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<concept id="GUID-E56EB25C-9B94-5486-9492-5151FDF79B6C" xml:lang="en"><title>Global

Surface Updates</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>Global surface updates are surface updates that are submitted to all displays

rather than just one display. By using global surface updates, the Video Renderer

can update surfaces on all displays including ones that it is not aware of.

When the Video Renderer sends a global surface update, the update is broadcast

by the Graphics <xref href="GUID-81A0A2E9-4BB9-58BF-B2D3-08098E7E9C7C.dita">Surface

Update</xref> component to all Composition Implementations present in the

system. Each Composition Implementation determines whether the surface is

displayed on its associated screen and if so, forces an update. For more information,

see <xref href="GUID-D2ECF215-B53C-5659-BA86-5B658C0C2D2F.dita">Global Surface

Updates</xref> in the Graphics Guide. </p>

<p>The Video Renderer registers and unregisters surfaces with the Window Server

for all available displays. When the client calls <xref href="GUID-AFEC8287-41C9-36BB-B0F7-ECC034D34DC6.dita"><apiname>CVideoRenderer::CreateSurfaceL()</apiname></xref>,

the Video Renderer creates the surface and then registers it with each display.

When the client calls <xref href="GUID-AFEC8287-41C9-36BB-B0F7-ECC034D34DC6.dita"><apiname>CVideoRenderer::DestroySurfaceL()</apiname></xref>,

the Video Renderer unregisters the surface with each display and then destroys

it. The following sequence diagram shows how the Video Renderer registers

and unregisters surfaces: </p>

<fig id="GUID-B9190405-76E6-557D-A1F7-03ADDB8E456D">

<title>           Surface registration          </title>

<image href="GUID-D729593E-C131-5F67-BF0C-6C9AD847C9F9_d0e328666_href.png" placement="inline"/>

</fig>

<p>The Video Renderer uses the global constant <codeph>KAllScreens</codeph> (provided

by the Surface Update component) to ensure all displays are updated with new

data. The following sequence diagram shows the Video Renderer passing <codeph>KAllScreens</codeph> in

the call to <xref href="GUID-AFEC8287-41C9-36BB-B0F7-ECC034D34DC6.dita"><apiname>RSurfaceUpdateSession::SubmitUpdate()</apiname></xref>: </p>

<fig id="GUID-4CA7A049-1B60-5CB5-956A-DDDFF0A5E3B1">

<title>           Data flow between client, Video Renderer and Surface Update

client-side API          </title>

<image href="GUID-3C8FD050-1CD4-5AFB-ACB7-4264536BB300_d0e328689_href.png" placement="inline"/>

</fig>

</conbody><related-links>

<link href="GUID-98FBEA7E-78BA-5A64-90D6-4641418003B4.dita"><linktext>Video Renderer

Component</linktext></link>

<link href="GUID-63CB6C7E-44EC-5D0B-A37D-FE78F7D76592.dita"><linktext>Graphics

Composition Collection</linktext></link>

</related-links></concept>