Struct SnapshotStack 

pub struct SnapshotStack { /* private fields */ }

The snapshot bracket’s inline emulation: how deep the walk is inside one, and what the outermost bracket installed.

Implementations

impl SnapshotStack

pub fn new() -> Self

A stack with no bracket open and nothing corrected.

pub fn reset(&mut self)

Drop every open bracket and its correction.

pub fn correction(&self) -> Affine

The affine to compose ahead of the frame root for every command inside the open bracket — the identity when none is open, or when the outermost one asked for no scale.

pub fn is_open(&self) -> bool

Whether a bracket is open.

pub fn enter(&mut self, rect: Rect, scale: f64, transform: Affine) -> bool

Enter a bracket, returning whether it is the outermost one.

The outermost bracket installs its presentation scale as the correction; an inner one installs nothing, which is the display list’s own rule that only the outermost bracket needs honouring.

pub fn record_layer(&mut self, bracket: usize)

Record that the outermost bracket opened a layer group, so the matching pop closes it.

Separate from enter because opening the layer is the compiler’s to do and can be declined — a bracket whose corrected transform does not survive composition opens none, and its pop must not then close a bracket it never opened. bracket is the group stack’s depth just after the layer’s own push — the handle leave uses to tell whether that group is still the one it would close.

pub fn leave(&mut self, open_brackets: usize) -> bool

Leave a bracket, returning whether the outermost one just closed having opened a layer group — that is, whether the caller now has a group to close.

A pop with no bracket open is ignored, the policy the display list states for an unbalanced PopSnapshot. open_brackets is the group stack’s current depth: when a stray pop inside the bracket’s body has already closed the group the snapshot opened, the recorded depth is no longer reachable and no group is reported — closing one anyway would lift an ancestor bracket the display list still holds open.

Trait Implementations

impl Debug for SnapshotStack

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SnapshotStack

fn default() -> Self

Returns the “default value” for a type.