From 14c2e5d3d5b1bce77b72e0c3367af0a2be9222d2 Mon Sep 17 00:00:00 2001
From: Lucas Meurer <hi@lucasmerlin.me>
Date: Thu, 10 Jul 2025 10:48:14 +0200
Subject: [PATCH] Set intrinsic size for Label (#7328)

Sets intrinsic size for labels
---
 crates/egui/src/response.rs          |  4 +-
 crates/egui/src/widgets/label.rs     |  4 +-
 tests/egui_tests/tests/test_atoms.rs | 59 ++++++++++++++++------------
 3 files changed, 38 insertions(+), 29 deletions(-)

diff --git a/crates/egui/src/response.rs b/crates/egui/src/response.rs
index d9dc61c3..85dc8a60 100644
--- a/crates/egui/src/response.rs
+++ b/crates/egui/src/response.rs
@@ -59,8 +59,8 @@ pub struct Response {
 
     /// The intrinsic / desired size of the widget.
     ///
-    /// For a button, this will be the size of the label + the frames padding,
-    /// even if the button is laid out in a justified layout and the actual size will be larger.
+    /// This is the size that a non-wrapped, non-truncated, non-justified version of the widget
+    /// would have.
     ///
     /// If this is `None`, use [`Self::rect`] instead.
     ///
diff --git a/crates/egui/src/widgets/label.rs b/crates/egui/src/widgets/label.rs
index b25cb908..1abac788 100644
--- a/crates/egui/src/widgets/label.rs
+++ b/crates/egui/src/widgets/label.rs
@@ -220,6 +220,7 @@ impl Label {
                 .rect_without_leading_space()
                 .translate(pos.to_vec2());
             let mut response = ui.allocate_rect(rect, sense);
+            response.intrinsic_size = Some(galley.intrinsic_size());
             for placed_row in galley.rows.iter().skip(1) {
                 let rect = placed_row.rect().translate(pos.to_vec2());
                 response |= ui.allocate_rect(rect, sense);
@@ -252,7 +253,8 @@ impl Label {
             };
 
             let galley = ui.fonts(|fonts| fonts.layout_job(layout_job));
-            let (rect, response) = ui.allocate_exact_size(galley.size(), sense);
+            let (rect, mut response) = ui.allocate_exact_size(galley.size(), sense);
+            response.intrinsic_size = Some(galley.intrinsic_size());
             let galley_pos = match galley.job.halign {
                 Align::LEFT => rect.left_top(),
                 Align::Center => rect.center_top(),
diff --git a/tests/egui_tests/tests/test_atoms.rs b/tests/egui_tests/tests/test_atoms.rs
index 98e90c1c..cf2abbe1 100644
--- a/tests/egui_tests/tests/test_atoms.rs
+++ b/tests/egui_tests/tests/test_atoms.rs
@@ -72,32 +72,39 @@ fn single_test(name: &str, mut f: impl FnMut(&mut Ui)) -> SnapshotResult {
 
 #[test]
 fn test_intrinsic_size() {
-    let mut intrinsic_size = None;
-    for wrapping in [
-        TextWrapMode::Extend,
-        TextWrapMode::Wrap,
-        TextWrapMode::Truncate,
-    ] {
-        _ = HarnessBuilder::default()
-            .with_size(Vec2::new(100.0, 100.0))
-            .build_ui(|ui| {
-                ui.style_mut().wrap_mode = Some(wrapping);
-                let response = ui.add(Button::new(
-                    "Hello world this is a long text that should be wrapped.",
-                ));
-                if let Some(current_intrinsic_size) = intrinsic_size {
-                    assert_eq!(
-                        Some(current_intrinsic_size),
-                        response.intrinsic_size,
-                        "For wrapping: {wrapping:?}"
+    let widgets = [Ui::button, Ui::label];
+
+    for widget in widgets {
+        let mut intrinsic_size = None;
+        for wrapping in [
+            TextWrapMode::Extend,
+            TextWrapMode::Wrap,
+            TextWrapMode::Truncate,
+        ] {
+            _ = HarnessBuilder::default()
+                .with_size(Vec2::new(100.0, 100.0))
+                .build_ui(|ui| {
+                    ui.style_mut().wrap_mode = Some(wrapping);
+                    let response = widget(
+                        ui,
+                        "Hello world this is a long text that should be wrapped.",
                     );
-                }
-                assert!(
-                    response.intrinsic_size.is_some(),
-                    "intrinsic_size should be set for `Button`"
-                );
-                intrinsic_size = response.intrinsic_size;
-            });
+                    if let Some(current_intrinsic_size) = intrinsic_size {
+                        assert_eq!(
+                            Some(current_intrinsic_size),
+                            response.intrinsic_size,
+                            "For wrapping: {wrapping:?}"
+                        );
+                    }
+                    assert!(
+                        response.intrinsic_size.is_some(),
+                        "intrinsic_size should be set for `Button`"
+                    );
+                    intrinsic_size = response.intrinsic_size;
+                    if wrapping == TextWrapMode::Extend {
+                        assert_eq!(Some(response.rect.size()), response.intrinsic_size);
+                    }
+                });
+        }
     }
-    assert_eq!(intrinsic_size.unwrap().round(), Vec2::new(305.0, 18.0));
 }