Configurable label text style for CollapsingHeader (#200)

CollapsingHeader: change label text style & enable options

egui/src/containers/collapsing_header.rs

@@ -138,6 +138,7 @@ pub struct CollapsingHeader {
     label: Label,
     default_open: bool,
     id_source: Id,
+    enabled: bool,
 }
 
 impl CollapsingHeader {
@@ -154,6 +155,7 @@ impl CollapsingHeader {
             label,
             default_open: false,
             id_source,
+            enabled: true,
         }
     }
 
@@ -170,6 +172,21 @@ impl CollapsingHeader {
         self.id_source = Id::new(id_source);
         self
     }
+
+    /// By default, the `CollapsingHeader` text style is `TextStyle::Button`.
+    /// Call `.text_style(style)` to change this.
+    pub fn text_style(mut self, text_style: TextStyle) -> Self {
+        self.label = self.label.text_style(text_style);
+        self
+    }
+
+    /// If you set this to `false`, the `CollapsingHeader` will be grayed out and un-clickable.
+    ///
+    /// This is a convenience for [`Ui::set_enabled`].
+    pub fn enabled(mut self, enabled: bool) -> Self {
+        self.enabled = enabled;
+        self
+    }
 }
 
 struct Prepared {
@@ -188,6 +205,7 @@ impl CollapsingHeader {
             label,
             default_open,
             id_source,
+            enabled: _,
         } = self;
 
         // TODO: horizontal layout, with icon and text as labels. Insert background behind using Frame.
@@ -263,37 +281,43 @@ impl CollapsingHeader {
         ui: &mut Ui,
         add_contents: impl FnOnce(&mut Ui) -> R,
     ) -> CollapsingResponse<R> {
-        // Make sure contents are bellow header,
+        let header_enabled = self.enabled;
-        // and make sure it is one unit (necessary for putting a `CollapsingHeader` in a grid).
+        ui.wrap(|ui| {
-        ui.vertical(|ui| {
+            ui.set_enabled(header_enabled);
-            let Prepared {
-                id,
-                header_response,
-                mut state,
-            } = self.begin(ui);
-            let ret_response = state.add_contents(ui, id, |ui| {
-                ui.indent(id, |ui| {
-                    // make as wide as the header:
-                    ui.expand_to_include_x(header_response.rect.right());
-                    add_contents(ui)
-                })
-                .inner
-            });
-            ui.memory().collapsing_headers.insert(id, state);
 
-            if let Some(ret_response) = ret_response {
+            // Make sure contents are bellow header,
-                CollapsingResponse {
+            // and make sure it is one unit (necessary for putting a `CollapsingHeader` in a grid).
+            ui.vertical(|ui| {
+                let Prepared {
+                    id,
                     header_response,
-                    body_response: Some(ret_response.response),
+                    mut state,
-                    body_returned: Some(ret_response.inner),
+                } = self.begin(ui);
+                let ret_response = state.add_contents(ui, id, |ui| {
+                    ui.indent(id, |ui| {
+                        // make as wide as the header:
+                        ui.expand_to_include_x(header_response.rect.right());
+                        add_contents(ui)
+                    })
+                    .inner
+                });
+                ui.memory().collapsing_headers.insert(id, state);
+
+                if let Some(ret_response) = ret_response {
+                    CollapsingResponse {
+                        header_response,
+                        body_response: Some(ret_response.response),
+                        body_returned: Some(ret_response.inner),
+                    }
+                } else {
+                    CollapsingResponse {
+                        header_response,
+                        body_response: None,
+                        body_returned: None,
+                    }
                 }
-            } else {
+            })
-                CollapsingResponse {
+            .inner
-                    header_response,
-                    body_response: None,
-                    body_returned: None,
-                }
-            }
         })
         .inner
     }