编辑代码

# coding:utf-8
#JSRUN引擎2.0，支持多达30种语言在线运行，全仿真在线交互输入输出。 
from tkinter import *
from tkinter.filedialog import *
from tkinter.colorchooser import *

win_width=900
win_heigth=450

class Application(Frame):

    def __init__(self, master=None,bgcolor='#000000'):
        super().__init__(master) # super()代表的是父类的定义，而不是父类对象
        self.master = master
        self.bgcolor = bgcolor
        self.pack()
        self.fgcolor = '#ff0000'
        self.createWidget()
        self.x=0
        self.y=0
        self.lastDraw = 0#表示最后绘制的图形
        self.startDrawFlag=False
        

    def createWidget(self):
        self.canvas=Canvas(self,width=win_width,height=win_heigth*0.9,bg=self.bgcolor)
        self.canvas.pack()

        btn_pen = Button(root,text="画笔",name="pen")
        btn_pen.pack(side="left",padx="10")
        btn_rect = Button(root,text="矩形",name="rect")
        btn_rect.pack(side="left",padx="10")
        btn_clear = Button(root,text="清屏",name="clear")
        btn_clear.pack(side="left",padx="10")
        btn_erasor = Button(root,text="橡皮擦",name="erasor")
        btn_erasor.pack(side="left",padx="10")
        btn_line = Button(root,text="直线",name="line")
        btn_line.pack(side="left",padx="10")
        btn_lineArrow = Button(root,text="箭头",name="lineArrow")
        btn_lineArrow.pack(side="left",padx="10")
        self.btn_color = Button(root,text="颜色",name="color")
        self.btn_color.pack(side="left",padx="10")

        #事件处理
        btn_pen.bind_class("Button","<Button-1>",self.eventManager)
        self.canvas.bind('<ButtonRelease-1>',self.stopDraw)#增加事件：鼠标左键释放是会停止画线

    def eventManager(self,event):#发生的全部事件包装成一个对象放入event里
        event_name=event.widget.winfo_name()
        print(event_name)
        if event_name == 'line':
            self.canvas.bind('<B1-Motion>',self.myline)#每次拖动都会触发myline方法
        elif event_name == 'lineArrow':
            self.canvas.bind('<B1-Motion>',self.mylineArrwo)
        elif event_name == 'rect':
            self.canvas.bind('<B1-Motion>',self.myRect)
        elif event_name == 'pen':
            self.canvas.bind('<B1-Motion>',self.myPen)
        elif event_name == 'erasor':
            self.canvas.bind('<B1-Motion>',self.myErasor)
        elif event_name == 'clear':
            self.canvas.delete('all')
        elif event_name == 'color:
            c = askcolor(color=self.fgcolor)
            self.fgcolor=c[1]

    def myRect(self,event):
        self.startDraw(event)

        self.lastDraw=self.canvas.create_rectangle(self.x,self.y,event.x,event.y,outline=self.fgcolor)#outline就是空心矩形，fill就是填充矩形

    def startDraw(self,event):
        self.canvas.delete(self.lastDraw)#会反复进入myline方法，所以要删除上一次进入myline时划得线

        if not self.startDrawFlag:
            self.startDrawFlag=True
            self.x=event.x
            self.y=event.y

    def mylineArrwo(self,event):
        self.startDraw(event)

        self.lastDraw=self.canvas.create_line(self.x,self.y,event.x,event.y,fill=self.fgcolor,arrow=LAST)



    def stopDraw(self,event):
        self.startDrawFlag=False
        self.lastDraw=0

    def myline(self,event):
        self.startDraw(event)

        self.lastDraw=self.canvas.create_line(self.x,self.y,event.x,event.y,fill=self.fgcolor)

    def myPen(self,event):
        self.startDraw(event)

        self.canvas.create_line(self.x,self.y,event.x,event.y,fill=self.fgcolor)
        self.x=event.x
        self.y=event.y

    def myErasor(self,event):
        self.startDraw(event)

        self.canvas.create_rectangle(self.x,self.y,event.x,event.y,fill=self.bgcolor)
        self.x=event.x
        self.y=event.y

    



if __name__ == '__main__':
    root = Tk()
    root.geometry(str(win_width)+"x"+str(win_heigth)+"+200+300")
    root.title("百战程序员的简易记事本")
    app = Application(master=root)
    root.mainloop()