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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 task |
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11 PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd"> |
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12 <task id="GUID-EA107811-240C-5F95-922B-7C042FA00A87" xml:lang="en"><title>Reading |
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13 a String Resource </title><abstract><p>The simplest use of a resource file involves reading string resources |
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14 and interpreting the source data. </p></abstract><prolog><metadata><keywords/></metadata></prolog><taskbody> |
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15 <context><p>Resources are defined in terms of structs which are accessed and |
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16 read by the <xref href="GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA.dita"><apiname>RResourceFile</apiname></xref> class, and interpreted by the <xref href="GUID-B375D32E-1F91-30FA-8605-A2E163111F9A.dita"><apiname>TResourceReader</apiname></xref>. |
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17 An application may also use resources from multiple files simultaneously. |
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18 See <xref href="GUID-98903A01-CD04-5345-84AE-2E440CE06E11.dita">Resource File examples</xref> for |
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19 more information. </p><p>Consider a sample resource file where a struct of |
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20 STRING is defined having a single member of type <codeph>LTEXT</codeph>: </p><codeblock xml:space="preserve">// define structures |
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21 STRUCT STRING |
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22 { |
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23 LTEXT text; |
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24 } |
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25 // define resources |
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26 RESOURCE STRING hello |
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27 { |
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28 text=Bonjour tout le monde!; |
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29 } |
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30 </codeblock> </context> |
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31 <steps id="GUID-F147E8CF-65D1-5025-BA85-E0D171DBEFFD"> |
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32 <step id="GUID-0BAEB54B-5A6E-59F6-B14E-FAF0A3D15F27"><cmd/> |
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33 <info>Compile the resource file using <xref href="GUID-9C57F0C6-E2E3-58A2-907D-924A7E22EA97-GENID-1-11-1-1-5-1-4-1.dita">the |
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34 resource compiler</xref> (rcomp) to generate an <filepath>.rsc</filepath> file |
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35 and an <filepath>.rsg</filepath> file. </info> |
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36 <substeps id="GUID-0B421705-A5CD-5FF7-BB95-C17559811267"> |
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37 <substep id="GUID-673E32C9-665C-5388-AE17-780A149F8837"><cmd/> |
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38 <info> <filepath>.rsc</filepath> file contains the resource data; this is |
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39 the resource file that must be referred to at run-time by the <codeph>RResourceFile</codeph> class |
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40 in the C++ code. </info> |
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41 </substep> |
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42 <substep id="GUID-AEE254EB-0716-5478-B1DF-F8ED8E4FF8E1"><cmd/> |
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43 <info> <filepath>.rsg</filepath> file is a <keyword>generated |
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44 header</keyword> file that contains <codeph>#define</codeph> statements |
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45 for each resource defined in the source file. In the resource file generated |
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46 here, the only resource is called <codeph>hello</codeph> and the generated |
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47 header file contains: </info> |
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48 <stepxmp><codeblock id="GUID-385BB8E3-FF77-5A95-8F65-043E72412959" xml:space="preserve">#define HELLO 1</codeblock> </stepxmp> |
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49 <info>Note that the name in the generated header file is converted to upper |
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50 case. </info> |
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51 </substep> |
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52 </substeps> |
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53 </step> |
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54 <step id="GUID-3367B1DD-C2E9-5780-A77A-7F574D2EC541"><cmd/> |
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55 <info> <codeph>#include</codeph> the <filepath>.rsg</filepath> file in the |
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56 file containing the C++ code, to access the resource IDs generated by the |
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57 resource compiler. For example, for a project refered as <codeph>ReadText</codeph>, |
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58 this might be: </info> |
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59 <stepxmp><codeblock id="GUID-AC615F67-6331-500C-B91E-ADD6A94464FB" xml:space="preserve">#include ReadText.rsg</codeblock> </stepxmp> |
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60 </step> |
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61 <step id="GUID-ACC66DA2-4AC8-536B-9912-7CE632C0A8DF"><cmd/> |
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62 <info>Initialize the <codeph>RResourceFile</codeph> object in the C++ program, |
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63 specifying the name of the resource file: </info> |
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64 <stepxmp><codeblock id="GUID-5CF79231-E42C-51DF-9002-FD1ED8AB21C1" xml:space="preserve"> |
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65 RResourceFile resourceFile; |
