fix(ui): show a paint-bucket cursor for the Paint Bucket tool (#3968) (#3989)

crates/ui-egui/src/canvas.rs

@@ -3527,6 +3527,14 @@ pub fn canvas_view(app: &mut PhotocraftApp, ui: &mut egui::Ui, idx: usize, rect:
                         pipette_cursor(ui.ctx(), p)
                     }
                 }
+                // The Paint Bucket: a bucket, or the crosshair for Precise Other Cursors (#3968).
+                Tool::PaintBucket => {
+                    if app.session.prefs().cursors.other == photocraft_engine::prefs::OtherCursor::Precise {
+                        egui::CursorIcon::Crosshair
+                    } else {
+                        paint_bucket_cursor(ui.ctx(), p)
+                    }
+                }
                 // Preferences › Cursors › Other Cursors: Precise shows a crosshair for every tool.
                 Tool::Move | Tool::Type | Tool::VerticalType | Tool::HorizontalTypeMask | Tool::VerticalTypeMask
                     if app.session.prefs().cursors.other == photocraft_engine::prefs::OtherCursor::Precise =>
@@ -4346,6 +4354,14 @@ pub(crate) fn pipette_cursor(ctx: &egui::Context, p: Pos2) -> egui::CursorIcon {
     egui::CursorIcon::None
 }
 
+/// The Paint Bucket's cursor: a bucket whose pouring corner is the filled pixel. Draws it at `p`
+/// and returns the OS cursor to set (hidden).
+pub(crate) fn paint_bucket_cursor(ctx: &egui::Context, p: Pos2) -> egui::CursorIcon {
+    // The left corner of the icon's bucket is at (2, 12) of its 24-unit box.
+    crate::icons::cursor(ctx, "paint-bucket", p, vec2(2.0, 12.0) / 24.0, 22.0);
+    egui::CursorIcon::None
+}
+
 /// Decided when the press starts, so ⌥ pressed or released mid-stroke never switches between
 /// painting and sampling.
 fn alt_eyedropper(app: &mut PhotocraftApp, ev: ToolEvent, mods: egui::Modifiers) -> bool {

crates/ui-egui/src/input_tests.rs

@@ -564,6 +564,22 @@ fn eyedropper_and_alt_sampling_show_a_pipette() {
     assert_eq!(precise(&mut h), (egui::CursorIcon::Crosshair, desktop));
 }
 
+/// The Paint Bucket shows a bucket instead of the crosshair (#3968); Precise Other Cursors keeps
+/// the crosshair.
+#[test]
+fn paint_bucket_shows_a_bucket_cursor() {
+    let mut h = harness();
+    let p = h.state().last_canvas_rect.center();
+    h.state_mut().ui.tool = crate::state::Tool::PaintBucket;
+    h.hover_at(p);
+    h.run_steps(2);
+    assert_eq!(h.output().platform_output.cursor_icon, egui::CursorIcon::None, "the bucket replaces the pointer");
+    h.state_mut().run("prefs.set", json!({"values": {"cursors.other": "precise"}})).unwrap();
+    h.hover_at(p);
+    h.run_steps(2);
+    assert_eq!(h.output().platform_output.cursor_icon, egui::CursorIcon::Crosshair, "Precise keeps the crosshair");
+}
+
 /// The Hand tool, and Space held over another tool, show an open hand while hovering and a fist
 /// while they pan (#2196). The OS draws those everywhere but Windows, where winit maps `Grab` to
 /// the four-arrow move cursor, so the app hands it a bitmap there (`Crosshair` is the fallback).