Reverse preset color order (#2568)

* Reverse preset color order

Add changelog

* End 4 color preset at red

* Fix codestyle

* Swap case order

CHANGES.rst

@@ -17,7 +17,7 @@ New Features
 
 - Reorder viewer and layer settings in Plot Options. [#2543, #2557]
 
-- Add button in Plot Options to apply preset RBG options to visible layers when in Monochromatic mode. [#2558]
+- Add button in Plot Options to apply preset RBG options to visible layers when in Monochromatic mode. [#2558, #2568]
 
 Cubeviz
 ^^^^^^^

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

@@ -616,13 +616,15 @@ def apply_RGB_presets(self):
                 self.image_color_mode_sync['mixed']):
             raise ValueError("RGB presets can only be applied if color mode is Monochromatic.")
         # Preselected colors we want to use for 5 or less layers
-        preset_colors = [self.swatches_palette[0][0],
-                         self.swatches_palette[1][0],
-                         "#00FF00",
+        preset_colors = [self.swatches_palette[4][1],
                          "#0000FF",
-                         self.swatches_palette[4][1]
+                         "#00FF00",
+                         self.swatches_palette[1][0],
+                         self.swatches_palette[0][0],
                          ]
 
+        preset_inds = {2: [1, 4], 3: [1, 2, 4], 4: [1, 2, 3, 4]}
+
         # Switch back to this at the end
         initial_layer = self.layer_selected
 
@@ -639,15 +641,14 @@ def apply_RGB_presets(self):
         default_opacity = 1
         if n_visible > 2:
             default_opacity = 1 / math.log2(n_visible)
+
         # Sample along a colormap if we have too many layers
-        if n_visible == 2:
-            preset_colors = [preset_colors[0], preset_colors[3]]
-        elif n_visible == 3:
-            preset_colors = [preset_colors[0], preset_colors[2], preset_colors[3]]
-        elif n_visible > len(preset_colors):
+        if n_visible > len(preset_colors):
             cmap = matplotlib.colormaps['gist_rainbow'].resampled(n_visible)
             preset_colors = [matplotlib.colors.to_hex(cmap(i), keep_alpha=True) for
                              i in range(n_visible)]
+        elif n_visible >= 2 and n_visible < len(preset_colors):
+            preset_colors = [preset_colors[i] for i in preset_inds[n_visible]]
 
         for i in range(n_visible):
             self.layer_selected = visible_layers[i]

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

@@ -257,8 +257,8 @@ def test_apply_presets(imviz_helper):
     arr = np.arange(36).reshape(6, 6)
     po = imviz_helper.plugins['Plot Options']
 
-    preset_colors = [po._obj.swatches_palette[0][0], po._obj.swatches_palette[1][0],
-                     "#00FF00", "#0000FF", po._obj.swatches_palette[4][1]]
+    preset_colors_4 = ["#0000FF", "#00FF00", po._obj.swatches_palette[1][0],
+                       po._obj.swatches_palette[0][0]]
 
     # Test applying presets with < 6 layers
 
@@ -272,7 +272,7 @@ def test_apply_presets(imviz_helper):
         po.layer = f"array_{i}"
         assert po.stretch_function.value == "arcsinh"
         assert po.stretch_preset.value == 99
-        assert po.image_color.value == preset_colors[i]
+        assert po.image_color.value == preset_colors_4[i]
 
     # Test applying presets with > 5 layers