From 1b79c369ca73b36874eec447da8eb9269cd4a6b1 Mon Sep 17 00:00:00 2001
From: Research Assistant <research@example.com>
Date: Wed, 20 May 2026 18:14:32 +0800
Subject: [PATCH] feat: add PDF.js internal overlay guards and tests

---
 paperforge/plugin/src/testable.js       | 40 +++++++++++++++++++++
 paperforge/plugin/tests/errors.test.mjs | 47 +++++++++++++++++++++++++
 2 files changed, 87 insertions(+)

diff --git a/paperforge/plugin/src/testable.js b/paperforge/plugin/src/testable.js
index 9266d085..f5902b1c 100644
--- a/paperforge/plugin/src/testable.js
+++ b/paperforge/plugin/src/testable.js
@@ -206,6 +206,43 @@ function canUseAnnotationOverlay(app, isMobile) {
     return true;
 }
 
+function hasPdfJsLayerAlignment(windowObj) {
+    try {
+        return !!(windowObj && windowObj.pdfjsLib && typeof windowObj.pdfjsLib.setLayerDimensions === 'function');
+    } catch { return false; }
+}
+
+function tryResolvePdfInternalViewer(view) {
+    if (!view) return null;
+    try {
+        // Try common internal property paths used by Obsidian's PDF viewer
+        var viewerComponent = view.viewer || view.pdfViewer || view.pdfViewerComponent;
+        if (!viewerComponent && view.constructor && view.constructor.prototype) {
+            var proto = view.constructor.prototype;
+            var desc = Object.getOwnPropertyDescriptor(proto, 'viewer')
+                || Object.getOwnPropertyDescriptor(proto, 'pdfViewer');
+            if (desc) {
+                viewerComponent = typeof desc.get === 'function' ? desc.get.call(view) : (desc.value || (view[desc]));
+            }
+        }
+        if (!viewerComponent && view.pdfViewer) viewerComponent = view.pdfViewer;
+        if (!viewerComponent) return null;
+        // Check if pdfViewer has getPageView
+        var pdfViewer = viewerComponent.pdfViewer || viewerComponent;
+        if (pdfViewer && typeof pdfViewer.getPageView === 'function') return pdfViewer;
+        return null;
+    } catch { return null; }
+}
+
+function canRenderPdfInternalOverlayHandle(handle) {
+    if (!handle) return false;
+    try {
+        return typeof handle.getPageView === 'function'
+            && typeof handle.currentScale === 'number'
+            && typeof handle.pagesCount === 'number';
+    } catch { return false; }
+}
+
 // ── Bridge helpers ──
 
 function runAnnotationSubprocess(vaultPath, pythonInfo, args, timeout, _spawn) {
@@ -461,6 +498,9 @@ module.exports = {
     toggleDisclosureState,
     detectConflictingPlugins,
     canUseAnnotationOverlay,
+    hasPdfJsLayerAlignment,
+    tryResolvePdfInternalViewer,
+    canRenderPdfInternalOverlayHandle,
     runAnnotationSubprocess,
     ANNOTATION_COLORS,
     ANNOTATION_DEFAULT_COLOR,
diff --git a/paperforge/plugin/tests/errors.test.mjs b/paperforge/plugin/tests/errors.test.mjs
index c2cf61bd..bd5acaf9 100644
--- a/paperforge/plugin/tests/errors.test.mjs
+++ b/paperforge/plugin/tests/errors.test.mjs
@@ -9,6 +9,9 @@ const {
     parseRuntimeStatus,
     detectConflictingPlugins,
     canUseAnnotationOverlay,
+    hasPdfJsLayerAlignment,
+    tryResolvePdfInternalViewer,
+    canRenderPdfInternalOverlayHandle,
 } = await import('../src/testable.js');
 
 describe('classifyError', () => {
@@ -157,3 +160,47 @@ describe('canUseAnnotationOverlay', () => {
         expect(canUseAnnotationOverlay(app, false)).toBe(false);
     });
 });
+
+describe('hasPdfJsLayerAlignment', () => {
+    it('returns true when setLayerDimensions exists', () => {
+        expect(hasPdfJsLayerAlignment({ pdfjsLib: { setLayerDimensions: function () {} } })).toBe(true);
+    });
+    it('returns false when pdfjsLib is missing', () => {
+        expect(hasPdfJsLayerAlignment({})).toBe(false);
+    });
+    it('returns false for null', () => {
+        expect(hasPdfJsLayerAlignment(null)).toBe(false);
+    });
+    it('returns false when setLayerDimensions is not a function', () => {
+        expect(hasPdfJsLayerAlignment({ pdfjsLib: { setLayerDimensions: 42 } })).toBe(false);
+    });
+});
+
+describe('tryResolvePdfInternalViewer', () => {
+    it('returns null for null view', () => {
+        expect(tryResolvePdfInternalViewer(null)).toBeNull();
+    });
+    it('returns null when view has no accessible pdf viewer', () => {
+        expect(tryResolvePdfInternalViewer({})).toBeNull();
+    });
+    it('resolves getPageView from deep pdfViewer path', () => {
+        var view = {
+            viewer: { pdfViewer: { getPageView: function () {}, currentScale: 1, pagesCount: 10 } },
+        };
+        var handle = tryResolvePdfInternalViewer(view);
+        expect(handle).toBeTruthy();
+        expect(typeof handle.getPageView).toBe('function');
+    });
+});
+
+describe('canRenderPdfInternalOverlayHandle', () => {
+    it('returns true for valid handle', () => {
+        expect(canRenderPdfInternalOverlayHandle({ getPageView: function () {}, currentScale: 1, pagesCount: 10 })).toBe(true);
+    });
+    it('returns false for null', () => {
+        expect(canRenderPdfInternalOverlayHandle(null)).toBe(false);
+    });
+    it('returns false when getPageView is missing', () => {
+        expect(canRenderPdfInternalOverlayHandle({ currentScale: 1, pagesCount: 10 })).toBe(false);
+    });
+});