#815: test that the toolbar's scroll bar stays a slim line

The toolbar's and the dock icon column's scroll bar widened to 10 points while the pointer was on it, covering the group labels and the tool icons' right edge. The test lays out a scrolling strip, rests the pointer on its bar and measures the widest filled rectangle drawn: at most 4 points. Without the slim scroll style it measures 10 points.
2026-10-24 09:46:59 -06:00 · 2026-10-22 13:10:42 -06:00
parent f8eaa4571f
commit 2796790161
1 changed files with 74 additions and 0 deletions
@@ -2970,3 +2970,77 @@ mod button_tests {
        out.textures_delta.clear();
    }
 }
+
+/// How the shared widgets look once laid out and painted: shapes of whole frames, measured.
+#[cfg(test)]
+pub(crate) mod look_tests {
+    use super::*;
+
+    /// A context with the fonts and the theme in `brightness`, in English.
+    pub(crate) fn themed(brightness: theme::Brightness) -> egui::Context {
+        crate::i18n::set_current(crate::i18n::Lang::EN);
+        let ctx = egui::Context::default();
+        theme::install_fonts(&ctx);
+        theme::apply(&ctx, brightness);
+        ctx
+    }
+
+    /// One frame at `time` seconds of `add` in a 600 × 400 window with `events` → the shapes it
+    /// drew, `Shape::Vec`s flattened.
+    pub(crate) fn frame(ctx: &egui::Context, time: f64, events: Vec<egui::Event>, add: impl FnMut(&mut Ui)) -> Vec<egui::Shape> {
+        fn flat(s: egui::Shape, out: &mut Vec<egui::Shape>) {
+            match s {
+                egui::Shape::Vec(v) => v.into_iter().for_each(|s| flat(s, out)),
+                s => out.push(s),
+            }
+        }
+        let raw =
+            egui::RawInput { time: Some(time), screen_rect: Some(Rect::from_min_size(Pos2::ZERO, vec2(600.0, 400.0))), events, ..Default::default() };
+        let mut out = ctx.run_ui(raw, add);
+        out.textures_delta.clear();
+        let mut shapes = vec![];
+        out.shapes.into_iter().for_each(|c| flat(c.shape, &mut shapes));
+        shapes
+    }
+
+    // Regression test for #808: the scroll bar of the toolbar and the dock's icon column widened to
+    // 10 points while it was dragged or the pointer was on it, covering the group labels and the
+    // right edge of the tool icons. It stays a slim line.
+    #[test]
+    fn the_strip_scroll_bar_stays_a_slim_line_while_the_pointer_is_on_it() {
+        let ctx = themed(Default::default());
+        let area = std::cell::Cell::new(Rect::NOTHING);
+        let mut add = |ui: &mut Ui| {
+            area.set(
+                ui.allocate_ui(vec2(80.0, 200.0), |ui| {
+                    strip_scroll(ui, "strip", |ui| {
+                        for i in 0..40 {
+                            ui.label(format!("Tool {i}"));
+                        }
+                    });
+                })
+                .response
+                .rect,
+            );
+        };
+        frame(&ctx, 0.0, vec![], &mut add);
+        let area = area.get();
+        assert!(area.height() >= 199.0, "the strip fills the height it was given: {area:?}");
+        // The pointer comes onto the bar's edge and stays there while the bar settles.
+        let on_the_bar = egui::Event::PointerMoved(pos2(area.right() - 1.0, area.center().y));
+        let mut widest = 0.0_f32;
+        for i in 1..=15 {
+            let shapes = frame(&ctx, f64::from(i) * 0.1, if i == 1 { vec![on_the_bar.clone()] } else { vec![] }, &mut add);
+            for s in shapes {
+                // The bar's track and handle are the filled rectangles.
+                if let egui::Shape::Rect(r) = s
+                    && r.fill != Color32::TRANSPARENT
+                {
+                    widest = widest.max(r.rect.width());
+                }
+            }
+        }
+        assert!(widest > 0.0, "the scroll bar is drawn");
+        assert!(widest <= 4.5, "the scroll bar is {widest} points wide");
+    }
+}