Collapsing header with custom header (#1538)

* Returns openness in CollapsingResponse
* Make CollapsingState a building block for custom collapsing headers
* Add a demo of the custom collapsing header
* Revert to much simpler tree demo
* Add CollapsingState::is_open and CollapsingState::set_open

CHANGELOG.md

@@ -21,6 +21,7 @@ NOTE: [`epaint`](epaint/CHANGELOG.md), [`eframe`](eframe/CHANGELOG.md), [`egui_w
 * Added `Ui::spinner()` shortcut method ([#1494](https://github.com/emilk/egui/pull/1494)).
 * Added `CursorIcon`s for resizing columns, rows, and the eight cardinal directions.
 * Added `Ui::toggle_value`.
+* Added ability to add any widgets to the header of a collapsing region ([#1538](https://github.com/emilk/egui/pull/1538)).
 
 ### Changed 🔧
 * `ClippedMesh` has been replaced with `ClippedPrimitive` ([#1351](https://github.com/emilk/egui/pull/1351)).

egui/src/containers/collapsing_header.rs

@@ -3,74 +3,194 @@ use std::hash::Hash;
 use crate::*;
 use epaint::Shape;
 
-#[derive(Clone, Copy, Debug, Default)]
+#[derive(Clone, Copy, Debug)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
-#[cfg_attr(feature = "serde", serde(default))]
+pub(crate) struct InnerState {
-pub(crate) struct State {
     open: bool,
 
     /// Height of the region when open. Used for animations
+    #[cfg_attr(feature = "serde", serde(default))]
     open_height: Option<f32>,
 }
 
-impl State {
+/// This is a a building block for building collapsing regions.
+///
+/// It is used by [`CollapsingHeader`] and [`Window`], but can also be used on its own.
+///
+/// See [`CollapsingState::show_header`] for how to show a collapsing header with a custom header.
+#[derive(Clone, Debug)]
+pub struct CollapsingState {
+    id: Id,
+    state: InnerState,
+}
+
+impl CollapsingState {
     pub fn load(ctx: &Context, id: Id) -> Option<Self> {
-        ctx.data().get_persisted(id)
+        ctx.data()
+            .get_persisted::<InnerState>(id)
+            .map(|state| Self { id, state })
     }
 
-    pub fn store(self, ctx: &Context, id: Id) {
+    pub fn store(&self, ctx: &Context) {
-        ctx.data().insert_persisted(id, self);
+        ctx.data().insert_persisted(self.id, self.state);
     }
 
-    pub fn from_memory_with_default_open(ctx: &Context, id: Id, default_open: bool) -> Self {
+    pub fn id(&self) -> Id {
-        Self::load(ctx, id).unwrap_or_else(|| State {
+        self.id
-            open: default_open,
+    }
-            ..Default::default()
+
+    pub fn load_with_default_open(ctx: &Context, id: Id, default_open: bool) -> Self {
+        Self::load(ctx, id).unwrap_or(CollapsingState {
+            id,
+            state: InnerState {
+                open: default_open,
+                open_height: None,
+            },
         })
     }
 
-    // Helper
+    pub fn is_open(&self) -> bool {
-    pub fn is_open(ctx: &Context, id: Id) -> Option<bool> {
+        self.state.open
-        if ctx.memory().everything_is_visible() {
+    }
-            Some(true)
+
-        } else {
+    pub fn set_open(&mut self, open: bool) {
-            State::load(ctx, id).map(|state| state.open)
+        self.state.open = open;
-        }
     }
 
     pub fn toggle(&mut self, ui: &Ui) {
-        self.open = !self.open;
+        self.state.open = !self.state.open;
         ui.ctx().request_repaint();
     }
 
