如何使用Zelle的'graphics.py'程序正确创建移动形状的函数？

Question

Question 17 of Ch. 6 in Zelle's 'Programming Python' books asks for a function that takes two arguments: 'shape', and 'newCenter', which will then move, or re-draw, an existing object based on the new points provided by a mouse-click.

I've been able to figure out how to do it if I add two more parameters to the function, "myX", and "myY", so I can then subtract the difference for the move method. What is eluding me is how to perform the same calculations using just the two parameters specified above. Here is my code:

def moveTo(shape, newCenter, myX, myY):
    myShape = shape
    myNewX = newCenter.getX()
    myNewY = newCenter.getY()
    myXUpd = myNewX - myX
    myYUpd = myNewY - myY
    myShape.move(myXUpd, myYUpd)
    return myNewX, myNewY

def main():
    win = GraphWin("My Graph Win", 500, 500)
    win.setBackground("white")
    win.setCoords(0, 0, 10, 10)
    Text(Point(5, 8.5), "Please click 10 times.").draw(win)
    myPoint = win.getMouse()
    myX = myPoint.getX()
    myY = myPoint.getY()
    myCircle = Circle(myPoint, 2)
    myCircle.draw(win)

    for x in range(1, 10):
        myNewPoint = win.getMouse()
        myX, myY = moveTo(myCircle, myNewPoint, myX, myY)

    win.close()

Also, any general tips for streamlining, style, or structure are also appreciated as I'm a rather new Python developer.

Thanks!

Answer 1

I figured this out on my own, so anyone going through the Zelle "Python Programming" book can learn from my experience. I just pulled the X and Y out of the shape object I was passing in, thus saving myself having to pass them in again separately. Here is the updated code with some of the fat trimmed down.

def moveTo(shape, newCenter):
    oldCenter = shape.getCenter()
    myOldX, myOldY = oldCenter.getX(), oldCenter.getY()
    myNewX, myNewY = newCenter.getX(), newCenter.getY()
    moveX = myNewX - myOldX
    moveY = myNewY - myOldY
    shape.move(moveX, moveY)
    return shape

def main():
    win = GraphWin("My Graph Win", 500, 500)
    win.setBackground("white")
    win.setCoords(0, 0, 10, 10)
    Text(Point(5, 8.5), "Please click 10 times.").draw(win)
    myPoint = win.getMouse()
    myX, myY = myPoint.getX(), myPoint.getY()
    myShape = Circle(myPoint, 2)
    myShape.draw(win)

    for x in range(1, 10):
        newCenter = win.getMouse()
        myShape = moveTo(myShape, newCenter)


    win.close()