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<!-- Initial Contributors:+
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    Nokia Corporation - initial contribution.+
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<!DOCTYPE concept+
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  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">+
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<concept id="GUID-22E46647-D677-5A47-A7E0-E1E0AE736B27" xml:lang="en"><title>DirectGDI+
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Adaptation Overview</title><prolog><metadata><keywords/></metadata></prolog><conbody>+
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<p>The DirectGDI Adaptation component, together with the DirectGDI Interface+
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component, forms the DirectGDI adaptation layer. The DirectGDI Interface component+
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defines the interfaces that the adaptations must implement and the DirectGDI+
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Adaptation component consists of the two DirectGDI implementations that are+
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provided in the Graphics package. </p>+
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<p><b>Target audience</b>: Device creators. </p>+
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<note type="note">DirectGDI is deprecated in Symbian^3.</note>+
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<p>The <xref href="GUID-A2E07A3C-B3A8-50B9-BD60-F1F01795FA24.dita">DirectGDI component</xref> provides+
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a framework that enables graphics hardware acceleration and interleaved rendering.+
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This framework provides an API for client applications and a Hardware Adaptation+
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Interface (HAI), which defines interfaces that must be implemented by device+
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and hardware manufacturers in order to provide the API functionality. The+
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framework has a dependency on the <xref href="GUID-82B0B4B9-6BC2-5BEF-B3B0-D57AC57F8D8A.dita">Graphics+
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Resource Component</xref>. </p>+
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<p>The Graphics package includes two DirectGDI adaptations: </p>+
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<ul>+
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<li id="GUID-B0C72AE2-2A06-59AD-98AA-BCE881ECD460"><p>A purely software adaptation+
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that uses existing components to draw to the screen in a similar manner to+
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BitGDI. This is suitable for use in phones that do not include graphics acceleration+
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hardware. </p> </li>+
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<li id="GUID-FB34D088-0046-5A1B-9C23-39D11C448ECD"><p>A hardware adaptation+
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that uses OpenVG and EGL APIs on the H4 platform. This is provided for reference+
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purposes and there is no requirement that the implementation use OpenVG. Hardware+
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manufacturers can in fact use any third-party rendering system that is suitable+
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for use with the target hardware. </p> </li>+
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</ul>+
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<p>The following diagram shows the generic DirectGDI API and implementation,+
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with one software and two hardware implementations. Although shown on the+
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same diagram, in fact only one implementation can exist on the same phone.+
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A configuration at ROM build time decides which implementation is used. </p>+
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<fig id="GUID-E4CD5B76-03E0-5F4C-8C65-C2F2B52969F5">+
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<title>           DirectGDI architecture          </title>+
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<image href="GUID-912643B5-0B8D-5836-B864-9A2DBAC86B00_d0e268181_href.png" placement="inline"/>+
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</fig>+
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<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.+
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Also notice that the hardware implementation uses asynchronous calls to the+
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graphic acceleration hardware driver. This means that the CPU can continue+
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with other processing while the GPU is busy processing the rendering request.+
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This improves the parallelism between the CPU and the GPU. </p>+
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<p>The software implementation does not use asynchronous calls, because the+
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rendering is performed by the CPU. </p>+
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<section id="GUID-134818CD-B113-4AE1-8C48-CDF9CB38C46E"><title>Generic layer</title> <p>The+
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following figure shows the classes in the DirectGDI generic layer (which is+
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shaded green). Classes that are provided by other components are shown in+
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red. Classes that cross the generic layer boundary have some parts that cannot+
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be modified (such as a fixed API), but have other parts that can be modified. </p> <fig id="GUID-1A830274-D596-586A-B469-0CB7619FB391">+
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<title>              The DirectGDI generic layer classes            </title>+
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<image href="GUID-26B3BB7B-53CC-518F-85DA-CBAAD52DCE1C_d0e268206_href.png" placement="inline"/>+
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</fig> </section>+
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</conbody><related-links>+
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<link href="GUID-A2E07A3C-B3A8-50B9-BD60-F1F01795FA24.dita"><linktext>DirectGDI+
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Component</linktext></link>+
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<link href="GUID-7B511CC2-CE38-5888-AF12-3568BEB416A6.dita"><linktext>DirectGDI+
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Interface Component</linktext></link>+
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<link href="GUID-EBE2D1D3-3A99-54BF-B5C0-08E9267F5750.dita"><linktext>Creating+
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a DirectGDI Adaptation</linktext></link>+
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</related-links></concept>+
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