SurfaceView的使用
16lz
2021-01-26
前言
在Android中更新UI操作都需要在主线程中操作。但是SurfaceView例外，他可以在子线程中更新View，这使他可以做一些复杂的动画更新而不必担心造成主线程的阻塞。接下来就开始介绍一下SurfaceView的使用。
实现
SurfaceView通过SurfaceHolder.Callback来通知SurfaceView的创建和销毁
surfaceView.holder.addCallback(object :SurfaceHolder.Callback{ //改变 override fun surfaceChanged(holder: SurfaceHolder?, p1: Int, p2: Int, p3: Int) { } //销毁 override fun surfaceDestroyed(holder: SurfaceHolder?) { } //创建 override fun surfaceCreated(holder: SurfaceHolder?) { }})在SurfaceView创建完成之后就可以对其进行绘制了，而他的绘制是可以放在子线程中的
//获取画布val canvas=surfaceView.holder.lockCanvas()//提交画布surfaceView.holder.unlockCanvasAndPost(canvas)创建动画
下面就是一个使用SurfaceView创建动画的简单示例
class MainActivity : Activity() { var surfaceView: SurfaceView? = null var mPath = Path() var mPaint = Paint(Paint.ANTI_ALIAS_FLAG) var mCanvas: Canvas? = null override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) surfaceView = findViewById(R.id.surface_view) surfaceView.holder.addCallback(object:SurfaceHolder.Callback{ override fun surfaceChanged(holder: SurfaceHolder?, p1: Int, p2: Int, p3: Int) { } override fun surfaceDestroyed(holder: SurfaceHolder?) { } override fun surfaceCreated(holder: SurfaceHolder?) { mPaint.color = Color.BLACK mPaint.style = Paint.Style.STROKE mPaint.strokeWidth = 10f mPaint.strokeCap = Paint.Cap.ROUND mPaint.strokeJoin = Paint.Join.ROUND mPath.moveTo(0f, 100f) Thread(Runnable { kotlin.run { draw(0) } }).start() } }) } private fun draw(x: Int) { if (x > 1080) { return } val y = (50 * Math.sin(x * Math.PI / 180) + 100).toInt() mPath.lineTo(x + 3f, y.toFloat()) try { mCanvas = holder.svView.holder.lockCanvas() mCanvas?.drawColor(Color.WHITE) mCanvas?.drawPath(mPath, mPaint) } catch (e: Exception) { e.printStackTrace() } finally { if (mCanvas != null) holder.svView.holder.unlockCanvasAndPost(mCanvas) } draw(x + 3) }}其他用途
SurfaceView还可以和MediaPlayer一起使用实现视频播放，以下就是简单的示例：
class MainActivity : Activity() { var surfaceView: SurfaceView? = null val url = "https://apd-fec3435b8e24a9f3815c886baf4b7682.v.smtcdns.com/om.tc.qq.com/A3h5f3r8PilbVshgbDGWN3dyaZ8zUFk92BfD1Npo4MBA/h0560ixm63g.mp4?sdtfrom=v1103&guid=2cd4a548b5a2146345f8214435e93e24&vkey=10A496F49B3530CF50C56B617F6DB75C6A69850F6E8AD27EF01C74C9B06E07A95E952146937CD25966DF570C447F3AA1570F392682DEEDA0953F1CA68941B5C3FD7552C0D4DC7666322C5B6EF983BCB32A09AD04252FD6CB536BBBB81CC1BAD7CB31E90E1D341D675E08ED216DCA77E0D868B2EE67C3D6F5&platform=2" val player = MediaPlayer() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) surfaceView = findViewById(R.id.surface_view) Thread(Runnable { player.setDataSource(this, Uri.parse(url)) player.prepare() }).start() surfaceView.holder.addCallback(object:SurfaceHolder.Callback{ override fun surfaceChanged(holder: SurfaceHolder?, p1: Int, p2: Int, p3: Int) { } override fun surfaceDestroyed(holder: SurfaceHolder?) { } override fun surfaceCreated(holder: SurfaceHolder?) { player.setDisplay(holder) } }) player.setOnPreparedListener(object : MediaPlayer.OnPreparedListener { override fun onPrepared(p0: MediaPlayer?) { player.start() player.isLooping = true } }) }}参考
SurfaceView
Android之SurfaceView使用总结
Android SurfaceView的使用
android中使用surfaceview＋MediaPlayer播放视频
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