     /// 0 for closed, 1 for open, with tweening
-    pub fn openness(&self, ctx: &Context, id: Id) -> f32 {
+    pub fn openness(&self, ctx: &Context) -> f32 {
         if ctx.memory().everything_is_visible() {
             1.0
         } else {
-            ctx.animate_bool(id, self.open)
+            ctx.animate_bool(self.id, self.state.open)
         }
     }
 
-    /// Show contents if we are open, with a nice animation between closed and open
+    /// Will toggle when clicked, etc.
-    pub fn add_contents<R>(
+    pub(crate) fn show_default_button_with_size(
         &mut self,
         ui: &mut Ui,
-        id: Id,
+        button_size: Vec2,
-        add_contents: impl FnOnce(&mut Ui) -> R,
+    ) -> Response {
+        let (_id, rect) = ui.allocate_space(button_size);
+        let response = ui.interact(rect, self.id, Sense::click());
+        if response.clicked() {
+            self.toggle(ui);
+        }
+        let openness = self.openness(ui.ctx());
+        paint_default_icon(ui, openness, &response);
+        response
+    }
+
+    /// Will toggle when clicked, etc.
+    fn show_default_button_indented(&mut self, ui: &mut Ui) -> Response {
+        let size = Vec2::new(ui.spacing().indent, ui.spacing().icon_width);
+        let (_id, rect) = ui.allocate_space(size);
+        let response = ui.interact(rect, self.id, Sense::click());
+        if response.clicked() {
+            self.toggle(ui);
+        }
+
+        let (mut icon_rect, _) = ui.spacing().icon_rectangles(response.rect);
+        icon_rect.set_center(pos2(
+            response.rect.left() + ui.spacing().indent / 2.0,
+            response.rect.center().y,
+        ));
+        let openness = self.openness(ui.ctx());
+        let small_icon_response = Response {
+            rect: icon_rect,
+            ..response.clone()
+        };
+        paint_default_icon(ui, openness, &small_icon_response);
+        response
+    }
+
+    /// Shows header and body (if expanded).
+    ///
+    /// The header will start with the default button in a horizontal layout, followed by whatever you add.
+    ///
+    /// Will also store the state.
+    ///
+    /// Returns the response of the collapsing button, the custom header, and the custom body.
+    ///
+    /// ```
+    /// # egui::__run_test_ui(|ui| {
+    /// let id = ui.make_persistent_id("my_collapsing_header");
+    /// egui::collapsing_header::CollapsingState::load_with_default_open(ui.ctx(), id, false)
+    ///     .show_header(ui, |ui| {
+    ///         ui.label("Header"); // you can put checkboxes or whatever here
+    ///     })
+    ///     .body(|ui| ui.label("Body"));
+    /// # });
+    /// ```
+    pub fn show_header<HeaderRet>(
+        mut self,
+        ui: &mut Ui,
+        add_header: impl FnOnce(&mut Ui) -> HeaderRet,
+    ) -> HeaderResponse<'_, HeaderRet> {
+        let header_response = ui.horizontal(|ui| {
+            ui.spacing_mut().item_spacing.x = 0.0; // the toggler button uses the full indent width
+            let collapser = self.show_default_button_indented(ui);
+            ui.spacing_mut().item_spacing.x = ui.spacing_mut().icon_spacing; // Restore spacing
+            (collapser, add_header(ui))
+        });
+        HeaderResponse {
+            state: self,
+            ui,
+            toggle_button_response: header_response.inner.0,
+            header_response: InnerResponse {
+                response: header_response.response,
+                inner: header_response.inner.1,
+            },
+        }
+    }
+
+    /// Show body if we are open, with a nice animation between closed and open.
+    /// Indent the body to show it belongs to the header.
+    ///
+    /// Will also store the state.
+    pub fn show_body_indented<R>(
+        &mut self,
+        header_response: &Response,
+        ui: &mut Ui,
+        add_body: impl FnOnce(&mut Ui) -> R,
     ) -> Option<InnerResponse<R>> {
-        let openness = self.openness(ui.ctx(), id);
+        let id = self.id;
+        self.show_body_unindented(ui, |ui| {
+            ui.indent(id, |ui| {
+                // make as wide as the header:
+                ui.expand_to_include_x(header_response.rect.right());
+                add_body(ui)
+            })
+            .inner
+        })
+    }
+
+    /// Show body if we are open, with a nice animation between closed and open.
+    /// Will also store the state.
+    pub fn show_body_unindented<R>(
+        &mut self,
+        ui: &mut Ui,
+        add_body: impl FnOnce(&mut Ui) -> R,
+    ) -> Option<InnerResponse<R>> {
+        let openness = self.openness(ui.ctx());
         if openness <= 0.0 {
+            self.store(ui.ctx()); // we store any earlier toggling as promised in the docstring
             None
         } else if openness < 1.0 {
             Some(ui.scope(|child_ui| {
-                let max_height = if self.open && self.open_height.is_none() {
+                let max_height = if self.state.open && self.state.open_height.is_none() {
                     // First frame of expansion.
                     // We don't know full height yet, but we will next frame.
                     // Just use a placeholder value that shows some movement:
                     10.0
                 } else {
-                    let full_height = self.open_height.unwrap_or_default();
+                    let full_height = self.state.open_height.unwrap_or_default();
                     remap_clamp(openness, 0.0..=1.0, 0.0..=full_height)
                 };
 
