A Mesh tool click within the hit tolerance outside a gradient mesh hit the
mesh, but object.mesh.addLine looked for the point inside the outline only
and failed with "point is outside the mesh". The same click on a path's edge
made a 1x1 mesh without the line.
- GradientMesh::locate_within takes a tolerance: a point outside the mesh
within it of the outline gives the nearest point of the edge.
- object.mesh.addLine and object.mesh.create take an optional `tolerance`
(0 by default), and the Mesh tool sends its hit tolerance.
Each patch of a gradient mesh was cut into 8 x 8 flat quads for SVG export,
Object > Expand and the other outputs that cannot shade a mesh, whatever its
colours, so a patch of one colour became 64 identical pieces. Neighbouring
quads are now joined into square blocks wherever the colour changes by no
more than about one 8-bit step across the block; the block's outline runs
through its quads' corners, and a patch that folds over itself is not joined.
PDF export (and the PDF-compatible .ai it writes) cut each gradient mesh
patch into 8 x 8 flat-coloured quads. Viewers showed colour bands and
hairline seams between them, and files with many meshes became very
large and slow to write.
An opaque mesh is now written as one Type 6 (Coons patch) shading
(ISO 32000-1, 8.7.4.5.7) filling its outline, through the PDF writer's
MeshGradient: each patch blends its corner colours bilinearly, as the
canvas draws it. Colours go through page_color as other fills do, and a
mesh mixing RGB with other models goes through RGB. A mesh with
see-through points, an invalid one, or one past the coordinate range
keeps the quads.
Create Gradient Mesh's To Center / To Edge highlight lightened every point
towards RGB white, so a CMYK (or grey) point became display RGB. A patch with
any non-CMYK corner then mixes in RGB, and the PDF writer separated those
colours back to CMYK with K = 0, moving ink off the K plate. Points now
lighten towards white in their own colour model (no ink for CMYK), so the
mesh stays CMYK and K shrinks with the other inks. Flat meshes (highlight 0)
already kept their inks.
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