Patheffect Demo

import matplotlib.pyplot as plt
import matplotlib.patheffects as PathEffects
import numpy as np

if 1:
    plt.figure(1, figsize=(8, 3))
    ax1 = plt.subplot(131)
    ax1.imshow([[1, 2], [2, 3]])
    txt = ax1.annotate("test", (1., 1.), (0., 0),
                       arrowprops=dict(arrowstyle="->",
                                       connectionstyle="angle3", lw=2),
                       size=20, ha="center",
                       path_effects=[PathEffects.withStroke(linewidth=3,
                                                            foreground="w")])
    txt.arrow_patch.set_path_effects([
        PathEffects.Stroke(linewidth=5, foreground="w"),
        PathEffects.Normal()])

    pe = [PathEffects.withStroke(linewidth=3,
                                 foreground="w")]
    ax1.grid(True, linestyle="-", path_effects=pe)

    ax2 = plt.subplot(132)
    arr = np.arange(25).reshape((5, 5))
    ax2.imshow(arr)
    cntr = ax2.contour(arr, colors="k")

    plt.setp(cntr.collections, path_effects=[
        PathEffects.withStroke(linewidth=3, foreground="w")])

    clbls = ax2.clabel(cntr, fmt="%2.0f", use_clabeltext=True)
    plt.setp(clbls, path_effects=[
        PathEffects.withStroke(linewidth=3, foreground="w")])

    # shadow as a path effect
    ax3 = plt.subplot(133)
    p1, = ax3.plot([0, 1], [0, 1])
    leg = ax3.legend([p1], ["Line 1"], fancybox=True, loc='upper left')
    leg.legendPatch.set_path_effects([PathEffects.withSimplePatchShadow()])

    plt.show()