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     4 "Eclipse Public License v1.0" which accompanies this distribution, 

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     7     Nokia Corporation - initial contribution.

     8 Contributors: 

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    10 <!DOCTYPE concept

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

    12 <concept id="GUID-A15C553D-9D64-5C48-9274-6DD1642CDC23" xml:lang="en"><title>Direct:

    13 Direct Screen Access example</title><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <section id="GUID-3CE6ED7C-72D8-5C99-8877-6FCB6C053D1D"><title>Description</title> <p> <filepath>Direct</filepath> demonstrates

    15 the window server's direct screen area (<codeph>CDirectScreenAccess</codeph>)

    16 interface. </p> <p>The example has an engine, <codeph>CLifeEngine</codeph>,

    17 for the famous "Game of Life" algorithm, which generates grids of cells, each

    18 update being derived by simple rules from the previous generation. The initial

    19 configuration of the cells is random. </p> <p>The UI simply has little user

    20 interaction. It simply draws the current grid using <codeph>CDirectScreenAccess</codeph>,

    21 and requests the engine to generate the next update. The UI classes are: </p> <ul>

    22 <li id="GUID-155FE7BA-3FC2-5C95-89C6-295CDB0C1B0E"><p> <codeph>CDirectDisplayLife</codeph>:

    23 the object that draws the grid through a <codeph>CDirectScreenAccess</codeph>,

    24 and which implements the API's <codeph>MDirectScreenAccess</codeph> callback

    25 interface, so that the window server can indicate when conditions (e.g. overlaying

    26 windows) change </p> </li>

    27 <li id="GUID-A01FC1E3-F76C-5892-A29D-7645263A5431"><p> <codeph>CExampleAppView</codeph>:

    28 the application's window, which owns the <codeph>CDirectDisplayLife</codeph> object </p> </li>

    29 <li id="GUID-8E45AD8C-642C-5DB9-8113-693BA4E0CA05"><p> <codeph>CExampleAppUi</codeph>:

    30 handles commands and calls the view appropriately </p> </li>

    31 </ul> </section>

    32 <section id="GUID-C81BD7D0-C899-5A8B-B704-91B81C3E0C1A"><title>Download</title><p>Click

    33 on the following link to download the example: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/zips/guid-51e33be2-ed3d-4412-8f0f-1535b86beb6f.zip" scope="external">Direct.zip</xref></p><p>Click: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/guid-51e33be2-ed3d-4412-8f0f-1535b86beb6f.html" scope="peer">browse</xref> to view the example code. </p> </section>

    34 <section><title>Class Summary</title><p><xref href="GUID-24C7AE25-B44A-3B6F-AA05-EA90A8D36129.dita"><apiname>CDirectScreenAccess</apiname></xref></p><p><xref href="GUID-5A289A8A-1485-3AB9-94CF-177B83D4F450.dita"><apiname>MDirectScreenAccess</apiname></xref></p><p><xref href="GUID-A6B66713-FECA-3BE7-BB81-1AE5551AD83D.dita"><apiname>RNotifier</apiname></xref></p></section>

    35 <section id="GUID-3B2CEB41-C76F-5C4A-82B8-05668190A5C6"><title>Usage</title> <p>Commands

    36 are given to the example through its Lifemenu. The commands are: </p> <ul>

    37 <li id="GUID-82639EB4-7E0A-5626-BC00-68E86A5E6188"><p> Start: starts or restarts

    38 the life display </p> </li>

    39 <li id="GUID-3BE84871-91A0-5230-96F8-F3565141CA43"><p> Test overlay: simulates

    40 a window from another program being placed partially over the display area.

    41 The display area is then clipped appropriately, so that the upper window is

    42 not overwritten </p> </li>

    43 </ul> </section>

    44 <section id="GUID-C1EE963E-9325-5DE2-A4A9-D327218A3C6E"><title>Note

    45 for developers</title> <p>While the DSA is in operation, the client should

    46 not make any call to the Window Server (WSERV) that will affect the visible

    47 area of the window in which the DSA is taking place. If this happens, it will

    48 cause a temporary deadlock (since the client will be waiting for WSERV to

    49 make the requested window rearrangement, and WSERV will be waiting for the

    50 client to acknowledge that the DSA has aborted). </p> </section>

    51 </conbody></concept>