htdp-draw-helper.py

from Tkinter import *
from math import hypot

class CircleDrawing:
    def __init__(self, canvas):
        self.canvas = canvas
    def click(self, e, color):
        self.color = color
        self.center = e.x, e.y
        self.obj_id = self.canvas.create_oval(e.x, e.y, e.x, e.y, outline=color)
    def drag(self, e):
        x1, y1 = self.center
        self.radius = distance = int(hypot(e.x-x1, e.y-y1))
        self.canvas.delete(self.obj_id)
        self.obj_id = self.canvas.create_oval(x1-distance, y1-distance, x1+distance, y1+distance, outline=self.color)
    def __str__(self):
        return "(draw-circle (make-posn {0[0]} {0[1]}) {1} '{2})".format(
            self.center, self.radius, self.color)

class LineDrawing:
    def __init__(self, canvas):
        self.canvas = canvas
    def click(self, e, color):
        self.color = color
        self.start = e.x, e.y
        self.obj_id = self.canvas.create_line(e.x, e.y, e.x, e.y, fill=self.color)
    def drag(self, e):
        x1, y1 = self.start
        self.end = e.x, e.y
        self.canvas.delete(self.obj_id)
        self.obj_id = self.canvas.create_line(x1, y1, e.x, e.y, fill=self.color)
    def __str__(self):
        return "(draw-solid-line (make-posn {0[0]} {0[1]}) (make-posn {1[0]} {1[1]}) '{2})".format(
            self.start, self.end, self.color)

class ShapeDump(Frame):
    def __init__(self, parent):
        self.objs = []

        Frame.__init__(self, parent)
        self.canvas = Canvas(self)
        self.canvas.pack(expand=1, fill=BOTH)
        self.canvas.bind('<Button-1>', self.click)
        self.canvas.bind('<ButtonRelease-1>', self.done)
        self.canvas.bind('<B1-Motion>', self.drag)

        frame = Frame(self)
        frame.pack(fill=BOTH)
        Button(frame, text='circle', command=self.set_circle_mode).pack(side=LEFT, expand=1, fill=BOTH)
        Button(frame, text='line', command=self.set_line_mode).pack(side=LEFT, expand=1, fill=BOTH)
        Button(frame, text='POP', command=self.pop).pack(side=LEFT, expand=1, fill=BOTH)
        Button(frame, text='DUMP', command=self.dump).pack(side=LEFT, expand=1, fill=BOTH)
        Button(frame, text='CLEAR', command=self.clear).pack(side=LEFT, expand=1, fill=BOTH)

        frame = Frame(self)
        frame.pack(fill=BOTH)
        for color in ('red', 'black', 'blue'):
            Button(frame, text="'"+color, command=lambda c=color: self.set_color(c)).pack(
                side=LEFT, expand=1, fill=BOTH)

        self.set_circle_mode()
        self.set_color('black')

    def set_color(self, color):
        self.color = color
    def set_circle_mode(self):
        self.drawing_cls = CircleDrawing
    def set_line_mode(self):
        self.drawing_cls = LineDrawing
    def click(self, e):
        self.drawing = self.drawing_cls(self.canvas)
        self.drawing.click(e, self.color)
    def drag(self, e):
        self.drawing.drag(e)
    def done(self, e):
        self.objs.append(self.drawing)
    def pop(self):
        obj = self.objs.pop()
        self.canvas.delete(obj.obj_id)
    def dump(self):
        for obj in self.objs:
            print obj
    def clear(self):
        del self.objs[:]
        self.canvas.delete(ALL)


root = Tk()
ShapeDump(root).pack(expand=1, fill=BOTH)
mainloop()