Add text overflow listener to label

examples/responsive/src/main.rs

@@ -1,33 +1,67 @@
 use floem::{
     peniko::Color,
+    reactive::create_signal,
     responsive::{range, ScreenSize},
+    style::TextOverflow,
     unit::UnitExt,
     view::View,
-    views::{label, stack, Decorators},
+    views::{h_stack, label, stack, text, Decorators},
 };
 
 fn app_view() -> impl View {
+    let (is_text_overflown, set_is_text_overflown) = create_signal(false);
+
     stack({
-        (label(|| "Resize the window to see the magic").style(|s| {
-            s.border(1.0)
-                .border_radius(10.0)
-                .padding(10.0)
-                .margin_horiz(10.0)
-                .responsive(ScreenSize::XS, |s| s.background(Color::CYAN))
-                .responsive(ScreenSize::SM, |s| s.background(Color::PURPLE))
-                .responsive(ScreenSize::MD, |s| s.background(Color::ORANGE))
-                .responsive(ScreenSize::LG, |s| s.background(Color::GREEN))
-                .responsive(ScreenSize::XL, |s| s.background(Color::PINK))
-                .responsive(ScreenSize::XXL, |s| s.background(Color::RED))
-                .responsive(range(ScreenSize::XS..ScreenSize::LG), |s| {
-                    s.width(90.0.pct()).max_width(500.0)
-                })
-                .responsive(
-                    // equivalent to: range(ScreenSize::LG..)
-                    ScreenSize::LG | ScreenSize::XL | ScreenSize::XXL,
-                    |s| s.width(300.0),
-                )
-        }),)
+        (
+            label(|| "Resize the window to see the magic").style(|s| {
+                s.border(1.0)
+                    .border_radius(10.0)
+                    .padding(10.0)
+                    .margin_horiz(10.0)
+                    .responsive(ScreenSize::XS, |s| s.background(Color::CYAN))
+                    .responsive(ScreenSize::SM, |s| s.background(Color::PURPLE))
+                    .responsive(ScreenSize::MD, |s| s.background(Color::ORANGE))
+                    .responsive(ScreenSize::LG, |s| s.background(Color::GREEN))
+                    .responsive(ScreenSize::XL, |s| s.background(Color::PINK))
+                    .responsive(ScreenSize::XXL, |s| s.background(Color::RED))
+                    .responsive(range(ScreenSize::XS..ScreenSize::LG), |s| {
+                        s.width(90.0.pct()).max_width(500.0)
+                    })
+                    .responsive(
+                        // equivalent to: range(ScreenSize::LG..)
+                        ScreenSize::LG | ScreenSize::XL | ScreenSize::XXL,
+                        |s| s.width(300.0),
+                    )
+            }),
+            text(
+                "Long text that will overflow on smaller screens since the available width is less",
+            )
+            .on_text_overflow(move |is_overflown| {
+                set_is_text_overflown.update(|overflown| *overflown = is_overflown);
+            })
+            .style(move |s| {
+                s.background(Color::DIM_GRAY)
+                    .padding(10.0)
+                    .color(Color::WHITE_SMOKE)
+                    .margin_top(30.)
+                    .width_pct(70.0)
+                    .font_size(20.0)
+                    .max_width(800.)
+                    .text_overflow(TextOverflow::Ellipsis)
+            }),
+            h_stack((
+                text("The text fits in the available width?:"),
+                label(move || if is_text_overflown.get() { "No" } else { "Yes" }.to_string())
+                    .style(move |s| {
+                        s.color(if is_text_overflown.get() {
+                            Color::RED
+                        } else {
+                            Color::GREEN
+                        })
+                        .font_bold()
+                    }),
+            )),
+        )
     })
     .style(|s| {
         s.size(100.pct(), 100.pct())

src/views/label.rs

@@ -24,6 +24,11 @@ prop_extracter! {
     }
 }
 
+struct TextOverflowListener {
+    last_is_overflown: Option<bool>,
+    on_change_fn: Box<dyn Fn(bool) + 'static>,
+}
+
 pub struct Label {
     data: ViewData,
     label: String,
@@ -32,6 +37,7 @@ pub struct Label {
     available_text: Option<String>,
     available_width: Option<f32>,
     available_text_layout: Option<TextLayout>,
+    text_overflow_listener: Option<TextOverflowListener>,
     font: FontProps,
     style: Extracter,
 }
@@ -46,6 +52,7 @@ impl Label {
             available_text: None,
             available_width: None,
             available_text_layout: None,
+            text_overflow_listener: None,
             font: FontProps::default(),
             style: Default::default(),
         }
@@ -70,6 +77,14 @@ pub fn label<S: Display + 'static>(label: impl Fn() -> S + 'static) -> Label {
 }
 
 impl Label {
+    pub fn on_text_overflow(mut self, is_text_overflown_fn: impl Fn(bool) + 'static) -> Self {
+        self.text_overflow_listener = Some(TextOverflowListener {
+            on_change_fn: Box::new(is_text_overflown_fn),
+            last_is_overflown: None,
+        });
+        self
+    }
+
     fn get_attrs_list(&self) -> AttrsList {
         let mut attrs = Attrs::new().color(self.style.color().unwrap_or(Color::BLACK));
         if let Some(font_size) = self.font.size() {
@@ -245,6 +260,16 @@ impl View for Label {
                 self.available_text_layout = None;
             }
         }
+
+        if let Some(listener) = self.text_overflow_listener.as_mut() {
+            let was_overflown = listener.last_is_overflown;
+            let now_overflown = width > available_width;
+
+            if was_overflown != Some(now_overflown) {
+                (listener.on_change_fn)(now_overflown);
+                listener.last_is_overflown = Some(now_overflown);
+            }
+        }
         None
     }