W3C home > Mailing lists > Public > www-svg@w3.org > September 2005

Re: [SVG] assigning to currentScale

From: Jonathan Watt <jonathan.watt@strath.ac.uk>
Date: Tue, 20 Sep 2005 04:33:32 +0100
Message-ID: <432F830C.3070409@strath.ac.uk>
To: www-svg@w3.org
CC: Jim Ley <jim@jibbering.com>

Jim Ley wrote:
> "Jonathan Watt" <jonathan.watt@strath.ac.uk> wrote in message 
> news:432EE5DF.3070408@strath.ac.uk...
> 
>>I hope this can all be sorted out in SVGMobile12, but note we'll also need 
>>an errata item for SVG 1.1 before the mess that is Firefox's 
>>scrolling/zooming and panning can be sorted out.
> 
> 
> I don't see what is actually broken in the spec, the spec doesn't place a 
> limit, placing a limit is something you're going to have to do for 
> implementation reasons, but that's not an actual spec problem, simply one in 
> your implementation.

This assumes that option 2 is unacceptable. Even given that (clamp 
instead of throw), the problem is people reading the spec. who don't 
realise a limit may be placed. A note in the errata and a sentance in 
mobile 1.2 indicating that authors should probably check the value of 
currentScale after assigning to it to make sure their value was accepted 
would be good.

> The SVG OM is pretty clear that setting the currentTranslate etc. properties 
> does not raise an error, therefore you shouldn't raise an error even if you 
> clamp the values, the only script errors raised when working with DOM should 
> be those in the specification, we cannot have scripters having to catch an 
> error when setting things which the specification doesn't say raises an 
> error, it leads to utterly unreadable scripts.
> 
> Option 1 of your original 3 options doesn't violate the specification (I see 
> nowhere that specifically states infinite zoom/pan, although it may make not 
> a high performance dynamic SVG UA) and is therefore completely reasonable. 
> Introducing new behaviour via errata may be popular in some Working Groups, 
> but I really hope the SVG WG doesn't go down that road, it's a very bad 
> idea.

Silently clamping is my prefered option too. I'm asking the WG to 
formally clarify that it is also their prefered option though.

-Jonathan
Received on Tuesday, 20 September 2005 03:33:28 GMT

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