add layout crate with resize handle

crates/layout/tests/resize_handle.rs

@@ -0,0 +1,201 @@
+use std::cell::RefCell;
+use std::rc::Rc;
+
+use gpui::{
+    Axis, Modifiers, MouseButton, MouseDownEvent, MouseMoveEvent, MouseUpEvent, ParentElement as _,
+    Pixels, Render, Styled as _, TestAppContext, VisualTestContext, Window, div, point, px,
+};
+use gpui_native_layout::resize_handle::ResizeHandle;
+use gpui_native_theme::Theme;
+
+type DeltaSink = Rc<RefCell<Vec<Pixels>>>;
+type ResetSink = Rc<RefCell<usize>>;
+
+struct Harness {
+    deltas: Rc<RefCell<Vec<Pixels>>>,
+    resets: Rc<RefCell<usize>>,
+    axis: Axis,
+    disabled: bool,
+}
+
+impl Render for Harness {
+    fn render(
+        &mut self,
+        _window: &mut Window,
+        _cx: &mut gpui::Context<Self>,
+    ) -> impl gpui::IntoElement {
+        let deltas = self.deltas.clone();
+        let resets = self.resets.clone();
+        div()
+            .size_full()
+            .flex()
+            .flex_row()
+            .child(div().w(px(120.)).h_full())
+            .child(
+                ResizeHandle::new("test-handle")
+                    .axis(self.axis)
+                    .disabled(self.disabled)
+                    .on_resize(move |delta, _, _| deltas.borrow_mut().push(delta))
+                    .on_reset(move |_, _| *resets.borrow_mut() += 1),
+            )
+            .child(div().flex_1().h_full())
+    }
+}
+
+fn handle_window(
+    axis: Axis,
+    disabled: bool,
+) -> (TestAppContext, DeltaSink, ResetSink, VisualTestContext) {
+    let mut cx = TestAppContext::single();
+    cx.update(Theme::init);
+    let deltas = Rc::new(RefCell::new(Vec::new()));
+    let resets = Rc::new(RefCell::new(0usize));
+    let deltas_for_window = deltas.clone();
+    let resets_for_window = resets.clone();
+    let window = cx.add_window(move |_, _| Harness {
+        deltas: deltas_for_window,
+        resets: resets_for_window,
+        axis,
+        disabled,
+    });
+    let mut visual = VisualTestContext::from_window(window.into(), &cx);
+    visual.update(|window, cx| {
+        window.draw(cx).clear(cx);
+    });
+    (cx, deltas, resets, visual)
+}
+
+fn handle_center(visual: &mut VisualTestContext) -> gpui::Point<gpui::Pixels> {
+    let bounds = visual
+        .debug_bounds("resize-handle")
+        .expect("resize handle missing");
+    point(bounds.center().x, bounds.center().y)
+}
+
+fn click(visual: &mut VisualTestContext, position: gpui::Point<gpui::Pixels>) {
+    visual.simulate_mouse_down(position, MouseButton::Left, Modifiers::default());
+    visual.simulate_mouse_up(position, MouseButton::Left, Modifiers::default());
+}
+
+#[test]
+fn dragging_reports_signed_deltas() {
+    let (_cx, deltas, _resets, mut visual) = handle_window(Axis::Horizontal, false);
+    let start = handle_center(&mut visual);
+
+    visual.simulate_mouse_down(start, MouseButton::Left, Modifiers::default());
+    visual.simulate_event(MouseMoveEvent {
+        position: point(start.x + px(30.), start.y),
+        pressed_button: Some(MouseButton::Left),
+        modifiers: Modifiers::default(),
+    });
+    visual.simulate_event(MouseMoveEvent {
+        position: point(start.x + px(10.), start.y),
+        pressed_button: Some(MouseButton::Left),
+        modifiers: Modifiers::default(),
+    });
+    visual.simulate_mouse_up(start, MouseButton::Left, Modifiers::default());
+
+    assert_eq!(*deltas.borrow(), vec![px(30.), px(-20.)]);
+}
+
+#[test]
+fn vertical_seams_report_y_deltas() {
+    let (_cx, deltas, _resets, mut visual) = handle_window(Axis::Vertical, false);
+    let start = handle_center(&mut visual);
+
+    visual.simulate_mouse_down(start, MouseButton::Left, Modifiers::default());
+    visual.simulate_event(MouseMoveEvent {
+        position: point(start.x, start.y + px(40.)),
+        pressed_button: Some(MouseButton::Left),
+        modifiers: Modifiers::default(),
+    });
+    visual.simulate_mouse_up(start, MouseButton::Left, Modifiers::default());
+
+    assert_eq!(*deltas.borrow(), vec![px(40.)]);
+}
+
+#[test]
+fn moves_without_a_drag_report_nothing() {
+    let (_cx, deltas, _resets, mut visual) = handle_window(Axis::Horizontal, false);
+    let start = handle_center(&mut visual);
+
+    // Hovering and moving across the seam without pressing does nothing.
