https://catenapdf.vercel.app/workers/pdf-to-pptx.worker.js

1/**
2 * PDF to PPTX Worker (via Pyodide + PyMuPDF + python-pptx)
3 * 
4 * Converts PDF pages to images and creates a PPTX with each page as a slide.
5 */
6
7import { loadPyodide } from '/pymupdf-wasm/pyodide.js';
8
9let pyodide = null;
10let initPromise = null;
11
12async function init() {
13    if (pyodide) return pyodide;
14
15    self.postMessage({ type: 'status', message: 'Loading Python environment...' });
16
17    // Initialize Pyodide
18    pyodide = await loadPyodide({
19        indexURL: '/pymupdf-wasm/',
20        fullStdLib: false
21    });
22
23    self.postMessage({ type: 'status', message: 'Installing dependencies...' });
24
25    const install = async (url) => {
26        await pyodide.loadPackage(url);
27    };
28
29    const basePath = '/pymupdf-wasm/';
30
31    // Mock missing non-critical dependencies
32    pyodide.runPython(`
33    import sys
34    from types import ModuleType
35    
36    # Mock tqdm (used for progress bars)
37    tqdm_mod = ModuleType("tqdm")
38    def tqdm(iterable=None, *args, **kwargs):
39        return iterable if iterable else []
40    tqdm_mod.tqdm = tqdm
41    sys.modules["tqdm"] = tqdm_mod
42  `);
43
44    // Install required packages
45    // Install Pillow (local wheel)
46    self.postMessage({ type: 'status', message: 'Installing Pillow...' });
47    await install(basePath + 'pillow-11.2.1-cp313-cp313-pyodide_2025_0_wasm32.whl');
48
49    await install(basePath + 'typing_extensions-4.12.2-py3-none-any.whl');
50    await install(basePath + 'lxml-5.4.0-cp313-cp313-pyodide_2025_0_wasm32.whl');
51    await install(basePath + 'pymupdf-1.26.3-cp313-none-pyodide_2025_0_wasm32.whl');
52
53    // Install python-pptx and its dependency
54    self.postMessage({ type: 'status', message: 'Installing python-pptx...' });
55    await install(basePath + 'python_pptx-1.0.2-py3-none-any.whl');
56
57    // Define the python processing script
58    self.postMessage({ type: 'status', message: 'Initializing converter script...' });
59
60    pyodide.runPython(`
61import os
62import io
63import fitz  # PyMuPDF
64from pptx import Presentation
65from pptx.util import Inches, Emu
66
67def convert_pdf_to_pptx(input_obj, dpi=150):
68    """
69    Convert PDF to PPTX by rendering each page as an image and adding to slides.
70    """
71    # Convert JsProxy to bytes
72    if hasattr(input_obj, "to_py"):
73        input_bytes = input_obj.to_py()
74    else:
75        input_bytes = input_obj
76
77    # Open PDF
78    pdf_doc = fitz.open(stream=input_bytes, filetype="pdf")
79    
80    # Create presentation
81    prs = Presentation()
82    
83    # Process each page
84    for page_num in range(len(pdf_doc)):
85        page = pdf_doc[page_num]
86        
87        # Get page dimensions
88        rect = page.rect
89        width_pt = rect.width
90        height_pt = rect.height
91        
92        # Set slide dimensions to match PDF page aspect ratio
93        # Standard slide is 10x7.5 inches, but we'll match PDF aspect ratio
94        aspect_ratio = width_pt / height_pt
95        
96        # Use standard width of 10 inches
97        slide_width = Inches(10)
98        slide_height = Emu(slide_width / aspect_ratio)
99        
100        prs.slide_width = slide_width
101        prs.slide_height = slide_height
102        
103        # Render page to image
104        mat = fitz.Matrix(dpi / 72, dpi / 72)  # Scale for DPI
105        pix = page.get_pixmap(matrix=mat, alpha=False)
106        img_bytes = pix.tobytes("png")
107        
108        # Add blank slide
109        blank_layout = prs.slide_layouts[6]  # Blank layout
110        slide = prs.slides.add_slide(blank_layout)
111        
112        # Save image temporarily
113        img_path = f"temp_page_{page_num}.png"
114        with open(img_path, "wb") as f:
115            f.write(img_bytes)
116        
117        # Add image to slide (full slide size)
118        slide.shapes.add_picture(
119            img_path,
120            left=0,
121            top=0,
122            width=slide_width,
123            height=slide_height
124        )
125        
126        # Cleanup temp image
127        os.remove(img_path)
128    
129    pdf_doc.close()
130    
131    # Save presentation to bytes
132    output = io.BytesIO()
133    prs.save(output)
134    output.seek(0)
135    pptx_bytes = output.read()
136    
137    return pptx_bytes
138  `);
139
140    return pyodide;
141}
142
143self.onmessage = async (event) => {
144    const { type, id, data } = event.data;
145
146    try {
147        if (type === 'init') {
148            if (!initPromise) initPromise = init();
149            await initPromise;
150            self.postMessage({ id, type: 'init-complete' });
151            return;
152        }
153
154        if (type === 'convert') {
155            if (!pyodide) {
156                if (!initPromise) initPromise = init();
157                await initPromise;
158            }
159
160            const { file, dpi = 150 } = data;
161            const arrayBuffer = await file.arrayBuffer();
162            const inputBytes = new Uint8Array(arrayBuffer);
163
164            self.postMessage({ type: 'status', message: 'Convert

164ing PDF pages to slides...' });
165
166            // Call Python function
167            const convertFunc = pyodide.globals.get('convert_pdf_to_pptx');
168            const resultProxy = convertFunc(inputBytes, dpi);
169            const resultBytes = resultProxy.toJs();
170            resultProxy.destroy();
171
172            const resultBlob = new Blob([resultBytes], {
173                type: 'application/vnd.openxmlformats-officedocument.presentationml.presentation'
174            });
175
176            self.postMessage({
177                id,
178                type: 'convert-complete',
179                result: resultBlob
180            });
181        }
182
183    } catch (error) {
184        console.error('Worker error:', error);
185        self.postMessage({
186            id,
187            type: 'error',
188            error: error.message || String(error)
189        });
190    }
191};