provide warning before clicking in dropdown and disable preset/function

CHANGES.rst

@@ -28,6 +28,8 @@ Imviz
 - There is now option for image rotation in Orientation (was Links Control) plugin.
   This feature requires WCS linking. [#2179]
 
+- Add "Random" colormap for visualizing image segmentation maps. [#2671]
+
 Mosviz
 ^^^^^^
 

jdaviz/configs/default/plugins/plot_options/plot_options.py

@@ -29,10 +29,34 @@
 from jdaviz.core.custom_traitlets import IntHandleEmpty, FloatHandleEmpty
 
 from scipy.interpolate import PchipInterpolator
+from photutils.utils import make_random_cmap
 
 __all__ = ['PlotOptions']
 
 
+def _register_random_cmap(
+    cmap_name,
+    bkg_color=[0, 0, 0],
+    bkg_alpha=1,
+    seed=42,
+    ncolors=10_000
+):
+    """
+    Custom random colormap, useful for rendering image
+    segmentation maps. The default background for
+    `label==0` is *transparent*. If the segmentation map
+    contains more than 10,000 labels, adjust the `ncolors`
+    kwarg to ensure uniqueness.
+    """
+    cmap = make_random_cmap(ncolors=ncolors, seed=seed)
+    cmap.colors[0] = bkg_color + [bkg_alpha]
+    cmap.name = cmap_name
+    colormaps.add(cmap_name, cmap)
+
+
+_register_random_cmap('Random', bkg_alpha=1)
+
+
 class SplineStretch:
     """
     A class to represent spline stretches.
@@ -1093,3 +1117,14 @@ def _is_image_viewer(viewer):
             viewers = [viewers]
 
         return np.all([_is_image_viewer(viewer) for viewer in viewers])
+
+    @observe('image_colormap_value')
+    def _random_cmap_limit_update(self, *args, **kwargs):
+        # if 'Random' colormap is used for visualizing image segmentation,
+        # ensure the stretch limits are the min and max, so all label colors
+        # are unique:
+        if self.image_colormap_value != 'Random':
+            return
+
+        self.stretch_preset.value = 100
+        self.stretch_function.value = 'linear'

jdaviz/configs/default/plugins/plot_options/plot_options.vue

@@ -439,7 +439,24 @@
             v-model="image_colormap_value"
             label="Colormap"
             dense
-          ></v-select>
+          >
+            <template slot="item" slot-scope="data">
+              <div class="single-line" style="width: 100%">
+                <j-tooltip v-if="data.item.text === 'Random'" tooltipcontent="Selecting the 'Random' colormap will set the stretch percentile preset
+                to min/max, the stretch function to linear, and prevent manually changing either.">
+                  <span>
+                    {{ data.item.text }}
+                  </span>
+                  <v-icon>
+                    mdi-information-outline
+                  </v-icon>
+                </j-tooltip>
+                <span v-else>
+                  {{ data.item.text }}
+                </span>
+              </div>
+            </template>
+          </v-select>
         </glue-state-sync-wrapper>
         <glue-state-sync-wrapper v-if="image_color_mode_value !== 'Colormaps' || image_color_mode_sync['mixed']" :sync="image_color_sync" :multiselect="layer_multiselect" @unmix-state="unmix_state('image_color')">
           <div>
@@ -493,7 +510,10 @@
           :items="stretch_function_sync.choices"
           v-model="stretch_function_value"
           label="Stretch Function"
-          class="no-hint"
+          :disabled="image_colormap_value==='Random'"
+          :hint="image_colormap_value==='Random' ? 'Cannot set while colormap is set to Random': null"
+          persistent-hint
+          dense
         ></v-select>
       </glue-state-sync-wrapper>
 
@@ -504,7 +524,10 @@
           :items="stretch_preset_sync.choices"
           v-model="stretch_preset_value"
           label="Stretch Percentile Preset"
-          class="no-hint"
+          :disabled="image_colormap_value==='Random'"
+          :hint="image_colormap_value==='Random' ? 'Cannot set while colormap is set to Random': null"
+          persistent-hint
+          dense
         ></v-select>
       </glue-state-sync-wrapper>
 

jdaviz/configs/default/plugins/plot_options/tests/test_plot_options.py

@@ -391,3 +391,26 @@ def test_track_mixed_states(imviz_helper):
     assert not po.stretch_function_sync['mixed']
     assert po.stretch_function_value == 'spline'
     assert not po.stretch_params_sync['mixed']
+
+
+def test_segmentation_image(imviz_helper):
+    # Make one circular segment for a hypothetical
+    # image with one source:
+    nx = ny = 100
+    radius = 15
+    x0 = y0 = 50
+
+    segmentation_map = np.zeros((nx, ny))
+    xx, yy = np.meshgrid(np.arange(nx), np.arange(ny))
+    in_circle = np.hypot(xx - x0, yy - y0) < radius
+    segmentation_map[in_circle] = 1
+
+    imviz_helper.load_data(segmentation_map)
+
+    plot_opts = imviz_helper.plugins['Plot Options']
+    plot_opts.image_colormap = 'Random'
+
+    # ensure that stretch preset is listening to the update to the
+    # random colormap so that all colors are uniquely displayed:
+    assert plot_opts.stretch_preset.value == 100
+    assert plot_opts.stretch_function.value == 'linear'

jdaviz/configs/imviz/tests/test_astrowidgets_api.py

@@ -182,7 +182,7 @@ def test_colormap_options(self):
             'Gray', 'Viridis', 'Plasma', 'Inferno', 'Magma', 'Purple-Blue',
             'Yellow-Green-Blue', 'Yellow-Orange-Red', 'Red-Purple', 'Blue-Green',
             'Hot', 'Red-Blue', 'Red-Yellow-Blue', 'Purple-Orange', 'Purple-Green',
-            'Rainbow', 'Seismic',
+            'Random', 'Rainbow', 'Seismic',
             'Reversed: Gray', 'Reversed: Viridis', 'Reversed: Plasma', 'Reversed: Inferno',
             'Reversed: Magma', 'Reversed: Hot', 'Reversed: Rainbow']