.. _event_handling-poly_editor: event_handling example code: poly_editor.py =========================================== [`source code `_] :: """ This is an example to show how to build cross-GUI applications using matplotlib event handling to interact with objects on the canvas """ import numpy as np from matplotlib.lines import Line2D from matplotlib.artist import Artist from matplotlib.mlab import dist_point_to_segment class PolygonInteractor(object): """ An polygon editor. Key-bindings 't' toggle vertex markers on and off. When vertex markers are on, you can move them, delete them 'd' delete the vertex under point 'i' insert a vertex at point. You must be within epsilon of the line connecting two existing vertices """ showverts = True epsilon = 5 # max pixel distance to count as a vertex hit def __init__(self, ax, poly): if poly.figure is None: raise RuntimeError('You must first add the polygon to a figure or canvas before defining the interactor') self.ax = ax canvas = poly.figure.canvas self.poly = poly x, y = zip(*self.poly.xy) self.line = Line2D(x, y, marker='o', markerfacecolor='r', animated=True) self.ax.add_line(self.line) #self._update_line(poly) cid = self.poly.add_callback(self.poly_changed) self._ind = None # the active vert canvas.mpl_connect('draw_event', self.draw_callback) canvas.mpl_connect('button_press_event', self.button_press_callback) canvas.mpl_connect('key_press_event', self.key_press_callback) canvas.mpl_connect('button_release_event', self.button_release_callback) canvas.mpl_connect('motion_notify_event', self.motion_notify_callback) self.canvas = canvas def draw_callback(self, event): self.background = self.canvas.copy_from_bbox(self.ax.bbox) self.ax.draw_artist(self.poly) self.ax.draw_artist(self.line) self.canvas.blit(self.ax.bbox) def poly_changed(self, poly): 'this method is called whenever the polygon object is called' # only copy the artist props to the line (except visibility) vis = self.line.get_visible() Artist.update_from(self.line, poly) self.line.set_visible(vis) # don't use the poly visibility state def get_ind_under_point(self, event): 'get the index of the vertex under point if within epsilon tolerance' # display coords xy = np.asarray(self.poly.xy) xyt = self.poly.get_transform().transform(xy) xt, yt = xyt[:, 0], xyt[:, 1] d = np.sqrt((xt - event.x)**2 + (yt - event.y)**2) indseq = np.nonzero(np.equal(d, np.amin(d)))[0] ind = indseq[0] if d[ind] >= self.epsilon: ind = None return ind def button_press_callback(self, event): 'whenever a mouse button is pressed' if not self.showverts: return if event.inaxes is None: return if event.button != 1: return self._ind = self.get_ind_under_point(event) def button_release_callback(self, event): 'whenever a mouse button is released' if not self.showverts: return if event.button != 1: return self._ind = None def key_press_callback(self, event): 'whenever a key is pressed' if not event.inaxes: return if event.key == 't': self.showverts = not self.showverts self.line.set_visible(self.showverts) if not self.showverts: self._ind = None elif event.key == 'd': ind = self.get_ind_under_point(event) if ind is not None: self.poly.xy = [tup for i, tup in enumerate(self.poly.xy) if i != ind] self.line.set_data(zip(*self.poly.xy)) elif event.key == 'i': xys = self.poly.get_transform().transform(self.poly.xy) p = event.x, event.y # display coords for i in range(len(xys) - 1): s0 = xys[i] s1 = xys[i + 1] d = dist_point_to_segment(p, s0, s1) if d <= self.epsilon: self.poly.xy = np.array( list(self.poly.xy[:i]) + [(event.xdata, event.ydata)] + list(self.poly.xy[i:])) self.line.set_data(zip(*self.poly.xy)) break self.canvas.draw() def motion_notify_callback(self, event): 'on mouse movement' if not self.showverts: return if self._ind is None: return if event.inaxes is None: return if event.button != 1: return x, y = event.xdata, event.ydata self.poly.xy[self._ind] = x, y self.line.set_data(zip(*self.poly.xy)) self.canvas.restore_region(self.background) self.ax.draw_artist(self.poly) self.ax.draw_artist(self.line) self.canvas.blit(self.ax.bbox) if __name__ == '__main__': import matplotlib.pyplot as plt from matplotlib.patches import Polygon theta = np.arange(0, 2*np.pi, 0.1) r = 1.5 xs = r*np.cos(theta) ys = r*np.sin(theta) poly = Polygon(list(zip(xs, ys)), animated=True) fig, ax = plt.subplots() ax.add_patch(poly) p = PolygonInteractor(ax, poly) #ax.add_line(p.line) ax.set_title('Click and drag a point to move it') ax.set_xlim((-2, 2)) ax.set_ylim((-2, 2)) plt.show() Keywords: python, matplotlib, pylab, example, codex (see :ref:`how-to-search-examples`)