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    12 <concept id="GUID-EF62BF88-3687-505D-8BD7-EEDF36246E56" xml:lang="en"><title>Graphics

    13 Hardware Acceleration</title><shortdesc>This topic describes some of the issues surrounding the use of

    14 graphics hardware to improve graphics performance. It also provides a summary

    15 of the components that device creators need to adapt to take advantage of

    16 graphics hardware. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    17 <section><title>Background</title> <p><b>Graphics acceleration hardware </b> </p> <p>A

    18 graphics accelerator or Graphics Processing Unit (GPU) is a dedicated hardware

    19 processor that works in parallel with the main processor (CPU). By relieving

    20 the CPU of highly intensive graphics processing, a GPU makes it is possible

    21 to achieve sophisticated screen displays (such as video, animated graphics

    22 and 3D games) without compromising other aspects of performance. </p> <p><b>Animations </b> </p> <p>Animation

    23 involves transferring and manipulating large amounts of data (stored as bitmaps

    24 or instructions) from one area of memory and putting them into another (the

    25 screen buffer). Frame rates may be between 10 and 30 frames per second (depending

    26 on requirements and sources). </p> <p><b>Composition </b> </p> <p>Manufacturers

    27 of smartphones face the complexity of displaying on the screen a mixture of

    28 different types of content, such as streaming video, the camera viewfinder

    29 and regular UI elements with animated icons. These different types of content

    30 come from different places—such as multimedia sources (streaming video), camera

    31 hardware, the Window Server and EGL (3D and vector graphics). The different

    32 types of content are displayed in different areas of the screen and are updated

    33 by different processes. The graphics system must be capable not only of creating

    34 sophisticated graphical output from each source simultaneously but also of

    35 composing (compositing) them at up to 30 frames per second. For an introduction

    36 to how ScreenPlay handles this challenge, see <xref href="GUID-859CAA08-59C9-5FD3-98DE-6BDD0D6ED50B.dita">Graphics

    37 Composition</xref>. </p> <p><b>Optimization </b> </p> <p>GPUs work best when

    38 they do so uninterrupted. They usually have a 'long processing pipe' (a lot

    39 of data cached in memory) and flushing it or allowing it to empty reduces

    40 effectiveness. This can be avoided by avoiding the following: </p> <ul>

    41 <li id="GUID-827CF5E4-86EE-5766-BAF4-395205461FF0"><p> <b>Context switching</b>.

    42 The working data (such as color information, vertex positions, transformations

    43 and textures) is known as the <i>context</i>. If more than one application

    44 wants to use the processor at the same time, the processor must swap between

    45 them. This involves the processor saving the context from one application,

    46 flushing its buffers, and loading the context from the next. Context switching

    47 is time consuming and disruptive. </p> </li>

    48 <li id="GUID-5C98575F-A0EA-5B9F-ACCC-C7A0D2B93058"><p> <b>Copying and reformatting

    49 data</b>. Changing the format and copying pixel data involves time and memory.

    50 If the GPU and CPU cannot share memory and data formats, much time, processing

    51 power and memory is required to copy and convert data. </p> </li>

    52 </ul> <p>ScreenPlay avoids context switching and reformatting and copying

    53 data wherever possible. </p> <p><b>Hardware variety </b> </p> <p>The combination

    54 of hardware acceleration, animation and composition would be a substantial

    55 challenge in a fixed, dedicated hardware architecture. The Symbian platform,

    56 however, is designed to operate on a variety of hardware architectures, only

    57 some of which are capable of graphics acceleration and processing. The Symbian

    58 graphics subsystem can be customized to take advantage of a variety graphics

    59 processing hardware. Customization is via 'back end' components which do not

    60 affect the public API. </p> </section>

    61 <section><title>The hardware adaptation components</title> <p>Here we provide

    62 information about which graphics components device creators can adapt or replace.

