使用SurfaceView实现异步动画绘图的小实例

主Activity类 StartActivity.java

import android.app.Activity;
import android.os.Bundle;
import android.view.View;

public class StartActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new ExampleSurfaceView(this));
                                      
    }    
}

view类ExampleSurfaceView及内部绘图线程类DrawingThread  ExampleSurfaceView.java

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;


public class ExampleSurfaceView extends SurfaceView implements SurfaceHolder.Callback{
DrawingThread mThread;
int mRed = 0;
int mGreen = 0;
int mBlue = 127;

//三角形使用线来定义，被称为顶点vertices()
float[] mVertices = new float[6];
int[] mColors = {
0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF,
0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF
};
Paint mPaint = new Paint();

//旋转角度
float mAngle = 0;

//三角形旋转支点
float mCenterX = 0;
float mCenterY = 0;



SurfaceHolder mSurfaceHolder;
public ExampleSurfaceView(Context context) {
super(context);
mSurfaceHolder = getHolder();
mSurfaceHolder.addCallback(this);
mThread = new DrawingThread();
mPaint.setColor(0xFFFFFFFF);
mPaint.setStyle(Paint.Style.FILL);


// TODO Auto-generated constructor stub
}


@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// 当视图尺寸变化时此方法被调用
mVertices[0] = width/2;
mVertices[1] = height/2;
mVertices[2] = width/2+width/5;
mVertices[3] = height/2+width/5;
mVertices[4] = width/2;
mVertices[5] = height/2+width/5;
mCenterX = width/2 + width/10;
mCenterY = height/2 + width/10;
}


@Override
public void surfaceCreated(SurfaceHolder holder) {
//此处开始绘图
mThread.keepRunning = true;
mThread.start();

}


@Override
public void surfaceDestroyed(SurfaceHolder arg0) {
mThread.keepRunning = false;
boolean retry = true;
while (retry) {
try {
mThread.join();
retry = false;

}catch (InterruptedException e){}
}
}
//内部类，绘图线程
private class DrawingThread extends Thread{
boolean keepRunning = true;

@Override
public void run() {
// TODO Auto-generated method stub
Canvas c;
while (keepRunning) {
c = null;
try {


c = mSurfaceHolder.lockCanvas();
synchronized (mSurfaceHolder) {
mAngle +=1;
onDraw(c);
}
}finally {
if(c != null)
mSurfaceHolder.unlockCanvasAndPost(c);
}
try {
Thread.sleep(20);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

}


@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
canvas.drawRGB(mRed, mGreen, mBlue);
canvas.rotate(mAngle, mCenterX, mCenterY);

canvas.drawVertices(Canvas.VertexMode.TRIANGLES, 6, mVertices, 0, null, 0, mColors, 0, null, 0, 0, mPaint);
}


@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
case MotionEvent.ACTION_MOVE:
synchronized(mSurfaceHolder) {
mRed = (int) (255*event.getX()/getWidth());
mGreen = (int) (255*event.getY()/getHeight());
}
return true;
}
return super.onTouchEvent(event);
}


}