Note
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12.3.10.1.23. Path editorΒΆ
![drag vertices to update path](../../../_images/sphx_glr_demo_path_editor_001.png)
import numpy as np
import matplotlib
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:
showverts = True
epsilon = 5 # max pixel distance to count as a vertex hit
def __init__(self, pathpatch: matplotlib.patches.PathPatch):
"""Path editor class. ``t`` toggle vertex markers on and off.
When vertex markers are on, you can move them, delete them.
Args:
pathpatch (matplotlib.patches.PathPatch): PathPatch instance
"""
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: matplotlib.backend_bases.DrawEvent):
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: matplotlib.patches.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 0.096 seconds)