.. DO NOT EDIT. .. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY. .. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE: .. "gallery/event_handling/poly_editor.py" .. LINE NUMBERS ARE GIVEN BELOW. .. only:: html .. note:: :class: sphx-glr-download-link-note Click :ref:`here ` to download the full example code .. rst-class:: sphx-glr-example-title .. _sphx_glr_gallery_event_handling_poly_editor.py: =========== Poly Editor =========== This is an example to show how to build cross-GUI applications using Matplotlib event handling to interact with objects on the canvas. .. GENERATED FROM PYTHON SOURCE LINES 9-212 .. image:: /gallery/event_handling/images/sphx_glr_poly_editor_001.png :alt: Click and drag a point to move it :class: sphx-glr-single-img .. code-block:: default import numpy as np from matplotlib.lines import Line2D from matplotlib.artist import Artist def dist(x, y): """ Return the distance between two points. """ d = x - y return np.sqrt(np.dot(d, d)) def dist_point_to_segment(p, s0, s1): """ Get the distance of a point to a segment. *p*, *s0*, *s1* are *xy* sequences This algorithm from http://geomalgorithms.com/a02-_lines.html """ v = s1 - s0 w = p - s0 c1 = np.dot(w, v) if c1 <= 0: return dist(p, s0) c2 = np.dot(v, v) if c2 <= c1: return dist(p, s1) b = c1 / c2 pb = s0 + b * v return dist(p, pb) class PolygonInteractor: """ A 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.cid = self.poly.add_callback(self.poly_changed) self._ind = None # the active vert canvas.mpl_connect('draw_event', self.on_draw) canvas.mpl_connect('button_press_event', self.on_button_press) canvas.mpl_connect('key_press_event', self.on_key_press) canvas.mpl_connect('button_release_event', self.on_button_release) canvas.mpl_connect('motion_notify_event', self.on_mouse_move) self.canvas = canvas def on_draw(self, event): self.background = self.canvas.copy_from_bbox(self.ax.bbox) self.ax.draw_artist(self.poly) self.ax.draw_artist(self.line) # do not need to blit here, this will fire before the screen is # updated def poly_changed(self, poly): """This method is called whenever the pathpatch 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): """ Return the index of the point closest to the event position or *None* if no point is within ``self.epsilon`` to the event position. """ # display coords xy = np.asarray(self.poly.xy) xyt = self.poly.get_transform().transform(xy) xt, yt = xyt[:, 0], xyt[:, 1] d = np.hypot(xt - event.x, yt - event.y) indseq, = np.nonzero(d == d.min()) ind = indseq[0] if d[ind] >= self.epsilon: ind = None return ind def on_button_press(self, event): """Callback for mouse button presses.""" 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 on_button_release(self, event): """Callback for mouse button releases.""" if not self.showverts: return if event.button != 1: return self._ind = None def on_key_press(self, event): """Callback for key presses.""" 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 = np.delete(self.poly.xy, ind, axis=0) 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.insert( self.poly.xy, i+1, [event.xdata, event.ydata], axis=0) self.line.set_data(zip(*self.poly.xy)) break if self.line.stale: self.canvas.draw_idle() def on_mouse_move(self, event): """Callback for mouse movements.""" 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 if self._ind == 0: self.poly.xy[-1] = x, y elif self._ind == len(self.poly.xy) - 1: self.poly.xy[0] = 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(np.column_stack([xs, ys]), animated=True) fig, ax = plt.subplots() ax.add_patch(poly) p = PolygonInteractor(ax, poly) ax.set_title('Click and drag a point to move it') ax.set_xlim((-2, 2)) ax.set_ylim((-2, 2)) plt.show() .. _sphx_glr_download_gallery_event_handling_poly_editor.py: .. only :: html .. container:: sphx-glr-footer :class: sphx-glr-footer-example .. container:: sphx-glr-download sphx-glr-download-python :download:`Download Python source code: poly_editor.py ` .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: poly_editor.ipynb ` .. only:: html .. rst-class:: sphx-glr-signature Keywords: matplotlib code example, codex, python plot, pyplot `Gallery generated by Sphinx-Gallery `_