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Re: [whatwg] Why does CanvasRenderingContext2D.drawImage not draw a video's poster?

From: Charles Pritchard <chuck@jumis.com>
Date: Wed, 25 Jul 2012 20:58:53 -0700
Message-Id: <0C4251AD-08C5-44B9-92D2-714A9F1F928B@jumis.com>
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Cc: "whatwg@lists.whatwg.org" <whatwg@lists.whatwg.org>, Mark Callow <callow_mark@hicorp.co.jp>
On Jul 21, 2012, at 1:20 PM, Silvia Pfeiffer <silviapfeiffer1@gmail.com> wrote:

>> I'm not opposed to the idea, but I'm failing to see the benefit.
> The advantage clearly is that if you have a canvas that is copying
> data out of the video, it includes the poster without having to write
> custom code for it. The poster is an integral part of the video (it's
> not distinguishable by the user whether it is a separate picture or a
> frame from the video), so I don't see why it should need custom
> handling.

Canvas is a lot of low level custom code. As a polyfill, it seems that Canvas coders ought to consider checking for a poster attribute in their code path regardless of how this goes.

>> Still, if
>> there's going to be one, we're going to need an onposterloaded event.
> Why? onmetadataloaded provides a sufficiently stable stuation: either
> the poster img or video frame is then loaded (if @preload is not
> "none") or it's black (if @poster is not set and @preload is "none").

Seems like a good place to spec this. +1.

I'm not up to speed on the video spec, but if this behavior for poster is not in there, consider proposing it to the editor(s).

Received on Thursday, 26 July 2012 03:59:25 UTC

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