fix(colours): v6 palettes without label sequences inherit the parent's labels

[willwade]

Summary

Fixes Dasher-Windows #47: "Yellow on Black colour theme — it's all black. The font is not yellow. There is no yellow anywhere."

Root cause

The v6 palette files (Data/colors/color.*.xml, RFC 0007) are authored with only defaultLabelColor and no per-group label sequences. Label resolution in GetNodeLabelColor/GetGroupLabelColor treats the empty sequences as "undefined" and falls through to the parent palette — whose group-specific label colours win before the child palette's own defaultLabel fallback can run. For "Yellow on Black" (parentName="Default"), the legacy Default palette supplies black labels → invisible on the dark background.

Fix

The v6 parser now defaults empty group label colours (groupLabelColor / nodeLabelColorSequence) to the palette's own defaultLabelColor — mirroring what ParseLegacy has always done when building its groups (ColorIO.cpp:105-128). Explicit per-group sequences still win; palettes that don't define defaultLabelColor keep the previous parent-inheritance behaviour.

Regression test

yellow_on_black_labels_carry_palette_default_label_colour (test_draw_commands.cpp): with "Yellow on Black" selected, every opcode-5 text command must be #FFFFFF00. Measured pre-fix: all #FF000000; post-fix: 21/21 yellow.

Full suite: 40/40 test executables green (incl. the #63 uppercase-colour regression, which shares this code path).

Notes

• Not related to fix(colours): letter-family group boxes lost their palette colours (uppercase distinctly coloured again) #63 (that fixed box colours via parse-order and legacy group defaults; this fixes label colour defaulting) — but the same family of "palette authored expecting v5 defaults".
• Dasher-GTK/Android/Apple consume the same palettes through the same parser — all frontends benefit.

Type of change

• Bug fix

Definition of Done

• 40/40 engine test suites green
• Regression test added
• clang-format clean
• DCO signed

Greptile Summary

The PR updates v6 palette parsing so groups with no explicit label colors use their palette’s own defaultLabelColor, preventing parent group colors from overriding intended high-contrast labels.

• Defaults wholly unspecified group and node label colors during parsing.
• Preserves explicit label sequences and existing inheritance when no palette-local default exists.
• Adds an end-to-end draw-command regression test for Yellow on Black.

Confidence Score: 5/5

The PR appears safe to merge with no actionable correctness, security, or quality issues identified.

The parser change is scoped to wholly unspecified label colors, preserves explicit definitions and no-default inheritance, and the regression test exercises the resulting frontend-visible draw commands.

Important Files Changed

Filename	Overview
src/DasherCore/ColorIO.cpp	Defaults wholly empty v6 group and node label definitions from the current palette while retaining explicit values and inheritance when no local default exists.
tests/test_draw_commands.cpp	Adds public-API rendering coverage that verifies every emitted Yellow on Black text command uses the palette’s yellow label color.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A[v6 palette group] --> B{Explicit label colors?}
  B -->|Yes| C[Use explicit group or node colors]
  B -->|No| D{Palette defines defaultLabelColor?}
  D -->|Yes| E[Materialize palette-local label default]
  D -->|No| F[Retain parent inheritance]
  C --> G[Render labels]
  E --> G
  F --> G

Loading

_{Reviews (1): Last reviewed commit: "fix(colours): v6 palettes without label ..." | Re-trigger Greptile}

Context used:

• Knowledge Base — Visual and control assets
• Knowledge Base — Automated testing