18_SurfaceView 其他线程绘图

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;

public class MainActivity extends Activity {     
 
    FastRenderView renderView;           
       
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                             WindowManager.LayoutParams.FLAG_FULLSCREEN);
        renderView = new FastRenderView(this);
        setContentView(renderView);
    }     
   
    protected void onResume() {
        super.onResume();
        renderView.resume();
    }
   
    protected void onPause() {
        super.onPause();        
        renderView.pause();
    }   
 
}

class FastRenderView extends SurfaceView implements Runnable {
    Thread renderThread = null;
    SurfaceHolder holder;
    volatile boolean running = false;
   
    public FastRenderView(Context context) {
        super(context);          
        holder = getHolder();           
    }

    public void resume() {         
        running = true;
        renderThread = new Thread(this);
        renderThread.start();        
    }
   
    public void pause() {       
        running = false;                       
        while(true) {
            try {
                renderThread.join();
                break;
            } catch (InterruptedException e) {
                // retry
            }
        }
        renderThread = null;       
    }
   
    public void run() {
        while(running) { 
            if(!holder.getSurface().isValid())
                continue;
           
            Canvas canvas = holder.lockCanvas();           
            drawSurface(canvas);                                          
            holder.unlockCanvasAndPost(canvas);           
        }
    }       
   
    private void drawSurface(Canvas canvas) {
     Paint paint =  new Paint();
     paint.setColor(Color.RED);
        canvas.drawRGB(255, 255, 0);
        canvas.drawLine(0, 0, 100, 100,paint);
        canvas.drawCircle(canvas.getWidth() / 2, canvas.getHeight() / 2, 40, paint);
        paint.setStyle(Style.FILL);
        paint.setColor(0x770000ff);
        canvas.drawRect(100, 100, 200, 200, paint);
    }
}