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perf(mister): fade grid covers in the presenter - #591
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Slint paints a landed cover once and the MiSTer presenters mix the pixels that were under it into each published row for the fade, so a page of covers no longer repaints the grid every frame. Covers for the page on screen land together, only art fetched from Core fades, and a placeholder colour that arrives in place fades too. Also: browse titles size from their neighbours instead of a fixed third, shorter list scroll, Accept, page slide and zoom timings, the options menu follows a held key and drops its page titles, the detail pane caches Core's metadata and fetches its neighbours, and the fast-scroll rail sits inside the HDMI list card.
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| Layer / File(s) | Summary |
|---|---|
Identify and coordinate cover arrivals rust/frontend/src/view_model.rs, rust/frontend/ui/tiles.slint, rust/frontend/src/games.rs, rust/frontend/src/hub.rs, rust/zaparoo-app/src/cover_landing.rs, rust/frontend/src/lib.rs |
Cell publication reports newly landed fetched art. On MiSTer, cover arrivals can be held while the active Games or Hub page is waiting for covers, then published together or after the hold expires. |
Map cover regions and compose fades rust/frontend/src/cover_fade.rs, rust/frontend/src/frame_transition.rs, rust/frontend/src/mister/mod.rs, rust/frontend/src/mister/transition.rs |
The frontend maps newly landed cells to rectangles. The fade compositor captures underlying pixels, mixes them with the landed cover over 11 frame periods, and ends fades when repaint, slide, or frame-size changes occur. Slide easing and browse transition duration also change. |
Integrate fades with MiSTer presentation rust/frontend/src/mister/ddr.rs, rust/frontend/src/mister/fb0.rs, rust/frontend/src/mister/latch.rs, rust/frontend/src/mister/platform.rs |
The presenters mix fade output into copied rows or rectangles and publish fade damage. Platform loops present active fades when no normal frame renders. |
Select fade policy and document behavior rust/frontend/src/display.rs, rust/frontend/src/lib.rs, rust/frontend/ui/theme.slint, rust/frontend/ui/tiles.slint, rust/frontend/src/route_motion.rs, docs/slint-gotchas.md |
Display seeding selects presenter or Slint tile fades. Tests distinguish fetched art from built-in logos. Documentation describes renderer-specific fades and updated reveal and zoom durations. |
Frontend motion and layout
| Layer / File(s) | Summary |
|---|---|
Update scrolling and motion timing rust/frontend/ui/theme.slint, rust/frontend/ui/app.slint, rust/frontend/ui/browse_list.slint, rust/frontend/ui/setup.slint, rust/frontend/src/games.rs, rust/frontend/src/hub.rs, rust/frontend/src/systems.rs, rust/zaparoo-app/src/input.rs, docs/style.md, docs/slint-gotchas.md |
A 120 ms Motion.scroll-ms duration is applied to scrolling controls. Page and swoop timings change, and press feedback changes from 90 ms to 50 ms. |
Adjust context-menu navigation and layout rust/frontend/ui/app.slint, rust/frontend/src/router.rs, rust/frontend/src/dual_head.rs |
The context menu no longer reserves a title band. Held-key navigation supplies a repeat interval used for steady row scrolling, and the dual-head overlay mirrors the new timing property. |
Size header titles around side content rust/frontend/ui/chrome.slint, rust/frontend/ui/app.slint, rust/frontend/translations/frontend.pot |
Header title sizing uses measured side-content widths. The non-CRT list fast-scroll rail is inset within its card. The translation catalog refreshes source references without changing message IDs or translations. |
Focused-detail metadata cache
| Layer / File(s) | Summary |
|---|---|
Cache and prefetch detail metadata rust/zaparoo-app/src/media_list.rs, rust/zaparoo-app/src/lib.rs, rust/frontend/src/games.rs, rust/frontend/src/lib.rs |
A bounded LRU cache stores detail rows by identity. The games view reads cached details, prefetches eligible neighbors, and clears the cache when media changes or jobs complete. |
Estimated code review effort: 4 (Complex) | ~60 minutes
Change: Bug fix · Severity of issue fixed: Medium
Sequence Diagram(s)
sequenceDiagram
participant MediaEvents
participant Frontend
participant GamesHub
participant ViewModel
participant PresenterFades
participant Presenter
MediaEvents->>Frontend: deliver settled covers
Frontend->>GamesHub: coordinate cover landing
GamesHub->>ViewModel: publish grid cells
ViewModel->>GamesHub: return newly landed indices
GamesHub->>PresenterFades: request cover rectangles
PresenterFades->>Presenter: provide mixed fade rows and damage bounds
Merge Risk: 
4a4b3
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Held context-menu scrolling may look uneven, an inactive cover fade may waste presentation work, and detail metadata may remain stale after an update. The PR is mergeable with owner acceptance of these fixes or follow-up.
