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

.. only:: html

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

        Click :ref:`here <sphx_glr_download_gallery_user_interfaces_canvasagg.py>`
        to download the full example code

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

.. _sphx_glr_gallery_user_interfaces_canvasagg.py:


==============
CanvasAgg demo
==============

This example shows how to use the agg backend directly to create images, which
may be of use to web application developers who want full control over their
code without using the pyplot interface to manage figures, figure closing etc.

.. note::

    It is not necessary to avoid using the pyplot interface in order to
    create figures without a graphical front-end - simply setting
    the backend to "Agg" would be sufficient.

In this example, we show how to save the contents of the agg canvas to a file,
and how to extract them to a string, which can in turn be passed off to PIL or
put in a numpy array.  The latter functionality allows e.g. to use Matplotlib
inside a cgi-script *without* needing to write a figure to disk.

.. GENERATED FROM PYTHON SOURCE LINES 21-52

.. code-block:: default


    from matplotlib.backends.backend_agg import FigureCanvasAgg
    from matplotlib.figure import Figure
    import numpy as np

    fig = Figure(figsize=(5, 4), dpi=100)
    # A canvas must be manually attached to the figure (pyplot would automatically
    # do it).  This is done by instantiating the canvas with the figure as
    # argument.
    canvas = FigureCanvasAgg(fig)

    # Do some plotting.
    ax = fig.add_subplot(111)
    ax.plot([1, 2, 3])

    # Option 1: Save the figure to a file; can also be a file-like object (BytesIO,
    # etc.).
    fig.savefig("test.png")

    # Option 2: Retrieve a view on the renderer buffer...
    canvas.draw()
    buf = canvas.buffer_rgba()
    # ... convert to a NumPy array ...
    X = np.asarray(buf)
    # ... and pass it to PIL.
    from PIL import Image
    im = Image.fromarray(X)

    # Uncomment this line to display the image using ImageMagick's `display` tool.
    # im.show()








.. GENERATED FROM PYTHON SOURCE LINES 53-60

------------

References
""""""""""

The use of the following functions, methods, classes and modules is shown
in this example:

.. GENERATED FROM PYTHON SOURCE LINES 61-68

.. code-block:: default


    import matplotlib
    matplotlib.backends.backend_agg.FigureCanvasAgg
    matplotlib.figure.Figure
    matplotlib.figure.Figure.add_subplot
    matplotlib.figure.Figure.savefig
    matplotlib.axes.Axes.plot




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

 Out:

 .. code-block:: none


    <function Axes.plot at 0x7f73be8efd30>




.. _sphx_glr_download_gallery_user_interfaces_canvasagg.py:


.. only :: html

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



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

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



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

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


.. only:: html

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

    Keywords: matplotlib code example, codex, python plot, pyplot
    `Gallery generated by Sphinx-Gallery
    <https://sphinx-gallery.readthedocs.io>`_
