[whatwg] Deferring image load

[Ola P. Kleiven]

On Mon, 13 Feb 2012 12:11:21 +0100, Charles McCathieNevile  
<chaals at opera.com> wrote:

> On Mon, 13 Feb 2012 12:00:52 +0100, Kang-Hao (Kenny) Lu  
> <kennyluck at csail.mit.edu> wrote:
>
>> (12/02/13 18:33), Bjartur Thorlacius wrote:
>>> On 2/13/12, Gray Zhang <otakustay at gmail.com> wrote:
>
>>>>    2. On an album page where hundreds of pictures are expected to be  
>>>> shown,
>>>>    it is often required that pictures currently in a user's screen  
>>>> should
>>>>    appear as fast as possible. Loading of a picture outside the  
>>>> screen can
>>>> be
>>>>    deferred to the time that the picture enters or is about to enter  
>>>> the
>>>>    screen, for the purpose of optimization user experience.
>>> This seems like something interactive user agents should implement.
>>
>> But it is currently not reliable to the extent that Web authors can rely
>> on it. The current spec for <img>[1] says
>>
>>   # User agents may obtain images immediately or on demand.
>>
>> Is there actually an existing user agent that obtain images on demand?
>
> Opera.

Depends which product. Even Opera on desktop would previously try to be  
clever about what to load and not, however this caused much headache as  
authors expected all sorts of events and intrinsic dimensions just as if  
the resources were loaded and visible. For compat reasons Opera now is in  
line with other user agents. For compatibility it is better to have such  
mechanisms specced.




-- 
Ola P. Kleiven, Core Compatibility, Opera Software