On Jun 2, 2008, at 4:57 PM, Vladimir Vukicevic wrote:
On Jun 2, 2008, at 2:39 PM, Oliver Hunt wrote:
That's exactly what i would be afraid of people doing. If I have a
fast system why should i have to experience low quality rendering?
It should be the job of the platform to determine what level of
performance or quality can be achieved on a given device.
Typically such a property would be considered a "hint", and as such
would likely be ignored.
If honouring this property was _required_ rather than being a hint
you would hit the following problems:
* Low power devices would have a significant potential for poor
performance if a developer found that their desktop performed well
so set the requirement to high quality.
* High power devices would be forced to use low quality rendering
modes when perfectly capable of providing better quality without
significant performance penalty.
Neither of these apply if the property were just a hint, but now
you have to think about what happens to content that uses this
property in 18 months time. You've told the UA to use a low
quality rendering when it may no longer be necessary, so now the UA
has a choice it either always obeys the property meaning lower
quality than is necessary so that new content performs well, or it
ignores the property in which case new content performs badly.
If web apps misuse the property, then bugs should be filed on those
apps that incorrectly use the property, and the app developer should
fix them. The web platform shouldn't prevent developers from
exercising control over how their content is rendered; most
developers, as you say, probably shouldn't change anything from the
default 'auto'. But the capability should be there. Arbitrarily
deciding what developers can and can't do isn't interesting from the
perspective of creating a full-featured platform, IMO.
No matter how fast smooth/bilinear filtering is, something more
complex is always going to be slower, and something less complex is
always going to be faster. If those perf differences are
significant to the web app, no matter how small, you're going to
want to be able to have that control. If they're not, then you
should just be using 'auto' and let the UA handle it.
I completely agree. Almost any feature can be abused. It's not our
job to withhold features just because they can be abused. It's also
worth pointing out that this is a common graphical knob supported by
Cairo and CoreGraphics. It is a proprietary MS CSS property and an
SVG CSS property. In other words, it seems to be a pretty widely
implemented feature and as such seems like it would be a worthwhile
addition to canvas.
If we add this, we should also add support for text rendering quality
as well, since canvas is picking up the ability to draw text.