A small HTML canvas drawing app (and embeddable widget) I did so I could use my (non-iPad) tablet for drawing quick sketches. A few people suggested I add collaboration, which was a nice excuse to play with node.js :)
Tech used: node.js/nowjs for synchronising the drawings, jquery/canvas for the frontend, flask for saving/posting the images.
Fair point and something we considered - we wanted to always have a valid account when drawing so that users could be identified when collaborating together, and with only 48 hours to get everything working the quickest way was to slap on Twitter/Facebook authentication.
As many as the memory allows (and up to 1024, but was nowhere close that number), and I think that wasn't the problem here - but it seems that once the canvas has been drawn on for long enough, the new users just can't get the previous image. I'll have to refactor the initial loading code, at the moment it naively passes all the previous drawing operations to the client with no regards to the limits.
Sorry about this, hopefully I'll be able to fix these problems soon.
The English copy on the home page needs a slight, but important once-over. "A Web Whiteboard is touch-friendly whiteboard app..." should be written: "Web Whiteboard is a touch-friendly whiteboard app..."
Sorry about that! Either the drawing is shared no more (eg the one linked in these comments - if that's the case, you'll always get the error trying to go to that drawing), or you've found a bug. In the latter case case, could you please tell me your browser/os combo? here, in a tweet to @awwapp or in the mail (listed in my HN profile page). Thanks!
Awesome work. I wanted to let you know that the erase function is not working on Firefox 3.6.19 Mac. I share the image with a Safari browser and the image there is erased when I erase in FF window but the erasure doesn't show up in the FF window I erased in.
Thanks! Yeah, the app draws a line between the points. This isn't noticable if you're drawing slower (or if the device is fast enough), but if you're driving faster than it can be processed, the lines do show. I'll try to see how to improve on that, the plan is for the app to be useful on Android phones and iPhones as well.
Even in Photoshop, if you draw a very quick curve, you can see individual vertices along it. But Photoshop seems to quickly interpolate curves instead of straight lines, so you get a rough approximation of the curve you're drawing between the vertices. It's pretty good for hiding how it works.
I wanted to stick to the whiteboarding/sketching basics - you get a pen and an eraser. Perhaps it makes sense to add a few more tools, but I'm wary of adding too much, because I want it to be useable on really small screens, without keyboard, and with touch input, as opposed to only mouse.
For a sophisticated HTML drawing app (albeit not collaborative one, and not very usable without a pointing device), take look at the awesome DeviantArt Muro app (http://muro.deviantart.com/).