Struct PanZoomWidget 

pub struct PanZoomWidget { /* private fields */ }

A pan/zoom viewport over one child — a node-and-edge graph, a map, a large image — without hand-rolling the gesture math. pan_zoom lays its child out at its natural size and places it under a scale-then-translate transform (PanZoomTransform) the user drives: primary drag pans (unless the child claims the press), a touch pinch or a desktop ctrl/⌘+wheel and trackpad pinch zooms about the gesture’s focal point, clamped to .min_scale/.max_scale. A plain wheel still reaches the child, and the child sees its own unscaled local coordinates at any zoom. Flat-re-exported from frust-widgets so app code never names that crate directly; see PanZoomView’s own doc for the full contract (.inertia glide, .on_transform notification, and the PanZoomController handle’s jump_to/fit_to_bounds/fit_rect).

use frust::authoring::{PaintCtx, PaintScene};
use frust::{AnyView, Component, PanZoomController, PanZoomTransform, any, canvas, pan_zoom};
use kurbo::{Point, Size};
use peniko::Color;

#[derive(Default)]
struct Board;

struct BoardState {
    zoom: PanZoomController,
    transform: PanZoomTransform,
}

impl Component for Board {
    type State = BoardState;

    fn init(&self) -> Self::State {
        BoardState {
            zoom: PanZoomController::new(),
            transform: PanZoomTransform::IDENTITY,
        }
    }

    fn build(&self, state: &mut Self::State) -> AnyView<Self::State> {
        let board = canvas(|scene: &mut dyn PaintScene, size: Size, _ctx: &PaintCtx| {
            scene.fill_rect(Point::ZERO, size, Color::from_rgb8(0x20, 0x20, 0x20));
        })
        .size(Size::new(2000.0, 1500.0));
        any(pan_zoom(board)
            .max_scale(4.0)
            .inertia(true)
            .controller(state.zoom.clone())
            .on_transform(|state: &mut BoardState, t| state.transform = t))
    }
}

frust::app!(Board);

The retained widget for a PanZoomView.

Implementations

impl PanZoomWidget

pub fn transform(&self) -> PanZoomTransform

The transform the child is currently placed under.

Trait Implementations

impl Widget for PanZoomWidget

fn layout(&mut self, ctx: &mut LayoutCtx<'_>, bc: &BoxConstraints) -> Size

Choose a size within bc and return it. The chosen size must satisfy bc (callers may additionally clamp via BoxConstraints::constrain).

fn paint(&mut self, ctx: &mut PaintCtx<'_>, scene: &mut dyn PaintScene)

Emit draw commands for this widget into scene.

fn event(&mut self, ctx: &mut EventCtx<'_>, event: &InputEvent) -> EventResult

Handle an input event, optionally mutating application state through ctx and reporting whether it was consumed.

fn semantics(&self, ctx: &mut SemanticsCtx)

Contribute this widget’s accessibility node(s) into ctx.

fn visit_children(&self, visitor: &mut dyn FnMut(&ChildPod))

Visit this widget’s owned ChildPods, in declaration (paint) order — the read-only seam that makes the retained hierarchy enumerable.

fn type_name(&self) -> &'static str

This widget’s concrete type name, for read-only tooling.