theme.hpp

/* Copyright (c) 2026 Steven Varga, Toronto, ON, Canada
 * MIT License — see LICENSE
 *
 * Colour themes for the SVG plotting layer. A `theme_t` bundles the structural
 * colours (background, panel, foreground text, grid, axis), a categorical series
 * palette (cycled by line/scatter), and a 3-stop continuous gradient (wired into
 * the continuous heatmap). Two Solarized presets plus a set of popular VS Code
 * palettes (Dark+/Light+, Monokai, Dracula, Nord, One Dark, Gruvbox dark/light,
 * Tomorrow Night, Night Owl, Material, Tokyo Night) ship inline; a process-global
 * default current theme can be set with `plot::theme(...)`, and any driver call
 * may override it for a single render with the `plot::use{...}` named argument.
 * Dependency-free (standard library only).
 */
#ifndef PLOT_THEME_HPP
#define PLOT_THEME_HPP
 
#include <cstdint>
#include <array>
#include <vector>
 
#include "tags.hpp"
 
namespace plot {
    struct theme_t {
        std::uint32_t bg;                       // page / canvas background
        std::uint32_t panel;                    // plotting-area panel
        std::uint32_t fg;                       // default text / foreground
        std::uint32_t grid;                     // grid lines / axis ticks
        std::uint32_t axis;                     // axis lines
        std::vector<std::uint32_t> series;      // categorical palette (cycled)
        std::array<std::uint32_t,3> gradient;   // continuous 3-stop gradient
    };
 
    // Solarized (Ethan Schoonover) — exact hex.
    inline const theme_t solarized_dark = {
        /*bg   base03*/ 0x002b36,
        /*panel base02*/0x073642,
        /*fg   base0 */ 0x839496,
        /*grid base01*/ 0x586e75,
        /*axis base01*/ 0x586e75,
        /*series*/ { 0x268bd2, 0x859900, 0xb58900, 0xcb4b16,
                     0xdc322f, 0xd33682, 0x6c71c4, 0x2aa198 },
        /*gradient*/ { 0x268bd2, 0xb58900, 0xdc322f }
    };
 
    inline const theme_t solarized_light = {
        /*bg   base3 */ 0xfdf6e3,
        /*panel base2*/ 0xeee8d5,
        /*fg   base00*/ 0x657b83,
        /*grid base1 */ 0x93a1a1,
        /*axis base00*/ 0x657b83,
        /*series*/ { 0x268bd2, 0x859900, 0xb58900, 0xcb4b16,
                     0xdc322f, 0xd33682, 0x6c71c4, 0x2aa198 },
        /*gradient*/ { 0x268bd2, 0xb58900, 0xdc322f }
    };
 
    // ---- Popular VS Code theme presets (canonical palettes) -----------------
 
    // VS Code Dark+ (default dark).
    inline const theme_t dark_plus = {
        /*bg   */ 0x1E1E1E,
        /*panel*/ 0x252526,
        /*fg   */ 0xD4D4D4,
        /*grid */ 0x3C3C3C,
        /*axis */ 0x808080,
        /*series*/ { 0x569CD6, 0x4EC9B0, 0xCE9178, 0xDCDCAA,
                     0xC586C0, 0x9CDCFE, 0xB5CEA8, 0xD16969 },
        /*gradient*/ { 0x569CD6, 0xDCDCAA, 0xCE9178 }
    };
 
    // VS Code Light+ (default light).
    inline const theme_t light_plus = {
        /*bg   */ 0xFFFFFF,
        /*panel*/ 0xF3F3F3,
        /*fg   */ 0x1E1E1E,
        /*grid */ 0xD4D4D4,
        /*axis */ 0x808080,
        /*series*/ { 0x0000FF, 0x267F99, 0xA31515, 0x795E26,
                     0xAF00DB, 0x001080, 0x098658, 0xCD3131 },
        /*gradient*/ { 0x0000FF, 0x795E26, 0xA31515 }
    };
 
    // Monokai.
    inline const theme_t monokai = {
        /*bg   */ 0x272822,
        /*panel*/ 0x3E3D32,
        /*fg   */ 0xF8F8F2,
        /*grid */ 0x49483E,
        /*axis */ 0x75715E,
        /*series*/ { 0xF92672, 0xA6E22E, 0x66D9EF, 0xFD971F,
                     0xAE81FF, 0xE6DB74, 0x75715E, 0xF8F8F0 },
        /*gradient*/ { 0x66D9EF, 0xA6E22E, 0xF92672 }
    };
 
    // Dracula.
    inline const theme_t dracula = {
        /*bg   */ 0x282A36,
        /*panel*/ 0x44475A,
        /*fg   */ 0xF8F8F2,
        /*grid */ 0x44475A,
        /*axis */ 0x6272A4,
        /*series*/ { 0xFF79C6, 0xBD93F9, 0x50FA7B, 0x8BE9FD,
                     0xFFB86C, 0xFF5555, 0xF1FA8C, 0x6272A4 },
        /*gradient*/ { 0x8BE9FD, 0xBD93F9, 0xFF79C6 }
    };
 
