Test on a fleet of physical devices with Android Device Streaming (android-developers.googleblog.com)

Thank you for sharing and being so generous with the licensing. I know this might be way out of scope, but do you have any plans for a "flipbook" visualization?

billconan · 3h ago

Very nice! I once had a side project with a built-in PDF viewer. My first version used pdf.js, but when zooming in quickly, it felt sluggish and hard to keep the zoom focus in the right place.

So I built my own PDF viewer, this time using pdfium in C++ with Metal for rendering — here’s a quick demo: https://youtu.be/jJMhVn5yzEI

I implemented a tiling technique to balance memory usage and performance. I didn’t realize pdfium could be so performant in WebAssembly — and honestly, I actually prefer developing UI on the web compared to C++.

bobsingor · 2h ago

Honestly, yours looks even snappier than what I had, the way it’s handling zoom feels super fluid. Really impressive work! Makes me want to dig back in and see if I can match that speed.

billconan · 1h ago

Thank you! Smooth zooming was the main thing I focused on optimizing. I haven’t implemented text search yet, that’s a whole other rabbit hole, with challenges like stitching text objects together and handling text normalization.

My code runs natively, so users need to download a client and I have to code the rest of the ui in cpp, that’s the downside. I did consider a hybrid approach with Electron or Tauri, but dropped the idea to avoid IPC overhead and get the best possible performance.

gurjeet · 1h ago

Gave it a quick try. Annotations didn't work at all in Fierfox, but all annotation types (underline, highlight, etc.) worked as expected in Chrome.

bobsingor · 29m ago

I haven’t had the chance to test annotations in Firefox yet, so thanks for pointing that out. I’ll check what’s going on there, good to know they’re working fine in Chrome.

looperhacks · 1h ago

I tried a random PDF that includes an annotation, but the annotation didn't show up. I assume the annotations this supports are no real annotations?

bobsingor · 1h ago

We already support quite a few real PDF annotations: circle, square, polygon, polyline, highlight, underline, squiggly, strikeout,free text, stamps, and ink. Some types are still on our list, like links, form fields, sound annotations, file attachments, and 3D models. Do you happen to know what annotation type it is in your PDF? I’m curious.

lucfranken · 2h ago

Seems to work great!

Little note: when you switch from redaction to view with the redaction tool (red lines) active it stays active in the view mode. Impossible to scroll because it still redacts.

Refresh fixes it.

bobsingor · 30m ago

Good catch, I’ll fix that. On mobile, it’s intentional that scrolling is disabled while in redaction mode so you can make precise selections, but if you switch back to the view tab it should definitely exit redaction mode. Thanks for spotting it!

gorgoiler · 52m ago

MIT license is generous. Good for you, and thanks!

layer8 · 7m ago

The underlying PDFium is Apache 2.0 though, and it looks to me that the present project doesn’t currently comply with https://www.apache.org/licenses/LICENSE-2.0#redistribution for that dependency.

bobsingor · 24m ago

Thanks! I wanted to make it as easy as possible for people to use, tweak, and build on top of it, so MIT felt like the right choice.

lysace · 2h ago

The repo appears to contain a copy of Foxit’s/Google’s pdfium along with a UI and lots of abstraction layers/examples for various JavaScript frameworks.

I’m not a JavaScript developer (perhaps there are cultural differences at play?), but in general I think it would be polite to credit the developers of the actual PDF engine.

davorak · 38m ago

The repo is marked with the pdfjs and pdfium topics so there is that.

Beyond that, powered by... and similar make sense if the library/engine allows or encourages the behavior.

bobsingor · 31m ago

Absolutely, and I agree, credit is important. I have a whole section in the docs about PDFium and its origins with Foxit/Google: https://www.embedpdf.com/docs/pdfium/introduction.

lysace · 16m ago

That’s neat.

I would also mention it in the README.md.

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