Merge pull request #10773 from TeamChillUTSC/10419-svg-alpha-text

jklymak · web-flow · commit 1707b1e21c69 · 2018-03-14T14:26:31.000-07:00
Consider alpha channel from RGBA color of text for SVG backend text opacity rendering
diff --git a/lib/matplotlib/backends/backend_svg.py b/lib/matplotlib/backends/backend_svg.py
@@ -901,8 +901,10 @@ def _draw_text_as_path(self, gc, x, y, s, prop, angle, ismath, mtext=None):
         style = {}
         if color != '#000000':
             style['fill'] = color
-        if gc.get_alpha() != 1.0:
-            style['opacity'] = short_float_fmt(gc.get_alpha())
+
+        alpha = gc.get_alpha() if gc.get_forced_alpha() else gc.get_rgb()[3]
+        if alpha != 1:
+            style['opacity'] = short_float_fmt(alpha)
 
         if not ismath:
             font = text2path._get_font(prop)
@@ -1002,8 +1004,10 @@ def _draw_text_as_text(self, gc, x, y, s, prop, angle, ismath, mtext=None):
         style = {}
         if color != '#000000':
             style['fill'] = color
-        if gc.get_alpha() != 1.0:
-            style['opacity'] = short_float_fmt(gc.get_alpha())
+
+        alpha = gc.get_alpha() if gc.get_forced_alpha() else gc.get_rgb()[3]
+        if alpha != 1:
+            style['opacity'] = short_float_fmt(alpha)
 
