我无法弄清楚的递归错误

Question

I am trying to make a scatter plane layout behave how I want it to but when I try to zoom out past a certain point I get the error "RuntimeError: maximum recursion depth exceeded while calling a Python object" I can't figure out why the recursion happens, tho by trial and error I have found out where it happens (it is marked in the code)

here is the traceback: http://pastebin.com/i2z8SXgc

class Controller(ScatterPlaneLayout):
    def __init__(self, **kwargs):
            super(Controller, self).__init__(**kwargs)

    def on_transform(self, instance, value):
        win = self.get_parent_window().size
        this = self.bbox[1]

        if win[0] > this[0] and win[1] > this[1]:
            if self.x < 0:
            self.x = 0
            if self.y < 0:
                self.y = 0
            if this[0] + self.x > win[0]:
                self.set_right(win[0])
            if this[1] + self.y > win[1]:
                self.set_top(win[1])

        else:
            if self.x > 0:
                self.x = 0
            if self.y > 0:
                self.y = 0
               #This is the part that causes the error
            if this[0] + self.x < win[0]:
                self.x = win[0] - this[0]
               #end of error
            if this[1] + self.y < win[1]:
                self.set_top(win[1])

Answer 1

What looks to be causing the error is the code self.x = win[0] - this[0] calling the function on_transform, passing the first if and calling itself all over again and again.

You may want to check that.