I don’t think this belongs in WebKit — it is not a feature post browsers need. You could easily implement this niche feature using <object> that hooks in your own native code. An object gets told when it resizes without the need for JavaScript events.
— Timothy Hatcher > On Sep 18, 2014, at 9:22 AM, Julien Isorce <[email protected]> wrote: > > Hi, > > A typical scenario when running WebKit in an embedded environment like a TV > or STB is to "punch through" graphics to the video plane. > > At Samsung Research UK we have developed a new <hole> element that acts much > like a <canvas> to > > - Expose a rectangular "hole" in a web page. > - Support a mechanism to retrieve the position and size of the hole from > JavaScript whenever its dimensions or location change. > > We realise that there is currently no W3 specification for this element, but > since our solution works we wanted to open the discussion to see if there is > any wider interest, and if there is, to start the process of drafting a > specification. Some details: > > - Principle: > > A hole is a rectangular area that behaves pretty much like a canvas, but > everything in its area is transparent. > Every layer behind the hole is transparent in this rectangle. > In JavaScript you can register a handler which is notified when the hole > position or size changes. > > - Use case: > > On TV this is useful to see the channel displayed behind the browser. > Retrieving the hole's position and size > from JavaScript allows to rescale the TV channel plane to match the hole area > whenever the hole changes. > Assume in JavaScript we have an object to control the TV channel plane. > This use case applies in many interactive TV applications, so it could be > useful for a lot of people. > > - Interfaces: > > We have defined a new tag <hole> which is similar to the <canvas> tag. > We have defined a "geometrychanged" JS event which is sent when the hole > dimensions change. > This event contains the hole width, height and position in screen coordinates. > > - Hole in canvas: > > A hole tag has been defined to be less intrusive and having the feature in > separate places in the code. > But we now think it may be better to actually put the "hole" capabilities > under the canvas. > For example <canvas style="background:hole;"> > > Note that setting it as transparent is not enough to have a hole as the > layers behind the canvas won't be necessarily transparent, and not only in > its area. > The whole point of the hole capability is to make transparent every layers > behind the hole and only in a specific rectangle. > > - Next steps: > > I would be very interested to hear if there are any other developers who need > this functionality. If so, let's discuss the best way to share it, or > possibly do it a better way. > > Comments are welcome. > > Julien > > _______________________________________________ > webkit-dev mailing list > [email protected] > https://lists.webkit.org/mailman/listinfo/webkit-dev _______________________________________________ webkit-dev mailing list [email protected] https://lists.webkit.org/mailman/listinfo/webkit-dev
