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[csswg-drafts] Provide a way to specify rastered content scale for transformed content

From: chrishtr via GitHub <sysbot+gh@w3.org>
Date: Fri, 24 Jun 2016 15:46:00 +0000
To: public-css-archive@w3.org
Message-ID: <issues.opened-162175217-1466783160-sysbot+gh@w3.org>
chrishtr has just created a new issue for 
https://github.com/w3c/csswg-drafts:

== Provide a way to specify rastered content scale for transformed 
content ==
[css-transforms]

Currently, developers have no control over the scale at which to 
raster content with transforms. If the transform is not 
compositor-animated, there is only one logical answer (layout content 
scale plus transform). However, for performance reasons, compositor 
animations often work by scaling a pre-rastered bitmap in the GPU. 
This begs the question of the scale at which to raster that bitmap.

Each browser has its own heuristics for choosing the scale of these 
bitmaps, and when to re-raster them
when the scale changes. This is a problem when the heuristics fail, 
because the developer has no control
over details of performance and quality that are important for a 
high-quality rendered output.

Blink has recently done work to improve this situation. Some documents
 on what we're doing and background:

What we're doing: 
https://docs.google.com/a/chromium.org/document/d/1f8WS99F9GORWP_m74l_JfsTHgCrHkbEorHYu72D4Xag/edit?usp=drive_web&usp=docs_home&ths=true

Investigation of situation before the above and alternatives 
considered:
https://docs.google.com/document/d/1CsDfsMxZaM094VhTDrHXF86_rmFnpjM8xL3iEh7HWgg/edit#heading=h.omyv4h6h0sym

One thing that the above plans do not  cover is control over 
current-frame raster scale, if the desired such scale differs from the
 "ideal" scale (meaning layout scale + transform). There are cases 
where this is desired, for example rastering at a destination scale 
then animating to it, to maximize quality and performance. (Note that 
this is how Blink actually implements declarative CSS animation 
rastering today)
See also this blink-dev thread for examples and related discussion:
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/Ufwrhx_iZ7U


Please view or discuss this issue at 
https://github.com/w3c/csswg-drafts/issues/236 using your GitHub 
account
Received on Friday, 24 June 2016 15:46:03 UTC

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