Re: Intent to ship: CSS Variables
On 03/18/2014 11:26 AM, Cameron McCormack wrote: CSS Variables is a feature that allows authors to define custom properties that cascade and inherit in the same way that regular properties do, and to reference the values of these custom properties in the values of regular properties (and other custom properties too). http://dev.w3.org/csswg/css-variables/ I blogged about the feature when it initially landed here: http://mcc.id.au/blog/2013/12/variables It lives behind the layout.css.variables.enabled pref, which is currently enabled by default only on Aurora/Nightly. One thing from the specification that we don't implement is the CSSVariableMap, but Tab tells me that this is going to be removed from the spec. I intend to enable this feature by default this Friday (March 21). That would target Firefox 31. The spec has been stable for a while, and the CSS Working Group already has a resolution to publish the document as a Candidate Recommendation. There has been a last minute proposal for a change to the syntax of custom property declarations, to align with other custom features in CSS that are coming down the pipeline (such as custom media queries). There are a couple of proposals on the table: to replace the var- prefix of the name of the custom property with a _ prefix, or perhaps just anywhere within the name. Similarly for -- rather than _. Tab wants to discuss this in this week's CSS Working Group telcon, so if the decision is made quickly enough we can update our implementation. The CSS Working Group is aware of our plans to ship. Bug to enable this feature: https://bugzilla.mozilla.org/show_bug.cgi?id=957833 Blink until recently had an implementation of CSS Variables, behind a flag, but not one that supported the fallback syntax (or CSSVariableMap). They have recently removed it saying that they need to rewrite as it had poor performance, but they say they are still interested in the feature Curious, how much have we tested the performance of our implementation and are there some known perf issues? -Olli ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
Re: Intent to ship: CSS Variables
smaug wrote:
Curious, how much have we tested the performance of our implementation
and are there some known perf issues?
I have not tested. The only extra work we should be doing at the moment
when variables aren't used in the style sheet is
nsRuleNode::ResolveVariableReferences. That iterates over all of the
properties we are computing for a given frame and checks to see if they
are a token stream, and if so, reparses them.
If this is a problem we could easily record on the
nsCSS{Compressed,Expanded}DataBlock object during the initial parsing
whether a property with a variable reference on the right hand side was
encountered, and copy that over when we map the properties into the
nsRuleData. Then we could skip the ResolveVariableReferences call if we
knew we didn't find any properties with variable references.
When variables are used, we do end up having to parse a
variable-reference-using property value twice (once to ensure that
variable references are syntactically valid and to record which
variables are referenced, and another time after expanding out the
variable references), but that is basically what is required by the spec.
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Intent to ship: CSS Variables
CSS Variables is a feature that allows authors to define custom properties that cascade and inherit in the same way that regular properties do, and to reference the values of these custom properties in the values of regular properties (and other custom properties too). http://dev.w3.org/csswg/css-variables/ I blogged about the feature when it initially landed here: http://mcc.id.au/blog/2013/12/variables It lives behind the layout.css.variables.enabled pref, which is currently enabled by default only on Aurora/Nightly. One thing from the specification that we don't implement is the CSSVariableMap, but Tab tells me that this is going to be removed from the spec. I intend to enable this feature by default this Friday (March 21). That would target Firefox 31. The spec has been stable for a while, and the CSS Working Group already has a resolution to publish the document as a Candidate Recommendation. There has been a last minute proposal for a change to the syntax of custom property declarations, to align with other custom features in CSS that are coming down the pipeline (such as custom media queries). There are a couple of proposals on the table: to replace the var- prefix of the name of the custom property with a _ prefix, or perhaps just anywhere within the name. Similarly for -- rather than _. Tab wants to discuss this in this week's CSS Working Group telcon, so if the decision is made quickly enough we can update our implementation. The CSS Working Group is aware of our plans to ship. Bug to enable this feature: https://bugzilla.mozilla.org/show_bug.cgi?id=957833 Blink until recently had an implementation of CSS Variables, behind a flag, but not one that supported the fallback syntax (or CSSVariableMap). They have recently removed it saying that they need to rewrite as it had poor performance, but they say they are still interested in the feature. ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
Re: Intent to ship: CSS Variables
On 2014-03-18, 5:26 AM, Cameron McCormack wrote: CSS Variables is a feature that allows authors to define custom properties that cascade and inherit in the same way that regular properties do, and to reference the values of these custom properties in the values of regular properties (and other custom properties too). http://dev.w3.org/csswg/css-variables/ I blogged about the feature when it initially landed here: http://mcc.id.au/blog/2013/12/variables Yay! I'm really excited about this. This feature is extremely useful to web developers and AFAIK they have been asking for it for quite a while! It lives behind the layout.css.variables.enabled pref, which is currently enabled by default only on Aurora/Nightly. One thing from the specification that we don't implement is the CSSVariableMap, but Tab tells me that this is going to be removed from the spec. I intend to enable this feature by default this Friday (March 21). That would target Firefox 31. The spec has been stable for a while, and the CSS Working Group already has a resolution to publish the document as a Candidate Recommendation. There has been a last minute proposal for a change to the syntax of custom property declarations, to align with other custom features in CSS that are coming down the pipeline (such as custom media queries). There are a couple of proposals on the table: to replace the var- prefix of the name of the custom property with a _ prefix, or perhaps just anywhere within the name. Similarly for -- rather than _. Tab wants to discuss this in this week's CSS Working Group telcon, so if the decision is made quickly enough we can update our implementation. The CSS Working Group is aware of our plans to ship. It's great that you mentioned this concern. It seems like this is something that we can address soon depending on the decision of the WG, so I don't think this is a blocker to proceeding (we seem to have enough time for pulling the brakes if the WG does not come to a decision in time for any reason.) Bug to enable this feature: https://bugzilla.mozilla.org/show_bug.cgi?id=957833 Blink until recently had an implementation of CSS Variables, behind a flag, but not one that supported the fallback syntax (or CSSVariableMap). They have recently removed it saying that they need to rewrite as it had poor performance, but they say they are still interested in the feature. Yes, I followed that discussion. It's unfortunate that Blink was not in a good position to ship this soon, but it seems like they are working on it, so I think it makes sense for us to ship this API at this point. Cheers, Ehsan ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
