Add the single-hue color ramps for GeoTIFF and Zarr layers - #172
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Blues was the only light-to-dark single-hue ramp, so a raster that wanted one in any other color had no option. Adds the rest of the ColorBrewer single-hue sequential family -- Greens, Oranges, Purples, Reds -- taking the registry from 14 ramps to 18. These are the easiest ramps to read a magnitude off, and the safest choice when a raster sits under coloured vector features: a single-hue underlay cannot be mistaken for a categorical overlay the way a rainbow can. Keystops were sampled from matplotlib 3.10 at twelve evenly spaced points, matching the existing convention. matplotlib's Greens/Oranges/Purples/Reds are the ColorBrewer maps of those names. The picker gains a "Single hue" group and Blues moves into it, leaving "Sequential" for the multi-hue maps plus grayscale -- which is called out in a comment as running dark to light, the opposite direction from the single-hue family. Display order only; the persisted rampName is unchanged, so existing layers render identically. Two invariants back the new family. Luminance must fall monotonically from a near-white first stop, which is the property the family exists for and which a mis-sampled table breaks. And each ramp's channel ranking at its darkest stop must match its name, because every other assertion holds for any light-to-dark ramp -- without it, a ramp wired to the wrong hue's table passed silently, which is exactly what mutation testing caught. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Blues was the only light-to-dark single-hue ramp, so a raster that wanted one in any other color had no option. Adds the rest of the ColorBrewer single-hue sequential family -- Greens, Oranges, Purples, Reds -- taking the registry from 14 ramps to 18.
These are the easiest ramps to read a magnitude off, and the safest choice when a raster sits under coloured vector features: a single-hue underlay cannot be mistaken for a categorical overlay the way a rainbow can.
Keystops were sampled from matplotlib 3.10 at twelve evenly spaced points, matching the existing convention. matplotlib's Greens/Oranges/Purples/Reds are the ColorBrewer maps of those names.
The picker gains a "Single hue" group and Blues moves into it, leaving "Sequential" for the multi-hue maps plus grayscale -- which is called out in a comment as running dark to light, the opposite direction from the single-hue family. Display order only; the persisted rampName is unchanged, so existing layers render identically.
Two invariants back the new family. Luminance must fall monotonically from a near-white first stop, which is the property the family exists for and which a mis-sampled table breaks. And each ramp's channel ranking at its darkest stop must match its name, because every other assertion holds for any light-to-dark ramp -- without it, a ramp wired to the wrong hue's table passed silently, which is exactly what mutation testing caught.