Function encode_image 

pub fn encode_image(
    data: &ImageData,
    sampler: ImageSampler,
    paint_transform: Affine,
    encoded_paints: &mut Vec<EncodedPaint>,
    images: &mut ImageResidency,
) -> Result<ImageEncoding, ImageSkip>

Make data resident and append its encoded entry, returning the paint that references it.

paint_transform is the forward mapping from the image’s natural pixel rectangle onto device space; the entry stores its inverse, because that is the direction the shader applies it in (device fragment to image texel).

A sampler alpha below one is folded into the entry’s tint rather than carried on the sampler: vello_common’s own image encoding unimplemented!()s on a non-unit sampler alpha, and the shader has no alpha field to read one from — but it always multiplies by a tint, so an identity tint scaled by the alpha produces exactly the same result with nothing left unimplemented on the frame path (E17).

Errors

Returns the ImageSkip the residency refused the image with, or ImageSkip::SingularTransform when paint_transform has no finite inverse.