Deprecate imread() reading from URLs

timhoffm · anntzer · commit 03d18841e5af · 2021-01-26T17:17:29.000+01:00
diff --git a/doc/api/next_api_changes/deprecations/18649-TH.rst b/doc/api/next_api_changes/deprecations/18649-TH.rst
@@ -0,0 +1,5 @@
+``imread()`` reading from URLs
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Passing a URL to `~.pyplot.imread()` is deprecated. Please open the URL before
+reading using ``urllib.request.urlopen()``.
diff --git a/lib/matplotlib/image.py b/lib/matplotlib/image.py
@@ -1430,6 +1430,9 @@ def imread(fname, format=None):
     fname : str or file-like
         The image file to read: a filename, a URL or a file-like object opened
         in read-binary mode.
+
+        Passing a URL is deprecated. Please open the URL before reading using
+        ``urllib.request.urlopen()``.
     format : str, optional
         The image file format assumed for reading the data. If not
         given, the format is deduced from the filename.  If nothing can
@@ -1472,9 +1475,12 @@ def imread(fname, format=None):
     img_open = (
         PIL.PngImagePlugin.PngImageFile if ext == 'png' else PIL.Image.open)
     if isinstance(fname, str):
-
         parsed = parse.urlparse(fname)
         if len(parsed.scheme) > 1:  # Pillow doesn't handle URLs directly.
+            cbook.warn_deprecated(
+                "3.4", message="Directly reading images from URLs is "
+                               "deprecated. Please open the URL before "
+                               "reading using urllib.request.urlopen().")
             # hide imports to speed initial import on systems with slow linkers
             from urllib import request
             ssl_ctx = mpl._get_ssl_context()
diff --git a/lib/matplotlib/tests/test_image.py b/lib/matplotlib/tests/test_image.py
@@ -12,7 +12,7 @@
 from PIL import Image
 
 from matplotlib import (
-    colors, image as mimage, patches, pyplot as plt, style, rcParams)
+    cbook, colors, image as mimage, patches, pyplot as plt, style, rcParams)
 from matplotlib.image import (AxesImage, BboxImage, FigureImage,
                               NonUniformImage, PcolorImage)
 from matplotlib.testing.decorators import check_figures_equal, image_comparison
@@ -714,7 +714,8 @@ def test_load_from_url():
     url = ('file:'
            + ('///' if sys.platform == 'win32' else '')
            + path.resolve().as_posix())
-    plt.imread(url)
+    with cbook._suppress_matplotlib_deprecation_warning():
+        plt.imread(url)
     with urllib.request.urlopen(url) as file:
         plt.imread(file)
 
@@ -1128,7 +1129,8 @@ def test_exact_vmin():
 @pytest.mark.network
 @pytest.mark.flaky
 def test_https_imread_smoketest():
-    v = mimage.imread('https://matplotlib.org/1.5.0/_static/logo2.png')
+    with cbook._suppress_matplotlib_deprecation_warning():
+        v = mimage.imread('https://matplotlib.org/1.5.0/_static/logo2.png')
 
 
 # A basic ndarray subclass that implements a quantity