@@ -78,10 +198,11 @@ impl State {
                 clip_rect.max.y = clip_rect.max.y.min(child_ui.max_rect().top() + max_height);
                 child_ui.set_clip_rect(clip_rect);
 
-                let ret = add_contents(child_ui);
+                let ret = add_body(child_ui);
 
                 let mut min_rect = child_ui.min_rect();
-                self.open_height = Some(min_rect.height());
+                self.state.open_height = Some(min_rect.height());
+                self.store(child_ui.ctx()); // remember the height
 
                 // Pretend children took up at most `max_height` space:
                 min_rect.max.y = min_rect.max.y.at_most(min_rect.top() + max_height);
@@ -89,16 +210,49 @@ impl State {
                 ret
             }))
         } else {
-            let ret_response = ui.scope(add_contents);
+            let ret_response = ui.scope(add_body);
             let full_size = ret_response.response.rect.size();
-            self.open_height = Some(full_size.y);
+            self.state.open_height = Some(full_size.y);
+            self.store(ui.ctx()); // remember the height
             Some(ret_response)
         }
     }
 }
 
+/// From [`CollapsingState::show_header`].
+#[must_use = "Remember to show the body"]
+pub struct HeaderResponse<'ui, HeaderRet> {
+    state: CollapsingState,
+    ui: &'ui mut Ui,
+    toggle_button_response: Response,
+    header_response: InnerResponse<HeaderRet>,
+}
+
+impl<'ui, HeaderRet> HeaderResponse<'ui, HeaderRet> {
+    /// Returns the response of the collapsing button, the custom header, and the custom body.
+    pub fn body<BodyRet>(
+        mut self,
+        add_body: impl FnOnce(&mut Ui) -> BodyRet,
+    ) -> (
+        Response,
+        InnerResponse<HeaderRet>,
+        Option<InnerResponse<BodyRet>>,
+    ) {
+        let body_response =
+            self.state
+                .show_body_indented(&self.header_response.response, self.ui, add_body);
+        (
+            self.toggle_button_response,
+            self.header_response,
+            body_response,
+        )
+    }
+}
+
+// ----------------------------------------------------------------------------
+
 /// Paint the arrow icon that indicated if the region is open or not
-pub(crate) fn paint_default_icon(ui: &mut Ui, openness: f32, response: &Response) {
+pub fn paint_default_icon(ui: &mut Ui, openness: f32, response: &Response) {
     let visuals = ui.style().interact(response);
     let stroke = visuals.fg_stroke;
 
