<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

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

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE concept

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

<concept id="GUID-E238B1FE-BBD8-5C6D-AE04-258188EFF9FF" xml:lang="en"><title>Creating

a Graphics Surface Tutorial</title><shortdesc>This tutorial first shows you how to create a composition surface

using the Surface Manager API. It then shows you how to create second surface

that shares the same memory. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p> <b>Variant</b>: <xref href="GUID-D93978BE-11A3-5CE3-B110-1DEAA5AD566C.dita">ScreenPlay</xref>. <b>Target

audience</b>: Device creators. </p>

<section id="GUID-B29CBC23-1A7A-5848-ACE1-65EFE25293DB"><title>Required background</title> <p>This

tutorial assumes a background knowledge of the following: </p> <ul>

<li id="GUID-5FC40F07-18E3-520D-9336-4C8D7D1D9F2C"><p><xref href="GUID-0DC3E5AA-1706-5255-ACD6-E7AB732E1095.dita">Graphics

Composition Collection Overview</xref>  </p> </li>

<li id="GUID-6688632B-48E1-5357-9451-C46487026585"><p><xref href="GUID-ADA8CECB-0E70-5B9C-8F36-0714AAF0CD13.dita">Graphics

Composition Surfaces</xref>  </p> </li>

<li id="GUID-86252B83-1503-588F-ACBC-2924D73F9729"><p><xref href="GUID-55EF3CEB-AF3E-5A32-96F3-F146D1A06C8F.dita">Surface

Manager</xref>  </p> </li>

<li id="GUID-8C7E9588-DF1B-56A2-8CAD-059F70C5DB9C"><p><xref href="GUID-81A0A2E9-4BB9-58BF-B2D3-08098E7E9C7C.dita">Surface

Update Server</xref>  </p> </li>

</ul> </section>

<section id="GUID-7ADE65B1-3DF6-5224-B783-382DC8448059"><title>Introduction</title> <p>This

topic shows you how to create one graphics surface and then another one that

shares the same memory. Because the screen is either in portrait or landscape

orientation, this approach is useful for handling two surfaces, one of which

is used for the portrait orientation and the other for the landscape orientation. </p> <p>For

example, suppose <i>Surface 1</i> is used for landscape orientation and <i>Surface

2</i> for portrait orientation. When a rotation is in progress from landscape

to portrait: </p> <ul>

<li id="GUID-B32ACAAE-91CC-5DB8-863F-224C5A5AAA06"><p>The first buffer in <i>Surface

1</i> is in use as an input to the composition engine. </p> </li>

<li id="GUID-AC1BA893-C782-5B02-B21B-83186B86B0A7"><p>The renderer renders

into the second buffer in <i>Surface 2</i>. </p> </li>

</ul> <p>Because both surfaces share the same memory, the buffers in the two

orientations must be at the same offsets in the chunk. This is shown in the

following diagram. </p> <fig id="GUID-552B25FF-A930-5F5B-9379-89F77AB0BE17">

<title>              Two double-buffered surfaces that share the same memory

           </title>

<image href="GUID-EFFEB18E-5BF5-5855-9D1F-E7C39CB569D0_d0e253301_href.png" placement="inline"/>

</fig> <p>In the example code below, some error handling has been omitted

for brevity. </p> </section>

<section><title>Creating the first surface</title> <ol id="GUID-90E6761F-7BE0-528C-ABC2-AEBCE4A8A120">

<li id="GUID-EB97C422-189F-51D0-AF56-5803C3AECB1E"><p>Call <xref href="GUID-733B8BFA-7BC2-3A6D-A66F-F788413D25A9.dita"><apiname>RSurfaceManager::Open()</apiname></xref> to

open a connection to the Surface Manager. </p> <p><codeblock id="GUID-89837128-5647-56CD-8C1B-2FF142DAFE46" xml:space="preserve">RSurfaceManager surfaceManager;

surfaceManager.Open();</codeblock> </p> <p>The Surface Manager is now ready

for use. </p> </li>

<li id="GUID-8B6DA00E-12F1-520B-9DC9-1AFC72EF4443"><p>Specify the surface

creation attributes using the <xref href="GUID-733B8BFA-7BC2-3A6D-A66F-F788413D25A9.dita"><apiname>TSurfaceCreationAttributes</apiname></xref> class. </p> <p><codeblock id="GUID-2B4FF1D8-69CB-5DA3-9A14-1A8B17DE85B5" xml:space="preserve">RSurfaceManager::TSurfaceCreationAttributesBuf bf;

RSurfaceManager::TSurfaceCreationAttributes& attributes = bf();

attributes.iSize.iWidth = 320;

attributes.iSize.iHeight = 240;

attributes.iBuffers = 2;

attributes.iPixelFormat = EUidPixelFormatARGB_4444;    

attributes.iStride = 640;

attributes.iOffsetToFirstBuffer = 100;

attributes.iAlignment = 4;

attributes.iContiguous = EFalse;

attributes.iCacheAttrib = TCacheAttribute::ECached; 

// Create two user-defined hints.

