Python tkinter事件高级用法实例

# -*- coding:utf-8-*-#! python3from tkinter import *import threading, timetrace = 0class CanvasEventsDemo:  def __init__(self, parent=None):    canvas = Canvas(width=300, height=300, bg='beige')    canvas.pack()    canvas.bind('<ButtonPress-1>', self.onStart)   # click    canvas.bind('<B1-Motion>',   self.onGrow)    # and drag    canvas.bind('<Double-1>',   self.onClear)   # delete all    canvas.bind('<ButtonPress-3>', self.onMove)    # move latest    self.canvas = canvas    self.drawn = None    self.kinds = [canvas.create_oval, canvas.create_rectangle]  def onStart(self, event):    self.shape = self.kinds[0]    self.kinds = self.kinds[1:] + self.kinds[:1]   # start dragout    self.start = event    self.drawn = None  def onGrow(self, event):               # delete and redraw    canvas = event.widget    if self.drawn: canvas.delete(self.drawn)    objectId = self.shape(self.start.x, self.start.y, event.x, event.y)    if trace: print(objectId)    self.drawn = objectId  def onClear(self, event):    event.widget.delete('all')            # use tag all  def onMove(self, event):    if self.drawn:                  # move to click spot      if trace: print(self.drawn)      canvas = event.widget      diffX, diffY = (event.x - self.start.x), (event.y - self.start.y)      canvas.move(self.drawn, diffX, diffY)      self.start = eventclass CanvasEventsDemoTags(CanvasEventsDemo):  def __init__(self, parent=None):    CanvasEventsDemo.__init__(self, parent)    self.canvas.create_text(100, 8, text='Press o and r to move shapes')    self.canvas.master.bind('<KeyPress-o>', self.onMoveOvals)    self.canvas.master.bind('<KeyPress-r>', self.onMoveRectangles)    self.kinds = self.create_oval_tagged, self.create_rectangle_tagged  def create_oval_tagged(self, x1, y1, x2, y2):    objectId = self.canvas.create_oval(x1, y1, x2, y2)    self.canvas.itemconfig(objectId, tag='ovals', fill='blue')    return objectId  def create_rectangle_tagged(self, x1, y1, x2, y2):    objectId = self.canvas.create_rectangle(x1, y1, x2, y2)    self.canvas.itemconfig(objectId, tag='rectangles', fill='red')    return objectId  def onMoveOvals(self, event):    print('moving ovals')    self.moveInSquares(tag='ovals')      # move all tagged ovals  def onMoveRectangles(self, event):    print('moving rectangles')    self.moveInSquares(tag='rectangles')  def moveInSquares(self, tag):         # 5 reps of 4 times per sec    for i in range(5):      for (diffx, diffy) in [(+20, 0), (0, +20), (-20, 0), (0, -20)]:        self.canvas.move(tag, diffx, diffy)        self.canvas.update()       # force screen redraw/update        time.sleep(0.25)         # pause, but don't block guiclass CanvasEventsDemoThread(CanvasEventsDemoTags):  def moveEm(self, tag):    for i in range(5):      for (diffx, diffy) in [(+20, 0), (0, +20), (-20, 0), (0, -20)]:        self.canvas.move(tag, diffx, diffy)        time.sleep(0.25)           # pause this thread only  def moveInSquares(self, tag):    threading.Thread(self.moveEm, (tag,)).start()if __name__ == '__main__':  CanvasEventsDemoThread()  mainloop()