android如何在触摸事件中每隔3秒随机xy绘制位图

Question

public class MyGameView extends View implements OnTouchListener{

    static int x, y;
    final static int radius = 25;
    private int androidX;
    private int androidY;
    Paint paint;
    Bitmap android;
    boolean touch = false;
    Handler handler = new Handler();

    private Runnable r = new Runnable() {

        @Override
        public void run() {
            invalidate();

        }


    };

    private Runnable r2 = new Runnable() {

        @Override
        public void run() {
            androidX = (int) Math.ceil(Math.random() * (MyGameView.this.getWidth()-android.getWidth()));
            androidY = (int) Math.ceil(Math.random() * (MyGameView.this.getHeight()-android.getHeight()));
        }
    };

    public MyGameView(Context context) {
        super(context);
        paint = new Paint();
        paint.setAntiAlias(true); // smooth rendering
        android = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
        setFocusable(true);
        setOnTouchListener(this);

    }


    @Override
    protected void onDraw(Canvas canvas) {
        if(touch == true){
            paint.setARGB(255, 222, 78, 112);
            canvas.drawBitmap(android, androidX, androidY, null);
            canvas.drawCircle(x,y,radius,paint);
        }
        handler.postDelayed(r, 1000);
        handler.postDelayed(r2, 3000);
        super.onDraw(canvas);
    }


    @Override
    public boolean onTouch(View view, MotionEvent event) {
        x=(int)event.getX()-(radius/2);      
        y=(int)event.getY()-(radius/2);
        switch(event.getAction()){
        case MotionEvent.ACTION_DOWN:
                touch = true;
                break;

        case MotionEvent.ACTION_UP:
                touch = false;
                break;
        }
        invalidate();  
        return true;
    }

}

Here my code What i want is when i hold my finger the bitmap start drawing every 3 second in random position x y. Everything work but the problem image draw like crazy to every position and i can't figure how to do that i try calling invalidate() on ACTION_DOWN but now my circle draw every 3 second to the position i touch. Any help is appreciate.

Answer 1

I'm not convinced that I totally understand what you want, but the problem with your code is the following: onDraw is called very often. In each of those calls, you run r2 with a delay of 3 seconds. So effectively, r2 is just run as often as onDraw , but the first time is delayed for 3 seconds.

What I think you want to do instead is run r2 in a separate thread and continuously update the position every 3 seconds, as in:

public class MyGameView extends View implements OnTouchListener{

    static int x, y;
    final static int radius = 25;
    private int androidX;
    private int androidY;
    Paint paint;
    Bitmap android;
    boolean touch = false;

    private Runnable r2 = new Runnable() {

        @Override
        public void run() {
            androidX = (int) Math.ceil(Math.random() * (MyGameView.this.getWidth()-android.getWidth()));
            androidY = (int) Math.ceil(Math.random() * (MyGameView.this.getHeight()-android.getHeight()));
        }
    };

    public MyGameView(Context context) {
        super(context);
        paint = new Paint();
        paint.setAntiAlias(true); // smooth rendering
        android = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
        setFocusable(true);
        setOnTouchListener(this);

        new Thread(r2).start(); // run r2 in a separate thread
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if(touch == true){
            paint.setARGB(255, 222, 78, 112);
            canvas.drawBitmap(android, androidX, androidY, null);
            canvas.drawCircle(x,y,radius,paint);
        }        
    }

    @Override
    public boolean onTouch(View view, MotionEvent event) {
        x=(int)event.getX()-(radius/2);      
        y=(int)event.getY()-(radius/2);
        switch(event.getAction()){
        case MotionEvent.ACTION_DOWN:
                touch = true;
                break;
        case MotionEvent.ACTION_UP:
                touch = false;
                break;
        }
        return true;
    }
}