feat: update druid

__gui/druid/examples/ex1.rs

@@ -0,0 +1,48 @@
+use druid::widget::{Align, Flex, Label, TextBox};
+use druid::{AppLauncher, Data, Env, Lens, LocalizedString, Widget, WindowDesc, WidgetExt};
+
+const VERTICAL_WIDGET_SPACING: f64 = 20.0;
+const TEXT_BOX_WIDTH: f64 = 200.0;
+const WINDOW_TITLE: LocalizedString<HelloState> = LocalizedString::new("Hello World!");
+
+#[derive(Clone, Data, Lens)]
+struct HelloState {
+    name: String,
+}
+
+fn main() {
+    // describe the main window
+    let main_window = WindowDesc::new(build_root_widget)
+        .title(WINDOW_TITLE)
+        .window_size((400.0, 400.0));
+
+    // create the initial app state
+    let initial_state = HelloState {
+        name: "World".into(),
+    };
+
+    // start the application
+    AppLauncher::with_window(main_window)
+        .launch(initial_state)
+        .expect("Failed to launch application");
+}
+
+fn build_root_widget() -> impl Widget<HelloState> {
+    // a label that will determine its text based on the current app data.
+    let label = Label::new(|data: &HelloState, _env: &Env| format!("Hello {}!", data.name));
+    // a text box that modifies `name`.
+    let text_box = TextBox::new()
+        .with_placeholder("Who are we greeting?")
+        .fix_width(TEXT_BOX_WIDTH)
+        // .expand_width()
+        .lens(HelloState::name);
+
+    // arrange the two widgets vertically, with some padding
+    let layout = Flex::column()
+        .with_child(label)
+        .with_spacer(VERTICAL_WIDGET_SPACING)
+        .with_child(text_box);
+
+    // center the two widgets in the available space
+    Align::centered(layout)
+}