@@ -126,13 +280,15 @@ pub type IconPainter = Box<dyn FnOnce(&mut Ui, f32, &Response)>;
 /// # egui::__run_test_ui(|ui| {
 /// egui::CollapsingHeader::new("Heading")
 ///     .show(ui, |ui| {
-///         ui.label("Contents");
+///         ui.label("Body");
 ///     });
 ///
 /// // Short version:
-/// ui.collapsing("Heading", |ui| { ui.label("Contents"); });
+/// ui.collapsing("Heading", |ui| { ui.label("Body"); });
 /// # });
 /// ```
+///
+/// If you want to customize the header contents, see [`CollapsingState::show_header`].
 #[must_use = "You should call .show()"]
 pub struct CollapsingHeader {
     text: WidgetText,
@@ -217,7 +373,7 @@ impl CollapsingHeader {
     /// let response = egui::CollapsingHeader::new("Select and open me")
     ///     .selectable(true)
     ///     .selected(selected)
-    ///     .show(ui, |ui| ui.label("Content"));
+    ///     .show(ui, |ui| ui.label("Body"));
     /// if response.header_response.clicked() {
     ///     selected = true;
     /// }
@@ -265,9 +421,9 @@ impl CollapsingHeader {
 }
 
 struct Prepared {
-    id: Id,
     header_response: Response,
-    state: State,
+    state: CollapsingState,
+    openness: f32,
 }
 
 impl CollapsingHeader {
@@ -283,9 +439,9 @@ impl CollapsingHeader {
             open,
             id_source,
             enabled: _,
-            selectable: _,
+            selectable,
-            selected: _,
+            selected,
-            show_background: _,
+            show_background,
         } = self;
 
         // TODO: horizontal layout, with icon and text as labels. Insert background behind using Frame.
@@ -315,9 +471,9 @@ impl CollapsingHeader {
             header_response.rect.center().y - text.size().y / 2.0,
         );
 
-        let mut state = State::from_memory_with_default_open(ui.ctx(), id, default_open);
+        let mut state = CollapsingState::load_with_default_open(ui.ctx(), id, default_open);
         if let Some(open) = open {
-            if open != state.open {
+            if open != state.is_open() {
                 state.toggle(ui);
                 header_response.mark_changed();
             }
@@ -329,12 +485,12 @@ impl CollapsingHeader {
         header_response
             .widget_info(|| WidgetInfo::labeled(WidgetType::CollapsingHeader, text.text()));
 
-        if ui.is_rect_visible(rect) {
+        let openness = state.openness(ui.ctx());
-            let visuals = ui
-                .style()
-                .interact_selectable(&header_response, self.selected);
 
-            if ui.visuals().collapsing_header_frame || self.show_background {
+        if ui.is_rect_visible(rect) {
+            let visuals = ui.style().interact_selectable(&header_response, selected);
+
+            if ui.visuals().collapsing_header_frame || show_background {
                 ui.painter().add(epaint::RectShape {
                     rect: header_response.rect.expand(visuals.expansion),
                     rounding: visuals.rounding,
@@ -344,8 +500,7 @@ impl CollapsingHeader {
                 });
             }
 
-            if self.selected
+            if selected || selectable && (header_response.hovered() || header_response.has_focus())
-                || self.selectable && (header_response.hovered() || header_response.has_focus())
             {
                 let rect = rect.expand(visuals.expansion);
 
@@ -363,7 +518,6 @@ impl CollapsingHeader {
                     rect: icon_rect,
                     ..header_response.clone()
                 };
-                let openness = state.openness(ui.ctx(), id);
                 if let Some(icon) = icon {
                     icon(ui, openness, &icon_response);
                 } else {
@@ -375,9 +529,9 @@ impl CollapsingHeader {
         }
 
         Prepared {
-            id,
             header_response,
             state,
+            openness,
         }
     }
 