    63 Components that can be adapted or replaced to suit the hardware are generally

    64 called <i>adaptations</i>. Adaptable and replaceable components that do not

    65 depend on the hardware are called <i>customizations</i> and are indicated

    66 by an asterisk (*) in the following table. </p> <p>The details vary depending

    67 on whether the <xref href="GUID-D93978BE-11A3-5CE3-B110-1DEAA5AD566C.dita">ScreenPlay</xref> or <xref href="GUID-F64E6551-670E-5E12-8103-DE504D3EC94F.dita">non-ScreenPlay</xref> variant

    68 is in use. </p> <table id="GUID-C401C8AE-7EE2-5B8F-9B17-B8C2E5E6B5B6">

    69 <tgroup cols="2"><colspec colname="col0"/><colspec colname="col1"/>

    70 <thead>

    71 <row>

    72 <entry>ScreenPlay</entry>

    73 <entry>Non-ScreenPlay</entry>

    74 </row>

    75 </thead>

    76 <tbody>

    77 <row>

    78 <entry><xref href="GUID-04D917A1-E1A0-5149-9660-80A1146D0984.dita">OpenGLES Implementation</xref> </entry>

    79 <entry><xref href="GUID-04D917A1-E1A0-5149-9660-80A1146D0984.dita">OpenGLES Implementation</xref> </entry>

    80 </row>

    81 <row>

    82 <entry><xref href="GUID-1A8ED0EB-B3B7-553F-95E3-2120D877966B.dita">OpenVG Implementation</xref></entry>

    83 <entry><xref href="GUID-1A8ED0EB-B3B7-553F-95E3-2120D877966B.dita">OpenVG Implementation</xref> </entry>

    84 </row>

    85 <row>

    86 <entry><xref href="GUID-DC8BFEF5-DA50-52DA-8CE2-5729A4A005F6.dita">EGL Implementation</xref> </entry>

    87 <entry><xref href="GUID-DC8BFEF5-DA50-52DA-8CE2-5729A4A005F6.dita">EGL Implementation</xref> </entry>

    88 </row>

    89 <row>

    90 <entry><xref href="GUID-9E7D563E-9FFB-5FA9-8944-9CBAC281FDD2.dita">Screen Driver</xref> </entry>

    91 <entry><xref href="GUID-9E7D563E-9FFB-5FA9-8944-9CBAC281FDD2.dita">Screen Driver</xref> </entry>

    92 </row>

    93 <row>

    94 <entry><xref href="GUID-D76C7759-739D-5C98-B718-7297687FE630.dita">Extended Bitmap

    95 Rasterizer Plug-in</xref> </entry>

    96 <entry><xref href="GUID-D76C7759-739D-5C98-B718-7297687FE630.dita">Extended Bitmap

    97 Rasterizer Plug-in</xref> </entry>

    98 </row>

    99 <row>

   100 <entry><xref href="GUID-BB4F5388-32EA-5A2E-845D-E5339D2040E9.dita">DirectGDI Adaptation</xref> </entry>

   101 <entry/>

   102 </row>

   103 <row>

   104 <entry><xref href="GUID-5E46C0EE-BD7D-5C85-8083-575BB2888AA7.dita">Graphics Resource

   105 Adaptation</xref> </entry>

   106 <entry/>

   107 </row>

   108 

   109 <row>

   110 <entry><xref href="GUID-8BEE0411-C6E9-5840-BE22-EC271A4D97DD.dita">OpenWF Composition

   111 Engine</xref></entry>

   112 <entry/>

   113 </row>

   114 <row>

   115 <entry><xref href="GUID-C7B420DE-CEDA-5D3F-8095-71136E862CDF.dita">Surface Manager</xref>  </entry>

   116 <entry/>

   117 </row>

   118 <row>

   119 <entry><xref href="GUID-8E8FE99A-5F4D-5B0F-87AB-A58EB4BEB6E9.dita">Surface Update</xref> </entry>

   120 <entry/>

   121 </row>

   122 <row>

   123 <entry><xref href="GUID-3A2785D4-6185-50C3-8D7E-5D94CD2B7C98.dita">Render Stages</xref>* </entry>

   124 <entry/>

   125 </row>

   126 </tbody>

   127 </tgroup>

   128 </table> </section>

   129 </conbody><related-links>

   130 <link href="GUID-99BC101A-9466-59EE-B5C9-7622BAF6E6FF.dita"><linktext>Graphics

   131 Concepts</linktext></link>

   132 <link href="GUID-D93978BE-11A3-5CE3-B110-1DEAA5AD566C.dita"><linktext>The ScreenPlay

   133 Architecture</linktext></link>

   134 <link href="GUID-F64E6551-670E-5E12-8103-DE504D3EC94F.dita"><linktext>The Non-ScreenPlay

   135 Architecture</linktext></link>

   136 </related-links></concept>