wehub-resource-sync
31 lines
3.5 KiB
Markdown
31 lines
3.5 KiB
Markdown
# markdown-viewer
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A split-pane markdown editor/preview authored in markup + Zig: the left pane is a `textarea` mirrored elm-style into the model, the right pane is one `<markdown>` element bound to the same bytes, so the preview tracks every keystroke with no debounce and no drift. The whole view lives in `src/viewer.native` (hot-reloaded in dev builds); `src/main.zig` is the logic — `Model`, `Msg`, `update`, effects, and a two-mode custom theme.
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```sh
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native dev
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```
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## What it demonstrates
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- **`<markdown>` in markup** — headings on the span scale, inline styles, clickable links (pointer cursor; opened in the system browser through `fx.spawn open`/`xdg-open`), task lists, fenced code, blockquotes, GFM tables with column alignment, and `<details>` blocks whose expansion flags live in the model (`details_expanded: [16]bool`), toggled in `update`.
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- **Real file I/O without native dialogs** — the Native SDK has no file-dialog service, so this app uses the honest pattern: an editable path field in the toolbar. **Open** reads it (`fx.readFile`), **Save** writes the editor back to the current document, **Save As** writes to whatever the field says and adopts it. Every result is one typed Msg with an explicit outcome; failures land in the status bar, never a dialog.
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- **Recent files persisted through the same effects** — opened/saved paths join a sidebar list that persists to the per-app data directory (`native_sdk.app_dirs`, resolved once in `main`) via `fx.writeFile`, and is restored at boot by `init_fx` + `fx.readFile`.
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- **System appearance, followed live** — a refined stone/indigo palette (light and dark) derives per rebuild through `tokens_fn` from the scheme `on_appearance` delivers, so flipping the OS between light and dark re-themes the window immediately; there is no in-window theme control by design.
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- **Controlled scrolling** — the preview's scroll offset is model-owned: `on-scroll` stores the applied offset, the `value` binding echoes it back, so rebuilds (every keystroke re-renders the preview) never lose the reading position.
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- **Derived state, never stored** — word/line/byte counts in the status bar are computed from the live document at view time.
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Selection and copy in the preview, native scrolling, and the standard edit context menus in the editor are framework defaults — no app code.
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## Bundled documents
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The sidebar ships four sample documents embedded from `src/samples/` (they live under `src/` because `@embedFile` is module-rooted there): a README-style welcome with a table, a full renderer tour, a spec with task lists and details blocks, and a notes page.
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## Fixed capacities
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Documents cap at 16 KiB (`max_document_bytes` — the view retains editor + preview text against the 64 KiB per-view widget-text budget; over-cap opens arrive cut with an explicit `.truncated` outcome, never silently), paths at 512 bytes, the recent list at 6 entries, and `<details>` expansion flags at 16 blocks.
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## Tests
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`native test` (or root `zig build test-example-markdown-viewer`) drives the real dispatch paths: open/save/save-as round-trips and recent-list persistence through the fake effect executor, link clicks spawning the browser command, details toggling via automation `widget-click`, editor edits updating the preview and derived counts, the system appearance re-deriving the tokens live through platform events, the controlled preview scroll round-trip, compiled/interpreter markup parity, and automation snapshot assertions over links, table cells, and task checkboxes.
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