From d72e85b6b4ed817899a77e204ccdf25bb6caf0fb Mon Sep 17 00:00:00 2001
From: lucasmerlin <hi@lucasmerlin.me>
Date: Wed, 19 Mar 2025 11:51:03 +0100
Subject: [PATCH] Add workaround for max_width

set_max_width and set_max_height will limit intrinsic size but not max_rect itself
---
 crates/egui/src/layout.rs               | 10 +++++++++-
 crates/egui/src/placer.rs               | 14 +++++++++++++-
 examples/hello_world_simple/src/main.rs |  3 ++-
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/crates/egui/src/layout.rs b/crates/egui/src/layout.rs
index cf165c281..8a9c1e870 100644
--- a/crates/egui/src/layout.rs
+++ b/crates/egui/src/layout.rs
@@ -46,7 +46,9 @@ pub(crate) struct Region {
     /// The cursor can thus be `style.spacing.item_spacing` pixels outside of the `min_rect`.
     pub(crate) cursor: Rect,
 
-    pub intrinsic_size: Vec2,
+    pub(crate) intrinsic_size: Vec2,
+    pub max_intrinsic_width: Option<f32>,
+    pub max_intrinsic_height: Option<f32>,
 }
 
 impl Region {
@@ -429,6 +431,8 @@ impl Layout {
             max_rect,
             cursor: self.initial_cursor(max_rect),
             intrinsic_size: Vec2::default(),
+            max_intrinsic_width: None,
+            max_intrinsic_height: None,
         };
         let seed = self.next_widget_position(&region);
         region.min_rect = Rect::from_center_size(seed, Vec2::ZERO);
@@ -533,6 +537,8 @@ impl Layout {
                 mut max_rect,
                 min_rect,
                 intrinsic_size: min_item_size,
+                max_intrinsic_width,
+                max_intrinsic_height,
             } = *region;
 
             match self.main_dir {
@@ -595,6 +601,8 @@ impl Layout {
                 max_rect,
                 cursor,
                 intrinsic_size: min_item_size,
+                max_intrinsic_width,
+                max_intrinsic_height,
             };
 
             self.next_frame_ignore_wrap(&region, child_size)
diff --git a/crates/egui/src/placer.rs b/crates/egui/src/placer.rs
index 26e2365f9..244a75584 100644
--- a/crates/egui/src/placer.rs
+++ b/crates/egui/src/placer.rs
@@ -200,7 +200,15 @@ impl Placer {
     }
 
     pub(crate) fn intrinsic_size(&self) -> Vec2 {
-        self.region.intrinsic_size
+        //self.region.intrinsic_size.min(self.max_rect().size())
+        let mut intrinsic = self.region.intrinsic_size;
+        if let Some(max_x) = self.region.max_intrinsic_width {
+            intrinsic.x = intrinsic.x.min(max_x);
+        }
+        if let Some(max_y) = self.region.max_intrinsic_height {
+            intrinsic.y = intrinsic.y.min(max_y);
+        }
+        intrinsic
     }
 
     /// Move to the next row in a grid layout or wrapping layout.
@@ -253,6 +261,8 @@ impl Placer {
         region.cursor.max.x = region.max_rect.max.x;
 
         region.sanity_check();
+
+        region.max_intrinsic_width = Some(width);
     }
 
     /// Set the maximum height of the ui.
@@ -268,6 +278,8 @@ impl Placer {
         region.cursor.max.y = region.max_rect.max.y;
 
         region.sanity_check();
+
+        region.max_intrinsic_height = Some(height);
     }
 
     /// Set the minimum width of the ui.
diff --git a/examples/hello_world_simple/src/main.rs b/examples/hello_world_simple/src/main.rs
index a25881a9c..015037479 100644
--- a/examples/hello_world_simple/src/main.rs
+++ b/examples/hello_world_simple/src/main.rs
@@ -89,12 +89,13 @@ fn main() -> eframe::Result {
             MenuButton::new("Menu")
                 .config(MenuConfig::new().close_behavior(PopupCloseBehavior::CloseOnClickOutside))
                 .ui(ui, |ui| {
-                    // ui.set_max_width(180.0);
+                    ui.set_max_width(180.0);
                     if ui.button("Close menu").clicked() {
                         ui.close_menu();
                     }
                     ui.collapsing("Collapsing", |ui| {
                         egui::ScrollArea::both().show(ui, |ui| {
+                            // ui.set_width(ui.available_width());
                             for _ in 0..10 {
                                 ui.label(
                                     "This is a long text label containing \