Merge pull request #9066 from dstansby/agg-jpg-dpi

WeatherGod · web-flow · commit 24817d58f392 · 2017-08-25T11:24:35.000-04:00
Let dpi be set when saving JPEG using Agg backend
diff --git a/lib/matplotlib/backends/backend_agg.py b/lib/matplotlib/backends/backend_agg.py
@@ -568,9 +568,13 @@ def print_jpg(self, filename_or_obj, *args, **kwargs):
             background = Image.new('RGB', size, color)
             background.paste(image, image)
             options = {k: kwargs[k]
-                       for k in ['quality', 'optimize', 'progressive']
+                       for k in ['quality', 'optimize', 'progressive', 'dpi']
                        if k in kwargs}
             options.setdefault('quality', rcParams['savefig.jpeg_quality'])
+            if 'dpi' in options:
+                # Set the same dpi in both x and y directions
+                options['dpi'] = (options['dpi'], options['dpi'])
+
             return background.save(filename_or_obj, format='jpeg', **options)
         print_jpeg = print_jpg
 
diff --git a/lib/matplotlib/tests/test_agg.py b/lib/matplotlib/tests/test_agg.py
@@ -234,3 +234,16 @@ def test_chunksize():
     rcParams['agg.path.chunksize'] = 105
     ax.plot(x, np.sin(x))
     fig.canvas.draw()
+
+
+@pytest.mark.backend('Agg')
+def test_jpeg_dpi():
+    try:
+        from PIL import Image
+    except Exception:
+        pytest.skip("Could not import PIL")
+    # Check that dpi is set correctly in jpg files
+    plt.plot([0, 1, 2], [0, 1, 0])
+    plt.savefig('test.jpg', dpi=200)
+    im = Image.open("test.jpg")
+    assert im.info['dpi'] == (200, 200)
