

.. _sphx_glr_gallery_event_handling_path_editor.py:


===========
Path Editor
===========





.. image:: /gallery/event_handling/images/sphx_glr_path_editor_001.png
    :align: center





.. code-block:: python

    import numpy as np
    import matplotlib.path as mpath
    import matplotlib.patches as mpatches
    import matplotlib.pyplot as plt

    Path = mpath.Path

    fig, ax = plt.subplots()

    pathdata = [
        (Path.MOVETO, (1.58, -2.57)),
        (Path.CURVE4, (0.35, -1.1)),
        (Path.CURVE4, (-1.75, 2.0)),
        (Path.CURVE4, (0.375, 2.0)),
        (Path.LINETO, (0.85, 1.15)),
        (Path.CURVE4, (2.2, 3.2)),
        (Path.CURVE4, (3, 0.05)),
        (Path.CURVE4, (2.0, -0.5)),
        (Path.CLOSEPOLY, (1.58, -2.57)),
        ]

    codes, verts = zip(*pathdata)
    path = mpath.Path(verts, codes)
    patch = mpatches.PathPatch(path, facecolor='green', edgecolor='yellow', alpha=0.5)
    ax.add_patch(patch)


    class PathInteractor(object):
        """
        An path editor.

        Key-bindings

          't' toggle vertex markers on and off.  When vertex markers are on,
              you can move them, delete them


        """

        showverts = True
        epsilon = 5  # max pixel distance to count as a vertex hit

        def __init__(self, pathpatch):

            self.ax = pathpatch.axes
            canvas = self.ax.figure.canvas
            self.pathpatch = pathpatch
            self.pathpatch.set_animated(True)

            x, y = zip(*self.pathpatch.get_path().vertices)

            self.line, = ax.plot(x, y, marker='o', markerfacecolor='r', animated=True)

            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.pathpatch)
            self.ax.draw_artist(self.line)
            self.canvas.blit(self.ax.bbox)

        def pathpatch_changed(self, pathpatch):
            'this method is called whenever the pathpatchgon object is called'
            # only copy the artist props to the line (except visibility)
            vis = self.line.get_visible()
            plt.Artist.update_from(self.line, pathpatch)
            self.line.set_visible(vis)  # don't use the pathpatch 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.pathpatch.get_path().vertices)
            xyt = self.pathpatch.get_transform().transform(xy)
            xt, yt = xyt[:, 0], xyt[:, 1]
            d = np.sqrt((xt - event.x)**2 + (yt - event.y)**2)
            ind = d.argmin()

            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

            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

            vertices = self.pathpatch.get_path().vertices

            vertices[self._ind] = x, y
            self.line.set_data(zip(*vertices))

            self.canvas.restore_region(self.background)
            self.ax.draw_artist(self.pathpatch)
            self.ax.draw_artist(self.line)
            self.canvas.blit(self.ax.bbox)


    interactor = PathInteractor(patch)
    ax.set_title('drag vertices to update path')
    ax.set_xlim(-3, 4)
    ax.set_ylim(-3, 4)

    plt.show()

**Total running time of the script:** ( 0 minutes  0.035 seconds)



.. container:: sphx-glr-footer


  .. container:: sphx-glr-download

     :download:`Download Python source code: path_editor.py <path_editor.py>`



  .. container:: sphx-glr-download

     :download:`Download Jupyter notebook: path_editor.ipynb <path_editor.ipynb>`

.. rst-class:: sphx-glr-signature

    `Generated by Sphinx-Gallery <https://sphinx-gallery.readthedocs.io>`_
