Fix not being able to update color and label of columns

It was no longer possible to update the labels and colors of the
detected columns because they were always overwritten by the default
values.

Fix this by only settings label and color once after column changes,
like it was done before.

This bug was introduced in #119.

Author: Rahix

src/gui.rs

@@ -320,11 +320,15 @@ impl MyApp {
                 ui.vertical(|ui| {
                     if let Ok(gui_data) = self.data_lock.read() {
                         self.data = gui_data.clone();
-                        self.labels = gui_data.plots.iter().map(|d| d.0.clone()).collect();
-                        self.colors = (0..max(self.labels.len(), 1))
-                            .map(|i| COLORS[i % COLORS.len()])
-                            .collect();
-                        self.color_vals = (0..max(self.data.plots.len(), 1)).map(|_| 0.0).collect();
+                        if self.data.plots.len() != self.labels.len() {
+                            self.labels = gui_data.plots.iter().map(|d| d.0.clone()).collect();
+                        }
+                        if self.colors.len() != self.labels.len() {
+                            self.colors = (0..max(self.labels.len(), 1))
+                                .map(|i| COLORS[i % COLORS.len()])
+                                .collect();
+                            self.color_vals = (0..max(self.data.plots.len(), 1)).map(|_| 0.0).collect();
+                        }
                     }
 
                     // TODO what about self.data.loaded_from_file