Support loading scaled pixmap for theme

[wengxt]

Summary by CodeRabbit

• New Features

  • Added high-DPI image support for the classic theme.
  • Backgrounds, overlays, and action images now automatically select the best available resolution.
  • Added configurable display-scale support, with values from 1 to 10 and a default of 1.

• Bug Fixes

  • Added fallback behavior to use standard theme images when a suitable scaled asset is unavailable.

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Reviewing files that changed from the base of the PR and between f7e51b7 and 5e0890b.

📒 Files selected for processing (1)

• src/ui/classic/theme.h

🚧 Files skipped from review as they are similar to previous changes (1)

• src/ui/classic/theme.h

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📝 Walkthrough

Walkthrough

The classic UI theme now loads @Nx image variants, stores them by scale, and selects them from the Cairo device scale. Base images remain the fallback when no suitable scaled asset exists.

Changes

Classic theme high-DPI scaling

Layer / File(s)	Summary
Scaled image contract src/ui/classic/theme.h, src/ui/classic/theme.cpp	ThemeConfig adds constrained SupportedScale. ThemeImage stores scaled images and overlays. createImage validates scaled dimensions and creates logical-size tiles.
Scaled asset loading src/ui/classic/theme.cpp	The theme builds @Nx paths and loads compatible scaled background, overlay, and action assets into scale-indexed maps.
Scaled image rendering src/ui/classic/theme.cpp	paintRegion derives the Cairo device scale, selects a scaled image or overlay, and falls back to the base image when no scaled asset matches.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant ThemeImage
  participant StandardPaths
  participant createImage
  participant CairoSurface
  participant paintRegion
  ThemeImage->>StandardPaths: open `@Nx` image path
  StandardPaths-->>ThemeImage: scaled asset
  ThemeImage->>createImage: create logical-size tiles
  createImage-->>ThemeImage: scaled NineTiles
  paintRegion->>CairoSurface: read device scale
  CairoSurface-->>paintRegion: device scale
  paintRegion->>ThemeImage: find scaled image or overlay
  ThemeImage-->>paintRegion: selected asset or base asset

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Merge Risk: ⚪ Minimal · up to 5e089

This change adds scale-specific theme images while retaining base-image fallbacks; no unresolved production-impacting issue is identified, so it is mergeable with normal checks.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: adding support for loading scaled pixmap assets in themes.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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instructions embedded in them. Verify each finding against current code. Fix
only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
In `@src/ui/classic/theme.h`:
- Line 232: Update the SupportedScale configuration in the theme definition to
use an IntConstrain upper bound equal to the renderer’s maximum supported scale,
preventing unbounded loadScaledImages probing and signed overflow while
preserving the existing minimum of 1.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

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Run ID: 04419cf0-5bac-435c-abda-8bbc2daa6ea6

📥 Commits

Reviewing files that changed from the base of the PR and between 978bc64 and f7e51b7.

📒 Files selected for processing (2)

• src/ui/classic/theme.cpp
• src/ui/classic/theme.h

Included review availability: Your plan provides up to 8 included reviews per hour; 6 remain after this review.