实现一个通过鼠标右键菜单切换的简单绘图程序，可以尝试绘制直线、三角形、正方形等常见图形。

创建一个简单的绘图程序，允许用户通过鼠标右键菜单选择绘制不同形状，可以使用一些基本的图形库，如Python的Tkinter或JavaScript的HTML5 Canvas。这里是一个简化的Python Tkinter示例：

import tkinter as tk
from tkinter import messagebox

class DrawingCanvas(tk.Canvas):
    def __init__(self, master):
        super().__init__(master)
        self.line_color = "black"
        self.shapes = {"line": self.draw_line, "triangle": self.draw_triangle, "square": self.draw_square}

    def bind_right_click(self):
        self.bind("<Button-3>", self.show_menu)

    def show_menu(self, event):
        menu = tk.Menu(self, tearoff=0)
        for shape in self.shapes.keys():
            menu.add_command(label=shape, command=lambda s=shape: self.start_shape(s))
        menu.post(event.x_root, event.y_root)

    def start_shape(self, shape):
        self.shapes[shape]()
        self.update()

    def draw_line(self):
        x1, y1 = self.canvasx(0), self.canvasy(0)
        x2, y2 = self.canvasx(200), self.canvasy(200)  # 这里只是一个示例，实际应获取点击点坐标
        self.create_line(x1, y1, x2, y2, fill=self.line_color)

    def draw_triangle(self):
        x1, y1 = self.canvasx(50), self.canvasy(50)
        x2, y2 = self.canvasx(150), self.canvasy(50)
        x3, y3 = self.canvasx(100), self.canvasy(100)
        self.create_polygon([x1, y1, x2, y2, x3, y3], outline=self.line_color, fill="none")

    def draw_square(self):
        x, y = self.canvasx(75), self.canvasy(75)
        side_length = 100
        self.create_rectangle(x, y, x + side_length, y + side_length, outline=self.line_color, fill="white")

root = tk.Tk()
canvas = DrawingCanvas(root)
canvas.pack()
canvas.bind_right_click()
root.mainloop()