Pre-merge checks: 
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Check name Status Explanation Resolution Out of Scope Changes check The PR includes changes with no demonstrated connection to issue [ #538]. These include detail metadata caching and prefetching, options-menu title removal and scrolling, title-width layout changes, fa…Remove the unrelated UI and metadata-cache changes from this PR, or link separate active issues that define their coding requirements and submit them as separate scoped changes. Retain changes that directly support the presenter cover fade,… Docstring Coverage Docstring coverage is 52.44% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documenta… Write docstrings for the functions missing them to satisfy the coverage threshold. Description check The description covers the required template sections: Summary (the opening paragraph), Motivation (Closes #538), Test plan (the Testing section, including the hardware tested and the untested present…Add a Screenshots / recordings section. The template requires one for visual changes. Include 720p and, if possible, 240p captures, or run just snapshotsand attach the output. Tick the checklist items that the author has completed, or st…-
Check name Status Explanation Title check The title "perf(mister): fade grid covers in the presenter" names the main change: grid-cover fades moved from Slint into the MiSTer presenter. The changeset matches this, including cover_fade.rs, fra… Linked Issues check Issue [ #538] requires presenter-side cover fades, early termination when other content changes, rectangle mapping including rotated layouts, support for vblank latch, fb0, native CRT, and dual-head ha…Full details: Title check
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Explanation
The title "perf(mister): fade grid covers in the presenter" names the main change: grid-cover fades moved from Slint into the MiSTer presenter. The changeset matches this, including cover_fade.rs, frame_transition.rs CoverFades, and the presenter integrations in mister/latch.rs, fb0.rs, and transition.rs. The title omits secondary changes such as motion timings, cover landing hold, and metadata caching, which the title does not need to cover.
Full details: Linked Issues check
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Explanation
Issue [
#538] requires presenter-side cover fades, early termination when other content changes, rectangle mapping including rotated layouts, support for vblank latch, fb0, native CRT, and dual-head handling.CoverFadescaptures pre-render pixels, narrows repaint damage, mixes rows for 11 frame periods, and ends fades on repaint, overlap, or frame-size changes.request_cover_fadesmaps and clips scene rectangles through window insets and rotation.PresenterFadesis integrated with the presenter transition path, and the platform exposes fade-only presentation for idle turns. The PR summary reports tests for compositor behavior, RGB565 mixing, landing detection, hold timing, and fetched-art versus logo routing. The implementation evidence supports the linked issue's coding requirements.
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Full details: Out of Scope Changes check
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Explanation
The PR includes changes with no demonstrated connection to issue [
#538]. These include detail metadata caching and prefetching, options-menu title removal and scrolling, title-width layout changes, fast-scroll-rail placement, and broad motion-timing changes such as press feedback and detail-pane fades. These changes are separate UI behavior and data-cache work, not presenter-side grid-cover fading.Resolution
Remove the unrelated UI and metadata-cache changes from this PR, or link separate active issues that define their coding requirements and submit them as separate scoped changes. Retain changes that directly support the presenter cover fade, its landing policy, rendering integration, tests, and documentation.
Full details: Docstring Coverage
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Explanation
Docstring coverage is 52.44% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 82 functions across 21 files. (9 skipped: 9 unsupported.)
Resolution
Write docstrings for the functions missing them to satisfy the coverage threshold.
Full details: Description check
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Explanation
The description covers the required template sections: Summary (the opening paragraph), Motivation (Closes
#538), Test plan (the Testing section, including the hardware tested and the untested presenters), and the Checklist items for lint and test. The Screenshots / recordings section is absent. The template marks it as required for visual changes, and this PR changes visual behaviour (fades, timings, title sizing, and the fast-scroll rail). The checklist boxes are not ticked, and the ARM32 and dirty-region items are not addressed explicitly.Resolution
Add a Screenshots / recordings section. The template requires one for visual changes. Include 720p and, if possible, 240p captures, or run
just snapshotsand attach the output. Tick the checklist items that the author has completed, or state why each one does not apply. In particular, state whether the software renderer dirty-region item and the ARM32 item were checked against docs/slint-gotchas.md and docs/architecture.md.
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Finishing Touches
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Generate docstrings
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- Create a new PR
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- A held key in the options menu glides at constant speed: a modal-owned repeat is now tracked on its own, without reaching the screen behind. - A metadata fetch that started before the detail cache was cleared no longer puts its result back. - Only the screen on display requests cover fades, and a request no render has taken within 100 ms is dropped.
Grid covers fade in again on a MiSTer HDMI render. The fade now runs in the presenter instead of in Slint, so a page of covers landing no longer repaints the grid every frame.
Closes #538
Cover fade
frame_transition::CoverFades). Slint keeps rendering everything else.zaparoo_app::cover_landing). Covers fetched a few at a time would otherwise each cost a slow frame while earlier ones were fading.GridCell.fetched). Built-in system logos cut in. A placeholder colour that arrives while its tile is on screen fades in too.Motion timings
Motion.scroll-ms)Other
Testing
just lintandjust testpass. New tests cover the fade compositor, RGB565 mixing, landing detection, the landing hold, the detail metadata cache, and the cover-fade route test for fetched art and logos.Summary by CodeRabbit