View > Pattern Preview only toggled a flag that nothing read. With it on, the
canvas now draws the document repeated around itself as a seamless tile, like
Photoshop, on the GPU canvas and the CPU fallback:
- pattern_preview.rs works out which copies cover the visible area (at most
31 per axis, centred on the view).
- GPU: each copy is another paint callback over the same document texture,
offset by whole document sizes in the shader (ViewParams::offset, the spare
view-uniform slots), so nothing is composited again and seams are exact.
- CPU: the same texture drawn again with a shifted view mapping.
- The drop shadow is off while tiling; selection, guides and other overlays
stay on the document itself.
Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>
