【python基础】 Tkinter小构件之canvas 画布

【python之tkinter画布】

 本文代码来源于机械工业出版社的一本python书籍.

要画布就要使用tkinter的小构件，canvas(结构化的图形，用于绘制图形，创建图形编辑器以及实现自定制的小构件类)

我们先使用create_rectangle, create_oval, create_arc, create_polygon, create_line分别绘制矩形，椭圆，圆弧，多边形，线段。

创建CanvasDemo.py的文件，代码如下：

# -*- coding: utf-8 -*-
###################
#画布，使用Canvas小构件
###################
from Tkinter import *

class CanvasDemo:
    def __init__(self):
        window = Tk() #创建窗口
        window.title("Canvas Demo") #给窗口命名

        #在窗口画布
        self.canvas = Canvas(window, width = 200, height = 100, bg = "white")
        self.canvas.pack()

        #创建frame的框架，窗口window为这个框架的父容器
        frame = Frame(window)
        frame.pack()
        #frame框架作为Button的父容器
        btRectangle = Button(frame, text="rectangle", command = self.displayRect)
        btOval = Button(frame, text = "Oval", command = self.displayOval)
        btArc = Button(frame, text = "Arc", command = self.displayArc)
        btPolygon = Button(frame, text = "Polygon", command = self.displayPolygon)
        btLine = Button(frame, text = "Line", command = self.displayLine)
        btString = Button(frame, text = "String", command = self.displayString)
        btClear = Button(frame, text = "Clear", command = self.displayClear)

        #Button在画布上布局
        btRectangle.grid(row = 1, column = 1)
        btOval.grid(row = 1, column = 2)
        btArc.grid(row = 1, column = 3)
        btPolygon.grid(row = 1, column = 4)
        btLine.grid(row = 1, column = 5)
        btString.grid(row = 1, column = 6)
        btClear.grid(row = 1, column = 7)

        #创建事件循环直到关闭主窗口
        window.mainloop()

    def displayRect(self):
        self.canvas.create_rectangle(10,10,190,90,tags = "rect")

    #fill填充oval的颜色
    def displayOval(self):
        self.canvas.create_oval(10,10,190,90, fill = "red", tags = "oval")

    # start为开始的度数，extent为要转的度数.全部以逆时针为正方向，0为x轴正方向
    def displayArc(self):
        self.canvas.create_arc(10,10,190,90, start = 0, extent = 90, width = 8, fill = "red",tags = "arc")

    def displayPolygon(self):
        self.canvas.create_polygon(10,10,190,90,10,90,tags = "polygon")

    #arrow表示line指向，activefill：当鼠标在line上时出现的特定风格，本例中鼠标移动到第二个line上时line变蓝
    def displayLine(self):
        self.canvas.create_line(10,10,190,90,fill = "red",tags = "line")
        self.canvas.create_line(10,90,190,10,width = 9,arrow = "first",activefill = "blue", tags = "line")

    #font定义字体（字体名，大小，风格）
    def displayString(self):
        self.canvas.create_text(60,40,text= "hi, i am string", font = "time 10 bold underline", tags = "string")

    #delete方法通过tags参数从画布上删除图形
    def displayClear(self):
        self.canvas.delete("rect","oval","arc","polygon","line","string")

CanvasDemo()

运行程序即可。

可能你不知道create_xx()里的数字意思，其实是坐标（x1,y1）,（x2,y2）,（x3,y3）create_xx(x1,y1,x2,y2,x3,y3)

Tkinter的坐标系是这样的：

2018.4.25更新: 经过Pangolin２ 的提醒上图错了, 在python3.6中x为横向(向右为正方向), y为纵向(向下为正方向), 偷个懒, 图就不改了哈.