- From: Benoit Jacob <bjacob@mozilla.com>
- Date: Wed, 5 Sep 2012 05:41:32 -0700 (PDT)
- To: Jonas Sicking <jonas@sicking.cc>
- Cc: whatwg@lists.whatwg.org, David Geary <david.mark.geary@gmail.com>, Boris Zbarsky <bzbarsky@mit.edu>
----- Original Message ----- > On Tue, Sep 4, 2012 at 10:15 AM, Boris Zbarsky <bzbarsky@mit.edu> > wrote: > > So now our list is: > > > > 1) Have a way for pages to opt in to software rendering. > > 2) Opt canvases in to software rendering via some sort of > > heuristic > > (e.g. software by default until there has been drawing to it > > for > > several event loop iterations, or whatever). > > 3) Have a way for pages to opt in to having snapshots taken. > > 4) Auto-snapshot based on some heuristics. > > 5) Save command stream. > > 6) Have a way for pages to explicitly snapshot a canvas. > > 7) Require opt in for hardware accelerated rendering. > > 8) Authors use toDataURL() when they want their data to stick > > around. > > 9) Context lost event that lets authors regenerate the canvas. > > 10) Do nothing, assume users will hit reload if their canvas goes > > blank. > > 11) Default to best-effort (current behavior), but allow opting in to > getting notifications about lost context, in which case the browser > would not need to do various tricks in order to attempt to save the > current state. > > I.e. basically 4, but with the ability for the page to opt in to 9. Keep in mind that snapshotting as in 4 will cause a large memory usage increase for large canvases, and will cause animation choppiness on certain pages on systems where readback is expensive. So the heuristics have to be specified in a precise manner, or else browser vendors could well decide that the best heuristic is "never". Benoit > > It sounds like no browsers do any such tricks right now, so > effectively the opt-in would be to just be notified. But possibly > browsers might feel the need to do various snap-shot heuristics on > mobile as they start to hardware accelerate there. > > / Jonas >
Received on Wednesday, 5 September 2012 12:42:09 UTC