Fix getting tuple of animated artists; add comments and test

Author: ericpre

lib/matplotlib/tests/test_widgets.py

@@ -916,6 +916,55 @@ def test_span_selector_bound(direction):
     assert tool._edge_handles.positions == handle_positions
 
 
+@pytest.mark.backend('QtAgg', skip_on_importerror=True)
+def test_span_selector_animated_artists_callback():
+    """Check that the animated artists changed in callbacks are updated."""
+    x = np.linspace(0, 2 * np.pi, 100)
+    values = np.sin(x)
+
+    fig, ax = plt.subplots()
+    (ln,) = ax.plot(x, values, animated=True)
+    (ln2, ) = ax.plot([], animated=True)
+
+    plt.pause(0.1)
+    ax.draw_artist(ln)
+    fig.canvas.blit(fig.bbox)
+
+    def mean(vmin, vmax):
+        indmin, indmax = np.searchsorted(x, (vmin, vmax))
+        v = values[indmin:indmax].mean()
+        print('here', x, v)
+        ln2.set_data(x, v)
+
+    span = widgets.SpanSelector(ax, mean, direction='horizontal',
+                                onmove_callback=mean,
+                                interactive=True,
+                                drag_from_anywhere=True,
+                                useblit=True)
+    press_data = [1, 2]
+    move_data = [2, 2]
+    do_event(span, 'press', xdata=press_data[0], ydata=press_data[1], button=1)
+    do_event(span, 'onmove', xdata=move_data[0], ydata=move_data[1], button=1)
+    assert span._get_animated_artists() == (ln, ln2)
+    assert ln.stale is False
+    assert ln2.stale
+    assert ln2.get_ydata() == 0.9547335049088455
+    span.update()
+    assert ln2.stale is False
+
+    press_data = [4, 2]
+    move_data = [5, 2]
+    release_data = [5, 2]
+    do_event(span, 'press', xdata=press_data[0], ydata=press_data[1], button=1)
+    do_event(span, 'onmove', xdata=move_data[0], ydata=move_data[1], button=1)
+    assert ln.stale is False
+    assert ln2.stale
+    assert ln2.get_ydata() == -0.9424150707548072
+    do_event(span, 'release', xdata=release_data[0],
+             ydata=release_data[1], button=1)
+    assert ln2.stale is False
+
+
 def check_lasso_selector(**kwargs):
     ax = get_ax()
 

lib/matplotlib/widgets.py

@@ -1840,12 +1840,19 @@ def set_active(self, active):
             self.update_background(None)
 
     def _get_animated_artists(self):
-        """Convenience method to get all animated artists of a figure."""
+        """
+        Convenience method to get all animated artists of a figure, except
+        those already present in self.artists.
+        """
         axes = self.ax.get_figure().get_axes()
         animated_artists = tuple()
         for ax in axes:
-            artists = sorted(ax.get_children(), key=lambda x: x.zorder)
-            animated_artists += tuple(a for a in artists if a.get_animated())
+            # Make sure we don't get the artists already in self.artists
+            artists = filter(
+                lambda a: a.get_animated() and a not in self.artists,
+                ax.get_children()
+                )
+            animated_artists += tuple(sorted(artists, key=lambda a: a.zorder))
         return animated_artists
 
     def update_background(self, event):
@@ -1857,6 +1864,9 @@ def update_background(self, event):
         # Make sure that widget artists don't get accidentally included in the
         # background, by re-rendering the background if needed (and then
         # re-re-rendering the canvas with the visible widget artists).
+        # We need to remove all artists which will be drawn when updating
+        # the selector: if we have animated artists in the figure, it is safer
+        # to redrawn by default, in case they have updated by the callback
         artists = self.artists + self._get_animated_artists()
         needs_redraw = any(artist.get_visible() for artist in artists)
         with ExitStack() as stack:
@@ -1913,9 +1923,10 @@ def update(self):
                 self.canvas.restore_region(self.background)
             else:
                 self.update_background(None)
+            # We need to draw all artists, which are not included in the
+            # background, therefore we add self._get_animated_artists()
             for artist in self.artists + self._get_animated_artists():
-                if artist.stale:
-                    self.ax.draw_artist(artist)
+                self.ax.draw_artist(artist)
             self.canvas.blit(self.ax.bbox)
         else:
             self.canvas.draw_idle()