Struct PanZoomView 

pub struct PanZoomView<State>
where
    State: 'static,
{ /* 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::{Component, PanZoomController, PanZoomTransform, View, 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) -> impl View<Self::State> {
        pan_zoom(Self::surface())
            .max_scale(4.0)
            .inertia(true)
            .controller(state.zoom.clone())
            .on_transform(|state: &mut BoardState, t| state.transform = t)
    }
}

impl Board {
    fn surface() -> impl View<BoardState> {
        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))
    }
}

frust::app!(Board);

A declarative pan/zoom container. See the module docs.

Implementations

impl<State> PanZoomView<State>

where State: 'static,

pub fn min_scale(self, scale: f64) -> PanZoomView<State>

The smallest scale a zoom may reach (default DEFAULT_MIN_SCALE). Non-positive or non-finite values are ignored.

pub fn max_scale(self, scale: f64) -> PanZoomView<State>

The largest scale a zoom may reach (default DEFAULT_MAX_SCALE). Non-positive or non-finite values are ignored.

pub fn inertia(self, inertia: bool) -> PanZoomView<State>

Let a released pan glide to rest (default false).

pub fn on_transform<F>(self, on_transform: F) -> PanZoomView<State>

where F: Fn(&mut State, PanZoomTransform) + 'static,

Run on_transform(state, transform) after every change to the transform (see the module docs).

pub fn controller(self, controller: PanZoomController) -> PanZoomView<State>

Attach a PanZoomController.

Trait Implementations

impl<State> View<State> for PanZoomView<State>

where State: 'static,

type Element = PanZoomWidget

The retained widget this view produces.

fn build(&self, ctx: &mut BuildCtx<'_>) -> PanZoomWidget

Materialise a fresh widget for this view.

fn rebuild( &self, prev: &PanZoomView<State>, element: &mut PanZoomWidget, ctx: &mut BuildCtx<'_>, ) -> ChangeFlags

Reconcile prev (the previous view of the same type) against the live element, mutating it in place and reporting what changed.

fn teardown(&self, element: &mut PanZoomWidget, ctx: &mut BuildCtx<'_>)

Tear down element when this view is being removed.

fn message(&self, _element: &mut Self::Element, _state: &mut State)

Deliver an event message to this view, mutating application state.