clicking on turtle

[Peter Otten]

Nicolas Graner wrote:

> I have a problem with the standard "turtle" module. When a turtle has
> a custom shape of type "compound", it doesn't seem to respond to click
> events. No problem with polygon shapes.
> 
> Running python 3.2.3, turtle version 1.1b on Windows XP.
> 
> Here is my test file:
> 
> ##################################################
> import turtle
> square = ((0,0),(0,20),(20,20),(20,0))
> turtle.addshape("sq1", square) # sq1 = polygon shape
> s = turtle.Shape("compound")
> s.addcomponent(square, "red")
> turtle.addshape("sq2", s) # sq2 = compound shape
> t1 = turtle.Turtle(shape="sq1")
> t2 = turtle.Turtle(shape="sq2")
> t2.fd(20) # set the turtles side by side
> def click(x,y): print("click at",x,y)
> t1.onclick(click)
> t2.onclick(click)
> turtle.mainloop()
> ##################################################
> 
> When I run this and click on the black square (i.e. t1), the message
> "click at..." gets printed on the console. When I click on the red
> square (i.e. t2), nothing happens.
> 
> Bug or feature?

I believe it's a bug. Please report it on http://bugs.python.org
As a quick-fix here's a monkey patch that seems to work:

import turtle

def _onclick(self, item, fun, num=1, add=None):
    if isinstance(item, list):
        for item in item:
            self._onclick(item, fun, num, add)
        return

    if fun is None:
        self.cv.tag_unbind(item, "<Button-%s>" % num)
    else:
        def eventfun(event):
            x, y = (self.cv.canvasx(event.x)/self.xscale,
                    -self.cv.canvasy(event.y)/self.yscale)
            fun(x, y)

        self.cv.tag_bind(item, "<Button-%s>" % num, eventfun, add)

turtle.TurtleScreenBase._onclick = _onclick

square = ((0,0),(0,20),(20,20),(20,0))
turtle.addshape("sq1", square) # sq1 = polygon shape
s = turtle.Shape("compound")
s.addcomponent(square, "red")
turtle.addshape("sq2", s) # sq2 = compound shape
t1 = turtle.Turtle(shape="sq1")
t2 = turtle.Turtle(shape="sq2")
t2.fd(20) # set the turtles side by side
def click(x,y): print("click at",x,y)
t1.onclick(click)
t2.onclick(click)
turtle.mainloop()