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Re: Resource priorities and SVG

From: Satoru Takagi <sa-takagi@kddi.com>
Date: Wed, 6 Nov 2013 15:03:19 +0900
To: dschulze@adobe.com, www-svg@w3.org
Cc: plh@w3.org
Message-Id: <201311061503.IDC90651.JTtLHBBBU@kddi.com>
Hi,
Thank you for comment.

>Something that would fulfill your requirements is the case of having multiple images in your 
document and many of them would not be within the currently visible area. These images would 
not be loaded until they get visible (by scrolling or panning).

Yes, for the use case of tiling, I expect this. It will become the following example.

 <?xml version="1.0" encoding="UTF-8"?>
 <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"
  width="50" height="50" viewBox="70,0,50,50">
   <image xlink:href="tile0-0.svg" x="0"   y="0"   width="100" height="100" postpone="true" />
   <image xlink:href="tile1-0.svg" x="100" y="0"   width="100" height="100" postpone="true" />
   <image xlink:href="tile2-0.svg" x="200" y="0"   width="100" height="100" postpone="true" />
   <image xlink:href="tile0-1.svg" x="0"   y="100" width="100" height="100" postpone="true" />
   <image xlink:href="tile1-1.svg" x="100" y="100" width="100" height="100" postpone="true" />
   <image xlink:href="tile2-1.svg" x="200" y="100" width="100" height="100" postpone="true" />
   <image xlink:href="tile0-2.svg" x="0"   y="200" width="100" height="100" postpone="true" />
   <image xlink:href="tile1-2.svg" x="100" y="200" width="100" height="100" postpone="true" />
   <image xlink:href="tile2-2.svg" x="200" y="200" width="100" height="100" postpone="true" />
 </svg>

In this example, tile0-0.svg and tile1-0.svg should be loaded. And other tile?-?.svg shoud not 
be loaded basically. If viewBox is changed to "70,70,50,50", then tile0-1.svg and tile1-1.svg 
should be loaded.

>In your proposal (if I understand it correctly), you suggest loading a part of one image 
resource. 
Therefore, I do not expect such a function.



On the other hand, the thing that I point out possibility about 'clip' with 'postpone' is the 
following.

 <?xml version="1.0" encoding="UTF-8"?>
 <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"
  width="100" height="100" viewBox="0,0,100,100">
   <image xlink:href="child.svg" x="0" y="0" width="500" height="500" postpone="true" clip="
rect(200,200,100,100)" />
 </svg>

With this example, child.svg is invisible in viewport by 'clip' attribute. Accordingly, there 
are cases that child.svg should not be loaded. When 'clip-path' is used in substitution for '
clip', it will be similar requirement. Though clip and clip-path do not change bounding box.


>(Note that 'clip' is not supported on  image elements though.) This is NOT part of the 
proposal from Resource Priorities.
When 'image' refers to SVG, I think 'clip' to be effective. 
>http://www.w3.org/TR/SVG/masking.html#OverflowAndClipProperties
>‘clip’Applies to:   elements which establish a new viewport, ....
And it is implemented in Firefox.


Regards,

Satoru Takagi


> 
> On Nov 1, 2013, at 7:54 AM, Satoru Takagi <sa-takagi@kddi.com> wrote:
> 
> > Hi,
> > Since I am participating in draft editing of the Embedded Content chapter*1
> > for SVG2.0, I am also doing examination*2 regarding Resource Priorities. 
> 
> In your proposal (if I understand it correctly), you suggest loading a part of one image 
resource. (Note that 祖lip' is not supported on  image elements though.) This is NOT part of 
the proposal from Resource Priorities.
> 
> Something that would fulfill your requirements is the case of having multiple images in your 
document and many of them would not be within the currently visible area. These images would 
not be loaded until they get visible (by scrolling or panning).
> 
> Hope that helps.
> 
> Greetings,
> Dirk
> 
> 
> > 
> > Although I have proposed it as an agenda of SVG WG F2F in TPAC*3, there
> > may be the way of the more suitable discussion with the consideration of a
> > relation with Web PerfWG.
> > 
> > [1] http://www.w3.org/Graphics/SVG/WG/wiki/Proposals/Embedded_Content
> > 
> > [2] http://www.w3.org/Graphics/SVG/WG/wiki/Proposals/ResourcePriorities_for_SVG
> > 
> > [3] http://www.w3.org/Graphics/SVG/WG/wiki/F2F/TPAC_2013/Agenda_proposals
> > 
> > Regards,
> > 
> > Satoru Takagi
> > 
> >> FYI,
> >> 
> >> the Web performance working group published a first draft of Resource
> >> Priorities. It allows the authors to give the user agent hints on the
> >> download priority of a resource.
> >> 
> >> Since SVG links to resources, the idea is to apply two content
> >> attributes to a few SVG elements:
> >>  http://www.w3.org/TR/2013/WD-resource-priorities-20131029/
> >> 
> >> Feedback is welcome of course and the Web Perf group will be at TPAC in
> >> case more discussion is needed.
> >> 
> >> Philippe
> >> 
> >> 
> > 
> 
> 
Received on Wednesday, 6 November 2013 06:04:11 UTC

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