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

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

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

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

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

     6 <!-- Initial Contributors:

     7     Nokia Corporation - initial contribution.

     8 Contributors: 

     9 -->

    10 <!DOCTYPE concept

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

    12 <concept id="GUID-22E46647-D677-5A47-A7E0-E1E0AE736B27" xml:lang="en"><title>DirectGDI

    13 Adaptation Overview</title><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <p>The DirectGDI Adaptation component, together with the DirectGDI Interface

    15 component, forms the DirectGDI adaptation layer. The DirectGDI Interface component

    16 defines the interfaces that the adaptations must implement and the DirectGDI

    17 Adaptation component consists of the two DirectGDI implementations that are

    18 provided in the Graphics package. </p>

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

    20 <note type="note">DirectGDI is deprecated in Symbian^3.</note>

    21 <p>The <xref href="GUID-A2E07A3C-B3A8-50B9-BD60-F1F01795FA24.dita">DirectGDI component</xref> provides

    22 a framework that enables graphics hardware acceleration and interleaved rendering.

    23 This framework provides an API for client applications and a Hardware Adaptation

    24 Interface (HAI), which defines interfaces that must be implemented by device

    25 and hardware manufacturers in order to provide the API functionality. The

    26 framework has a dependency on the <xref href="GUID-82B0B4B9-6BC2-5BEF-B3B0-D57AC57F8D8A.dita">Graphics

    27 Resource Component</xref>. </p>

    28 <p>The Graphics package includes two DirectGDI adaptations: </p>

    29 <ul>

    30 <li id="GUID-B0C72AE2-2A06-59AD-98AA-BCE881ECD460"><p>A purely software adaptation

    31 that uses existing components to draw to the screen in a similar manner to

    32 BitGDI. This is suitable for use in phones that do not include graphics acceleration

    33 hardware. </p> </li>

    34 <li id="GUID-FB34D088-0046-5A1B-9C23-39D11C448ECD"><p>A hardware adaptation

    35 that uses OpenVG and EGL APIs on the H4 platform. This is provided for reference

    36 purposes and there is no requirement that the implementation use OpenVG. Hardware

    37 manufacturers can in fact use any third-party rendering system that is suitable

    38 for use with the target hardware. </p> </li>

    39 </ul>

    40 <p>The following diagram shows the generic DirectGDI API and implementation,

    41 with one software and two hardware implementations. Although shown on the

    42 same diagram, in fact only one implementation can exist on the same phone.

    43 A configuration at ROM build time decides which implementation is used. </p>

    44 <fig id="GUID-E4CD5B76-03E0-5F4C-8C65-C2F2B52969F5">

    45 <title>           DirectGDI architecture          </title>

    46 <image href="GUID-912643B5-0B8D-5836-B864-9A2DBAC86B00_d0e240364_href.png" placement="inline"/>

    47 </fig>

    48 <p>Notice that all three of the implementations implement the common <xref href="GUID-97E3E8DD-A2DA-3961-96E3-41AEAFFDD275.dita"><apiname>MDirectGdiEngine</apiname></xref> interface.

    49 Also notice that the hardware implementation uses asynchronous calls to the

    50 graphic acceleration hardware driver. This means that the CPU can continue

    51 with other processing while the GPU is busy processing the rendering request.

    52 This improves the parallelism between the CPU and the GPU. </p>

    53 <p>The software implementation does not use asynchronous calls, because the

    54 rendering is performed by the CPU. </p>

    55 <section id="GUID-134818CD-B113-4AE1-8C48-CDF9CB38C46E"><title>Generic layer</title> <p>The

    56 following figure shows the classes in the DirectGDI generic layer (which is

    57 shaded green). Classes that are provided by other components are shown in

    58 red. Classes that cross the generic layer boundary have some parts that cannot

    59 be modified (such as a fixed API), but have other parts that can be modified. </p> <fig id="GUID-1A830274-D596-586A-B469-0CB7619FB391">

    60 <title>              The DirectGDI generic layer classes            </title>

    61 <image href="GUID-26B3BB7B-53CC-518F-85DA-CBAAD52DCE1C_d0e240389_href.png" placement="inline"/>

    62 </fig> </section>

    63 </conbody><related-links>

    64 <link href="GUID-A2E07A3C-B3A8-50B9-BD60-F1F01795FA24.dita"><linktext>DirectGDI

    65 Component</linktext></link>

    66 <link href="GUID-7B511CC2-CE38-5888-AF12-3568BEB416A6.dita"><linktext>DirectGDI

    67 Interface Component</linktext></link>

    68 <link href="GUID-EBE2D1D3-3A99-54BF-B5C0-08E9267F5750.dita"><linktext>Creating

    69 a DirectGDI Adaptation</linktext></link>

    70 </related-links></concept>