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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

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

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

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

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

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

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

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

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

    20 system. Each Composition Implementation determines whether the surface is

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

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

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

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

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

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

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

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

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

    30 and unregisters surfaces: </p>

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

    32 <title>           Surface registration          </title>

    33 <image href="GUID-D729593E-C131-5F67-BF0C-6C9AD847C9F9_d0e328353_href.png" placement="inline"/>

    34 </fig>

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

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

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

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

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

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

    41 client-side API          </title>

    42 <image href="GUID-3C8FD050-1CD4-5AFB-ACB7-4264536BB300_d0e328376_href.png" placement="inline"/>

    43 </fig>

    44 </conbody><related-links>

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

    46 Component</linktext></link>

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

    48 Composition Collection</linktext></link>

    49 </related-links></concept>