         if not ismath:
             font = self._get_font(prop)
diff --git a/lib/matplotlib/tests/baseline_images/test_text/text_as_path_opacity.svg b/lib/matplotlib/tests/baseline_images/test_text/text_as_path_opacity.svg
@@ -0,0 +1,114 @@
+<?xml version="1.0" encoding="utf-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
+  "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Created with matplotlib (https://matplotlib.org/) -->
+<svg height="432pt" version="1.1" viewBox="0 0 576 432" width="576pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+ <defs>
+  <style type="text/css">
+*{stroke-linecap:butt;stroke-linejoin:round;}
+  </style>
+ </defs>
+ <g id="figure_1">
+  <g id="patch_1">
+   <path d="M 0 432 
+L 576 432 
+L 576 0 
+L 0 0 
+z
+" style="fill:#ffffff;"/>
+  </g>
+  <g id="axes_1">
+   <g id="text_1">
+    <!-- c -->
+    <defs>
+     <path d="M 48.78125 52.59375 
+L 48.78125 44.1875 
+Q 44.96875 46.296875 41.140625 47.34375 
+Q 37.3125 48.390625 33.40625 48.390625 
+Q 24.65625 48.390625 19.8125 42.84375 
+Q 14.984375 37.3125 14.984375 27.296875 
+Q 14.984375 17.28125 19.8125 11.734375 
+Q 24.65625 6.203125 33.40625 6.203125 
+Q 37.3125 6.203125 41.140625 7.25 
+Q 44.96875 8.296875 48.78125 10.40625 
+L 48.78125 2.09375 
+Q 45.015625 0.34375 40.984375 -0.53125 
+Q 36.96875 -1.421875 32.421875 -1.421875 
+Q 20.0625 -1.421875 12.78125 6.34375 
+Q 5.515625 14.109375 5.515625 27.296875 
+Q 5.515625 40.671875 12.859375 48.328125 
+Q 20.21875 56 33.015625 56 
+Q 37.15625 56 41.109375 55.140625 
+Q 45.0625 54.296875 48.78125 52.59375 
+z
+" id="DejaVuSans-63"/>
+    </defs>
+    <g style="opacity:0.5;" transform="translate(183.6 302.4)scale(0.12 -0.12)">
+     <use xlink:href="#DejaVuSans-63"/>
+    </g>
+   </g>
+   <g id="text_2">
+    <!-- a -->
+    <defs>
+     <path d="M 34.28125 27.484375 
+Q 23.390625 27.484375 19.1875 25 
+Q 14.984375 22.515625 14.984375 16.5 
+Q 14.984375 11.71875 18.140625 8.90625 
+Q 21.296875 6.109375 26.703125 6.109375 
+Q 34.1875 6.109375 38.703125 11.40625 
+Q 43.21875 16.703125 43.21875 25.484375 
+L 43.21875 27.484375 
+z
+M 52.203125 31.203125 
+L 52.203125 0 
+L 43.21875 0 
+L 43.21875 8.296875 
+Q 40.140625 3.328125 35.546875 0.953125 
+Q 30.953125 -1.421875 24.3125 -1.421875 
+Q 15.921875 -1.421875 10.953125 3.296875 
+Q 6 8.015625 6 15.921875 
+Q 6 25.140625 12.171875 29.828125 
+Q 18.359375 34.515625 30.609375 34.515625 
+L 43.21875 34.515625 
+L 43.21875 35.40625 
+Q 43.21875 41.609375 39.140625 45 
+Q 35.0625 48.390625 27.6875 48.390625 
+Q 23 48.390625 18.546875 47.265625 
+Q 14.109375 46.140625 10.015625 43.890625 
+L 10.015625 52.203125 
+Q 14.9375 54.109375 19.578125 55.046875 
+Q 24.21875 56 28.609375 56 
+Q 40.484375 56 46.34375 49.84375 
+Q 52.203125 43.703125 52.203125 31.203125 
+z
+" id="DejaVuSans-61"/>
+    </defs>
+    <g style="opacity:0.5;" transform="translate(183.6 216)scale(0.12 -0.12)">
+     <use xlink:href="#DejaVuSans-61"/>
+    </g>
+   </g>
+   <g id="text_3">
+    <!-- x -->
+    <defs>
+     <path d="M 54.890625 54.6875 
+L 35.109375 28.078125 
+L 55.90625 0 
+L 45.3125 0 
+L 29.390625 21.484375 
+L 13.484375 0 
+L 2.875 0 
+L 24.125 28.609375 
+L 4.6875 54.6875 
+L 15.28125 54.6875 
+L 29.78125 35.203125 
+L 44.28125 54.6875 
+z
+" id="DejaVuSans-78"/>
+    </defs>
+    <g style="opacity:0.5;" transform="translate(183.6 129.6)scale(0.12 -0.12)">
+     <use xlink:href="#DejaVuSans-78"/>
+    </g>
+   </g>
+  </g>
+ </g>
+</svg>
diff --git a/lib/matplotlib/tests/baseline_images/test_text/text_as_text_opacity.svg b/lib/matplotlib/tests/baseline_images/test_text/text_as_text_opacity.svg
@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
+  "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Created with matplotlib (https://matplotlib.org/) -->
+<svg height="432pt" version="1.1" viewBox="0 0 576 432" width="576pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+ <defs>
+  <style type="text/css">
+*{stroke-linecap:butt;stroke-linejoin:round;}
+  </style>
+ </defs>
+ <g id="figure_1">
+  <g id="patch_1">
+   <path d="M 0 432 
+L 576 432 
+L 576 0 
+L 0 0 
+z
+" style="fill:#ffffff;"/>
+  </g>
+  <g id="axes_1">
+   <g id="text_1">
+    <text style="font-family:DejaVu Sans;font-size:12px;font-style:normal;font-weight:normal;opacity:0.5;text-anchor:start;" transform="rotate(-0, 183.6, 302.4)" x="183.6" y="302.4">50% using `color`</text>
+   </g>
+   <g id="text_2">
+    <text style="font-family:DejaVu Sans;font-size:12px;font-style:normal;font-weight:normal;opacity:0.5;text-anchor:start;" transform="rotate(-0, 183.6, 216)" x="183.6" y="216">50% using `alpha`</text>
+   </g>
+   <g id="text_3">
+    <text style="font-family:DejaVu Sans;font-size:12px;font-style:normal;font-weight:normal;opacity:0.5;text-anchor:start;" transform="rotate(-0, 183.6, 129.6)" x="183.6" y="129.6">50% using `alpha` and 100% `color`</text>
+   </g>
+  </g>
+ </g>
+</svg>
diff --git a/lib/matplotlib/tests/test_text.py b/lib/matplotlib/tests/test_text.py
@@ -474,3 +474,25 @@ def test_single_artist_usetex():
     fig, ax = plt.subplots()
     ax.text(.5, .5, r"$\frac12$", usetex=True)
     fig.canvas.draw()
+
+
+@image_comparison(baseline_images=['text_as_path_opacity'],
+                  extensions=['svg'])
+def test_text_as_path_opacity():
+    plt.figure()
+    plt.gca().set_axis_off()
+    plt.text(0.25, 0.25, 'c', color=(0, 0, 0, 0.5))
+    plt.text(0.25, 0.5, 'a', alpha=0.5)
+    plt.text(0.25, 0.75, 'x', alpha=0.5, color=(0, 0, 0, 1))
+
+
+@image_comparison(baseline_images=['text_as_text_opacity'],
+                  extensions=['svg'])
+def test_text_as_text_opacity():
+    matplotlib.rcParams['svg.fonttype'] = 'none'
+    plt.figure()
+    plt.gca().set_axis_off()
+    plt.text(0.25, 0.25, '50% using `color`', color=(0, 0, 0, 0.5))
+    plt.text(0.25, 0.5, '50% using `alpha`', alpha=0.5)
+    plt.text(0.25, 0.75, '50% using `alpha` and 100% `color`', alpha=0.5,
+             color=(0, 0, 0, 1))
