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Rendering order of region backgrounds

From: Michael Foster <foster@PacketVideo.COM>
Date: Fri, 30 May 2003 16:51:35 -0700
Message-ID: <72263E8E8622D611975C0002B32C19D84A365E@MISTY>
To: "'www-smil@w3.org'" <www-smil@w3.org>

> Hi everyone,
> 
> I have a couple of questions about the rendering order of region
> backgrounds. I have searched the newsgroup archives and SMIL spec, but
> can't find any discussion of these issues.
> 
> Here is the first question. In the following SMIL file, all regions have
> the same z-index. Two media elements share the same region ('full'). At
> t=8s, according to the z-index processing described in the spec, 'img1'
> will be rendered first, followed by 'img2' and then 'img3'. The question
> is when will the background of region 'full' be rendered? Will it be
> rendered before rendering 'img1' and then again before rendering 'img3'?
> If so, no portion of 'img1' would be visible if 'img3' were smaller than
> 'img1'. Or will it be rendered only once before either 'img1' or 'img3' is
> rendered? If it were only rendered before 'img1', then 'img3' could be
> rendered on top of 'img2' without its background.
> ......................................
> <smil>
>     <head>
>         <layout>
>             <root-layout width="100" height="100" z-index="1"
> background-color="#000000" />
>             <region id="full" top="0%" left="0%" width="100%"
> height="100%" z-index="1" background-color="#0000FF" />
>             <region id="top_right" top="0%" left="50%" width="50%"
> height="50%" z-index="1" background-color="#FF0000" />
>         </layout>
>     </head>
>     <body>
>         <par dur="10s">
>             <img id="img1" begin="0s" region="full" type="image/gif"
> src="img1.gif" />
>             <img id="img2" begin="4s" region="top_right" type="image/gif"
> src="img2.gif" />
>             <img id="img3" begin="6s" region="full" type="image/gif"
> src="img3.gif" />
>         </par>
>     </body>
> </smil>
> ......................................
> 
> 
> Here is the second question. In the following SMIL file, all regions have
> the same z-index. Region 'top_right' does not have any media elements
> associated with it, however since the default value of the showBackground
> attribute is always, this region background will be rendered. At t=6s,
> according to the z-index processing described in the spec, 'img1' will be
> rendered first, followed by 'img2'. The question is when will the
> background of region 'top_right' be rendered? The z-index processing
> described in the spec cannot be used to determine the rendering order for
> this region background because there is no media element associated with
> it. 
> ......................................
> <smil>
>     <head>
>         <layout>
>             <root-layout width="100" height="100" z-index="1"
> background-color="#000000" />
>             <region id="full" top="0%" left="0%" width="100%"
> height="100%" z-index="1" background-color="#0000FF" />
>             <region id="top_right" top="0%" left="50%" width="50%"
> height="50%" z-index="1" background-color="#FF0000" />
>         </layout>
>     </head>
>     <body>
>         <par dur="10s">
>             <img id="img1" begin="0s" region="full" type="image/gif"
> src="img1.gif" />
>             <img id="img2" begin="4s" region="full" type="image/gif"
> src="img2.gif" />
>         </par>
>     </body>
> </smil>
> ......................................
> 
> 
> Thanks for any help you can provide
> 
> 
> Mike
> 
> _________________________________________________
> Michael Foster  *  PacketVideo  *  (858) 731-5543
> Senior Member of Technical Staff
> foster@pv.com  *  www.packetvideo.com   
> 
> 
Received on Friday, 30 May 2003 19:51:58 GMT

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