Does anyone know how gecko 1.9.1's full page zoom interacts with <canvas>?
2009/5/16 Albert Cahalan <acaha...@gmail.com>: > Martin Langhoff writes: > >> The short version of it is that canvas (and image rendering in >> general) is hurting lots due to the dpi being hardcoded to 134 >> which forces Gecko into image scaling games. Just setting >> layout.css.dpi to 96 makes Browse much snappier in general, >> and incredibly faster in canvas painting. > > This was discovered when scaling was first enabled. > > One could write a special-case scaler for that DPI, > avoiding the more generic scaling code. > > The XO also suffers from 5:6:5 pixel layout, which requires > lots of bit shifting. > >> It also makes pages unreadably small though. > > It's not just the size. The XO screen purposely smears the pixels > to reduce color fringing. > >> Questions: >> >> - I am intrigued, hulahop sources say it's hardcoded to 200dpi >> (and that jives with our screen) - why does it end up being 134? >> Should it be 200dpi? > > 134 puts 860x645 web pixels on the screen. We do this partly because > it is enough pixels for most modern web pages, and partly because of > a persistant myth that the XO screen resolution is equal to 800x600. > In other words, it's an arbitrary number with feeble justification. > > There are at least two reasonable ways to deal with this problem. > > The first way is to use the hardware scaling. This involves telling > the X server to change screen resolution. Sugar would need to manage > this on a per-activity basis, with adjustments to the frame as needed. > Besides elimination of scaling, the browser would move fewer pixels > and need less memory. It'd be amazing for performance. A downside is > that text would be less sharp, both from the scaler operation and more > directly from having fewer pixels. > > The second way is to choose a scaling factor that is easy to optimize, > and then do so. Easy would be 128 (3:4 ratio, 900x645 web pixels) or > 144 (2:3 ratio, 800x600 web pixels). You could optimize both, along > with 192 (1:2 ratio, 600x450 web pixels), and let users get a choice. > Unscaled can be an option too. > _______________________________________________ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel