[WC-3431]: Doc Viewer Checkbox Fix

[samuelreichert]

Pull request type

Bug fix (non-breaking change which fixes an issue)

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Description

Fix PDF standard font rendering in Document Viewer

Problem: PDFs containing glyphs from ZapfDingbats (e.g. checkmarks generated by .NET PDF libraries) rendered as blank rectangles in Document Viewer. The browser's native PDF viewer displayed them correctly.

Root cause: standardFontDataUrl and cMapUrl were relative paths. The PDF.js worker is loaded from //unpkg.com (cross-origin), so fetch() in the worker context has no document origin to resolve relative URLs against — throwing TypeError: Failed to parse URL.

Fix: Prepend window.location.origin to both URLs, making them absolute and resolvable from any worker origin.

Tested with:

• Customer W9 PDF (C corporation checkbox now shows as checked ✓)
• Plain PDF with no form fields (no regression ✓)

[github-actions]

AI Code Review

⚠️ Approved with suggestions — low-severity items only, safe to merge

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What was reviewed

File	Change
packages/pluggableWidgets/document-viewer-web/src/components/PDFViewer.tsx	Core fix: absolute origin prepended to cMapUrl and standardFontDataUrl
packages/pluggableWidgets/document-viewer-web/typings/global.d.ts	New: Window.mx.appUrl type declaration
packages/pluggableWidgets/document-viewer-web/typings/modules.d.ts	New: *.css module declaration
packages/pluggableWidgets/document-viewer-web/src/components/__tests__/PDFViewer.spec.tsx	New: comprehensive unit tests for PDFViewer
packages/pluggableWidgets/document-viewer-web/src/components/__tests__/BaseViewer.spec.tsx	New: unit tests for BaseViewer/BaseControlViewer
packages/pluggableWidgets/document-viewer-web/src/utils/__tests__/dimension.spec.ts	New: unit tests for constructWrapperStyle
packages/pluggableWidgets/document-viewer-web/src/utils/__tests__/helpers.spec.ts	New: unit tests for downloadFile
packages/pluggableWidgets/document-viewer-web/src/utils/__tests__/useZoomScale.spec.ts	New: unit tests for useZoomScale hook
packages/pluggableWidgets/document-viewer-web/package.json	test script now runs pluggable-widgets-tools test:unit:web
packages/pluggableWidgets/document-viewer-web/CHANGELOG.md	[Unreleased] Fixed entry added
openspec/changes/archive/2026-06-12-document-viewer-render-forms-fix/	OpenSpec archived change artefacts

Skipped (out of scope): dist/, pnpm-lock.yaml

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Findings

⚠️ Low — "Fit to width" button has wrong disabled condition

File: packages/pluggableWidgets/document-viewer-web/src/components/PDFViewer.tsx line 186
Problem: The "Fit to width" / reset button is disabled when zoomLevel >= 10, which is the zoom-in upper bound. The reset button should only be disabled when the zoom is already at the default level (1), or not disabled at all — it's never harmful to reset.
Fix:

<button
    onClick={reset}
    disabled={zoomLevel === 1}
    className="icons icon-FitToWidth btn btn-icon-only"
    aria-label={"Fit to width"}
    title={"Fit to width"}
></button>

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⚠️ Low — window.mx type is narrower than the rest of the monorepo

File: packages/pluggableWidgets/document-viewer-web/typings/global.d.ts
Problem: Other packages (e.g. google-tag-web) declare a richer Window.mx type (mx.session, mx.ui, etc.). The new declaration only adds mx?: { appUrl?: string }. Because TypeScript merges interface declarations, this is safe at compile time, but the minimal shape is silently inconsistent with the broader platform contract and could mislead future readers.
Note: If there is ever a shared @mendix/widget-plugin-platform-types package this should move there. For now, widening to include at least session (as the other widgets do) would be consistent. Not blocking — the existing pattern of per-package declarations is already in use across the monorepo.

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⚠️ Low — Module-scope window access is not guarded at module evaluation time

File: packages/pluggableWidgets/document-viewer-web/src/components/PDFViewer.tsx line 11
Problem: window.mx?.appUrl is read at module-scope (outside any function/hook). This is generally safe in a browser context, but if the module is ever loaded in a Node-based environment (SSR, test, tooling) window will be undefined and throw. The design doc acknowledges this risk. Currently tests rely on jsdom's window, so they pass, but the lack of a guard is a latent footgun.
Note: A simple guard: const origin = typeof window !== "undefined" ? (window.mx?.appUrl ?? window.location.origin).replace(/\/$/, "") : "" would make it robust. Low priority because Mendix pluggable widgets are browser-only.

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Positives

• The root-cause analysis is precise: relative URLs cannot be resolved from a cross-origin worker thread — the fix directly addresses this rather than working around it (useWorkerFetch: false was correctly rejected).
• Using window.mx.appUrl as the primary source correctly handles Mendix apps served from a subpath, which window.location.origin alone would not cover.
• The trailing-slash strip (replace(/\/$/, "")) prevents double-slash artifacts; and standardFontDataUrl now correctly ends with a trailing slash, matching the cMap URL convention.
• jest.resetModules() + dynamic require() to re-evaluate the module-scope origin constant between test cases is an elegant and correct solution to a real testing challenge — well documented in the test comment.
• Test coverage is extensive: all four window.mx states, worker URL variants, pagination edge cases, zoom bounds, and keyboard input filtering are all covered.
• The test script was changed from echo 'FIXME: Add unit tests' to the real test runner — closing a long-standing gap.
• CHANGELOG entry is user-focused and matches the Keep a Changelog format.