DragRegion

DragRegion — flexible drag region inside a TitleBar.

Public functions

DragRegion

Detailed description

Captures pointer events that are not consumed by inner content and forwards them to the platform host: drag gestures begin a window move, double taps toggle maximize, and right-clicks open the system window menu (Wayland only). On Windows the drag rect is published into HitRegions::drag so the wndproc subclass returns HTCAPTION for the same area — but the actual publish happens from crate::title_bar::TitleBar::after_paint, which aggregates this drag region and the three control buttons into one snapshot per frame. This widget no longer publishes from paint().

The region grows via flex = 1.0 to claim all remaining horizontal space in the parent HStack, so it naturally sits between any leading widgets (app icon, document title) and the trailing WindowControls cluster. An optional child widget — typically a centered title — is placed at the full region bounds and passes pointer events upward to the drag handler when it does not consume them.

A finger on the title bar

The drag region is deliberately not a press-time actor: the window move starts from DragPhase::Started, after the recognizer has decided the press is a drag, which is why a quick press still reaches the double-tap recognizer and why a contact that turns out to be a scroll is never stolen. Nothing here changes that.

Three routes serve a contact:

• Double tap → maximise / restore. The same handler a double click drives; the multi-tap recognizer already tunes its slop per pointer kind, so a finger's looser aim is accounted for without a second code path.
• Long press → the window menu. A mouse reaches it with the secondary button, which a finger does not have. Where the platform owns the menu (Wayland's xdg_toplevel.show_window_menu) the long press asks the host for it, and that menu's Move entry is a finger's only route to a window move — see below. Where it does not (X11), this widget's .context_menu(..) factory is the menu, and it is reached through the framework's own long-press context-menu route rather than through a second copy of the opening machinery here.
• Drag → nothing, on purpose. BackendCaps::touch_window_drag is false on every platform Teksilo supports, and it is not a to-do: xdg_toplevel::move needs a serial from an input event on a toplevel the compositor agrees the client owns, and winit 0.30's drag_window harvests a pointer serial internally, so a finger cannot reach it however the app asks. Calling it anyway would be a silent no-op — the compositor drops a request whose serial does not match — so the drag handler does not call it for a direct pointer, and the long-press menu is the documented alternative. This is also the WCAG 2.5.7 single-pointer alternative to the dragging operation. A headless test cannot detect the real failure (a fake PlatformTitleBarHost will happily record a begin_drag that a compositor would have ignored), so this is a hardware-checklist line.

// Used internally by TitleBar; the snippet shows the construction pattern.
let region = DragRegion::with_child(host.clone(), TextWidget::new(lit!("My App")));

API reference

📖 Full rustdoc API for this module

pub struct DragRegion

Import: use teksilo::widgets::DragRegion;

Flexible, hit-transparent region inside a title bar that routes pointer events to the platform host for window dragging, maximize-toggle, and the system window menu.

#![allow(unused)]
fn main() {
pub struct DragRegion { /* fields */ }
}

Methods

pub fn new(host: Rc<dyn PlatformTitleBarHost>) -> Self

Create a drag region with no inner content — the entire region is a pure drag handle.

pub fn with_child(host: Rc<dyn PlatformTitleBarHost>, child: Box<dyn Widget>) -> Self

Create a drag region wrapping an arbitrary boxed child widget (typically a centered title). Pointer events not consumed by the child bubble up to the drag handler.

pub fn with_child_id(host: Rc<dyn PlatformTitleBarHost>, id: WidgetId) -> Self

Create a drag region with an already-registered child identified by id. Use this when the child widget was added to the tree before constructing the region (e.g. when you need the child's WidgetId for another reference).

pub fn close_action( mut self, action: Option<Rc<dyn Fn(&mut teksilo_core::widget::EventContext)>>, ) -> Self (default: None)

Forward the title bar's close-action override, so the fallback window menu's Close entry matches the close button. No effect on platforms that provide their own window menu.