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66 resourceFile.OpenL( fsSession,_L( Z:\\system\\data\\ReadText.rsc ) );</codeblock> </stepxmp> |
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67 <info>Note: To access the resource file contents, a session with the file |
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68 server must be started using an instance of <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita"><apiname>RFs</apiname></xref> class. </info> |
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69 </step> |
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70 <step id="GUID-CA53A8D1-E13E-50A8-96A7-B6B397B82DB3"><cmd/> |
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71 <info>Use one of the three functions (<xref href="GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA.dita#GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA/GUID-9B16E6B8-84A4-37DF-BBB4-EC8B04FDB14C"><apiname>RResourceFile::AllocReadLC()</apiname></xref>, <xref href="GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA.dita#GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA/GUID-8CEE29E0-78F3-3DD6-B068-85C8E0403884"><apiname>RResourceFile::AllocReadL()</apiname></xref> or <xref href="GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA.dita#GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA/GUID-DF6DFFD5-E923-3C4E-87F0-BC4EE7C8B586"><apiname>RResourceFile::ReadL()</apiname></xref> to read a resource as shown in the following |
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72 code fragment: </info> |
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73 <stepxmp><codeblock id="GUID-92AC4270-4A4D-52F1-B5C4-CFF6FBD19700" xml:space="preserve">HBufC8* dataBuffer = resourceFile.AllocReadLC( HELLO );</codeblock> </stepxmp> |
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74 </step> |
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75 <step id="GUID-77F9A976-6E09-5158-B515-256F4B878CDB"><cmd/> |
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76 <info>Interpret the resource data using a <codeph>TResourceReader</codeph> object. |
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77 This provides access to the text string through a pointer descriptor as shown |
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78 in the following code fragment: </info> |
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79 <stepxmp><codeblock id="GUID-CB3BE44D-72F5-5E15-8D1D-52F513D9D980" xml:space="preserve"> |
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80 TResourceReader theReader; |
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81 ... |
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82 theReader.SetBuffer( datafBuffer ); |
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83 TPtrC textdata = reader.ReadTPtrC();</codeblock> </stepxmp> |
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84 </step> |
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85 </steps> |
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86 <result><p>In this example, once the resource data is no longer needed, the |
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87 heap descriptor, dataBuffer, can be removed from the cleanup stack and destroyed |
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88 as shown in the code fragment: </p><codeblock xml:space="preserve">CleanupStack::PopAndDestroy();</codeblock><p>When |
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89 all operations on the resource file are complete, the resource file can be |
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90 closed using the RResourceFile::close() function as: </p><codeblock xml:space="preserve">resourceFile.Close();</codeblock></result> |
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91 <example><title>Example</title> <p>Consider a resource constructed |
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92 from the following definition. </p> <codeblock id="GUID-538D959C-A85A-5675-9B14-ED81AB860F47" xml:space="preserve">RESOURCE ARRAY anarray |
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93 { |
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94 items= |
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95 { |
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96 LBUF { txt="Esc"; }, |
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97 LBUF { txt="Enter"; }, |
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98 LBUF { txt="Tab"; }, |
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99 LBUF { txt="Del"; }, |
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100 LBUF { txt="Space"; } |
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101 }; |
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102 }</codeblock> <p>A <codeph>TPtrC</codeph> representing the second item can |
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103 be constructed using the <codeph>ReadTPtrC()</codeph> function. The example |
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104 simply takes the length of the text <codeph>Enter</codeph>: </p> <codeblock id="GUID-9817910D-0661-513D-BB3A-9557D70688AD" xml:space="preserve">// open the resource file |
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105 ... |
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106 HBufC8* res = resourceFile.AllocReadLC( ANARRAY ); |
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107 TResourceReader theReader; |
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108 ... |
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109 TInt len; |
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110 len = ( theReader.ReadTPtrC( 1,res ) ).Length(); // len == 5 |
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111 ...</codeblock> </example> |
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112 </taskbody><related-links> |
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113 <link href="GUID-3AF1F492-3D7D-5F8C-B1AE-16FBD8224775.dita"><linktext>Resource |
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114 files</linktext></link> |
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115 <link href="GUID-07C031C2-7FFC-5B0E-9691-E6E678E65C4B.dita"><linktext>Resource |
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116 file format</linktext></link> |
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117 <link href="GUID-3527AAEE-210F-524B-A655-A65F1CE86C80.dita"><linktext>Resource |
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118 compilation</linktext></link> |
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119 </related-links></task> |