eventBasedAnimationClass.py

# eventBasedAnimationClass.py
# CITATION: This is taken from course notes.
from Tkinter import *

class EventBasedAnimationClass(object):
    def onMousePressed(self, event): pass
    def onKeyPressed(self, event): pass
    def onTimerFired(self): pass
    def redrawAll(self): pass
    def initAnimation(self): pass

    def __init__(self, width=300, height=300):
        self.width = width
        self.height = height
        self.timerDelay = 250 # in milliseconds (set to None to turn off timer)

    def onMousePressedWrapper(self, event):
        self.onMousePressed(event)
        self.redrawAll()

    def onKeyPressedWrapper(self, event):
        self.onKeyPressed(event)
        self.redrawAll()

    def onTimerFiredWrapper(self):
        if (self.timerDelay == None):
            return # turns off timer
        self.onTimerFired()
        self.redrawAll()
        self.canvas.after(self.timerDelay, self.onTimerFiredWrapper)

    def onMouseMovedWrapper(self, event):
        self.canvas = event.widget.canvas
        ctrl  = ((event.state & 0x0004) != 0)
        shift = ((event.state & 0x0001) != 0)    
        self.canvas.data["info"] = eventInfo("mouseMotion", event.x, event.y, ctrl, shift)
        self.canvas.data["motionPosn"] = (event.x, event.y)
        redrawAll(canvas)

    def run(self):
        # create the root and the canvas
        self.root = Tk()
        self.canvas = Canvas(self.root, width=self.width, height=self.height)
        self.canvas.pack()
        self.initAnimation()
        # set up events
        # DK: You can use a local function with a closure
        # to store the canvas binding, like this:
        def f(event): self.onMousePressedWrapper(event)    
        self.root.bind("<Button-1>", f)
        # DK: Or you can just use an anonymous lamdba function, like this:
        self.root.bind("<Key>", lambda event: self.onKeyPressedWrapper(event))
        self.onTimerFiredWrapper()
        # and launch the app (This call BLOCKS, so your program waits
        # until you close the window!)
        self.root.mainloop()

# EventBasedAnimationClass(300,300).run()