老师，请问，我有四个问题：1、创建的实例对象app是放在root窗口哪里的呢，在没有创建canvas对象的时候，将self.bgcolor="#000000",实例对象app的背景颜色设置成黑色，运行之后也没看到黑色区域。
2、在画直线代码的时候，self.x 和 self.y是什么意思呢
3、在橡皮擦代码的时候，起始点，终点的坐标是什么意思呢，event.x-4,event.y-4,event.x+4,event.y+4。
4、然用fgcolor测试橡皮擦的时候,是这种，跟老师运行之后的不一样
# coding=utf-8
from tkinter.filedialog import *
from tkinter.colorchooser import *
#窗口的宽度和高度
win_width=900
win_height=450
class Application(Frame):
def __init__(self,master=None,bgcolor="#000000"):
super().__init__(master)
self.master=master
self.bgcolor=bgcolor
self.x=0
self.y=0
self.lastDraw=0
self.startDrawFlag=False
self.pack()
self.fgcolor = "#ff0000"
self.createWidget()
def createWidget(self):
#创建绘图区
self.drawpad=Canvas(root,width=win_width,height=win_height*0.9,bg=self.bgcolor)
self.drawpad.pack()
#创建按钮
btn_start=Button(root,text="开始",name="start")
btn_start.pack(side="left",padx="10")
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="箭头直线", name="lineArrow")
btn_lineArrow.pack(side="left",padx="10")
btn_start=Button(root,text="开始",name="start")
btn_start.pack(side="left",padx="10")
btn_color = Button(root, text="颜色", name="color")
btn_color.pack(side="left", padx="10")
# 事件处理
btn_pen.bind_class("Button","<1>",self.eventManager)
self.drawpad.bind("<ButtonRelease-1>",self.stopDraw)
# 添加切换颜色的快捷键
root.bind("<KeyPress-r>",self.kuaijiejian)
root.bind("<KeyPress-g>",self.kuaijiejian)
root.bind("<KeyPress-y>",self.kuaijiejian)
def eventManager(self,event):
name=event.widget.winfo_name()
print(name)
if name=="line":
self.drawpad.bind("<B1-Motion>",self.myline)
elif name=="lineArrow":
self.drawpad.bind("<B1-Motion>",self.mylineArrow)
elif name=="rect":
self.drawpad.bind("<B1-Motion>",self.myRect)
elif name=="pen":
self.drawpad.bind("<B1-Motion>",self.myPen)
elif name=="erasor":
self.drawpad.bind("<B1-Motion>",self.myErasor)
elif name=="clear":
self.drawpad.delete("all")
elif name=="color":
c=askcolor(color=self.fgcolor,title="选择画笔颜色")
self.fgcolor=c[1]
def stopDraw(self,event):
self.startDrawFlag=False
self.lastDraw=0
def startDraw(self,event):
self.drawpad.delete(self.lastDraw)
if not self.startDrawFlag:
self.x=event.x
self.y=event.y
self.startDrawFlag=True
def myline(self,event):
self.startDraw(event)
self.lastDraw = self.drawpad.create_line(self.x, self.y, event.x, event.y, fill=self.fgcolor)
def mylineArrow(self,event):
self.startDraw(event)
self.lastDraw=self.drawpad.create_line(self.x,self.y,event.x,event.y,arrow=LAST,fill=self.fgcolor)
def myRect(self,event):
self.startDraw(event)
self.lastDraw=self.drawpad.create_rectangle(self.x,self.y,event.x,event.y,outline=self.fgcolor)
def myPen(self,event):
self.startDraw(event)
self.drawpad.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.drawpad.create_rectangle(event.x-4,event.y-4,event.x+4,event.y+4,fill=self.fgcolor)
self.x=event.x
self.y=event.y
def kuaijiejian(self,event):
if event.char=="r":
self.fgcolor="#ff0000"
elif event.char=="g":
self.fgcolor="#00ff00"
elif event.char=="y":
self.fgcolor="#ffff00"
if __name__=="__main__":
root=Tk()
root.geometry(str(win_width)+'x'+str(win_height)+"+200+300")
root.title("百战程序员的简易记事本")
app=Application(master=root)
root.mainloop()
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