如何交换两个圈子

Question

I drew 36 circles on Canvas in my class which is extended from View class.

What I want to learn about, how can I change their positions between two of them like Two Dots game in Play Store.

How can I do that?

Here is my onDraw method code:

@Override
protected void onDraw (Canvas canvas){
    // TODO Auto-generated method stub
    super.onDraw(canvas);
    int xArt = 0, yArt = 0, x, y;
    x = getWidth() / 4 - 50;
    y = getHeight() / 2 - 50;

    canvas.drawARGB(96, 25, 139, 10);
    for (int i = 1; i < 37; i++) {
        canvas.drawCircle(x + xArt, y + yArt, 30, paint.get(i));

        yArt += 100;
        if (i % 6 == 0) {
            xArt += 100;
            yArt = 0;
        }
    }

}

Here is the picture: tinypic.com/r/20a9m4j/9

Answer 1

So you have 36 circles drawn in a custom View and you want to swap just two of them? It is possible. Just store the x and y coordinates ( x + xArt, y + yArt ) of the circles in an ArrayList . You can later use this to swap the circles. But swapping here means that you need to redraw all the 36 circles. That's the problem with custom view, even if you make a slight change you need to redraw the whole view.

In your case, I think this is expensive and unnecessary. Instead, what you need to do is write a custom ViewGroup or use any layout if that's sufficient. Add your Circles as children to the ViewGroup . Now you can simply use getChild and swap them. This will not require you to redraw all the 36 circles.