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🎨 Figure checks: colour and type

Status: reference.

The rules about how a figure is coloured and set: a border or a line too pale for its ground, words too pale for their fill, type smaller than the body, a colour from outside the house palette, and a card filled outside the house tint band. README.md explains how to read a report and how to record a deliberate exception.

Each rule below shows a faulty figure, the line figure check prints for it, and the fixed figure. Both are real files in examples/, and tests/test_figure_check_examples.py compiles them, so the report lines on this page are what the check prints today. The listings show the picture only; every file also carries the house style block above it.

🖌️ The house palette

Every fix on this page names one of three roles. Each hue in the house block has a pale tint to fill with, a darker Line shade to draw with, and a darker still Text shade to write with. cgInk is the house black, for labels and default strokes. cgPaper is the card ground, one step off white.

Hue Fill (a tint, 6 to 12) Line (border, edge, rule) Text (coloured words)
cgFlow cgFlow!7 cgFlowLine cgFlowText
cgAccent cgAccent!11 cgAccentLine cgAccentText
cgAlt cgAlt!9 cgAltLine cgAltText
cgAux cgAux!10 cgAuxLine cgAuxText
cgWarm cgWarm!12 cgWarmLine cgWarmText
cgRose cgRose!10 cgRoseLine cgRoseText
cgMute cgPaper cgMuteLine cgMuteText

The fill column is what the house styles use (cgbox, cgkey, cgalt, cgaux, cgwarm, cgrose, cgplain); any tint from 6 to 12 is in the band. The Line and Text shades are mixed towards cgInk until they clear WCAG's 3:1 and 4.5:1 over white, cgPaper and every tint the house block fills with. TIKZ-STYLE.md gives the mixing shares and the reasons for each hue.

🧭 Rules on this page

k1-stroke

Catches. A box's border, or a connector, under WCAG's 3:1 against its ground. The target is the node or the edge, a->b, and the measurement names both colours and the ratio. The ground is the box's own fill, else the innermost filled box that contains it, else white; a connector's ground is the innermost filled box that holds both its ends. Colours are what pgf drew with, so a style or #1 argument is resolved. A translucent fill is read as opaque, a shadow is not a ground, and a connector crossing a third zone is measured against its ends' ground.

Why it matters. A border drawn in the same pale tint as its fill vanishes in print and on a projector, and a pale line looks like a gap.

Faulty: the Sync card is drawn in cgAux, the hue it is filled with.

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\node[cgaux, draw=cgAux, text width=26mm] (sync) {\cglab{Sync}{read the export}};
\node[cgbox, text width=26mm, right=10mm of sync] (parse) {\cglab{Parse}{read the PDF}};
\draw[cgedge] (sync) -- (parse);

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  k1-stroke             sync       border cgAux on fill cgAux!10: 2.13:1, needs 3:1

cgAux is a palette hue, so the same line does not also count as colour-off-palette: the colour is the house's, used for the wrong job.

Fixed: the override goes, and cgaux draws in cgAuxLine.

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\node[cgaux, text width=26mm] (sync) {\cglab{Sync}{read the export}};
Faulty Fixed
Sync card with a faint pale-blue border beside Parse Sync card with a darker grey-blue border that holds its edge

Fix. Draw in the hue's Line shade (draw=cgAuxLine, not draw=cgAux); a palette name fills, a Line name draws.

k2-text

Catches. A run of a node's text under 4.5:1 against the same ground as k1-stroke, or under 3:1 where it is WCAG's large text (14pt bold, or 18pt), measured from the typeset size. The target is the node, or tag on a->b. It is read from the glyphs, so text=, \textcolor, \color and a macro are all seen.

Why it matters. Grey or tinted words on a tinted box are the first thing lost when a page is printed, photocopied or read by someone with low vision.

Faulty: the gloss of the warm Rank card is written in cgWarm, the hue its fill is a tint of.

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\node[cgwarm, text width=26mm, right=10mm of parse] (rank) {\textbf{Rank}\\[1.5pt]\textcolor{cgWarm}{order passages}};

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  k2-text               rank       text cgWarm on fill cgWarm!12: 2.05:1, needs 4.5:1

Fixed: the gloss is written in cgWarmText.

