GPU-aware rendering
Offscreen PDF thumbnail renderer
Move thumbnail painting out of React and into a Worker. Canvas ownership is transferred once, then the Worker paints thumbnails directly with OffscreenCanvas and WebGL2 post-processing.
Upload a PDF to render page thumbnails in a background Worker.
Memory release checklist
Use “Release memory” when closing a huge PDF. It terminates the Worker, asks pdf.js to destroy its document, clears canvas references, and lets the browser reclaim transferred ArrayBuffers and GPU textures.
User guide
How to use Offscreen PDF Thumbnails
Render many PDF page previews through a Worker and OffscreenCanvas where the browser supports it.
- 1
Upload a multi-page PDF.
- 2
Choose thumbnail scale and the visible page range.
- 3
Start background rendering and scroll through the virtualized grid.
- 4
Close the document to release canvases, bitmaps, and the Worker.
Best for
- Large PDF page browsers
- Testing responsive thumbnail rendering
Important limitation
Support varies by browser. PDF.js rasterization is not automatically WebGL2, and main-thread CPU use cannot be guaranteed near zero.
Frequently asked questions
Does it render all 1,000 pages at once?
No. Windowing and a bounded queue prevent unnecessary work.
What happens without OffscreenCanvas?
The component must use a supported fallback or report that the feature is unavailable.
PDFPerch processes files locally unless this guide explicitly identifies a cloud-dependent feature. Always keep an original copy and verify critical output before submission, printing, signing, or accounting use.