Draw RadioButtons using scatter to ensure circular buttons.

anntzer · anntzer · commit 26580cc4be40 · 2022-11-15T00:03:46.000+01:00
To ensure backcompat without bothering the majority of users who don't
actually access the .circles attribute, dynamically (and irreversibly)
switch back to the old draw method (list of Circles) whenever that
attribute is accessed for the first time (if ever).
diff --git a/lib/matplotlib/tests/baseline_images/test_widgets/check_bunch_of_radio_buttons.png b/lib/matplotlib/tests/baseline_images/test_widgets/check_bunch_of_radio_buttons.png
diff --git a/lib/matplotlib/tests/test_widgets.py b/lib/matplotlib/tests/test_widgets.py
@@ -1003,18 +1003,21 @@ def test_check_radio_buttons_image():
     plt.subplots_adjust(left=0.3)
     rax1 = plt.axes([0.05, 0.7, 0.15, 0.15])
     rax2 = plt.axes([0.05, 0.2, 0.15, 0.15])
-    widgets.RadioButtons(rax1, ('Radio 1', 'Radio 2', 'Radio 3'))
+    rb = widgets.RadioButtons(rax1, ('Radio 1', 'Radio 2', 'Radio 3'))
+    with pytest.warns(DeprecationWarning):
+        rb.circles  # Trigger the old-style elliptic radiobuttons.
     widgets.CheckButtons(rax2, ('Check 1', 'Check 2', 'Check 3'),
                          (False, True, True))
 
 
-@image_comparison(['check_bunch_of_radio_buttons.png'],
-                  style='mpl20', remove_text=True)
-def test_check_bunch_of_radio_buttons():
-    rax = plt.axes([0.05, 0.1, 0.15, 0.7])
-    widgets.RadioButtons(rax, ('B1', 'B2', 'B3', 'B4', 'B5', 'B6',
-                               'B7', 'B8', 'B9', 'B10', 'B11', 'B12',
-                               'B13', 'B14', 'B15'))
+@check_figures_equal(extensions=["png"])
+def test_radio_buttons(fig_test, fig_ref):
+    widgets.RadioButtons(fig_test.subplots(), ["tea", "coffee"])
+    ax = fig_ref.add_subplot(xticks=[], yticks=[])
+    ax.scatter([.15, .15], [2/3, 1/3], transform=ax.transAxes,
+               s=(plt.rcParams["font.size"] / 2) ** 2, c=["C0", "none"])
+    ax.text(.25, 2/3, "tea", transform=ax.transAxes, va="center")
+    ax.text(.25, 1/3, "coffee", transform=ax.transAxes, va="center")
 
 
 def test_slider_slidermin_slidermax_invalid():
diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
@@ -1404,41 +1404,25 @@ def __init__(self, ax, labels, active=0, activecolor='blue'):
         """
         super().__init__(ax)
         self.activecolor = activecolor
-        self.value_selected = None
+        self.value_selected = labels[active]
 
         ax.set_xticks([])
         ax.set_yticks([])
         ax.set_navigate(False)
-        dy = 1. / (len(labels) + 1)
-        ys = np.linspace(1 - dy, dy, len(labels))
-        cnt = 0
-        axcolor = ax.get_facecolor()
 
-        # scale the radius of the circle with the spacing between each one
-        circle_radius = dy / 2 - 0.01
-        # default to hard-coded value if the radius becomes too large
-        circle_radius = min(circle_radius, 0.05)
+        ys = np.linspace(1, 0, len(labels) + 2)[1:-1]
+        text_size = mpl.rcParams["font.size"] / 2
 
         self.labels = []
-        self.circles = []
         for y, label in zip(ys, labels):
             t = ax.text(0.25, y, label, transform=ax.transAxes,
                         horizontalalignment='left',
                         verticalalignment='center')
-
-            if cnt == active:
-                self.value_selected = label
-                facecolor = activecolor
-            else:
-                facecolor = axcolor
-
-            p = Circle(xy=(0.15, y), radius=circle_radius, edgecolor='black',
-                       facecolor=facecolor, transform=ax.transAxes)
-
             self.labels.append(t)
-            self.circles.append(p)
-            ax.add_patch(p)
-            cnt += 1
+        self._buttons = ax.scatter(
+            [.15] * len(ys), ys, transform=ax.transAxes, s=text_size**2,
+            c=[activecolor if i == active else "none" for i in range(len(ys))],
+            edgecolor="black")
 
         self.connect_event('button_press_event', self._clicked)
 
@@ -1448,11 +1432,20 @@ def _clicked(self, event):
         if self.ignore(event) or event.button != 1 or event.inaxes != self.ax:
             return
         pclicked = self.ax.transAxes.inverted().transform((event.x, event.y))
+        _, inds = self._buttons.contains(event)
+        coords = self._buttons.get_offset_transform().transform(
+            self._buttons.get_offsets())
         distances = {}
-        for i, (p, t) in enumerate(zip(self.circles, self.labels)):
-            if (t.get_window_extent().contains(event.x, event.y)
-                    or np.linalg.norm(pclicked - p.center) < p.radius):
-                distances[i] = np.linalg.norm(pclicked - p.center)
+        if hasattr(self, "_circles"):  # Remove once circles is removed.
+            for i, (p, t) in enumerate(zip(self._circles, self.labels)):
+                if (t.get_window_extent().contains(event.x, event.y)
+                        or np.linalg.norm(pclicked - p.center) < p.radius):
+                    distances[i] = np.linalg.norm(pclicked - p.center)
+        else:
+            for i, t in enumerate(self.labels):
+                if (i in inds["ind"]
+                        or t.get_window_extent().contains(event.x, event.y)):
+                    distances[i] = np.linalg.norm(pclicked - coords[i])
         if len(distances) > 0:
             closest = min(distances, key=distances.get)
             self.set_active(closest)
@@ -1465,19 +1458,14 @@ def set_active(self, index):
         """
         if index not in range(len(self.labels)):
             raise ValueError(f'Invalid RadioButton index: {index}')
-
         self.value_selected = self.labels[index].get_text()
-
-        for i, p in enumerate(self.circles):
-            if i == index:
-                color = self.activecolor
-            else:
-                color = self.ax.get_facecolor()
-            p.set_facecolor(color)
-
+        self._buttons.get_facecolor()[:] = colors.to_rgba("none")
+        self._buttons.get_facecolor()[index] = colors.to_rgba(self.activecolor)
+        if hasattr(self, "_circles"):  # Remove once circles is removed.
+            for i, p in enumerate(self._circles):
+                p.set_facecolor(self.activecolor if i == index else "none")
         if self.drawon:
             self.ax.figure.canvas.draw()
-
         if self.eventson:
             self._observers.process('clicked', self.labels[index].get_text())
 
@@ -1493,6 +1481,20 @@ def disconnect(self, cid):
         """Remove the observer with connection id *cid*."""
         self._observers.disconnect(cid)
 
+    @_api.deprecated("3.7")
+    @property
+    def circles(self):
+        radius = min(.5 / (len(self.labels) + 1) - .01, .05)
+        circles = self._circles = [
+            Circle(xy=self._buttons.get_offsets()[i], edgecolor="black",
+                   facecolor=self._buttons.get_facecolor()[i],
+                   radius=radius, transform=self.ax.transAxes)
+            for i in range(len(self.labels)) ]
+        self._buttons.set_visible(False)
+        for circle in self._circles:
+            self.ax.add_patch(circle)
+        return circles
+
 
 class SubplotTool(Widget):
     """
