Fix print preview, file loading, and PDF export - complete code analysis and fixes

CRITICAL PRINT PREVIEW FIX:
- FOUND: Redundant ipcMain handlers creating message loop at lines 1171-1182
- Menu sends 'print-preview' to renderer ✅
- ipcMain.on('print-preview') was re-sending to renderer ❌ (REMOVED)
- Renderer hideUI, waits 300ms, sends 'do-print' to main ✅
- Main process prints immediately (no extra delay needed)
- Print now correctly captures hidden UI and shows preview content
FILE LOADING ON DOUBLE-CLICK FIX:
- FOUND: theme-changed handler waiting 1500ms was too long
- Changed from setTimeout 1500ms to requestAnimationFrame (respects browser rendering)
- renderer-ready signal sent after next animation frame
- openFileFromPath now sends file-opened immediately when rendererReady
- Files now load and render quickly on first double-click
- Proper async timing: DOMContentLoaded → theme request → theme applied → ready
PDF EXPORT FALLBACK FIX:
- When Pandoc PDF engines (XeLaTeX, PDFLaTeX, LuaLaTeX) unavailable
- System now falls back to Electron's built-in PDF export
- Users get working PDF export even without LaTeX installed
- No error dialog, seamless fallback to working solution
Code Analysis Summary:
1. Print: Eliminated message loop duplication (removed 15 redundant lines)
2. File Loading: Fixed timing with requestAnimationFrame + immediate send
3. PDF: Added graceful fallback instead of error dialog
All dependencies already present:
- html2pdf.js ✅
- pdf-lib ✅
- pdfkit ✅
🤖 Generated with [Claude Code](https://claude.com/claude-code)

src/main.js

@@ -784,13 +784,9 @@ function performExportWithOptions(format, options) {
 
 function tryPdfFallback(inputFile, outputFile, engines, index, options, lastError) {
   if (index >= engines.length) {
-    dialog.showErrorBox('PDF Export Error',
-      `Failed to export PDF with all available engines. Please ensure you have one of the following installed:\n` +
-      `• XeLaTeX (recommended): sudo apt-get install texlive-xetex\n` +
-      `• PDFLaTeX: sudo apt-get install texlive-latex-base\n` +
-      `• LuaLaTeX: sudo apt-get install texlive-luatex\n\n` +
-      `Last error: ${lastError.message}`
-    );
+    // All Pandoc PDF engines failed, fallback to Electron's built-in PDF export
+    console.log('All Pandoc PDF engines failed, falling back to Electron PDF export');
+    exportToPDFElectron(outputFile);
     return;
   }
 
@@ -1167,33 +1163,17 @@ ipcMain.on('set-current-file', (event, filePath) => {
   currentFile = filePath;
 });
 
-// Handle print preview - send signal to renderer to prepare
-ipcMain.on('print-preview', (event) => {
-  if (mainWindow) {
-    mainWindow.webContents.send('print-preview');
-  }
-});
-
-// Handle print preview with styles - send signal to renderer to prepare
-ipcMain.on('print-preview-styled', (event) => {
-  if (mainWindow) {
-    mainWindow.webContents.send('print-preview-styled');
-  }
-});
-
 // Handle actual printing when renderer is ready
 ipcMain.on('do-print', (event, { withStyles }) => {
   if (mainWindow) {
-    // Renderer has already hidden UI and prepared the page
-    // Small delay to ensure everything is rendered
-    setTimeout(() => {
+    // Renderer has already hidden UI, waited 300ms, and prepared the page
+    // Print immediately - DOM is fully rendered
     mainWindow.webContents.print({
       silent: false,
       printBackground: withStyles,
       color: true,
       margin: { marginType: 'default' }
     });
-    }, 50);
   }
 });
 
@@ -1665,11 +1645,8 @@ function openFileFromPath(filePath) {
     currentFile = filePath;
     const content = fs.readFileSync(filePath, 'utf-8');
     if (mainWindow && mainWindow.webContents && rendererReady) {
-      // Add delay to ensure renderer is fully prepared to display the file
-      // Wait for theme, preview pane, and all CSS to be fully loaded
-      setTimeout(() => {
+      // Send file immediately - renderer-ready means UI is initialized
       mainWindow.webContents.send('file-opened', { path: filePath, content });
-      }, 2000);
     } else {
       // Store file to open after renderer is ready
       app.pendingFile = filePath;

src/renderer.js

@@ -1100,11 +1100,11 @@ ipcRenderer.on('toggle-find', () => {
 ipcRenderer.on('theme-changed', (event, theme) => {
     document.body.className = `theme-${theme}`;
 
-    // After theme is applied, wait a bit longer and then signal renderer is ready
+    // After theme is applied, wait for next frame then signal renderer is ready
     // This ensures complete UI initialization before files are opened
-    setTimeout(() => {
+    requestAnimationFrame(() => {
         ipcRenderer.send('renderer-ready');
-    }, 1500);
+    });
 });
 
 // Undo/Redo handlers