fix: stub DOMMatrix before custom PDF.js resolver import (closes #48)

johannschopplich · johannschopplich · commit 573aedc4b4ff · 2026-04-13T10:10:04.000+02:00
diff --git a/src/_internal/canvas.ts b/src/_internal/canvas.ts
@@ -104,15 +104,15 @@ export async function resolveCanvasModule(canvasImport: () => Promise<typeof imp
  * Node.js environments that do not support these constructors natively.
  *
  * @remarks
- * If a constructor is already defined in the global scope,
- * it will not be overridden.
+ * `DOMMatrix` is always set because {@link stubBrowserGlobals} may have
+ * installed a minimal stub to allow PDF.js to import – the real
+ * `@napi-rs/canvas` implementation must take precedence for rendering.
  */
 export function injectCanvasConstructors() {
   if (!resolvedCanvasModule)
     return
 
-  if (typeof globalThis.DOMMatrix === 'undefined')
-    globalThis.DOMMatrix = resolvedCanvasModule.DOMMatrix as unknown as typeof DOMMatrix
+  globalThis.DOMMatrix = resolvedCanvasModule.DOMMatrix as unknown as typeof DOMMatrix
 
   if (typeof globalThis.ImageData === 'undefined')
     globalThis.ImageData = resolvedCanvasModule.ImageData as unknown as typeof ImageData
diff --git a/src/_internal/env.ts b/src/_internal/env.ts
@@ -0,0 +1,14 @@
+/**
+ * Stubs browser globals that PDF.js expects at the module level
+ * in non-browser environments.
+ *
+ * @remarks
+ * Must be called before importing any PDF.js module, since PDF.js
+ * accesses these globals at parse time (top-level constants).
+ */
+export function stubBrowserGlobals(): void {
+  if (typeof globalThis.DOMMatrix === 'undefined') {
+    // @ts-expect-error: Minimal stub
+    globalThis.DOMMatrix = class DOMMatrix {}
+  }
+}
diff --git a/src/utils.ts b/src/utils.ts
@@ -1,5 +1,6 @@
 import type { DocumentInitParameters, PDFDocumentProxy } from 'pdfjs-dist/types/src/display/api'
 import type * as PDFJS from 'pdfjs-dist/types/src/pdf'
+import { stubBrowserGlobals } from './_internal/env'
 
 let resolvedModule: typeof PDFJS | undefined
 
@@ -46,6 +47,8 @@ export async function resolvePDFJSImport(
     return
   }
 
+  stubBrowserGlobals()
+
   if (pdfjsResolver) {
     try {
       resolvedModule = await interopDefault(pdfjsResolver())
