The renderer composited in 8-bit integers, so where a partly transparent
anti-aliased edge crossed opaque art (or a background colour) the result
came out at alpha 254 on some pixels, and PNG, TIFF and WebP files were
written with an alpha channel. Raster exports (and Save for Web) now
composite in floating point (vello_cpu's f32 pipeline, enabled as a
feature), offscreen groups, masks and patterns included; the canvas keeps
the faster 8-bit path.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
PNG is written by an in-code chunk writer with the resolution in pHYs and optional Adam7
interlacing (JPEG stores the resolution in JFIF). document.export takes ppi (72/150/300/other,
wins over scale), background (transparent, white, black or a colour) and antiAlias (none, art,
type: text snapped to whole pixels); Export for Screens rows take them too (plus one top-level
antiAlias, and a row's ppi names its @Nx suffix), and so does object.rasterize. Hard edges stay
hard in every offscreen pass (groups, masks, filters), whatever the thread count.
RenderOptions.anti_alias and render::encode::RasterExportOptions; PNG/JPEG/WebP Options dialog
(pngOptions/jpgOptions/webpOptions) after File > Export As PNG.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
On screen, a group (or object) with opacity, a blend mode, an opacity mask or
knockout whose content blends is drawn offscreen over a copy of its backdrop
and mixed back in by its opacity, mask and clip (a group blend mode then
applies to the backdrop-free result, as PDF defines it). Isolate Blending keeps
the content starting from transparency. Clip groups no longer isolate their
children (blending content is clipped per drawing), and non-isolated knockout
groups composite their elements against the art below the group. Groups
without blending inside still render as plain layers.
In PDF, such groups are written as non-isolated transparency groups (a
constant-alpha soft mask instead of the writer's isolated opacity group),
knockout groups included.
doc: Node::blends_through / children_blend.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
