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

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

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

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

defines the interfaces that the adaptations must implement and the DirectGDI

Adaptation component consists of the two DirectGDI implementations that are

provided in the Graphics package. </p>

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

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

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

a framework that enables graphics hardware acceleration and interleaved rendering.

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

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

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

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

Resource Component</xref>. </p>

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

<ul>

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

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

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

hardware. </p> </li>

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

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

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

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

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

</ul>

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

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

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

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

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

<title>           DirectGDI architecture          </title>

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

</fig>

<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.

Also notice that the hardware implementation uses asynchronous calls to the

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

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

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

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

rendering is performed by the CPU. </p>

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

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

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

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

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

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

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

</fig> </section>

</conbody><related-links>

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

Component</linktext></link>

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

Interface Component</linktext></link>

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

a DirectGDI Adaptation</linktext></link>