Before/After button: Show Original (\) does not light it (fixes #1497)

The bottom bar's Before/After (Y) button was lit for every mode but Off,
so holding or toggling \ (Show Original) lit it too, and a click then
opened the side-by-side layout: one lit button for two different views.
It now stands only for the Before/After layouts.

crates/ui-egui/src/panels/bottombar.rs

@@ -6,7 +6,7 @@ use serde_json::json;
 
 use crate::LightcraftApp;
 use crate::icons::{Icon, paint};
-use crate::state::{BeforeAfter, ViewMode, Zoom};
+use crate::state::{ViewMode, Zoom};
 use crate::theme::Tokens;
 use crate::widgets::{icon_button, register, stars};
 
@@ -178,16 +178,8 @@ fn right_side(app: &mut LightcraftApp, ui: &mut egui::Ui, full: Rect, compact_zo
     if app.ui.view == ViewMode::Survey {
         // no zoom or thumbnail size in Survey
     } else if matches!(app.ui.view, ViewMode::Detail | ViewMode::Compare) {
-        if icon_button(
-            &mut child,
-            "beforeAfter",
-            Icon::BeforeAfter,
-            vec2(30.0, 30.0),
-            app.ui.before_after != BeforeAfter::Off,
-            true,
-            "Before/After (Y)",
-        )
-        .clicked()
+        if icon_button(&mut child, "beforeAfter", Icon::BeforeAfter, vec2(30.0, 30.0), app.ui.before_after.is_layout(), true, "Before/After (Y)")
+            .clicked()
         {
             let _ = app.run("view.beforeAfter", json!({}));
         }

crates/ui-egui/src/state.rs

@@ -70,6 +70,14 @@ pub enum BeforeAfter {
     SplitTopBottom,
 }
 
+impl BeforeAfter {
+    /// One of the Before / After layouts (two views or a split line), which the bottom bar's
+    /// Before/After (Y) button stands for. Show Original (`\`) is a view of its own, not a layout.
+    pub fn is_layout(self) -> bool {
+        !matches!(self, BeforeAfter::Off | BeforeAfter::Original)
+    }
+}
+
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub enum CropOverlay {

crates/ui-egui/src/tests_before_after.rs

@@ -132,3 +132,30 @@ fn zoomed_in_the_after_side_shows_the_edits() {
         }
     }
 }
+
+/// Show Original (`\`) is not one of the Before / After layouts, so the bottom bar's
+/// Before/After (Y) button stays dark for it; clicking the button then lays out Before and After
+/// side by side, as it does from the plain view. It used to light up for `\` too, so the same
+/// lit button stood for two different views (#1497).
+#[test]
+fn show_original_does_not_light_the_before_after_button() {
+    assert!(!BeforeAfter::Off.is_layout());
+    assert!(!BeforeAfter::Original.is_layout());
+    for mode in [BeforeAfter::SideBySide, BeforeAfter::Split, BeforeAfter::TopBottom, BeforeAfter::SplitTopBottom] {
+        assert!(mode.is_layout(), "{mode:?}");
+    }
+    let app = LightcraftApp::new(lightcraft_engine::Session::with_demo(), Services { png: None, ..Default::default() });
+    let mut h = Headless::new(app, [1400.0, 900.0], 1.0);
+    let id = h.app.session.visible_cloned()[2];
+    h.request("engine.execute", json!({"command": "library.select", "params": {"ids": [id.0], "active": id.0}}), T);
+    h.app.ui.view = ViewMode::Detail;
+    h.settle(SETTLE);
+    assert_eq!(h.request("engine.execute", json!({"command": "view.showOriginal"}), T)["ok"], true);
+    assert_eq!(h.app.ui.before_after, BeforeAfter::Original);
+    assert!(!h.app.ui.before_after.is_layout(), "the button is dark while the original is shown");
+    h.settle(SETTLE);
+    assert_eq!(h.request("ui.clickWidget", json!({"id": "icon:beforeAfter"}), T)["ok"], true);
+    assert_eq!(h.app.ui.before_after, BeforeAfter::SideBySide, "a click on the dark button opens the layout");
+    assert_eq!(h.request("ui.clickWidget", json!({"id": "icon:beforeAfter"}), T)["ok"], true);
+    assert_eq!(h.app.ui.before_after, BeforeAfter::Off, "a second click closes it");
+}