Make app state a struct

examples/taffy.rs

@@ -1,4 +1,5 @@
 use xilem::{view::View, App, AppLauncher};
+use vello::peniko::Color;
 
 const COLORS: [Color; 4] = [
     Color::LIGHT_GREEN,
@@ -7,23 +8,34 @@ const COLORS: [Color; 4] = [
     Color::HOT_PINK,
 ];
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+struct AppState {
+    count: u32,
+}
+
+impl AppState {
+    fn new() -> Self {
+        Self { count: 1 }
+    }
+}
+
 #[cfg(not(feature = "taffy"))]
-fn app_logic(_data: &mut i32) -> impl View<i32> {
+fn app_logic(_data: &mut AppState) -> impl View<AppState> {
     "Error: this example requires the 'taffy' feature to be enabled"
 }
 
 #[cfg(feature = "taffy")]
-fn app_logic(data: &mut i32) -> impl View<i32> {
+fn app_logic(state: &mut AppState) -> impl View<AppState> {
     use taffy::style::{AlignItems, FlexWrap, JustifyContent};
     use taffy::style_helpers::length;
-    use vello::peniko::Color;
+
     use xilem::view::{button, div, flex_column, flex_row, scroll_view};
 
     // here's some logic, deriving state for the view from our state
-    let label = if *data == 1 {
+    let label = if state.count == 1 {
         "Square count: 1".to_string()
     } else {
-        format!("Square count: {data}")
+        format!("Square count: {}", state.count)
     };
 
     // The actual UI Code starts here
@@ -36,19 +48,19 @@ fn app_logic(data: &mut i32) -> impl View<i32> {
 
                 flex_row((
                     label,
-                    button("increase", |data| {
+                    button("increase", |state: &mut AppState| {
                         println!("clicked increase");
-                        *data += 1;
+                        state.count += 1;
                     }),
-                    button("decrease", |data| {
+                    button("decrease", |state: &mut AppState| {
                         println!("clicked decrease");
-                        if *data > 0 {
-                            *data -= 1;
+                        if state.count > 0 {
+                            state.count -= 1;
                         }
                     }),
-                    button("reset", |data| {
+                    button("reset", |state: &mut AppState| {
                         println!("clicked reset");
-                        *data = 1;
+                        state.count = 1;
                     }),
                 ))
                 .with_background_color(Color::BLUE_VIOLET)
@@ -67,7 +79,7 @@ fn app_logic(data: &mut i32) -> impl View<i32> {
                     .with_background_color(Color::RED)
                     .with_style(|s| s.padding = length(20.0)),
 
-                flex_row((0..*data).map(|i| {
+                flex_row((0..state.count).map(|i| {
                     div(()).with_background_color(COLORS[(i % 4) as usize]).with_style(|s| {
                         s.size.width = length(200.0);
                         s.size.height = length(200.0);
@@ -100,6 +112,6 @@ fn app_logic(data: &mut i32) -> impl View<i32> {
 }
 
 fn main() {
-    let app = App::new(1, app_logic);
+    let app = App::new(AppState::new(), app_logic);
     AppLauncher::new(app).run()
 }