@@ -385,48 +539,42 @@ impl CollapsingHeader {
     pub fn show<R>(
         self,
         ui: &mut Ui,
-        add_contents: impl FnOnce(&mut Ui) -> R,
+        add_body: impl FnOnce(&mut Ui) -> R,
     ) -> CollapsingResponse<R> {
-        self.show_dyn(ui, Box::new(add_contents))
+        self.show_dyn(ui, Box::new(add_body))
     }
 
     fn show_dyn<'c, R>(
         self,
         ui: &mut Ui,
-        add_contents: Box<dyn FnOnce(&mut Ui) -> R + 'c>,
+        add_body: Box<dyn FnOnce(&mut Ui) -> R + 'c>,
     ) -> CollapsingResponse<R> {
-        // Make sure contents are bellow header,
+        // Make sure body is bellow header,
         // and make sure it is one unit (necessary for putting a [`CollapsingHeader`] in a grid).
         ui.vertical(|ui| {
             ui.set_enabled(self.enabled);
 
             let Prepared {
-                id,
                 header_response,
                 mut state,
-            } = self.begin(ui);
+                openness,
+            } = self.begin(ui); // show the header
 
-            let ret_response = state.add_contents(ui, id, |ui| {
+            let ret_response = state.show_body_indented(&header_response, ui, add_body);
-                ui.indent(id, |ui| {
-                    // make as wide as the header:
-                    ui.expand_to_include_x(header_response.rect.right());
-                    add_contents(ui)
-                })
-                .inner
-            });
-            state.store(ui.ctx(), id);
 
             if let Some(ret_response) = ret_response {
                 CollapsingResponse {
                     header_response,
                     body_response: Some(ret_response.response),
                     body_returned: Some(ret_response.inner),
+                    openness,
                 }
             } else {
                 CollapsingResponse {
                     header_response,
                     body_response: None,
                     body_returned: None,
+                    openness,
                 }
             }
         })
@@ -436,9 +584,27 @@ impl CollapsingHeader {
 
 /// The response from showing a [`CollapsingHeader`].
 pub struct CollapsingResponse<R> {
+    /// Response of the actual clickable header.
     pub header_response: Response,
+
     /// None iff collapsed.
     pub body_response: Option<Response>,
+
     /// None iff collapsed.
     pub body_returned: Option<R>,
+
+    /// 0.0 if fully closed, 1.0 if fully open, and something in-between while animating.
+    pub openness: f32,
+}
+
+impl<R> CollapsingResponse<R> {
+    /// Was the [`CollapsingHeader`] fully closed (and not being animated)?
+    pub fn fully_closed(&self) -> bool {
+        self.openness <= 0.0
+    }
+
+    /// Was the [`CollapsingHeader`] fully open (and not being animated)?
+    pub fn fully_open(&self) -> bool {
+        self.openness >= 1.0
+    }
 }

egui/src/containers/mod.rs

@@ -3,7 +3,7 @@
 //! For instance, a [`Frame`] adds a frame and background to some contained UI.
 
 pub(crate) mod area;
-pub(crate) mod collapsing_header;
+pub mod collapsing_header;
 mod combo_box;
 pub(crate) mod frame;
 pub mod panel;

egui/src/containers/window.rs

@@ -1,5 +1,6 @@
 // WARNING: the code in here is horrible. It is a behemoth that needs breaking up into simpler parts.
 
+use crate::collapsing_header::CollapsingState;
 use crate::{widget_text::WidgetTextGalley, *};
 use epaint::*;
 
@@ -269,10 +270,10 @@ impl<'open> Window<'open> {
         let area_id = area.id;
         let area_layer_id = area.layer();
         let resize_id = area_id.with("resize");
-        let collapsing_id = area_id.with("collapsing");
+        let mut collapsing =
+            CollapsingState::load_with_default_open(ctx, area_id.with("collapsing"), true);
 
-        let is_collapsed = with_title_bar
+        let is_collapsed = with_title_bar && !collapsing.is_open();
-            && !collapsing_header::State::is_open(ctx, collapsing_id).unwrap_or_default();
         let possible = PossibleInteractions::new(&area, &resize, is_collapsed);
 
         let area = area.movable(false); // We move it manually, or the area will move the window when we want to resize it
@@ -326,19 +327,12 @@ impl<'open> Window<'open> {
             let frame_stroke = frame.stroke;
             let mut frame = frame.begin(&mut area_content_ui);
 
-            let default_expanded = true;
-            let mut collapsing = collapsing_header::State::from_memory_with_default_open(
-                ctx,
-                collapsing_id,
-                default_expanded,
-            );
             let show_close_button = open.is_some();
             let title_bar = if with_title_bar {
                 let title_bar = show_title_bar(
                     &mut frame.content_ui,
                     title,
                     show_close_button,
-                    collapsing_id,
                     &mut collapsing,
                     collapsible,
                 );
@@ -349,7 +343,7 @@ impl<'open> Window<'open> {
             };
 
             let (content_inner, content_response) = collapsing
-                .add_contents(&mut frame.content_ui, collapsing_id, |ui| {
+                .show_body_unindented(&mut frame.content_ui, |ui| {
                     resize.show(ui, |ui| {
                         if title_bar.is_some() {
                             ui.add_space(title_content_spacing);
@@ -380,7 +374,7 @@ impl<'open> Window<'open> {
                 );
             }
 
-            collapsing.store(ctx, collapsing_id);
+            collapsing.store(ctx);
 
             if let Some(interaction) = interaction {
                 paint_frame_interaction(
@@ -781,8 +775,7 @@ fn show_title_bar(
     ui: &mut Ui,
     title: WidgetText,
     show_close_button: bool,
-    collapsing_id: Id,
+    collapsing: &mut CollapsingState,
-    collapsing: &mut collapsing_header::State,
     collapsible: bool,
 ) -> TitleBar {
     let inner_response = ui.horizontal(|ui| {
@@ -798,14 +791,7 @@ fn show_title_bar(
 
         if collapsible {
             ui.add_space(pad);
-
+            collapsing.show_default_button_with_size(ui, button_size);
-            let (_id, rect) = ui.allocate_space(button_size);
-            let collapse_button_response = ui.interact(rect, collapsing_id, Sense::click());
-            if collapse_button_response.clicked() {
-                collapsing.toggle(ui);
-            }
-            let openness = collapsing.openness(ui.ctx(), collapsing_id);
-            collapsing_header::paint_default_icon(ui, openness, &collapse_button_response);
         }
 
         let title_galley = title.into_galley(ui, Some(false), f32::INFINITY, TextStyle::Heading);
@@ -854,7 +840,7 @@ impl TitleBar {
         outer_rect: Rect,
         content_response: &Option<Response>,
         open: Option<&mut bool>,
-        collapsing: &mut collapsing_header::State,
+        collapsing: &mut CollapsingState,
         collapsible: bool,
     ) {
         if let Some(content_response) = &content_response {

egui/src/context.rs

@@ -1238,11 +1238,12 @@ impl Context {
         ui.horizontal(|ui| {
             ui.label(format!(
                 "{} collapsing headers",
-                self.data().count::<containers::collapsing_header::State>()
+                self.data()
+                    .count::<containers::collapsing_header::InnerState>()
             ));
             if ui.button("Reset").clicked() {
                 self.data()
-                    .remove_by_type::<containers::collapsing_header::State>();
+                    .remove_by_type::<containers::collapsing_header::InnerState>();
             }
         });
 

egui/src/style.rs

@@ -267,9 +267,13 @@ pub struct Spacing {
     pub text_edit_width: f32,
 
     /// Checkboxes, radio button and collapsing headers have an icon at the start.
-    /// This is the width/height of this icon.
+    /// This is the width/height of the outer part of this icon (e.g. the BOX of the checkbox).
     pub icon_width: f32,
 
