文本路径演示

使用文本作为路径。允许这种转换的工具是 TextPath。可以采用所得的路径，例如，作为图像的剪辑路径。

文本路径演示

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import matplotlib.pyplot as plt
from matplotlib.image import BboxImage
import numpy as np
from matplotlib.transforms import IdentityTransform

import matplotlib.patches as mpatches

from matplotlib.offsetbox import AnnotationBbox,\
    AnchoredOffsetbox, AuxTransformBox

from matplotlib.cbook import get_sample_data

from matplotlib.text import TextPath


class PathClippedImagePatch(mpatches.PathPatch):
    """
    The given image is used to draw the face of the patch. Internally,
    it uses BboxImage whose clippath set to the path of the patch.

    FIXME : The result is currently dpi dependent.
    """

    def __init__(self, path, bbox_image, **kwargs):
        mpatches.PathPatch.__init__(self, path, **kwargs)
        self._init_bbox_image(bbox_image)

    def set_facecolor(self, color):
        """simply ignore facecolor"""
        mpatches.PathPatch.set_facecolor(self, "none")

    def _init_bbox_image(self, im):

        bbox_image = BboxImage(self.get_window_extent,
                               norm=None,
                               origin=None,
                               )
        bbox_image.set_transform(IdentityTransform())

        bbox_image.set_data(im)
        self.bbox_image = bbox_image

    def draw(self, renderer=None):

        # the clip path must be updated every draw. any solution? -JJ
        self.bbox_image.set_clip_path(self._path, self.get_transform())
        self.bbox_image.draw(renderer)

        mpatches.PathPatch.draw(self, renderer)


if 1:

    usetex = plt.rcParams["text.usetex"]

    fig = plt.figure(1)

    # EXAMPLE 1

    ax = plt.subplot(211)

    arr = plt.imread(get_sample_data("grace_hopper.png"))

    text_path = TextPath((0, 0), "!?", size=150)
    p = PathClippedImagePatch(text_path, arr, ec="k",
                              transform=IdentityTransform())

    # p.set_clip_on(False)

    # make offset box
    offsetbox = AuxTransformBox(IdentityTransform())
    offsetbox.add_artist(p)

    # make anchored offset box
    ao = AnchoredOffsetbox(loc='upper left', child=offsetbox, frameon=True,
                           borderpad=0.2)
    ax.add_artist(ao)

    # another text
    from matplotlib.patches import PathPatch
    if usetex:
        r = r"\mbox{textpath supports mathtext \& \TeX}"
    else:
        r = r"textpath supports mathtext & TeX"

    text_path = TextPath((0, 0), r,
                         size=20, usetex=usetex)

    p1 = PathPatch(text_path, ec="w", lw=3, fc="w", alpha=0.9,
                   transform=IdentityTransform())
    p2 = PathPatch(text_path, ec="none", fc="k",
                   transform=IdentityTransform())

    offsetbox2 = AuxTransformBox(IdentityTransform())
    offsetbox2.add_artist(p1)
    offsetbox2.add_artist(p2)

    ab = AnnotationBbox(offsetbox2, (0.95, 0.05),
                        xycoords='axes fraction',
                        boxcoords="offset points",
                        box_alignment=(1., 0.),
                        frameon=False
                        )
    ax.add_artist(ab)

    ax.imshow([[0, 1, 2], [1, 2, 3]], cmap=plt.cm.gist_gray_r,
              interpolation="bilinear",
              aspect="auto")

    # EXAMPLE 2

    ax = plt.subplot(212)

    arr = np.arange(256).reshape(1, 256)/256.

    if usetex:
        s = (r"$\displaystyle\left[\sum_{n=1}^\infty"
             r"\frac{-e^{i\pi}}{2^n}\right]$!")
    else:
        s = r"$\left[\sum_{n=1}^\infty\frac{-e^{i\pi}}{2^n}\right]$!"
    text_path = TextPath((0, 0), s, size=40, usetex=usetex)
    text_patch = PathClippedImagePatch(text_path, arr, ec="none",
                                       transform=IdentityTransform())

    shadow1 = mpatches.Shadow(text_patch, 1, -1,
                              props=dict(fc="none", ec="0.6", lw=3))
    shadow2 = mpatches.Shadow(text_patch, 1, -1,
                              props=dict(fc="0.3", ec="none"))

    # make offset box
    offsetbox = AuxTransformBox(IdentityTransform())
    offsetbox.add_artist(shadow1)
    offsetbox.add_artist(shadow2)
    offsetbox.add_artist(text_patch)

    # place the anchored offset box using AnnotationBbox
    ab = AnnotationBbox(offsetbox, (0.5, 0.5),
                        xycoords='data',
                        boxcoords="offset points",
                        box_alignment=(0.5, 0.5),
                        )
    # text_path.set_size(10)

    ax.add_artist(ab)

    ax.set_xlim(0, 1)
    ax.set_ylim(0, 1)

    plt.show()

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