.. 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 .. meta:: :keywords: codex .. note:: :class: sphx-glr-download-link-note :ref:`Go to the end ` 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. .. note:: This example exercises the interactive capabilities of Matplotlib, and this will not appear in the static documentation. Please run this code on your machine to see the interactivity. You can copy and paste individual parts, or download the entire example using the link at the bottom of the page. .. GENERATED FROM PYTHON SOURCE LINES 17-209 .. image-sg:: /gallery/event_handling/images/sphx_glr_poly_editor_001.png :alt: Click and drag a point to move it :srcset: /gallery/event_handling/images/sphx_glr_poly_editor_001.png, /gallery/event_handling/images/sphx_glr_poly_editor_001_2_00x.png 2.00x :class: sphx-glr-single-img .. code-block:: Python import numpy as np from matplotlib.artist import Artist from matplotlib.lines import Line2D def dist_point_to_segment(p, s0, s1): """ Get the distance from the point *p* to the segment (*s0*, *s1*), where *p*, *s0*, *s1* are ``[x, y]`` arrays. """ s01 = s1 - s0 s0p = p - s0 if (s01 == 0).all(): return np.hypot(*s0p) # Project onto segment, without going past segment ends. p1 = s0 + np.clip((s0p @ s01) / (s01 @ s01), 0, 1) * s01 return np.hypot(*(p - p1)) 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 sphx-glr-footer-example .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: poly_editor.ipynb ` .. container:: sphx-glr-download sphx-glr-download-python :download:`Download Python source code: poly_editor.py ` .. only:: html .. rst-class:: sphx-glr-signature `Gallery generated by Sphinx-Gallery `_