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1 <?xml version="1.0" encoding="utf-8"?> |
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2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. --> |
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3 <!-- This component and the accompanying materials are made available under the terms of the License |
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4 "Eclipse Public License v1.0" which accompanies this distribution, |
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5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". --> |
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6 <!-- Initial Contributors: |
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7 Nokia Corporation - initial contribution. |
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8 Contributors: |
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9 --> |
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10 <!DOCTYPE concept |
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11 PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
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12 <concept id="GUID-D34DB4A1-1B17-5FAF-A48B-E06D247B0A83" xml:lang="en"><title>Keyboard Mapping DLL Tutorial</title><shortdesc/><prolog><metadata><keywords/></metadata></prolog><conbody> |
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13 <p>A keyboard mapping DLL provides a set of lookup tables that the |
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14 generic <filepath>ektran.dll</filepath> uses to convert scancodes |
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15 to keycodes. A keyboard mapping DLL is implemented in a base port. </p> |
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16 <p>The basic purpose of the tables is to provide a mapping from scancodes |
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17 to keycodes, so that, given a scancode, the corresponding keycode |
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18 can be found. The tables are organized so that there is, in effect, |
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19 one set of lookup tables for each likely combination of modifier key |
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20 states. <filepath>ektran.dll</filepath> compares the modifier keys |
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21 that have been pressed with the stored modifier key state combinations |
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22 to decide which set of lookup tables to use. </p> |
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23 <p>An outline set of tables is provided in the template port.</p> |
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24 <p>The following list outlines the structure of the tables. </p> |
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25 <ol id="GUID-54817A2B-F65D-5BDF-BFCF-3E68A582C91A"> |
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26 <li id="GUID-0C32BD32-0EFD-5622-9C66-2610A3D7F660"><p>The tables are |
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27 organized in a hierarchical structure. The start of this hierarchy |
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28 is the root table, defined by a <xref href="GUID-F7DFE751-C534-36A8-9B57-9C8417B1BE06.dita"><apiname>SConvTable</apiname></xref> struct. |
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29 This contains: </p> <ul> |
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30 <li id="GUID-98675F02-D273-5C0D-8AF1-A9F93F8A5AC2"><p>an array of |
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31 pointers to nodes, where each node is defined by the <xref href="GUID-3D2F56DB-DD36-3787-8653-C5AC114D69A1.dita"><apiname>SConvTableNode</apiname></xref> struct. Each node corresponds to a specific combination of modifier |
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32 key states. </p> </li> |
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33 <li id="GUID-8321989A-20FE-58C3-90D0-2D3BE29E11F6"><p>a field containing |
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34 the total number of such nodes. </p> </li> |
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35 </ul> <fig id="GUID-A8C68654-2D56-501F-8D45-C0F75E63B630"> |
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36 <title>Keyboard Mapping Table</title> |
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37 <image href="GUID-FB69F45C-2256-5F2D-8D2C-98C93B865962_d0e14972_href.png" placement="inline"/> |
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38 </fig> </li> |
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39 <li id="GUID-C232C328-190D-59F1-A1CB-BC9D736367B0"><p>The combination |
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40 of modifier key states that each node represents is encapsulated by |
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41 a <xref href="GUID-7D0DE872-AC17-3045-9F97-E25A13B5CFB0.dita"><apiname>TMaskedModifiers</apiname></xref> object. One of these objects |
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42 is embedded within each node. </p> <p>A <xref href="GUID-7D0DE872-AC17-3045-9F97-E25A13B5CFB0.dita"><apiname>TMaskedModifiers</apiname></xref> object consists of a mask, and a value for comparison. For example, |
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43 if an instance is set to the following: </p> <codeblock id="GUID-E53A8286-C304-50BD-9DB5-81777B48A2E3" xml:space="preserve">iMask = EModifierShift | EModifierCtrl | EModifierFunc |
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44 iValue = EModifierShift | EModifierFunc</codeblock> <p>then a match |
