Window management

Every laufey application is built around one or more native windows. A Window controls its title, size, position, resizable and always-on-top flags, opacity, visibility, and focus. The type is a builder, so you can configure a window fluently when you create it, and each property also has a plain setter you can call later while the window is open.

#![allow(unused)]
fn main() {
use laufey::Window;

let win = Window::new(800, 600)
  .title("My App")
  .position(100, 100)
  .resizable(true)
  .opacity(0.95)
  .load("index.html"); // or .navigate("https://example.com")

win.set_size(1024, 768);
let (width, height) = win.get_size();
win.focus();
win.hide();
}

A few properties can only be chosen when the operating system creates the window and cannot be changed afterwards: whether the window is frameless (drawn without operating-system chrome), whether it is a non-activating panel that does not steal keyboard focus, and whether it has a transparent background. You set those through Window::new_with_options. Everything else is a live setter. All positions and sizes are expressed in density-independent pixels with the origin at the top-left of the screen. The Winit backend can create and manage windows, but because it has no web engine it cannot navigate to a URL or execute JavaScript.

Opacity and transparency

These are two distinct things:

• Opacity (Window::opacity / set_opacity / get_opacity) fades the entire window — web content and native chrome alike — by a uniform factor in 0.0..=1.0, where 1.0 is fully opaque (the default), like CSS opacity on the whole window. It is a live setter you can animate at runtime. The web backends implement it on every desktop platform (macOS NSWindow.alphaValue, Windows layered-window alpha, Linux gtk_widget_set_opacity). The Winit backend has no opacity API, so the call is a no-op there and get_opacity returns 1.0.

  #![allow(unused)]
  fn main() {
  win.set_opacity(0.8); // 80% opaque
  }

• Transparency (WindowOptions::transparent) gives the window a transparent background so the web content’s own alpha composites against whatever is behind the window. Any region the page leaves transparent (e.g. a transparent root background) shows the desktop through it. This must be chosen at creation time and is commonly paired with frameless.

  #![allow(unused)]
  fn main() {
  use laufey::{Window, WindowOptions};
  
  let win = Window::new_with_options(
    400,
    300,
    WindowOptions { frameless: true, transparent: true, ..Default::default() },
  )
  .load("index.html");
  }

  Transparency is supported by the system-WebView backend on macOS and on Linux (WebKitGTK, on a compositing window manager), and by the Winit backend. It is not supported by the Windows WebView2 backend or the CEF backend, which paint an opaque window background; the flag is ignored there.