Struct webrender_api::ReferenceFrameMapper

pub struct ReferenceFrameMapper {
    frames: Vec<ReferenceFrameState>,
}

Maps from stacking context layout coordinates into reference frame relative coordinates.

Fields

frames: Vec<ReferenceFrameState>

A stack of reference frame scopes.

Implementations

impl ReferenceFrameMapper

pub fn new() -> Self

pub fn push_scope(&mut self)

Push a new scope. This resets the current offset to zero, and is used when a new reference frame or iframe is pushed.

pub fn pop_scope(&mut self)

Pop a reference frame scope off the stack.

pub fn push_offset(&mut self, offset: LayoutVector2D)

Push a new offset for the current scope. This is used when a new stacking context is pushed.

pub fn pop_offset(&mut self)

Pop a local stacking context offset from the current scope.

pub fn current_offset(&self) -> LayoutVector2D

Retrieve the current offset to allow converting a stacking context relative coordinate to be relative to the owing reference frame. TODO(gw): We could perhaps have separate coordinate spaces for this, however that’s going to either mean a lot of changes to public API code, or a lot of changes to internal code. Before doing that, we should revisit how Gecko would prefer to provide coordinates. TODO(gw): For now, this includes only the reference frame relative offset. Soon, we will expand this to include the initial scroll offsets that are now available on scroll nodes. This will allow normalizing the coordinates even between display lists where APZ has scrolled the content.

Trait Implementations

impl Clone for ReferenceFrameMapper

fn clone(&self) -> ReferenceFrameMapper

Returns a copy of the value.

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

Performs copy-assignment from source.