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\node[cgwarm, text width=26mm, right=10mm of parse] (rank) {\textbf{Rank}\\[1.5pt]\textcolor{cgWarmText}{order passages}};
Faulty Fixed
Rank card whose gloss is pale orange on a cream fill Rank card whose gloss is a dark brown that reads

Fix. Write in the hue's Text shade (text=cgAccentText, \textcolor{cgAccentText}{...}), or cgInk.

type-below-floor

Catches. Text set smaller than the body, 12pt, which is the probe's and the render's default. The target is the node, and the measurement is the node's smallest text, 8.0pt, floor 12pt. It is read from the glyphs, so \scriptsize, a size inherited from a group and a macro are all seen. A math run is left alone, since a subscript sets at script size on purpose, unless the node has nothing larger. Text inside a subscript ($k_{\text{in}}$) is text and fires; write \mathrm there.

Why it matters. A figure whose labels run smaller than the paragraph beside it reads as an afterthought. Shrinking the type is never the fix for a box with too many words in it: that is the conciseness defect, and the fix is fewer words or a wider box.

Faulty: the gate's gloss is shrunk to \scriptsize to keep it on one line.

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\node[cgkey, text width=26mm, right=10mm of draft] (gate) {\textbf{Gate}\\[1.5pt]{\scriptsize\textcolor{cgMuteText}{check citekeys}}};

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  type-below-floor      gate       8.0pt, floor 12pt

Fixed: the size command goes, and the gloss wraps.

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\node[cgkey, text width=26mm, right=10mm of draft] (gate) {\textbf{Gate}\\[1.5pt]{\textcolor{cgMuteText}{check citekeys}}};
Faulty Fixed
Gate card with a gloss in visibly smaller type than Draft's Gate card with its gloss at the same size as Draft's

Fix. Set the text at the body size: delete \small, \scriptsize and the like. If it does not fit, change the layout, never the type.

colour-off-palette

Catches. A border, fill, text run or line in a colour the figure's house block does not define, nor a white tint of one: draw=blue, fill=red!10, black (the house black is cgInk), or a hue darkened by hand. A framed node with no draw= colour is reported as border (current colour): a node half in the house style. The rule decides by the colour pgf used, so a \foreach variable is read. A line is named a->b, or by its first point. It is not measured without the house block, and a path's fill outside a node is not read.

Why it matters. A figure that invents its own hues reads as imported from somewhere else, and its colours stop meaning what the palette says they mean.

Faulty: the arrow from draft to render is drawn in LaTeX's blue.

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\node[cgbox, text width=26mm] (draft) {\cglab{Draft}{cite from the ledger}};
\node[cgbox, text width=26mm, right=10mm of draft] (render) {\cglab{Render}{build the PDF}};
\draw[cgedge, draw=blue] (draft) -- (render);

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  colour-off-palette    draft->render line blue

Fixed: the line is drawn in cgFlowLine, the colour cgedge already gives it.

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\draw[cgedge, draw=cgFlowLine] (draft) -- (render);
Faulty Fixed
A saturated pure-blue arrow between two house cards The same arrow in the house blue of the card borders

Fix. Use the house colour for the job: a cg<Hue> tint to fill, cg<Hue>Line to draw, cg<Hue>Text or cgInk to write. A (current colour) border means a draw with no house style: use cgbox.

tint-outside-band

Catches. A node with text, filled with a house hue mixed with white outside 6 to 12, or filled solid: the hue itself, or its Line or Text shade, which the label drowns in. The target is the node, and the measurement is the fill, cgAlt!15, band 6 to 12. A round node under 7mm (a step badge, a Text-shade disc) and a node with no text (a timeline's tick) are left out.

Why it matters. The band is what keeps a card a wash that text reads through. A darker tint pulls the eye to that card for no reason, and the further it goes the closer its label comes to failing k2-text.

Faulty: the Index card is filled with cgAlt!15, past the band.

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\node[cgbox, text width=26mm] (sync) {\cglab{Sync}{read the export}};
\node[cgalt, fill=cgAlt!15, text width=26mm, right=10mm of sync] (index) {\cglab{Index}{store passages}};
\draw[cgedge] (sync) -- (index);

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  tint-outside-band     index      cgAlt!15, band 6 to 12

Fixed: the override goes, and cgalt fills with cgAlt!9.

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\node[cgalt, text width=26mm, right=10mm of sync] (index) {\cglab{Index}{store passages}};
Faulty Fixed
Index card in a heavier green wash than the house cards Index card in the house's pale green wash

Fix. Fill a card with a tint from 6 to 12 (fill=cgFlow!8), never the hue or its shade.