.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/misc/svg_filter_pie.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. meta::
        :keywords: codex

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_gallery_misc_svg_filter_pie.py>`
        to download the full example code

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_gallery_misc_svg_filter_pie.py:


==============
SVG filter pie
==============

Demonstrate SVG filtering effects which might be used with Matplotlib.
The pie chart drawing code is borrowed from pie_demo.py

Note that the filtering effects are only effective if your SVG renderer
support it.

.. GENERATED FROM PYTHON SOURCE LINES 12-99



.. image-sg:: /gallery/misc/images/sphx_glr_svg_filter_pie_001.png
   :alt: svg filter pie
   :srcset: /gallery/misc/images/sphx_glr_svg_filter_pie_001.png, /gallery/misc/images/sphx_glr_svg_filter_pie_001_2_00x.png 2.00x
   :class: sphx-glr-single-img


.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    Saving 'svg_filter_pie.svg'






|

.. code-block:: Python


    import io
    import xml.etree.ElementTree as ET

    import matplotlib.pyplot as plt

    from matplotlib.patches import Shadow

    # make a square figure and axes
    fig = plt.figure(figsize=(6, 6))
    ax = fig.add_axes([0.1, 0.1, 0.8, 0.8])

    labels = 'Frogs', 'Hogs', 'Dogs', 'Logs'
    fracs = [15, 30, 45, 10]

    explode = (0, 0.05, 0, 0)

    # We want to draw the shadow for each pie, but we will not use "shadow"
    # option as it doesn't save the references to the shadow patches.
    pies = ax.pie(fracs, explode=explode, labels=labels, autopct='%1.1f%%')

    for w in pies[0]:
        # set the id with the label.
        w.set_gid(w.get_label())

        # we don't want to draw the edge of the pie
        w.set_edgecolor("none")

    for w in pies[0]:
        # create shadow patch
        s = Shadow(w, -0.01, -0.01)
        s.set_gid(w.get_gid() + "_shadow")
        s.set_zorder(w.get_zorder() - 0.1)
        ax.add_patch(s)


    # save
    f = io.BytesIO()
    plt.savefig(f, format="svg")


    # Filter definition for shadow using a gaussian blur and lighting effect.
    # The lighting filter is copied from http://www.w3.org/TR/SVG/filters.html

    # I tested it with Inkscape and Firefox3. "Gaussian blur" is supported
    # in both, but the lighting effect only in Inkscape. Also note
    # that, Inkscape's exporting also may not support it.

    filter_def = """
      <defs xmlns='http://www.w3.org/2000/svg'
            xmlns:xlink='http://www.w3.org/1999/xlink'>
        <filter id='dropshadow' height='1.2' width='1.2'>
          <feGaussianBlur result='blur' stdDeviation='2'/>
        </filter>

        <filter id='MyFilter' filterUnits='objectBoundingBox'
                x='0' y='0' width='1' height='1'>
          <feGaussianBlur in='SourceAlpha' stdDeviation='4%' result='blur'/>
          <feOffset in='blur' dx='4%' dy='4%' result='offsetBlur'/>
          <feSpecularLighting in='blur' surfaceScale='5' specularConstant='.75'
               specularExponent='20' lighting-color='#bbbbbb' result='specOut'>
            <fePointLight x='-5000%' y='-10000%' z='20000%'/>
          </feSpecularLighting>
          <feComposite in='specOut' in2='SourceAlpha'
                       operator='in' result='specOut'/>
          <feComposite in='SourceGraphic' in2='specOut' operator='arithmetic'
        k1='0' k2='1' k3='1' k4='0'/>
        </filter>
      </defs>
    """


    tree, xmlid = ET.XMLID(f.getvalue())

    # insert the filter definition in the svg dom tree.
    tree.insert(0, ET.XML(filter_def))

    for i, pie_name in enumerate(labels):
        pie = xmlid[pie_name]
        pie.set("filter", 'url(#MyFilter)')

        shadow = xmlid[pie_name + "_shadow"]
        shadow.set("filter", 'url(#dropshadow)')

    fn = "svg_filter_pie.svg"
    print(f"Saving '{fn}'")
    ET.ElementTree(tree).write(fn)


.. _sphx_glr_download_gallery_misc_svg_filter_pie.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

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

    .. container:: sphx-glr-download sphx-glr-download-python

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


.. only:: html

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

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_