Enum ExternalSource

pub enum ExternalSource {
    Texture(Arc<dyn Fn(&Context, Rect) -> Option<Texture> + Send + Sync>),
    Cpu(Arc<dyn Fn(&mut Canvas, Rect) + Send + Sync>),
}

Backends an External widget can pull pixels from.

The only variant today is ExternalSource::Texture, a closure returning the current GL texture name. Future variants (DMA-BUF imports, software pixmaps for the CPU backend, …) can be added without changing call sites.

Variants

Texture(Arc<dyn Fn(&Context, Rect) -> Option<Texture> + Send + Sync>)

Closure invoked once per frame with LTK’s [glow::Context] current and the widget’s laid-out rect (in physical pixels of the host surface). The producer can allocate textures, bind extension- imported EGLImages, etc., and returns the texture name to sample. Returning None paints transparent — useful while the producer is still warming up its first frame. The rect is exposed so embedders can size their inner viewport to match LTK’s actual allocation (e.g. resize a WPEToplevel on layout change) and translate input coordinates by rect.origin.

Cpu(Arc<dyn Fn(&mut Canvas, Rect) + Send + Sync>)

Closure invoked once per frame with LTK’s Canvas and the widget’s laid-out rect, for immediate-mode CPU drawing (no GL texture). Used to host an Android View’s custom onDraw straight onto the LTK canvas. Works on both the GLES and software backends.

Trait Implementations

impl Clone for ExternalSource

fn clone(&self) -> ExternalSource

Returns a copy of the value.

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

Performs copy-assignment from source.