+    /// Checkboxes, radio button and collapsing headers have an icon at the start.
+    /// This is the width/height of the inner part of this icon (e.g. the check of the checkbox).
+    pub icon_width_inner: f32,
+
     /// Checkboxes, radio button and collapsing headers have an icon at the start.
     /// This is the spacing between the icon and the text
     pub icon_spacing: f32,
@@ -289,15 +293,14 @@ pub struct Spacing {
 impl Spacing {
     /// Returns small icon rectangle and big icon rectangle
     pub fn icon_rectangles(&self, rect: Rect) -> (Rect, Rect) {
-        let box_side = self.icon_width;
+        let icon_width = self.icon_width;
         let big_icon_rect = Rect::from_center_size(
-            pos2(rect.left() + box_side / 2.0, rect.center().y),
+            pos2(rect.left() + icon_width / 2.0, rect.center().y),
-            vec2(box_side, box_side),
+            vec2(icon_width, icon_width),
         );
 
-        let small_rect_side = 8.0; // TODO: make a parameter
         let small_icon_rect =
-            Rect::from_center_size(big_icon_rect.center(), Vec2::splat(small_rect_side));
+            Rect::from_center_size(big_icon_rect.center(), Vec2::splat(self.icon_width_inner));
 
         (small_icon_rect, big_icon_rect)
     }
@@ -634,6 +637,7 @@ impl Default for Spacing {
             slider_width: 100.0,
             text_edit_width: 280.0,
             icon_width: 14.0,
+            icon_width_inner: 8.0,
             icon_spacing: 4.0,
             tooltip_width: 600.0,
             combo_height: 200.0,
@@ -909,6 +913,7 @@ impl Spacing {
             slider_width,
             text_edit_width,
             icon_width,
+            icon_width_inner,
             icon_spacing,
             tooltip_width,
             indent_ends_with_horizontal_line,
@@ -972,7 +977,12 @@ impl Spacing {
             ui.label("Checkboxes etc:");
             ui.add(
                 DragValue::new(icon_width)
-                    .prefix("width:")
+                    .prefix("outer icon width:")
+                    .clamp_range(0.0..=60.0),
+            );
+            ui.add(
+                DragValue::new(icon_width_inner)
+                    .prefix("inner icon width:")
                     .clamp_range(0.0..=60.0),
             );
             ui.add(

egui_demo_lib/src/apps/demo/misc_demo_window.rs

@@ -14,6 +14,7 @@ pub struct MiscDemoWindow {
 
     widgets: Widgets,
     colors: ColorWidgets,
+    custom_collapsing_header: CustomCollapsingHeader,
     tree: Tree,
     box_painting: BoxPainting,
 
@@ -32,6 +33,7 @@ impl Default for MiscDemoWindow {
 
             widgets: Default::default(),
             colors: Default::default(),
+            custom_collapsing_header: Default::default(),
             tree: Tree::demo(),
             box_painting: Default::default(),
 
@@ -82,6 +84,10 @@ impl View for MiscDemoWindow {
                 self.colors.ui(ui);
             });
 
+        CollapsingHeader::new("Custom Collapsing Header")
+            .default_open(false)
+            .show(ui, |ui| self.custom_collapsing_header.ui(ui));
+
         CollapsingHeader::new("Tree")
             .default_open(false)
             .show(ui, |ui| self.tree.ui(ui));
@@ -351,6 +357,44 @@ impl BoxPainting {
 