RSurfaceManager::THintPair hints[2];

hints[0].Set(0x124578, 25, ETrue);

hints[1].Set(0x237755, 50, ETrue);

attributes.iHints = hints;

attributes.iHintCount = 2;</codeblock> </p> </li>

<li id="GUID-BC9CCB88-C7FE-54D8-83B6-957D274CBC9F"><p>Call <xref href="GUID-733B8BFA-7BC2-3A6D-A66F-F788413D25A9.dita"><apiname>RSurfaceManager::CreateSurface(const

                TSurfaceCreationAttributesBuf&amp;, TSurfaceId&amp;)</apiname></xref> to

create the first surface. </p> <p>This function takes the surface creation

attributes as input and returns the new surface ID. </p> <p><codeblock id="GUID-9B155DBD-C343-5103-B2A3-CE6DB30CA020" xml:space="preserve">TSurfaceId surfaceId;

TInt err = surfaceManager.CreateSurface(bf, surfaceId);</codeblock> </p> </li>

<li id="GUID-5C36F371-D0D4-52ED-87D8-B87B9FE7C947"><p>Call <xref href="GUID-733B8BFA-7BC2-3A6D-A66F-F788413D25A9.dita"><apiname>RSurfaceManager::MapSurface(const

TSurfaceId&amp;,                 RChunk&amp;)</apiname></xref> to map the surface. </p> <p>This

function takes the surface ID as input and returns a handle to the shared

chunk. </p> <p><codeblock id="GUID-C0058D19-355B-5A16-B6A2-602DD35C90D1" xml:space="preserve">if (err == KErrNone)

    {

    // We have a surface, so map it in.

    RChunk chunk;

    err = surfaceManager.MapSurface(surfaceId, chunk);

    if ( err == KErrNone)

        { 

        // Get info about it

        RSurfaceManager::TInfoBuf buf;

        RSurfaceManager::TSurfaceInfoV01& surfaceInfo = buf(); 

        surfaceManager.SurfaceInfo(surfaceId, buf); 

        }</codeblock> </p> </li>

</ol> </section>

<section><title>Creating the second surface</title> <p>An overload of <xref href="GUID-733B8BFA-7BC2-3A6D-A66F-F788413D25A9.dita"><apiname>RSurfaceManager::CreateSurface()</apiname></xref> allows

you to supply a shared chunk as an input parameter. The shared chunk must

be successfully allocated by the calling code before it is passed in to the

surface creation API. We will use the shared chunk returned in the last step. </p> <ol id="GUID-9E4CE367-00ED-5F39-829C-BF3B5CD8446C">

<li id="GUID-6144B775-CFB1-5CFF-9AF4-AC7AA823D375"><p>Specify the surface

creation attributes in a <xref href="GUID-733B8BFA-7BC2-3A6D-A66F-F788413D25A9.dita"><apiname>TSurfaceCreationAttributes</apiname></xref> class. </p> <codeblock id="GUID-EF7EFC61-9AE9-53C9-93DA-2E7E259DA4B2" xml:space="preserve">// We have a surface, so create an another surface with a different             

// orientation.

RSurfaceManager::TSurfaceCreationAttributesBuf bf2;

attributes = bf2();

// Initialize the surface creation attributes.  

attributes.iSize.iWidth  = 240; // Change the orientation .

attributes.iSize.iHeight = 320;   

attributes.iBuffers = 2;

attributes.iPixelFormat = EUidPixelFormatARGB_4444;    

attributes.iStride = 480;    // Width has changed to 240.

// Read the offset to the first buffer from the first surface.

TInt offset;

surfaceManager.GetBufferOffset(surfaceId, 0, offset); 

attributes.iOffsetToFirstBuffer = offset;

// iCacheAttribute and iContiguous are not used for already existing

// chunks.</codeblock> </li>

<li id="GUID-868F20E1-9A6A-52F7-8979-15793E634659"><p>Call <xref href="GUID-733B8BFA-7BC2-3A6D-A66F-F788413D25A9.dita"><apiname>RSurfaceManager::CreateSurface(const

                TSurfaceCreationAttributesBuf&, TSurfaceId&, const

                RChunk&amp;)</apiname></xref> to create a surface in the specified

shared chunk. This overload takes the surface creation attributes and the

handle of the existing chunk (returned in step 4 above) as inputs and returns

the new surface ID. </p> <codeblock id="GUID-DC3C332D-CBD0-5804-8A44-66545A1558AF" xml:space="preserve">TSurfaceId surfaceId1;

err = surfaceManager.CreateSurface(bf2, surfaceId1, chunk);    

if (err == KErrNone)

    {

    // Surface created successfully.

    }</codeblock> </li>

</ol> </section>

</conbody><related-links>

<link href="GUID-55EF3CEB-AF3E-5A32-96F3-F146D1A06C8F.dita"><linktext>Surface Manager

Overview</linktext></link>

<link href="GUID-ADA8CECB-0E70-5B9C-8F36-0714AAF0CD13.dita"><linktext>Graphics

Surfaces</linktext></link>

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

Composition Collection</linktext></link>

</related-links></concept>