Windowing

lui uses winit for windowing. The lui-driver-winit crate provides a complete window driver.

WinitDriver

use lui_driver_winit::WinitDriver;

let event_loop = EventLoop::new()?;
let window = Arc::new(event_loop.create_window(
    Window::default_attributes()
        .with_title("My App")
        .with_inner_size(PhysicalSize::new(800, 600))
)?);

let mut driver = WinitDriver::bind(window, tree);

Event Handling

WinitDriver::handle_event() handles all window events automatically:

// In ApplicationHandler::window_event():
match event {
    WindowEvent::RedrawRequested => {
        driver.handle_event(&event);
    }
    WindowEvent::CursorMoved { .. } |
    WindowEvent::MouseInput { .. } |
    WindowEvent::MouseWheel { .. } |
    WindowEvent::KeyboardInput { .. } |
    WindowEvent::Resized { .. } |
    WindowEvent::ScaleFactorChanged { .. } => {
        driver.handle_event(&event);
    }
    _ => {}
}

Returns Option<PipelineTimings> on render frames for profiling.

Built-in Features

The winit driver includes:

Feature	Key/Trigger
Viewport scrolling	Mouse wheel
Scrollbar paint + drag	Mouse on scrollbar
Text selection	Drag-select
Clipboard copy	Ctrl+C
Clipboard paste	Ctrl+V
Clipboard cut	Ctrl+X
Select all	Ctrl+A
Screenshot	F12 (configurable)
Devtools toggle	F11 (when Devtools::attach() used)
Profiler dump	F9 (when profiler enabled)
Exit	Escape (configurable)
System font discovery	Automatic at startup

Multiple Windows

let devtools_win = Arc::new(event_loop.create_window(
    Window::default_attributes().with_title("Devtools")
)?);
let mut dd = WinitDriver::bind(devtools_win, Tree::default());

// In event loop, dispatch to both:
driver.handle_event(&event);
dd.dispatch_to(&event, devtools.tree_mut());
dd.render(devtools.tree_mut());

DPI Handling

DPI scale factor is tracked from the winit window. The engine stores a dpi_scale_override on the tree for testing:

tree.set_dpi_scale_override(Some(1.5)); // Force 1.5x DPI
let effective = tree.effective_dpi_scale(host_scale); // Resolves override vs host

Physical pixel coordinates in layout and paint account for the DPI scale factor.

Cursor Management

CSS cursor property values are mapped to OS cursor icons:

CSS Cursor	OS Cursor
pointer	Hand
text	I-beam
move	Move/SizeAll
default	Arrow
not-allowed	NotAllowed
crosshair	Crosshair
col-resize	SizeWe
row-resize	SizeNs
etc.	etc.