Android：如何将OnTouchListener添加到Canvas？

Question

I have a class with animation on the canvas. I need to handle touching, but OnTouchListener doesn't work. I tried to put a listener to main activity, but it didn't work anyway.

public class Animation extends View implements View.OnTouchListener{

    private Paint paint;
    private Snake snake;

    public Animation(Context context) {
        super(context);
        snake = new Snake(10, 10, 1, 0, 1, 50);
        paint = new Paint();
        paint.setColor(Color.BLACK);
    }

    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        snake.move(canvas);
        invalidate();
    }

    public boolean onTouch(View v, MotionEvent event) {
        System.out.println("asfaf");
        float x = event.getX();
        float y = event.getY();

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                System.out.println(x + ' ' + y);
                break;
            case MotionEvent.ACTION_MOVE:
                System.out.println(x + ' ' + y);
                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_CANCEL:
                System.out.println(x + ' ' + y);
                break;
        }
        return true;
    }

}

Answer 1

Replace your onTouch() method with onTouchEvent() .

@Override
public boolean onTouchEvent(MotionEvent event) {
    System.out.println("asfaf");
    float x = event.getX();
    float y = event.getY();

    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            System.out.println(x + ' ' + y);
            break;
        case MotionEvent.ACTION_MOVE:
            System.out.println(x + ' ' + y);
            break;
        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_CANCEL:
            System.out.println(x + ' ' + y);
            break;
    }
    return true;
}

and remove implements View.OnTouchListener .

Answer 2

删除implements View.OnTouchListener从你的类，并把一个@Override在你onTouchEvent()方法。