Started fixing density map in scatter viewer for many points

glue_jupyter/bqplot/scatter/layer_artist.py

@@ -48,8 +48,6 @@ def __init__(self, view, viewer_state, layer_state=None, layer=None):
         self.counts = None
         self.image = ImageGL(scales=self.scales_image, image=EMPTY_IMAGE)
         on_change([(self.state, 'density_map')])(self._on_change_density_map)
-        on_change([(self.state, 'bins')])(self._update_scatter)
-        self._viewer_state.add_global_callback(self._update_scatter)
 
         self.view.figure.marks = (list(self.view.figure.marks)
                                   + [self.image, self.scatter, self.quiver])
@@ -117,7 +115,7 @@ def _on_change_cmap(self, ignore=None):
 
     def _on_change_density_map(self):
         self._update_visibility()
-        self._update_scatter()
+        self._update_density_map()
 
     def _update_visibility(self, *args):
         self.image.visible = self.state.density_map
@@ -149,7 +147,7 @@ def _workaround_unselected_style(self, change=None):
             self.quiver.unselected_style = {'fill': 'none', 'stroke': 'none'}
 
     @debounced(method=True)
-    def update_histogram(self):
+    def _update_density_map(self):
         if isinstance(self.layer, Subset):
             data = self.layer.data
             subset_state = self.layer.subset_state
@@ -171,10 +169,8 @@ def update_histogram(self):
                 self.image.x = range_x
                 self.image.y = range_y
                 self.image.image = self.counts.T.astype(np.float32, copy=True)
-
-    def _update_scatter(self, **changes):
-        self.update_histogram()
-        self.update()
+        else:
+            self.image.image = None
 
     def update(self):
 
@@ -212,13 +208,18 @@ def update(self):
             self.enable()
 
         if self.state.density_map:
-            pass
+            self.scatter.x = []
+            self.scatter.y = []
+            self.quiver.x = []
+            self.quiver.y = []
         else:
             self.scatter.x = x.astype(np.float32).ravel()
             self.scatter.y = y.astype(np.float32).ravel()
             self.quiver.x = self.scatter.x
             self.quiver.y = self.scatter.y
 
+        self._update_density_map()
+
         if isinstance(self.layer, Subset):
 
             try:

glue_jupyter/bqplot/scatter/tests/test_visual.py

@@ -29,3 +29,42 @@ def test_visual_scatter2d(
     figure = scatter.figure_widget
     figure.layout = {"width": "400px", "height": "250px"}
     return figure
+
+
+@visual_widget_test
+def test_visual_scatter2d_density(
+    tmp_path,
+    page_session,
+    solara_test,
+):
+
+    # Test that for many points, density maps are shown
+
+    np.random.seed(12345)
+
+    app = jglue()
+
+    x = np.random.normal(3, 1, 100)
+    y = np.random.normal(2, 1.5, 100)
+    c = np.hypot(x - 3, y - 2)
+    s = (x - 3)
+
+    data1 = app.add_data(a={"x": x, "y": y, "c": c, "s": s})[0]
+
+    xx = np.random.normal(3, 1, 1000000)
+    yy = np.random.normal(2, 1.5, 1000000)
+
+    data2 = app.add_data(a={"x": xx, "y": yy})[0]
+
+    scatter = app.scatter2d(show=False, data=data1)
+    scatter.add_data(data2)
+
+    scatter.state.layers[0].cmap_mode = 'Linear'
+    scatter.state.layers[0].cmap_att = data1.id['c']
+    scatter.state.layers[0].cmap = plt.cm.viridis
+    scatter.state.layers[0].size_mode = 'Linear'
+    scatter.state.layers[0].size_att = data1.id['s']
+
+    figure = scatter.figure_widget
+    figure.layout = {"width": "400px", "height": "250px"}
+    return figure