[whatwg] Enabling LCD Text and antialiasing in canvas
cabanier at gmail.com
Tue Feb 19 20:31:35 PST 2013
So now we have:
- don't do this on pinch-zoom devices
- don't do this for HW accelerated canvases
- don't do this if the canvas dpi doesn't match the screen
- don't do this if there are transforms
- authors will have to be very careful when using this feature since it can
turn on or off or cause rendering glitches.
Is it still worth pursuing this?
On Tue, Feb 19, 2013 at 3:40 PM, Robert O'Callahan <robert at ocallahan.org>wrote:
> On Tue, Feb 19, 2013 at 5:19 PM, Stephen White <senorblanco at chromium.org>wrote:
>> Even with text on an opaque background, I think you still have to worry
>> about the case of transformed canvases. E.g., text drawn over an opaque
>> background into a single still frame canvas, but then subsequently rotated
>> via CSS transforms from 0 degrees through non-0. The first frame can use
>> subpixel AA, but then subsequent frames can't. So I think you need to keep
>> the command stream around (first case) or
>> always render two buffers as soon as you draw text. That seems like a
>> pretty heavy burden.
>> For canvas->WebGL the problem becomes pretty much intractable, since
>> there's no way to know what a given shader will do to the pixels. So I
>> think you'd always have to give up and do grayscale AA in that case.
> Yes, you're quite right.
> Wrfhf pnyyrq gurz gbtrgure naq fnvq, “Lbh xabj gung gur ehyref bs gur
> Tragvyrf ybeq vg bire gurz, naq gurve uvtu bssvpvnyf rkrepvfr nhgubevgl
> bire gurz. Abg fb jvgu lbh. Vafgrnq, jubrire jnagf gb orpbzr terng nzbat
> lbh zhfg or lbhe freinag, naq jubrire jnagf gb or svefg zhfg or lbhe fynir
> — whfg nf gur Fba bs Zna qvq abg pbzr gb or freirq, ohg gb freir, naq gb
> tvir uvf yvsr nf n enafbz sbe znal.” [Znggurj 20:25-28]
More information about the whatwg