Struct Composite 

pub struct Composite { /* private fields */ }

Draw an overlay over a base.

Input order is [base, overlay], matching the reading order of “composite this over that”. The two may differ in format: the result has the base’s depth, gains colour when the overlay has it and the base is grey, and gains alpha when the blend can make an opaque base translucent.

Implementations

impl Composite

pub const fn new(placement: Placement, blend: Blend) -> Composite

Draw the overlay where placement says, combined by blend.

pub const fn at(x: i64, y: i64, blend: Blend) -> Composite

Draw the overlay with its top-left corner at (x, y) in base coordinates.

Negative offsets are allowed: the overlay is clipped to the base rather than rejected, which is what makes “centre a watermark” expressible without the caller doing the clipping arithmetic.

pub const fn over() -> Composite

Draw the overlay over the base at the origin with source-over.

pub const fn placement(&self) -> Placement

Where the overlay goes.

pub const fn blend(&self) -> Blend

The blend mode.

Trait Implementations

impl Clone for Composite

fn clone(&self) -> Composite

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Composite

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

Formats the value using the given formatter.

impl Op for Composite

fn rescaled(&self) -> Option<Arc<dyn Op>>

Never rescaled, for two independent reasons: the overlay position is in pixels, and the second input is a separate image that would not be reduced alongside the first.

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

A short, stable name for this op, used in diagnostics.

fn arity(&self) -> usize

The number of inputs this op consumes.

fn output_descriptor( &self, inputs: &[ImageDescriptor], ) -> Result<ImageDescriptor, PixelsError>

Compute the output shape from the input shapes.

fn input_regions( &self, output: Region, inputs: &[ImageDescriptor], ) -> Result<Vec<Region>, PixelsError>

The input regions needed to produce output.

fn compute( &self, inputs: &[Tile<'_>], output: &mut TileMut<'_>, ) -> Result<(), PixelsError>

Fill output from inputs — the kernel entry point.

fn access_pattern(&self) -> AccessPattern

How this op reads its inputs; drives tile negotiation (ADR-0003).