WIP: working on converting the demo

crates/egui/src/containers/scene.rs

@@ -9,8 +9,8 @@ use crate::{emath::TSTransform, LayerId, Rect, Response, Sense, Ui, UiBuilder, V
 
 /// Creates a transformation that fits a given scene rectangle into the available screen size.
 ///
-/// The resulting visual scene bounds can be larger, ue to letterboxing.
-fn fit_to_rect_in_scene(rect_in_ui: Rect, rect_in_scene: Rect) -> TSTransform {
+/// The resulting visual scene bounds can be larger, due to letterboxing.
+pub fn fit_to_rect_in_scene(rect_in_ui: Rect, rect_in_scene: Rect) -> TSTransform {
     let available_size_in_ui = rect_in_ui.size();
 
     // Compute the scale factor to fit the bounding rectangle into the available screen size.
@@ -55,7 +55,7 @@ impl Scene {
     /// Provides a zoom-pan area for a given view.
     ///
     /// Will fill the entire `max_rect` of the `parent_ui`.
-    fn show_scene(
+    pub fn show_scene(
         &self,
         parent_ui: &mut Ui,
         to_global: &mut TSTransform,
@@ -111,7 +111,7 @@ impl Scene {
     }
 
     /// Helper function to handle pan and zoom interactions on a response.
-    fn register_pan_and_zoom(&self, ui: &Ui, resp: &Response, ui_from_scene: &mut TSTransform) {
+    pub fn register_pan_and_zoom(&self, ui: &Ui, resp: &Response, ui_from_scene: &mut TSTransform) {
         if resp.dragged() {
             ui_from_scene.translation += ui_from_scene.scaling * resp.drag_delta();
         }

crates/egui_demo_lib/src/demo/demo_app_windows.rs

@@ -77,7 +77,7 @@ impl Default for DemoGroups {
                 Box::<super::modals::Modals>::default(),
                 Box::<super::multi_touch::MultiTouch>::default(),
                 Box::<super::painting::Painting>::default(),
-                Box::<super::pan_zoom::PanZoom>::default(),
+                Box::<super::scene::SceneDemo>::default(),
                 Box::<super::panels::Panels>::default(),
                 Box::<super::screenshot::Screenshot>::default(),
                 Box::<super::scrolling::Scrolling>::default(),

crates/egui_demo_lib/src/demo/mod.rs

@@ -21,9 +21,9 @@ pub mod modals;
 pub mod multi_touch;
 pub mod paint_bezier;
 pub mod painting;
-pub mod pan_zoom;
 pub mod panels;
 pub mod password;
+pub mod scene;
 pub mod screenshot;
 pub mod scrolling;
 pub mod sliders;

crates/egui_demo_lib/src/demo/scene.rs

@@ -0,0 +1,127 @@
+use egui::emath::TSTransform;
+use egui::scene::{fit_to_rect_in_scene, Scene};
+use egui::{Pos2, Rect, Sense, TextWrapMode, UiBuilder, Vec2};
+
+#[derive(Clone, Default, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub struct SceneDemo {
+    transform: Option<TSTransform>,
+    drag_value: f32,
+    scene_rect: Option<Rect>,
+}
+
+impl Eq for SceneDemo {}
+
+impl crate::Demo for SceneDemo {
+    fn name(&self) -> &'static str {
+        "🔍 Scene"
+    }
+
+    fn show(&mut self, ctx: &egui::Context, open: &mut bool) {
+        use crate::View as _;
+        let window = egui::Window::new("Pan Zoom")
+            .default_width(300.0)
+            .default_height(300.0)
+            .vscroll(false)
+            .open(open);
+        window.show(ctx, |ui| self.ui(ui));
+    }
+}
+
+impl crate::View for SceneDemo {
+    fn ui(&mut self, ui: &mut egui::Ui) {
+        ui.label(
+            "Pan, zoom in, and zoom out with scrolling (see the plot demo for more instructions). \
+                   Double click on the background to reset.",
+        );
+        ui.vertical_centered(|ui| {
+            ui.add(crate::egui_github_link_file!());
+        });
+        ui.separator();
+
+        let (_, rect) = ui.allocate_space(ui.available_size());
+
+        // TODO: Actually write that back
+        let mut state = self.clone();
+
+        let to_global = self.transform.get_or_insert_with(|| {
+            fit_to_rect_in_scene(
+                rect,
+                Rect::from_min_max(Pos2::new(0., 0.), Pos2::new(120., 120.)),
+            )
+        });
+
+        let scene = Scene::new();
+        scene.show_scene(ui, to_global, |ui| {
+            for (i, (pos, callback)) in [
+                (
+                    egui::Pos2::new(0.0, 0.0),
+                    Box::new(|ui: &mut egui::Ui, _: &mut Self| {
+                        ui.button("top left").on_hover_text("Normal tooltip")
+                    })
+                        as Box<dyn Fn(&mut egui::Ui, &mut Self) -> egui::Response>,
+                ),
+                (
+                    egui::Pos2::new(0.0, 120.0),
+                    Box::new(|ui: &mut egui::Ui, _| {
+                        ui.button("bottom left").on_hover_text("Normal tooltip")
+                    }),
+                ),
+                (
+                    egui::Pos2::new(120.0, 120.0),
+                    Box::new(|ui: &mut egui::Ui, _| {
+                        ui.button("right bottom")
+                            .on_hover_text_at_pointer("Tooltip at pointer")
+                    }),
+                ),
+                (
+                    egui::Pos2::new(120.0, 0.0),
+                    Box::new(|ui: &mut egui::Ui, _| {
+                        ui.button("right top")
+                            .on_hover_text_at_pointer("Tooltip at pointer")
+                    }),
+                ),
+                (
+                    egui::Pos2::new(60.0, 60.0),
+                    Box::new(|ui, state| {
+                        use egui::epaint::{
+                            pos2, CircleShape, Color32, QuadraticBezierShape, Stroke,
+                        };
+                        // Smiley face.
+                        let painter = ui.painter();
+                        painter.add(CircleShape::filled(pos2(0.0, -10.0), 1.0, Color32::YELLOW));
+                        painter.add(CircleShape::filled(pos2(10.0, -10.0), 1.0, Color32::YELLOW));
+                        painter.add(QuadraticBezierShape::from_points_stroke(
+                            [pos2(0.0, 0.0), pos2(5.0, 3.0), pos2(10.0, 0.0)],
+                            false,
+                            Color32::TRANSPARENT,
+                            Stroke::new(1.0, Color32::YELLOW),
+                        ));
+
+                        ui.add(
+                            egui::Slider::new(&mut state.drag_value, 0.0..=100.0).text("My value"),
+                        )
+                    }),
+                ),
+            ]
+            .into_iter()
+            .enumerate()
+            {
+                let builder = UiBuilder::new()
+                    .max_rect(Rect::from_center_size(pos, Vec2::new(200., 200.)))
+                    .sense(Sense::click());
+
+                let mut content_ui = ui.new_child(builder);
+                let content_resp = callback(&mut content_ui, &mut state);
+                state.scene_rect = Some(
+                    state
+                        .scene_rect
+                        .get_or_insert(Rect::NOTHING)
+                        .union(content_resp.rect),
+                );
+            }
+        });
+
+        // scene.register_pan_and_zoom(ui, &resp, &mut self.transform);
+    }
+}