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45 occurs only for the following combination of modifier key states: </p> <p> <codeph>ctrl</codeph> + <codeph>shift</codeph> + <i>not</i> <codeph>Fn</codeph> </p> <p>i.e. a match occurs only if <codeph>ctrl</codeph> <i>and</i> <codeph>shift</codeph> are pressed, and only if <codeph>Fn</codeph> is <i>not</i> pressed. Other modifier keys are ignored, |
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46 i.e. it does not matter whether or not they are pressed. </p> <p>In |
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47 C++ code, this is expressed as: </p> <codeblock id="GUID-E84542A2-932F-50C6-90B6-2AFC72CBE75F" xml:space="preserve">inline TBool MatchesMaskedValue(TInt aModifiers,const TMaskedModifiers &aMaskedModifiers) |
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48 { |
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49 return (TBool)((aModifiers & aMaskedModifiers.iMask) == aMaskedModifiers.iValue); |
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50 }</codeblock> <p>where <codeph>aModifiers</codeph> contains the |
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51 modifier key combination to be tested. </p> </li> |
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52 <li id="GUID-C147C929-63EE-593B-8CB7-689E5E6E60C2"><p>In principle, |
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53 each node represents scancode-to-keycode mappings by associating one |
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54 or more <i>pairs</i> (or range) of scancodes with corresponding blocks |
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55 of keycodes. Each pair represents an inclusive and contiguous range |
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56 of scancodes. </p> <p>Each pair (or range) of scancodes may be "discontiguous" |
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57 from the next. </p> <p>The association is made through a table defined |
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58 by the <xref href="GUID-35A21F70-F080-364D-8655-5E1781B378EB.dita"><apiname>SConvSubTable</apiname></xref> struct. This has: </p> <ul> |
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59 <li id="GUID-9A023CDD-FADF-5641-8DD8-30C11F73E8BE"><p>a <xref href="GUID-DB86A3E5-D118-3A1D-8A76-BEC6111993E8.dita"><apiname>SScanCodeBlockList</apiname></xref> object that contains pointers to a number of <xref href="GUID-F18D6A71-122E-3202-927B-25DCEF1576A4.dita"><apiname>SScanCodeBlock</apiname></xref> objects, each of which contains the start and end values defining |
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60 a range of scancodes. </p> </li> |
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61 <li id="GUID-AC4820E0-F3D9-547A-9437-964D5A7FE540"><p>a pointer to |
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62 a table containing the target keycodes. The target keycodes are arranged |
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63 so that successive scancode pairs are associated with successive blocks |
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64 of keycodes as the following diagram shows. </p> </li> |
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65 </ul> <fig id="GUID-4B2FBB49-6CBD-5030-82D0-9B4DDF2D3DBF"> |
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66 <title>Target keycodes</title> |
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67 <image href="GUID-DFADEB44-4D57-564F-ABDF-A3CCD38ACABC_d0e15086_href.png" placement="inline"/> |
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68 </fig> <p>This means that successive scancodes, for example, from |
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69 "A1" through to "B1" are represented by the successive keycodes "keycode |
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70 for A1" through to "keycode for B1"; scancode "A2" is represented |
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71 by "keycode for A2", which follows "keycode for B1" in the keycode |
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72 table. </p> </li> |
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73 <li id="GUID-68C8A342-A3D2-5975-82F1-F635E366F741"><p>To allow for |
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74 possible reuse of keycode tables, a node can point to more than one <xref href="GUID-35A21F70-F080-364D-8655-5E1781B378EB.dita"><apiname>SConvSubTable</apiname></xref>. The following diagram shows an example of |
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75 this: </p> <fig id="GUID-3F5514B5-86E6-52BE-A4C2-38882A1CEACA"> |
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76 <title>Reusing keycode tables</title> |
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77 <image href="GUID-5FDAF564-6BE1-544A-B5C0-E0D6E25D82E7_d0e15107_href.png" placement="inline"/> |
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78 </fig> </li> |
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79 <li id="GUID-C6001149-460A-57D4-A9FE-BCB050B49791"><p>If no keycode |
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80 can be found that matches the scancode, for a given modifier combination, |
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81 then the algorithm returns the <xref href="GUID-76B2E62E-EC09-3CA9-8B2D-EBAC6BF1FFDB.dita"><apiname>EKeyNull</apiname></xref> keycode. </p> </li> |
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82 </ol> |
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83 <section id="GUID-A7823728-26DD-4C2F-A97F-91CC4D58B404"><title>See |
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84 also</title> <p> <xref href="GUID-EB76FAF8-CD4B-5CB6-9F23-C852ED91866F.dita">Concepts</xref> </p> </section> |
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85 </conbody></concept> |