，而且对程序的执行效率要求很高时，View类就不能满足需求了，这时必须用SurfaceView类进行开发。
例 如，对速度要求很高的游戏时，View类就不能满足需求了，这时必须使用SurfaceView类进行开发。例如，对速度要求很高的游戏，可以使用双缓冲 来显示。游戏中的背景、人物、动画等都需要绘制在一个画布(Canvas)上，而SurfaceView可以直接访问一个画布，SurfaceView 是提供给需要直接画像素而不是使用窗体部件的应用使用的。 每个Surface创建一个Canvas对象(但属性时常改变),用来管理View和Surface上的绘图操作。
具体示例：
Activity
public class Activity01 extends Activity {
GameSurfaceView gameView = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
gameView = new GameSurfaceView(this);
setContentView(gameView);
}
}
GameSurfaceView
public class GameSurfaceView extends SurfaceView implements SurfaceHolder.Callback, Runnable{
private Activity01 mActivity = null;
private SurfaceHolder mHolder = null;
private Thread mThread = null;;
private boolean mLoop = false;
private Canvas mCanvas = null;
private Paint mPaint = null;
private long drawStartTime = 0, drawCostTime = 0, drawTotalTime = 30;
private float x, y;
private int screenWidth = 480, screenHeight = 800;
public GameSurfaceView(Context context) {
super(context);
mActivity = (Activity01)context;
mHolder = this.getHolder();
mHolder.addCallback(this);
setFocusable(true);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
mPaint = new Paint();
mPaint.setColor(Color.CYAN);
mLoop = true;
new Thread(this).start();
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
screenWidth = width;
screenHeight = height;
x = screenWidth / 2;
y = screenHeight / 2;
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
mLoop = false;
}
@Override
public void run() {
while(mLoop){
drawStartTime = SystemClock.uptimeMillis();
synchronized (mHolder) {
try {
mCanvas = mHolder.lockCanvas();
onDraw();// repaint
} catch (Exception e) {
e.printStackTrace();
} finally {
if(mCanvas != null){
mHolder.unlockCanvasAndPost(mCanvas);
}
}
}
drawCostTime = SystemClock.uptimeMillis() - drawStartTime;
Log.i("drawCostTime", "drawCostTime = " + drawCostTime);
try {
if(drawCostTime < drawTotalTime){
Thread.sleep(drawTotalTime - drawCostTime);// sleep elapse time
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
private void onDraw(){
if(mHolder == null && mPaint == null){
return;
}
mPaint.setAntiAlias(true);
mPaint.setAlpha(100);
mPaint.setColor(Color.CYAN); // paint background color
mCanvas.drawRect(0, 0, screenWidth, screenHeight, mPaint);
mPaint.setColor(Color.BLUE); // paint foreground color
mCanvas.drawCircle(x, y, 50, mPaint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
super.onTouchEvent(event);
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
this.x = event.getX();
this.y = event.getY();
break;
case MotionEvent.ACTION_MOVE:
this.x = event.getX();
this.y = event.getY();
break;
case MotionEvent.ACTION_UP:
this.x = event.getX();
this.y = event.getY();
break;
default:
this.x = event.getX();
this.y = event.getY();
break;
}
return true; // true then event can be implemented again
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event){
super.onKeyDown(keyCode, event);
if(keyCode == KeyEvent.ACTION_DOWN){
this.mActivity.finish();
}
return true;
}
}
运行效果：
