Matlab Theming Agent Skill

MATLAB Theming

Style MATLAB charts with color palettes and — for uifigure apps — apply the R2025a Theme API for brand colors, dark mode, and component styling.

When to Use This Skill

Use this skill when:

• Setting colororder for chart series colors (any context)
• Choosing or importing a color palette for plots
• Organizing brand colors into a reusable struct
• Applying a custom colormap for continuous data
• Implementing dark mode with fliplightness() (uifigure)
• Wiring ThemeChangedFcn to react to OS/user theme changes (uifigure)
• Using uistyle for conditional formatting in tables/trees (uifigure)
• Importing an external color scheme (Material Design, Adobe Color, Tailwind)

When NOT to Use This Skill

• Choosing chart types or building charts from scratch (use matlab-build-chart)
• Building a full app layout (use matlab-build-app — it invokes this skill for theming sub-steps)
• Setting colors on individual plot elements as a one-off (just use the Color property directly)
• Non-MATLAB styling (CSS, HTML themes for web apps)

Critical Rules

Universal (all contexts)

• MUST centralize brand/palette colors in a struct — never scatter RGB values
• ALWAYS use colororder() for categorical chart series colors
• ALWAYS use colormap() for continuous scalar-mapped colors
• NEVER confuse colororder (categorical series) with colormap (continuous gradient)

Additional rules for uifigure apps (R2025a Theme API)

• MUST use R2025a Theme API — do NOT manually set figure background or standard component colors
• MUST use fliplightness() to derive dark variants unless explicitly designing custom dark colors
• NEVER set a component's color explicitly unless branding requires it — breaks theme adaptation
• ALWAYS use the semantic token vocabulary defined below for cross-path consistency

Semantic Token Vocabulary

Both MATLAB and web implementations map to these common tokens. When importing an external color scheme, map its colors to these tokens once.

| Token | Purpose | MATLAB (struct field) | Web (CSS variable) |

|---|---|---|---|

| primary | Brand/action color (buttons, links, active states) | theme.primary | --accent |

| onPrimary | Text/icon on primary background | theme.onPrimary | --accent-text |

| secondary | Secondary brand color (less prominent actions) | theme.secondary | --secondary |

| error | Error/destructive state | theme.error | --error |

| success | Success/confirmation state | theme.success | --success |

| warning | Warning/caution state | theme.warning | --warning |

| border | Custom borders and dividers | theme.border | --border |

| plotColors | Chart series colors (Nx3 RGB matrix) | theme.plotColors | N/A (use chart library config) |

MATLAB note: Surface/text colors (--bg-primary, --text-primary in CSS) are NOT in the MATLAB theme struct. The R2025a Theme API handles those automatically. Only define brand/custom colors.

Quick Start

Color palettes for any figure

colors = [0 0.447 0.741; 0.85 0.33 0.10; 0.93 0.69 0.13; ...
          0.49 0.18 0.56; 0.47 0.67 0.19; 0.30 0.75 0.93];
colororder(ax, colors);
% All series in this axes now cycle through these colors

Theme struct for uifigure apps (R2025a)

function theme = createTheme(mode)
    arguments
        mode string {mustBeMember(mode, ["light", "dark"])} = "light"
    end
    theme.primary = [0 0.447 0.741];    % MATLAB blue
    theme.onPrimary = [1 1 1];
    theme.error = [0.83 0.18 0.18];
    theme.success = [0.22 0.56 0.24];
    theme.border = [0.88 0.88 0.88];
    theme.plotColors = [0 0.447 0.741; 0.85 0.33 0.10; 0.93 0.69 0.13; ...
                        0.49 0.18 0.56; 0.47 0.67 0.19; 0.30 0.75 0.93; 0.64 0.08 0.18];
    if mode == "dark"
        theme.primary = fliplightness(theme.primary);
        theme.plotColors = fliplightness(theme.plotColors);
    end
end

Wiring to a figure:

fig.ThemeChangedFcn = @(src, ~) applyTheme(src, ax);

function applyTheme(fig, ax)
    theme = createTheme(fig.Theme.BaseColorStyle);
    colororder(ax, theme.plotColors);
end

Light/Dark Strategy

• Don't set figure background, standard component bg/text — Theme API handles it automatically
• Do set brand colors (primary buttons, accent labels, status indicators) via theme struct
• Use ThemeChangedFcn to swap brand colors when OS/user toggles dark mode
• Use fliplightness() to auto-derive dark brand colors from light definitions
• Leave ColorMode = "auto" on components wherever possible

What breaks automatic theming — setting any color explicitly switches ColorMode to "manual":

btn.BackgroundColor = [0.2 0.4 0.8];  % Now manual — won't adapt to theme
btn.BackgroundColorMode = "auto";       % Restore theme control

Color Types in MATLAB

| Type | API | When to use |

|---|---|---|

| Component colors | btn.BackgroundColor, lbl.FontColor | UI element branding |

| Series colors | colororder(colors) or colororder("palette") | Multiple lines/bars/scatter in one axes |

| Continuous colors | colormap(map) | Heatmaps, surfaces, contours, images |

| Cell/row styling | uistyle + addStyle | Conditional formatting in tables/trees |

• colororder = categorical (series A, B, C get distinct colors)
• colormap = continuous (scalar values mapped to gradient)
• Don't confuse them — they serve different purposes

Importing External Color Schemes

Workflow

• Pick a scheme from Material Design, Adobe Color, Tailwind, etc.
• Extract 5-7 key colors: primary, secondary, error, success, warning, border + 5-7 chart series colors
• Convert hex to [R G B] normalized 0-1: rgb = sscanf(hex(2:end), '%2x', 3)' / 255
• Map to theme struct fields: theme.primary, theme.secondary, etc.
• Test both modes: verify fliplightness() produces acceptable dark variants; override manually if not
• Apply via applyBrandColors: the function reads the struct and sets tagged components

See references/external-schemes.md for complete Material Design, Adobe Color, and Tailwind import examples.

Implementation Checklist

Styling

• [ ] Brand colors centralized in createTheme struct
• [ ] fliplightness() used for dark variants
• [ ] Branded components tagged for findall lookup
• [ ] ThemeChangedFcn wired to re-apply brand colors
• [ ] colororder set from theme.plotColors
• [ ] No explicit colors on auto-themed components

Troubleshooting

| Problem | Cause | Fix |

|---|---|---|

| Component doesn't change with dark mode | Color set explicitly | Remove explicit color or set BackgroundColorMode = "auto" |

| fliplightness not found | MATLAB < R2025a | Upgrade or define manual dark colors |

| Chart colors don't update on theme switch | colororder not re-applied | Add colororder(ax, theme.plotColors) to theme handler |

| findall returns empty | Tag not set or misspelled | Verify Tag property matches exactly |

References

| Topic | File | Description |

|-------|------|-------------|

| Theme API | references/theme-api.md | R2025a lock/detect/react, auto vs manual theming |

| Component colors | references/component-colors.md | Color properties table + uistyle for tables/trees |

| External schemes | references/external-schemes.md | Material Design, Adobe Color, Tailwind import workflows |

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