[Python编程(第4版)].(Programming.Python.4th.Edition).Mark.Lutz.文字版

pickPens = ['elastic', 'scribble', 'trails']

class MovingPics:
def init(self, parent=None):
canvas = Canvas(parent, width=500, height=500, bg= 'white')
canvas.pack(expand=YES, fill=BOTH)
canvas.bind('', self.onStart)
canvas.bind('', self.onGrow)
canvas.bind('', self.onClear)
canvas.bind('', self.onMove)
canvas.bind('', self.onSelect)
canvas.bind('', self.onDrag)
parent.bind('', self.onOptions)
self.createMethod = Canvas.create_oval
self.canvas = canvas
self.moving = []
self.images = []
self.object = None
self.where = None
self.scribbleMode = 0
parent.title('PyDraw - Moving Pictures 1.1')
parent.protocol('WM_DELETE_WINDOW', self.onQuit)
self.realquit = parent.quit
self.textInfo = self.canvas.create_text(
5, 5, anchor=NW,
font=HelpFont,
text='Press? for help')

def onStart(self, event):
self.where = event
self.object = None

def onGrow(self, event):
canvas = event.widget
if self.object and pickPens[0] == 'elastic':
canvas.delete(self.object)
self.object = self.createMethod(canvas,
self.where.x, self.where.y, # start
event.x, event.y, # stop
fill=pickFills[0], width=pickWidths[0])
if pickPens[0] == 'scribble':
self.where = event # from here next time

def onClear(self, event):
if self.moving: return # ok if moving but confusing
event.widget.delete('all') # use all tag
self.images = []
self.textInfo = self.canvas.create_text(
5, 5, anchor=NW,
font=HelpFont,
text='Press? for help')

def plotMoves(self, event):
diffX = event.x - self.where.x # plan animated moves
diffY = event.y - self.where.y # horizontal then vertical

PyDraw: Painting and Moving Graphics| 741