SurfaceView是Android中专门用于绘制复杂、频繁刷新的视图控件,它可以在单独的线程中绘制图像,提高绘制的效率和性能。SurfaceView的使用方法较复杂,需要与SurfaceHolder配合使用。
一、基本用法
1. 在XML布局文件中添加SurfaceView控件:
```xml
android:layout_width="match_parent" android:layout_height="match_parent" /> ``` 2. 在Activity中找到SurfaceView控件并获取其SurfaceHolder对象: ```java SurfaceView surfaceView = findViewById(R.id.surfaceview); SurfaceHolder holder = surfaceView.getHolder(); ``` 3. 设置SurfaceHolder的回调方法: ```java holder.addCallback(new SurfaceHolder.Callback() { @Override public void surfaceCreated(SurfaceHolder holder) { // Surface被创建时调用 } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { // Surface改变时调用 } @Override public void surfaceDestroyed(SurfaceHolder holder) { // Surface被销毁时调用 } }); ``` 4. 在相应的回调方法中进行绘制操作: ```java @Override public void surfaceCreated(SurfaceHolder holder) { // 获取Canvas对象,并在其上进行绘制操作 Canvas canvas = holder.lockCanvas(); // 绘制操作... holder.unlockCanvasAndPost(canvas); } ``` 二、SurfaceView的主要方法和作用 1. surfaceCreated(SurfaceHolder holder):Surface被创建时调用,一般在这里初始化绘制资源。 2. surfaceChanged(SurfaceHolder holder, int format, int width, int height):Surface改变时调用,如旋转屏幕等,一般在这里重新设置绘制参数。 3. surfaceDestroyed(SurfaceHolder holder):Surface被销毁时调用,一般在这里释放绘制资源。 三、SurfaceHolder的主要方法和作用 1. lockCanvas():获取Canvas对象,用于绘制操作。 2. unlockCanvasAndPost(Canvas canvas):解锁Canvas对象,并将绘制内容提交显示在Surface上。 四、使用案例:绘制动画 下面以绘制一个简单的动画为例,说明SurfaceView的使用方法。 1. 新建一个名为MySurfaceView的类,继承SurfaceView,并实现SurfaceHolder.Callback接口: ```java public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback { private MyThread thread; public MySurfaceView(Context context) { super(context); getHolder().addCallback(this); } @Override public void surfaceCreated(SurfaceHolder holder) { thread = new MyThread(getHolder(), this); thread.setRunning(true); thread.start(); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { } @Override public void surfaceDestroyed(SurfaceHolder holder) { boolean retry = true; thread.setRunning(false); while (retry) { try { thread.join(); retry = false; } catch (InterruptedException e) { e.printStackTrace(); } } } public void update() { // 更新绘制内容 } public void draw(Canvas canvas) { // 绘制操作 } } ``` 2. 新建一个名为MyThread的线程类,用于在单独的线程中进行绘制操作: ```java public class MyThread extends Thread { private SurfaceHolder surfaceHolder; private MySurfaceView surfaceView; private boolean running; public MyThread(SurfaceHolder surfaceHolder, MySurfaceView surfaceView) { this.surfaceHolder = surfaceHolder; this.surfaceView = surfaceView; } public void setRunning(boolean running) { this.running = running; } @Override public void run() { Canvas canvas; while (running) { canvas = null; try { canvas = surfaceHolder.lockCanvas(); synchronized (surfaceHolder) { surfaceView.update(); surfaceView.draw(canvas); } } finally { if (canvas != null) { surfaceHolder.unlockCanvasAndPost(canvas); } } } } } ``` 3. 在Activity中使用MySurfaceView: ```java public class MainActivity extends AppCompatActivity { private MySurfaceView surfaceView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); surfaceView = findViewById(R.id.surfaceview); } @Override protected void onPause() { super.onPause(); surfaceView.surfaceDestroyed(surfaceView.getHolder()); } @Override protected void onResume() { super.onResume(); surfaceView.surfaceCreated(surfaceView.getHolder()); } } ``` 以上就是SurfaceView的详细使用方法和一个绘制动画的简单案例。通过使用SurfaceView,我们可以更高效地进行复杂、频繁刷新的绘制操作,提高应用的性能和用户体验。 如果你喜欢我们三七知识分享网站的文章,
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