colorramp.h File Reference

RasterColorRamp — gradient mapping from a normalised value in [0,1] to a display QColor. More...

#include <QColor>
#include <QGradientStops>
#include <QJsonObject>
#include <QMetaType>
#include <QString>
#include <QStringList>

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Classes
struct	RasterColorRamp
	Gradient mapping from a normalised value in [0,1] to a QColor. More...

Enumerations
enum class	RampInterp : int {   Rgb = 0 ,   HsvShort = 1 ,   HsvLong = 2 }
	Colour-space used when interpolating between two adjacent ramp stops. More...

Detailed Description

RasterColorRamp — gradient mapping from a normalised value in [0,1] to a display QColor.

Author

Caleb Buahin caleb.nosp@m..bua.nosp@m.hin@g.nosp@m.mail.nosp@m..com

Date

2026

License\n GPL-3.0-or-later

Slice BB-α (2026-05-24): the struct's previous home was layers/gisrasterlayer.h; it has been relocated here so any code that needs a ramp (raster rendering, GraduatedRenderer, the color-ramp combobox / editor) can include it without pulling in GDAL transitively. The struct stays at global scope to keep the ~20 existing call sites (Q_DECLARE_METATYPE, GISRasterLayer, SWMMResultsLayer, ColorRampEditorDialog, …) compiling unchanged.

Extensions over the previous form:

• interp field selects RGB vs HSV-short-arc vs HSV-long-arc interpolation between adjacent stops. Defaults to RGB to preserve existing built-in visuals; the editor sets HSV-short as the default for user-authored ramps per user request.
• 12 built-in named ramps reachable via builtin(name) — Viridis / Plasma / Magma / Inferno / Cividis / Turbo / RdBu / RdYlGn / Spectral / BrBG / legacy-SWMM-5interval / legacy-SWMM-pollutant. Plus the pre-existing grayscale and viridis static factories.
• toJson / fromJson round-trip for .oswp persistence and for the PreferencesManager custom-ramp library.

Cross-slice: GUI_IMPLEMENTATION_PLAN.md §L.BB-α.

Enumeration Type Documentation

RampInterp

enum class RampInterp : int

strong

Colour-space used when interpolating between two adjacent ramp stops.

• Rgb — linear interpolation in RGBA-F. Standard for published palettes (Viridis, Plasma, etc.) whose RGB tuples were authored assuming RGB interpolation between them. Default for built-in ramps.
• HsvShort — interpolate in HSV space, taking the shorter arc on the hue wheel (e.g. red → blue goes via magenta, not via green). Saturation and value interpolate linearly. Default for user-authored custom ramps per the Slice BB-α user request — produces smoother transitions when the stops are chosen by hand rather than from a perceptually-tuned LUT.
• HsvLong — interpolate via the longer arc on the hue wheel. Useful for rainbow-style ramps where the user wants to traverse the whole wheel between two stops.

Enumerator
Rgb
HsvShort
HsvLong