Rescale the waveform view when the waveforms type changes

docs/changelog.md

@@ -50,6 +50,10 @@ behavior they verify rather than listed separately.
   Escape, and outside clicks release filter focus so global shortcuts resume.
 - Display metadata columns containing multiple values in the Cluster and
   Similarity Views instead of leaving their cells blank.
+- Rescale the Waveform View y axis when the waveforms type changes. Templates
+  and mean waveforms are no longer drawn as flat lines after switching away
+  from raw waveforms, and raw waveforms no longer overflow their box after
+  switching back.
 - Sort text columns holding numbers, such as the channel column `ch`, by
   numeric value in the Cluster and Similarity Views. Channel 2 no longer
   appears after channel 10.

phy/cluster/views/tests/test_waveform.py

@@ -113,3 +113,59 @@ def on_select_channel(sender, channel_id=None, button=None, key=None):
     v.set_state(v.state)
 
     _stop_and_close(qtbot, v)
+
+
+def test_waveform_view_rescale_on_waveforms_type(qtbot, gui):
+    nc = 5
+    ns = 10
+
+    raw = 100 * artificial_waveforms(ns, 20, nc)
+    # Mean waveforms are a thousand times smaller here, the way templates typically
+    # are next to raw traces.
+    mean = raw / 1000.0
+
+    def _waveforms(data):
+        def get_waveforms(cluster_id):
+            return Bunch(
+                data=data,
+                channel_ids=np.arange(nc),
+                channel_positions=staggered_positions(nc),
+            )
+
+        return get_waveforms
+
+    v = WaveformView(
+        waveforms={'waveforms': _waveforms(raw), 'mean_waveforms': _waveforms(mean)},
+        sample_rate=10000.0,
+    )
+    with qtbot.waitExposed(v.canvas):
+        v.show()
+    v.attach(gui)
+
+    v.on_select(cluster_ids=[0])
+    raw_max = v.data_bounds[3]
+    assert raw_max > 0
+
+    # The y axis follows the displayed waveforms type, otherwise the smaller
+    # waveforms are drawn as flat lines.
+    v.next_waveforms_type()
+    assert v.waveforms_type == 'mean_waveforms'
+    ac(v.data_bounds[3], raw_max / 1000.0, rtol=1e-5)
+
+    v.previous_waveforms_type()
+    assert v.waveforms_type == 'waveforms'
+    ac(v.data_bounds[3], raw_max, rtol=1e-5)
+
+    v.toggle_mean_waveforms(True)
+    assert v.waveforms_type == 'mean_waveforms'
+    ac(v.data_bounds[3], raw_max / 1000.0, rtol=1e-5)
+
+    v.toggle_mean_waveforms(False)
+    assert v.waveforms_type == 'waveforms'
+    ac(v.data_bounds[3], raw_max, rtol=1e-5)
+
+    v.waveforms_type = 'mean_waveforms'
+    v.plot()
+    ac(v.data_bounds[3], raw_max / 1000.0, rtol=1e-5)
+
+    _stop_and_close(qtbot, v)

phy/cluster/views/waveform.py

@@ -511,27 +511,45 @@ def waveforms_type(self):
 
     @waveforms_type.setter
     def waveforms_type(self, value):
+        previous_type = self.waveforms_type
         self.waveforms_types.set(value)
+        self._rescale_if_waveforms_type_changed(previous_type)
+
+    def _rescale_if_waveforms_type_changed(self, previous_type):
+        """Discard the cached y axis bounds when the waveforms type has changed.
+
+        Raw waveforms, mean waveforms and templates have very different amplitude
+        scales, so bounds computed for one type make the others unreadable, either as
+        flat lines or as traces overflowing their box. Dropping the bounds makes the
+        next plot recompute them for the type now displayed.
+
+        """
+        if self.waveforms_type != previous_type:
+            self.data_bounds = None
 
     def next_waveforms_type(self):
         """Switch to the next waveforms type."""
+        previous_type = self.waveforms_type
         self.waveforms_types.next()
+        self._rescale_if_waveforms_type_changed(previous_type)
         logger.debug('Switch to waveforms type %s.', self.waveforms_type)
         self.plot()
 
     def previous_waveforms_type(self):
         """Switch to the previous waveforms type."""
+        previous_type = self.waveforms_type
         self.waveforms_types.previous()
+        self._rescale_if_waveforms_type_changed(previous_type)
         logger.debug('Switch to waveforms type %s.', self.waveforms_type)
         self.plot()
 
     def toggle_mean_waveforms(self, checked):
         """Switch to the `mean_waveforms` type, if it is available."""
         if self.waveforms_type == 'mean_waveforms' and 'waveforms' in self.waveforms:
-            self.waveforms_types.set('waveforms')
+            self.waveforms_type = 'waveforms'
             logger.debug('Switch to raw waveforms.')
             self.plot()
         elif 'mean_waveforms' in self.waveforms:
-            self.waveforms_types.set('mean_waveforms')
+            self.waveforms_type = 'mean_waveforms'
             logger.debug('Switch to mean waveforms.')
             self.plot()