Struct ZoomState 

pub struct ZoomState { /* private fields */ }

Shared zoom/pan transform state for Modifier::zoomable.

Cloning shares the same underlying state (like ScrollState).

Implementations

impl ZoomState

pub fn new() -> Self

Creates a state at scale 1.0 with a 1.0..=8.0 zoom range.

pub fn with_scale_range(min_scale: f32, max_scale: f32) -> Self

Creates a state at scale 1.0 clamping zoom to min_scale..=max_scale.

pub fn id(&self) -> u64

Stable identity of this state (shared across clones).

pub fn scale(&self) -> f32

Current scale (reactive — subscribes the caller to changes).

pub fn scale_non_reactive(&self) -> f32

Current scale without snapshot subscription.

pub fn offset(&self) -> Point

Current pan offset in dp (reactive).

pub fn offset_non_reactive(&self) -> Point

Current pan offset without snapshot subscription.

pub fn min_scale(&self) -> f32

pub fn max_scale(&self) -> f32

pub fn is_transformed(&self) -> bool

Whether the content is currently transformed away from identity.

pub fn is_zoomed_in(&self) -> bool

Whether the content is currently zoomed in beyond identity.

Pan gestures only apply while this is true: an image at (or below) its natural size has nothing to pan, and drags over it belong to enclosing scrollables.

pub fn set_scale(&self, scale: f32)

Sets the scale directly (clamped to the configured range).

pub fn set_offset(&self, offset: Point)

Sets the pan offset directly.

pub fn reset(&self)

Resets to identity (scale clamped into range, zero offset).

pub fn apply_transform(&self, centroid: Point, pan: Point, zoom: f32)

Applies one gesture step: zoom by zoom about centroid, then pan.

centroid and pan are in the element’s display frame; for finger gestures the anchor must be the centroid of the pointers BEFORE the step (as reported by TransformGestureEvent::Transform). With the top-left-origin layer produced by ZoomState::layer, a content point c renders at p = c * scale + offset; this update applies p' = zoom * (p - centroid) + centroid + pan, which keeps the content glued to the fingers.

Pan is inert while not zoomed in: whenever the resulting scale is at (or below) identity the offset is clamped back to zero, so a pinch that zooms out to scale <= 1 — or a pure centroid pan at identity — never leaves the content stranded at a stray offset.

pub fn layer(&self) -> GraphicsLayer

Builds the GraphicsLayer rendering this transform.

Reads the state reactively, so it is meant for the lazy Modifier::graphics_layer(move || state.layer()) form.

Trait Implementations

impl Clone for ZoomState

fn clone(&self) -> ZoomState

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for ZoomState

fn default() -> Self

Returns the “default value” for a type.