( context, TextClockWallpaperService::class.java ) ) } startActivity(intent) }
经过前面四步,我们成功的爱了一把国,效果如图:

相关API说明
壁纸描述文件
首先,这个描述文件是必须的,在声明服务的时候必须在meta-data上配置上。知道为什么吗?
- 这个描述文件中有三个可选属性
description(对壁纸服务的描述)
settingsActivity(对此壁纸进行参数设置的Activity)
thumbnail(壁纸服务缩略图)
//示例代码 <?xml version="1.0" encoding="utf-8"?> <wallpaper xmlns:android="http://schemas.android.com/apk/res/android" android:description="@string/description" android:settingsActivity="me.erwa.xxx.SettingsActivity" android:thumbnail="@mipmap/ic_launcher"> </wallpaper>
- 通过源码可知,在壁纸服务启动之前会进行三个检查,其中第三个检查就是对meta-data中提供关于壁纸的描写叙述信息的检查用以创建一个叫
WallpaperInfo
的实例。(关于原理部分解析,我在拜读的文章中贴出了链接,大家可自行食用)
壁纸服务的声明
其中必须要加的是:
- 权限:
android:permission="android.permission.BIND_WALLPAPER"
- 处理Service的Action:
<action android:name="android.service.wallpaper.WallpaperService"/>
对!这两个也分别对应壁纸服务启动前的第一个检查和第二个检查
壁纸服务的实现
- 继承
WallpaperService
并复写抽象方法public abstract Engine onCreateEngine();
/** * Must be implemented to return a new instance of the wallpaper's engine. * Note that multiple instances may be active at the same time, such as * when the wallpaper is currently set as the active wallpaper and the user * is in the wallpaper picker viewing a preview of it as well. * * 必须实现并返回一个壁纸引擎的新实例。 * 注意同一时间可能有多个实例在运行,比如当前壁纸正在运行时,用户在挑选壁纸页面浏览该壁纸的预览画面。 */ public abstract Engine onCreateEngine(); /** * The actual implementation of a wallpaper. A wallpaper service may * have multiple instances running (for example as a real wallpaper * and as a preview), each of which is represented by its own Engine * instance. You must implement {@link WallpaperService#onCreateEngine()} * to return your concrete Engine implementation. * * 壁纸的实际实现。一个壁纸服务可能有多个实例在运行(例如一个是真实的壁纸和一个处于预览的壁纸), * 每个壁纸都只能由其相应的引擎实例来做实现。 * 你必须实现{@link WallpaperService#onCreateEngine()}并返回你创建的引擎的实例。 */ public class Engine { ...省略代码 }
Engine
的关键生命周期,它们是从上到下依次执行的。我们重点关注onVisibilityChanged
onSurfaceDestroyed
即可。inner class MyEngine : Engine() { override fun onCreate(surfaceHolder: SurfaceHolder?) { super.onCreate(surfaceHolder) Log.d("clock", "onCreate") } override fun onSurfaceCreated(holder: SurfaceHolder?) { super.onSurfaceCreated(holder) Log.d("clock", "onSurfaceCreated") } override fun onSurfaceChanged(holder: SurfaceHolder?, format: Int, width: Int, height: Int) { super.onSurfaceChanged(holder, format, width, height) Log.d("clock", "onSurfaceChanged") } /** * Called to inform you of the wallpaper becoming visible or * hidden. <em>It is very important that a wallpaper only use * CPU while it is visible.</em>. * * 当壁纸显示或隐藏是会回调该方法。 * 很重要的一点是,要只在壁纸显示的时候做绘制操作(占用CPU)。 */ override fun onVisibilityChanged(visible: Boolean) { super.onVisibilityChanged(visible) Log.d("clock", "onVisibilityChanged >>> $visible") } override fun onSurfaceDestroyed(holder: SurfaceHolder?) { super.onSurfaceDestroyed(holder) Log.d("clock", "onSurfaceDestroyed") } override fun onDestroy() { super.onDestroy() Log.d("clock", "onDestroy") } }
- 绘制相关的API
/** * Provides access to the surface in which this wallpaper is drawn. * 提供对绘制壁纸时实际Surface(表面)的访问 */ public SurfaceHolder getSurfaceHolder() { return mSurfaceHolder; } /** * Start editing the pixels in the surface. The returned Canvas can be used * to draw into the surface's bitmap. A null is returned if the surface has * not been created or otherwise cannot be edited. You will usually need * to implement {@link Callback#surfaceCreated Callback.surfaceCreated} * to find out when the Surface is available for use. * * 开始在Surface上编辑像素。这个返回的画布可以用来在Surface的位图上绘制。如果Surface还没创建或者不能被编辑会返回null。 * 一般情况下,你需要通过实现{@link Callback#surfaceCreated Callback.surfaceCreated}这个方法, * 来得知surface什么时候可用。 * * <p>The content of the Surface is never preserved between unlockCanvas() and * lockCanvas(), for this reason, every pixel within the Surface area * must be written. The only exception to this rule is when a dirty * rectangle is specified, in which case, non-dirty pixels will be * preserved. * * Surface的内容在unlockCanvas()和lockCanvas()之间是不会保存的,因此,Surface区域必须写入每个像素。 * 这个规则有个例外就是指定一个特殊的脏矩形区域,这种情况下,非脏区域的像素才会被保存。 * * <p>If you call this repeatedly when the Surface is not ready (before * {@link Callback#surfaceCreated Callback.surfaceCreated} or after * {@link Callback#surfaceDestroyed Callback.surfaceDestroyed}), your calls * will be throttled to a slow rate in order to avoid consuming CPU. * * 如果你在Surface创建前或销毁后重复调用该方法,为了避免占用CPU,你的调用将被限制为慢速率。 * * <p>If null is not returned, this function internally holds a lock until * the corresponding {@link #unlockCanvasAndPost} call, preventing * {@link SurfaceView} from creating, destroying, or modifying the surface * while it is being drawn. This can be more convenient than accessing * the Surface directly, as you do not need to do special synchronization * with a drawing thread in {@link Callback#surfaceDestroyed * Callback.surfaceDestroyed}. * * 如果返回值不为null,该方法内部持有锁,直到相应的{@link #unlockCanvasAndPost}方法被调用,并会防止Surface * 在绘制时被创建、销毁或修改。这样比直接访问Surface更方便,因为你不需要在{@link Callback#surfaceDestroyed * Callback.surfaceDestroyed}和绘制线程中做特殊的同步。 * * @return Canvas Use to draw into the surface. * 返回一个用来绘制到Surface上的画布 */ public Canvas lockCanvas(); /** * Finish editing pixels in the surface. After this call, the surface's * current pixels will be shown on the screen, but its content is lost, * in particular there is no guarantee that the content of the Surface * will remain unchanged when lockCanvas() is called again. * * 完成Surface上像素的编辑。该方法调用完,Surface上的像素将会展示到屏幕上,但是它的内容会丢失, * 尤其再次调用lockCanvas()时也不能保证它的内容不会变动。 * * @see #lockCanvas() * * @param canvas The Canvas previously returned by lockCanvas(). * 参数需传入之前lockCanvas()返回的画布 */ public void unlockCanvasAndPost(Canvas canvas);
文字时钟动态壁纸实践
有了前面的铺垫,这部分就相对简单了。不过我们依旧先思考🤔下思路:
- 如何绘制文字时钟?「上篇」中我们已经有了「TextClockView」,我们直接把它当做一个
封装好的对象
,再扩展添加几个我们需要的方法即可使用。 - 如何让壁纸动起来?跟「上篇」中一样,开一个定时器,每秒钟调用一次
TextClockView
的doInvalidate()
方法。
扩展TextClockView
- 首先要能在外部初始化绘制时依赖的宽高
/** * 初始化宽高,供动态壁纸使用 */ fun initWidthHeight(width: Float, height: Float) { if (this.mWidth < 0) { this.mWidth = width this.mHeight = height mHourR = mWidth * 0.143f mMinuteR = mWidth * 0.35f mSecondR = mWidth * 0.35f } }
- 绘制方法中增加回调,用于将实际绘制调用放到壁纸服务中
/** * 开始绘制 */ fun doInvalidate(block: (() -> Unit)? = null) { this.mBlock = block Calendar.getInstance().run { ...省略代码 mAnimator.addUpdateListener { ...省略代码 if (this@TextClockView.mBlock != null) { this@TextClockView.mBlock?.invoke() } else { invalidate() } } mAnimator.start() } }
- 停止后续绘制的方法
/** * 停止后续绘制,供动态壁纸使用 */ fun stopInvalidate() { mAnimator.removeAllUpdateListeners() }
处理壁纸服务的具体绘制实现
- 相关初始化
inner class MyEngine : Engine() { private val mClockView = TextClockView(this@TextClockWallpaperService.baseContext) private val mHandler = Handler() private var mTimer: Timer? = null ...省略代码 }
- 核心绘制操作
override fun onVisibilityChanged(visible: Boolean) { super.onVisibilityChanged(visible) Log.d("clock", "onVisibilityChanged >>> $visible") if (visible) { startClock() } else { stopClock() } } /** * 开始绘制 */ private fun startClock() { if (mTimer != null) return mTimer = timer(period = 1000) { mHandler.post { mClockView.doInvalidate { if (mTimer != null && surfaceHolder != null) { surfaceHolder.lockCanvas()?.let { canvas -> mClockView.initWidthHeight(canvas.width.toFloat(), canvas.height.toFloat()) mClockView.draw(canvas) surfaceHolder.unlockCanvasAndPost(canvas) } } } } } } /** * 停止绘制 */ private fun stopClock() { mTimer?.cancel() mTimer = null mClockView.stopInvalidate() }
到这里就完成啦!撒花!撒花!(欢迎食用源码并实际体验~)
文末
个人能力有限,如有不正之处欢迎大家批评指出,我会虚心接受并第一时间修改,以不误导大家。