#237: test that wrapped colour picker swatches stay inset inside the picker

The "On this page" swatches were indented by a single add_space, so once they wrapped the later rows started at the picker's left edge and ran past its right edge. The test fills a page with 40 distinct colours, opens the picker and checks every painted swatch lies at least 16 pt inside both sides of the picker window. Without the fix the rightmost swatch ends 3 pt inside the edge instead of 16.

crates/ui-egui/src/colorpicker_selection_tests.rs

@@ -52,3 +52,54 @@ fn picker_closes_when_another_layer_is_selected() {
     u.frame(vec![]);
     assert!(u.app.ui.picker.is_none(), "selecting another layer closes the picker: {:?}", u.app.ui.picker);
 }
+
+// Regression test for #237: the "On this page" swatches wrapped onto rows that started at the picker's
+// left edge (only the first row was indented) and ran past its right edge.
+#[test]
+fn wrapped_page_colour_swatches_stay_inset_inside_the_picker() {
+    use egui::Shape;
+    let mut s = Session::new();
+    let mut first = None;
+    for i in 0..40 {
+        let v = s
+            .execute(
+                "shape.rectangle",
+                &json!({"x": i * 30, "y": 0, "width": 20, "height": 20, "props": {"fill": format!("#{:02X}{:02X}80", i * 6, 255 - i * 6)}}),
+            )
+            .unwrap();
+        first.get_or_insert(NodeId(v["id"].as_u64().unwrap()));
+    }
+    let a = first.unwrap();
+    s.execute("select.set", &json!({"ids": [a]})).unwrap();
+    let mut u = Ui::new(s);
+    u.app.ui.picker = Some(PickerTarget::Paint { fills: true, index: 0, ids: vec![a] });
+    for _ in 0..3 {
+        u.frame(vec![]);
+    }
+    let out = u.frame_output(vec![]);
+    // The picker is the only floating window open.
+    let picker = u
+        .ctx
+        .memory(|m| m.areas().visible_layer_ids().into_iter().filter(|l| l.order == egui::Order::Middle).find_map(|l| m.area_rect(l.id)))
+        .expect("the picker is open");
+    // A swatch is a 14 pt square with a 1 pt outline.
+    let swatches: Vec<egui::Rect> = out
+        .shapes
+        .iter()
+        .filter_map(|c| match &c.shape {
+            Shape::Rect(r) if r.stroke.width == 1.0 && (r.rect.width() - 14.0).abs() < 0.01 && (r.rect.height() - 14.0).abs() < 0.01 => Some(r.rect),
+            _ => None,
+        })
+        .filter(|r| picker.contains_rect(*r))
+        .collect();
+    let mut rows: Vec<f32> = swatches.iter().map(|r| r.min.y).collect();
+    rows.sort_by(f32::total_cmp);
+    rows.dedup_by(|a, b| (*a - *b).abs() < 1.0);
+    assert!(rows.len() >= 2, "expected the page colours to wrap onto several rows, got {} swatches in {} row(s)", swatches.len(), rows.len());
+    for r in &swatches {
+        assert!(
+            r.min.x >= picker.min.x + 16.0 - 0.5 && r.max.x <= picker.max.x - 16.0 + 0.5,
+            "swatch {r:?} is not inset 16 pt from both sides of the picker {picker:?}"
+        );
+    }
+}