8000 Simplify image.thumbnail. · matplotlib/matplotlib@c564e6f · GitHub
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Simplify image.thumbnail.
Per-filetype backend selection is already implemented by FigureCanvasBase.print_figure, no need to reinvent the wheel.
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‎doc/api/next_api_changes/2018-05-26-AL.rst

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Change to the output of `.image.thumbnail`
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``````````````````````````````````````````
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When called with ``preview=False``, ``image.thumbnail`` previously returned an
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figure whose canvas class was set according to the output file extension. It
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now returns a figure whose canvas class is the base `FigureCanvasBase` (and
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relies on `FigureCanvasBase.print_figure`) to handle the canvas switching
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properly).
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As a side effect of this change, `image.thumbnail` now also supports .ps, .eps,
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and .svgz output.

‎lib/matplotlib/image.py

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"""
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The image module supports basic image loading, rescaling and display
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operations.
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"""
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from io import BytesIO
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from matplotlib import rcParams
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import matplotlib.artist as martist
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from matplotlib.artist import allow_rasterization
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from matplotlib.backend_bases import FigureCanvasBase
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import matplotlib.colors as mcolors
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import matplotlib.cm as cm
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import matplotlib.cbook as cbook
@@ -1447,81 +1447,58 @@ def pil_to_array(pilImage):
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def thumbnail(infile, thumbfile, scale=0.1, interpolation='bilinear',
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preview=False):
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"""
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make a thumbnail of image in *infile* with output filename
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*thumbfile*.
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*infile* the image file -- must be PNG or Pillow-readable if you
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have `Pillow <http://python-pillow.org/>`_ installed
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*thumbfile*
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the thumbnail filename
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*scale*
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the scale factor for the thumbnail
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Make a thumbnail of image in *infile* with output filename *thumbfile*.
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*interpolation*
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the interpolation scheme used in the resampling
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*preview*
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if True, the default backend (presumably a user interface
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backend) will be used which will cause a figure to be raised
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if :func:`~matplotlib.pyplot.show` is called. If it is False,
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a pure image backend will be used depending on the extension,
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'png'->FigureCanvasAgg, 'pdf'->FigureCanvasPdf,
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'svg'->FigureCanvasSVG
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See :doc:`/gallery/misc/image_thumbnail_sgskip`.
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Parameters
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----------
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infile
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The image file -- must be PNG, Pillow-readable if you have `Pillow
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<http://python-pillow.org/>`_ installed.
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See examples/misc/image_thumbnail.py.
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thumbfile
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The thumbnail filename.
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.. only:: html
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scale
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The scale factor for the thumbnail.
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:ref:`sphx_glr_gallery_misc_image_thumbnail_sgskip.py`
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interpolation
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The interpolation scheme used in the resampling.
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Return value is the figure instance containing the thumbnail
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preview
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If True, the default backend (presumably a user interface
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backend) will be used which will cause a figure to be raised if
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`~matplotlib.pyplot.show` is called. If it is False, the figure is
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created using `FigureCanvasBase` and the drawing backend is selected
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as `~matplotlib.figure.savefig` would normally do.
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Returns
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-------
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figure :
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The figure instance containing the thumbnail.
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"""
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basedir, basename = os.path.split(infile)
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baseout, extout = os.path.splitext(thumbfile)
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im = imread(infile)
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rows, cols, depth = im.shape
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# this doesn't really matter, it will cancel in the end, but we
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# need it for the mpl API
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# This doesn't really matter (it cancels in the end) but the API needs it.
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dpi = 100
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height = rows / dpi * scale
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width = cols / dpi * scale
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extension = extout.lower()
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if preview:
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# let the UI backend do everything
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# Let the UI backend do everything.
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import matplotlib.pyplot as plt
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fig = plt.figure(figsize=(width, height), dpi=dpi)
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else:
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if extension == '.png':
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from matplotlib.backends.backend_agg \
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import FigureCanvasAgg as FigureCanvas
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elif extension == '.pdf':
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from matplotlib.backends.backend_pdf \
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import FigureCanvasPdf as FigureCanvas
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elif extension == '.svg':
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from matplotlib.backends.backend_svg \
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import FigureCanvasSVG as FigureCanvas
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else:
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raise ValueError("Can only handle "
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"extensions 'png', 'svg' or 'pdf'")
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from matplotlib.figure import Figure
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fig = Figure(figsize=(width, height), dpi=dpi)
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FigureCanvas(fig)
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FigureCanvasBase(fig)
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ax = fig.add_axes([0, 0, 1, 1], aspect='auto',
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frameon=False, xticks=[], yticks=[])
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basename, ext = os.path.splitext(basename)
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ax.imshow(im, aspect='auto', resample=True, interpolation=interpolation)
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fig.savefig(thumbfile, dpi=dpi)
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return fig

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