Module scene 

Scene — a pan/zoom container that hosts one child widget subtree in an infinite scrollable/zoomable canvas.

What it does

Scene applies a translation + uniform-scale transform (a SceneTransform) to its content’s painting and its pointer input, so the hosted widgets stay fully interactive while the user pans (drag on empty background, or middle-drag) and zooms (mouse wheel, anchored on the cursor). Double-clicking the empty background resets the view, matching egui’s Scene container. The current visible region is exposed as a scene-space rect via Scene::scene_rect / Scene::with_scene_rect_cell.

The content is a first-class framework child

The hosted subtree lives in children like any other container’s content, laid out in scene space (pinned at the origin). The pan/zoom is injected through the framework’s child_transform hook: painting, hit-testing, event dispatch, focus, and the inspector all map coordinates through that transform when they descend into the Scene, so the content is fully interactive and reachable by:

• keyboard focus — Tab traversal and click-to-focus reach widgets inside the Scene, so text fields hosted here accept typing;
• the inspector — hosted widgets appear in the tree at their on-screen (transformed) bounds.

Scene’s own on_event handles only the background gestures (pan / zoom / double-click reset). It receives a pointer event exactly when no hosted child consumed it — the framework’s leaf→root bubble delivers the press to the Scene only after the content declined it — so a press on empty canvas pans while a press on a hosted button clicks the button. While a pan is in progress the Scene claims the pointer exclusively (see claims_pointer_exclusively) so the drag keeps landing on the Scene regardless of what sits under the moving cursor.

Relationship to other modules: mirrors the builder style of crate::widgets::ScrollView; the transform math lives in the [transform] submodule (unit-tested independently); the background-gesture handling lives in the [events] submodule.

Structs

Scene

A pan/zoom canvas hosting a single content widget subtree.

SceneTransform

Translation + uniform scale mapping scene space to Scene-local screen space.

Constants

DEFAULT_ZOOM_RANGE

Default zoom range, matching egui’s Scene (0.1..=2.0).