    // Nord.
    inline const theme_t nord = {
        /*bg   */ 0x2E3440,
        /*panel*/ 0x3B4252,
        /*fg   */ 0xD8DEE9,
        /*grid */ 0x434C5E,
        /*axis */ 0x4C566A,
        /*series*/ { 0x88C0D0, 0x81A1C1, 0xA3BE8C, 0xEBCB8B,
                     0xBF616A, 0xB48EAD, 0xD08770, 0x8FBCBB },
        /*gradient*/ { 0x88C0D0, 0xEBCB8B, 0xBF616A }
    };
 
    // Atom One Dark.
    inline const theme_t one_dark = {
        /*bg   */ 0x282C34,
        /*panel*/ 0x21252B,
        /*fg   */ 0xABB2BF,
        /*grid */ 0x3B4048,
        /*axis */ 0x5C6370,
        /*series*/ { 0x61AFEF, 0x98C379, 0xE06C75, 0xE5C07B,
                     0xC678DD, 0x56B6C2, 0xD19A66, 0xABB2BF },
        /*gradient*/ { 0x61AFEF, 0x98C379, 0xE06C75 }
    };
 
    // Gruvbox Dark.
    inline const theme_t gruvbox_dark = {
        /*bg   */ 0x282828,
        /*panel*/ 0x3C3836,
        /*fg   */ 0xEBDBB2,
        /*grid */ 0x504945,
        /*axis */ 0x665C54,
        /*series*/ { 0x83A598, 0xB8BB26, 0xFB4934, 0xFABD2F,
                     0xD3869B, 0x8EC07C, 0xFE8019, 0xEBDBB2 },
        /*gradient*/ { 0x83A598, 0xFABD2F, 0xFB4934 }
    };
 
    // Gruvbox Light.
    inline const theme_t gruvbox_light = {
        /*bg   */ 0xFBF1C7,
        /*panel*/ 0xEBDBB2,
        /*fg   */ 0x3C3836,
        /*grid */ 0xD5C4A1,
        /*axis */ 0x7C6F64,
        /*series*/ { 0x076678, 0x79740E, 0x9D0006, 0xB57614,
                     0x8F3F71, 0x427B58, 0xAF3A03, 0x3C3836 },
        /*gradient*/ { 0x076678, 0xB57614, 0x9D0006 }
    };
 
    // Tomorrow Night.
    inline const theme_t tomorrow_night = {
        /*bg   */ 0x1D1F21,
        /*panel*/ 0x282A2E,
        /*fg   */ 0xC5C8C6,
        /*grid */ 0x373B41,
        /*axis */ 0x969896,
        /*series*/ { 0x81A2BE, 0xB5BD68, 0xCC6666, 0xF0C674,
                     0xB294BB, 0x8ABEB7, 0xDE935F, 0xC5C8C6 },
        /*gradient*/ { 0x81A2BE, 0xB5BD68, 0xCC6666 }
    };
 
    // Night Owl (Sarah Drasner).
    inline const theme_t night_owl = {
        /*bg   */ 0x011627,
        /*panel*/ 0x0B2942,
        /*fg   */ 0xD6DEEB,
        /*grid */ 0x122D42,
        /*axis */ 0x5F7E97,
        /*series*/ { 0x82AAFF, 0xADDB67, 0xEF5350, 0xFFCB8B,
                     0xC792EA, 0x7FDBCA, 0xF78C6C, 0xD6DEEB },
        /*gradient*/ { 0x82AAFF, 0xADDB67, 0xEF5350 }
    };
 
    // Material Theme (Mattia Astorino).
    inline const theme_t material = {
        /*bg   */ 0x263238,
        /*panel*/ 0x2E3C43,
        /*fg   */ 0xEEFFFF,
        /*grid */ 0x37474F,
        /*axis */ 0x546E7A,
        /*series*/ { 0x82AAFF, 0xC3E88D, 0xF07178, 0xFFCB6B,
                     0xC792EA, 0x89DDFF, 0xF78C6C, 0xEEFFFF },
        /*gradient*/ { 0x89DDFF, 0xC3E88D, 0xF07178 }
    };
 
    // Tokyo Night.
    inline const theme_t tokyo_night = {
        /*bg   */ 0x1A1B26,
        /*panel*/ 0x24283B,
        /*fg   */ 0xA9B1D6,
        /*grid */ 0x2F334D,
        /*axis */ 0x565F89,
        /*series*/ { 0x7AA2F7, 0x9ECE6A, 0xF7768E, 0xE0AF68,
                     0xBB9AF7, 0x7DCFFF, 0xFF9E64, 0xA9B1D6 },
        /*gradient*/ { 0x7AA2F7, 0x9ECE6A, 0xF7768E }
    };
 
    // process-global default current theme (header-only inline definition).
    // The default can be overridden at build time with
    // -DPLOT_DEFAULT_THEME=<preset> (e.g. nord) — used to regenerate the
    // theme-aware doxy gallery without editing sources. The runtime default is
    // unchanged (solarized_dark) unless the macro is defined.
#ifndef PLOT_DEFAULT_THEME
#define PLOT_DEFAULT_THEME solarized_dark
#endif
    inline theme_t current_theme = PLOT_DEFAULT_THEME;
 
    // setter for the global default.
    inline void theme(const theme_t& t){ current_theme = t; }
 
    // per-call override: `plot::use{ plot::solarized_light }`. Carries a theme as
    // a named argument that line/scatter/heatmap honour over the global default.
    struct use {
        using value_type = tag::theme_t;
        theme_t value;
    };
}
#endif