"""
draw_polygon.py
Draw a simple polygon using matplotlib with mouse event handling
Copyright (C) 2013 Greg von Winckel
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
Created: Sat Oct 26 22:04:59 MDT 2013
"""
import matplotlib.pyplot as plt
[docs]
class Canvas(object):
def __init__(self,ax):
self.ax = ax
# Set limits to unit square
# self.ax.set_xlim((0,1))
# self.ax.set_ylim((0,1))
# turn off axis
self.ax.set_xticklabels([])
self.ax.set_yticklabels([])
self.path, = ax.plot([],[],'o-',lw=3)
self.vert = []
self.ax.set_title('LEFT: new point, MIDDLE: delete last point, RIGHT: close polygon')
self.x = []
self.y = []
self.mouse_button = {1: self._add_point, 2: self._delete_point, 3: self._close_polygon}
[docs]
def set_location(self,event):
if event.inaxes:
self.x = event.xdata
self.y = event.ydata
def _add_point(self):
self.vert.append((self.x,self.y))
def _delete_point(self):
if len(self.vert)>0:
self.vert.pop()
def _close_polygon(self):
self.vert.append(self.vert[0])
[docs]
def update_path(self,event):
# If the mouse pointer is not on the canvas, ignore buttons
if not event.inaxes: return
# Do whichever action correspond to the mouse button clicked
self.mouse_button[event.button]()
x = [self.vert[k][0] for k in range(len(self.vert))]
y = [self.vert[k][1] for k in range(len(self.vert))]
self.path.set_data(x,y)
plt.draw()
if __name__ == '__main__':
fig = plt.figure(1,(8,8))
ax = fig.add_subplot(111)
cnv = Canvas(ax)
plt.connect('button_press_event',cnv.update_path)
plt.connect('motion_notify_event',cnv.set_location)
plt.show()