+    visual.simulate_event(MouseMoveEvent {
+        position: point(start.x + px(30.), start.y),
+        pressed_button: None,
+        modifiers: Modifiers::default(),
+    });
+    // A press-and-move that started elsewhere must not reach the handle either.
+    visual.simulate_mouse_down(
+        point(px(20.), px(20.)),
+        MouseButton::Left,
+        Modifiers::default(),
+    );
+    visual.simulate_event(MouseMoveEvent {
+        position: point(px(50.), px(20.)),
+        pressed_button: Some(MouseButton::Left),
+        modifiers: Modifiers::default(),
+    });
+
+    assert!(deltas.borrow().is_empty());
+}
+
+#[test]
+fn arrow_keys_move_the_seam_when_focused() {
+    let (_cx, deltas, _resets, mut visual) = handle_window(Axis::Horizontal, false);
+    let center = handle_center(&mut visual);
+    click(&mut visual, center);
+
+    visual.simulate_keystrokes("left");
+    visual.simulate_keystrokes("right");
+    assert_eq!(*deltas.borrow(), vec![px(-32.), px(32.)]);
+}
+
+#[test]
+fn double_click_resets_and_starts_no_drag() {
+    let (_cx, deltas, resets, mut visual) = handle_window(Axis::Horizontal, false);
+    let center = handle_center(&mut visual);
+
+    for click_count in [1usize, 2] {
+        visual.simulate_event(MouseDownEvent {
+            position: center,
+            click_count,
+            modifiers: Modifiers::default(),
+            button: MouseButton::Left,
+            first_mouse: false,
+        });
+        visual.simulate_event(MouseUpEvent {
+            position: center,
+            click_count,
+            modifiers: Modifiers::default(),
+            button: MouseButton::Left,
+        });
+    }
+    assert_eq!(*resets.borrow(), 1);
+
+    // The double click must not leave a drag behind.
+    visual.simulate_event(MouseMoveEvent {
+        position: point(center.x + px(20.), center.y),
+        pressed_button: Some(MouseButton::Left),
+        modifiers: Modifiers::default(),
+    });
+    assert!(deltas.borrow().is_empty());
+}
+
+#[test]
+fn disabled_handle_ignores_drag_and_keys() {
+    let (_cx, deltas, resets, mut visual) = handle_window(Axis::Horizontal, true);
+    let center = handle_center(&mut visual);
+
+    visual.simulate_mouse_down(center, MouseButton::Left, Modifiers::default());
+    visual.simulate_event(MouseMoveEvent {
+        position: point(center.x + px(30.), center.y),
+        pressed_button: Some(MouseButton::Left),
+        modifiers: Modifiers::default(),
+    });
+    visual.simulate_mouse_up(center, MouseButton::Left, Modifiers::default());
+    visual.simulate_keystrokes("left");
+
+    assert!(deltas.borrow().is_empty());
+    assert_eq!(*resets.borrow(), 0);
+}