A chain of geometry effects makes at most 2 million anchors of a path (of a
type, symbol or image art's paths together) and about 8 million lines for the
renderer to draw at 1 px/pt, or what the path costs when that is more.
Roughen spaces its points further apart, Zig Zag makes fewer ridges a
segment, Free Distort, Twist and the warps split segments into longer pieces
(map_nonlinear_within) and Transform makes fewer copies where they would pass
it; a result drawn with too many lines is built again with fewer points, and
an effect that still doesn't fit is left out.
Three Roughens of a rectangle in a 25 KB file needed gigabytes of geometry,
and 2 million anchors of them flattened into 141 million lines (7 GB, past
vello's 2^27 lines a path); the file now opens in 0.4 s at about 450 MB.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Roughen's jitter can put a point behind its predecessor, so the path
turns back. The Catmull-Rom tangent next - prev then shrinks to almost
nothing and the anchor becomes a cusp, which PDF viewers (MuPDF,
poppler, Ghostscript) draw with a miter spike; the preview doesn't.
catmull_rom now keeps the tangent at least half as long as the longer
chord, and where it is shorter (turns of more than about 150 degrees)
points it along the bisector of the two chords: the turn becomes a round
hairpin. Gentler turns keep the plain Catmull-Rom tangent, so Zig Zag,
Scribble and the render goldens are unchanged.
Fixes#1643