 // ----------------------------------------------------------------------------
 
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+struct CustomCollapsingHeader {
+    selected: bool,
+    radio_value: bool,
+}
+
+impl Default for CustomCollapsingHeader {
+    fn default() -> Self {
+        Self {
+            selected: true,
+            radio_value: false,
+        }
+    }
+}
+
+impl CustomCollapsingHeader {
+    pub fn ui(&mut self, ui: &mut egui::Ui) {
+        ui.label("Example of a collapsing header with custom header:");
+
+        let id = ui.make_persistent_id("my_collapsing_header");
+        egui::collapsing_header::CollapsingState::load_with_default_open(ui.ctx(), id, true)
+            .show_header(ui, |ui| {
+                ui.toggle_value(&mut self.selected, "Click to select/unselect");
+                ui.radio_value(&mut self.radio_value, false, "");
+                ui.radio_value(&mut self.radio_value, true, "");
+            })
+            .body(|ui| {
+                ui.label("The body is always custom");
+            });
+
+        CollapsingHeader::new("Normal collapsing header for comparison").show(ui, |ui| {
+            ui.label("Nothing exciting here");
+        });
+    }
+}
+
+// ----------------------------------------------------------------------------
+
 #[derive(Clone, Copy, PartialEq)]
 enum Action {
     Keep,
@@ -359,53 +403,30 @@ enum Action {
 
 #[derive(Clone, Default)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
-struct Tree(String, SubTree);
+struct Tree(Vec<Tree>);
 
 impl Tree {
     pub fn demo() -> Self {
-        Self(
+        Self(vec![
-            String::from("root"),
+            Tree(vec![Tree::default(); 4]),
-            SubTree(vec![
+            Tree(vec![Tree(vec![Tree::default(); 2]); 3]),
-                SubTree(vec![SubTree::default(); 4]),
+        ])
-                SubTree(vec![SubTree(vec![SubTree::default(); 2]); 3]),
-            ]),
-        )
     }
     pub fn ui(&mut self, ui: &mut Ui) -> Action {
-        self.1.ui(ui, 0, "root", &mut self.0)
+        self.ui_impl(ui, 0, "root")
     }
 }
 
-#[derive(Clone, Default)]
+impl Tree {
-#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+    fn ui_impl(&mut self, ui: &mut Ui, depth: usize, name: &str) -> Action {
-struct SubTree(Vec<SubTree>);
+        CollapsingHeader::new(name)
-
-impl SubTree {
-    pub fn ui(
-        &mut self,
-        ui: &mut Ui,
-        depth: usize,
-        name: &str,
-        selected_name: &mut String,
-    ) -> Action {
-        let response = CollapsingHeader::new(name)
             .default_open(depth < 1)
-            .selectable(true)
+            .show(ui, |ui| self.children_ui(ui, depth))
-            .selected(selected_name.as_str() == name)
+            .body_returned
-            .show(ui, |ui| self.children_ui(ui, name, depth, selected_name));
+            .unwrap_or(Action::Keep)
-        if response.header_response.clicked() {
-            *selected_name = name.to_string();
-        }
-        response.body_returned.unwrap_or(Action::Keep)
     }
 
-    fn children_ui(
+    fn children_ui(&mut self, ui: &mut Ui, depth: usize) -> Action {
-        &mut self,
-        ui: &mut Ui,
-        parent_name: &str,
-        depth: usize,
-        selected_name: &mut String,
-    ) -> Action {
         if depth > 0
             && ui
                 .button(RichText::new("delete").color(Color32::RED))
@@ -419,13 +440,7 @@ impl SubTree {
             .into_iter()
             .enumerate()
             .filter_map(|(i, mut tree)| {
-                if tree.ui(
+                if tree.ui_impl(ui, depth + 1, &format!("child #{}", i)) == Action::Keep {
-                    ui,
-                    depth + 1,
-                    &format!("{}/{}", parent_name, i),
-                    selected_name,
-                ) == Action::Keep
-                {
                     Some(tree)
                 } else {
                     None
@@ -434,7 +449,7 @@ impl SubTree {
             .collect();
 
         if ui.button("+").clicked() {
-            self.0.push(SubTree::default());
+            self.0.push(Tree::default());
         }
 
         Action::Keep