[whatwg] Some media element details

[Ian Hickson]

On Fri, 16 May 2008, James Justin Harrell wrote:
>
> The current HTMLMediaElement interface is inconsistent and is designed 
> in such a way that making changes to it will be extremely difficult.
> 
> The network state is given by the "networkState" attribute, and is one 
> of: EMPTY, LOADING, LOADED_METADATA, LOADED_FIRST_FRAME, LOADED
> 
> The ready state is given by the "readyState" attribute, and is one of: 
> DATA_UNAVAILABLE, CAN_SHOW_CURRENT_FRAME, CAN_PLAY, CAN_PLAY_THROUGH
> 
> Although adding states for either of these would not be fun, it could be 
> done. But the playback state is different.
> 
> The consistent and upgradeable design would be to have a "playbackState" 
> attribute that is one of: PAUSED, PLAYING
> 
> But because there are currently only two states, we instead have a 
> single boolean attribute. Boolean attributes are great when you're sure 
> there will always be only two states, but they're terrible if there's a 
> chance you'll want to add additional states.
> 
> It isn't difficult to imagine all kinds of additional playback states. 
> For example, what if there was great demand for forward-seeking and 
> backward-seeking states? (e.g. the states that are usually associated 
> with those >> and << buttons) How could those states be added?

This is already supported, and is independent of the pause state. (You 
could easily imagine a UI where you could pause while fast-forwarding.)


> The media error state is also inconsistent, and this time for no 
> apparent reason, although it would at least be easy to update. A more 
> consistent design would be to have an "errorState" attribute that is one 
> of: NO_ERROR, ABORTED, NETWORK_ERROR, DECODING_ERROR

We want to be able to include much more information, hence the use of an 
object for now.


> And why are the error state names prefixed with "MEDIA_ERR" when the 
> names for the other states are not prefixed? e.g. LOADING instead of 
> MEDIA_NET_LOADING.

The other state constants are prefixed (LOAD and CAN_ respectively) except 
for the zero state (which doesn't have a constant at all for errors).


On Fri, 16 May 2008, Maciej Stachowiak wrote:
> > 
> > But because there are currently only two states, we instead have a 
> > single boolean attribute. Boolean attributes are great when you're 
> > sure there will always be only two states, but they're terrible if 
> > there's a chance you'll want to add additional states.
> 
> I'm not sure adding states is all that safe. Any code that does a switch 
> on the state would now fall through to an untested code path.

Indeed, we're unlikely to ever add states, we're more likely to add 
orthogonal attributes.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
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