Merge pull request #6961 from dotCooCoo/fix/gradient-repeat-runs

Gradients: a repeated gradient with many stops keeps every run

docs/mcp.md

@@ -1270,11 +1270,19 @@ is written with its stops repeated as many times as the shape needs: at most 256
 legacy `.ai`), and for a radial or diamond gradient no farther from its center than 65,536 runs, or than a million
 times the smallest gap between its stops (measured in runs) when that is less. Past those it pads, with a warning.
 The `.ai` editing data has no spread either: it holds the stops repeated across the shape, at most 256 of them, with
-a warning. PDF import finds a sharp step between two colors in an axial or radial shading, in any PDF, by halving
-the spans between its samples, so the step reads back where it is in the file (to 1/64 × 2^-14 of the axis, with at
-most 16,384 samples a shading) instead of blurred across the samples around it. Object › Expand expands the
-repeated stops, into the same whole number of `steps` objects for each run (at least one, so about `steps` in all),
-each run starting on an object's edge:
+a warning. When the runs need more stops than these limits allow, every run is still written, without the stops that
+change its colors least. Each run keeps its ends; sharp steps and swatch-linked stops are the last to be left out,
+but a run with more of them than its share of the limit loses some. The same applies to a gradient along or across a
+stroke, and to CSS's conic gradient, past 16,384 stops, and to Outline Stroke's mesh past 1,024. For CSS the 16,384
+counts the gradient's stops before they are written: CSS then adds a stop for each midpoint, and for a Perceptual
+gradient stops along each span's curve, so the written gradient can hold more. PDF
+import finds a sharp step between two colors in an axial or radial shading by halving the spans between its samples,
+so the step reads back where it is in the file (to 1/64 × 2^-14 of the axis) instead of blurred across the samples
+around it. A shading takes at most 16,384 samples, so the steps past the point where that budget runs out stay
+blurred, and a color band narrower than 1/64 of the axis can be missed when no sample lands in it. Object › Expand
+expands the repeated stops, into the same whole number of `steps` objects for each run (at least one, so about
+`steps` in all), each run starting on an object's edge; a gradient that needs more than 256 runs across the box stays
+a gradient:
 
 ```json
 {"name":"run_command","arguments":{"command":"paint.editGradient","params":{"spread":"reflect","repeats":3}}}