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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-548CC331-8E38-5627-A925-EA386BE90258" xml:lang="en"><title>Compressing |
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13 and Decompressing File - GZip Format </title><abstract><shortdesc>The Zip Compression Library, EZLib provides file compression |
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14 and decompression functionality for the Symbian platforms. The files can be |
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15 compressed to two formats namely zip and gzip. gzip is normally used to compress |
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16 single files. </shortdesc> <p/> </abstract><prolog><metadata><keywords/></metadata></prolog><taskbody> |
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17 <context id="GUID-48E514AC-C78B-570F-A96C-389BABA02472"><p>Compression and |
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18 Decompression are performed iteratively, till the completion of required task. </p> </context> |
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19 <steps id="GUID-2D2DC7F3-64FA-5C96-95DE-615650E10160"> |
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20 <step id="GUID-C384EAE0-B1EE-5098-A557-1231D35F8A2A"><cmd/> |
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21 <info>Input the source file and the name of the target gzip file to an instance |
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22 of the <xref href="GUID-417AB4E0-FF07-34CB-A4A8-CEF31C48A162.dita"><apiname>CEZFileToGZip</apiname></xref> class. </info> |
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23 </step> |
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24 <step id="GUID-2A30A687-A777-5790-8145-5AE956F35FFC"><cmd/> |
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25 <info> <xref href="GUID-417AB4E0-FF07-34CB-A4A8-CEF31C48A162.dita#GUID-417AB4E0-FF07-34CB-A4A8-CEF31C48A162/GUID-4E51D7C5-C624-3F27-A5CD-01E92F96F72B"><apiname>CEZFileToGZip::DeflateL()</apiname></xref> is used to compress the |
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26 file. </info> |
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27 </step> |
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28 </steps> |
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29 <example><p>The code below depicts how the source file "input.doc" file is |
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30 converted to target file "output.gz". </p><codeblock xml:space="preserve">/* |
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31 * If input and output file names are not specified then it is assumed that |
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32 * the file names are contained in a provided .ini file. |
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33 */ |
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34 |
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35 void CEZlibEZipTests::DoEZlibGZipDeflateL() |
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36 { |
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37 |
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38 |
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39 RFs iFs; |
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40 iFS.connect(); |
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41 |
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42 |
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43 //Open the source file in read mode |
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44 _LIT(KInputFileLocation, "c:\\private\\E80000B7\\zip\\input\\input.doc"); |
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45 TFileName inputFile(KInputFileLocation); |
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46 |
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47 RFile input; |
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48 err = input.Open(iFS, inputFile, EFileStream | EFileRead | EFileShareExclusive); |
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49 |
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50 if(err != KErrNone) |
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51 { |
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52 INFO_PRINTF1(KOpenFileError); |
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53 User::Leave(err); |
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54 } |
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55 |
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56 |
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57 //create a target file |
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58 |
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59 _LIT(KOutputFileLocation, "c:\\private\\E80000B7\\zip\\input\\output.gz"); |
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60 TFileName outputFile(KOutputFileLocation); |
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61 |
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62 |
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63 |
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64 CEZFileToGZip *compressor = CEZFileToGZip::NewLC(iFs, outputFile, input); |
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65 |
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66 |
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67 while(compressor->DeflateL()) |
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68 { |
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69 } |
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70 input.Close(); |
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71 iFS.Close(); |
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72 |
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73 |
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74 } |
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75 </codeblock></example> |
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76 <postreq><p>The decompression of a gzip file can be achieved through the following |
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77 the steps: </p> <ol id="GUID-A4771CC4-2704-56E3-BBD5-4AB2A58F9468"> |
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78 <li id="GUID-4E130CBF-C626-5CD0-9A83-A2F138B12B68"><p>Pass the file to the |
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79 constructor of the <xref href="GUID-8DE05785-D058-3855-A11F-7132EB4DE078.dita"><apiname>CEZGZipToFile</apiname></xref> class. </p> </li> |
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80 <li id="GUID-CB642B02-8A19-5CB9-96E4-80AB7596F6E1"><p> <xref href="GUID-8DE05785-D058-3855-A11F-7132EB4DE078.dita#GUID-8DE05785-D058-3855-A11F-7132EB4DE078/GUID-4A30D99E-EC51-359F-90B5-9CFA3841A538"><apiname>CEZGZipToFile::InflateL()</apiname></xref> is |
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81 called repeatedly to complete the decompression. </p> </li> |
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82 </ol> <p>The code below depicts how "output.gz" is decompressed to "input.doc". </p> <codeblock id="GUID-01545D8D-CE1F-5903-9558-CE35D4C3067E" xml:space="preserve">/* |
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83 * If input and output file names are not specified then it is assumed that |
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84 * the file names are contained in a provided .ini file. |
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85 */ |
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86 void CEZlibEZipTests::DoEZlibGZipInflateL() |
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87 { |
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88 RFs iFs; |
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89 iFS.connect(); |
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90 |
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91 |
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92 //open output file |
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93 |
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94 _LIT(KOutputFile, "c:\\private\\E80000B7\\zip\\input\\input.doc"); |
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95 TFileName outputFile(KOutputFile); |
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96 RFile output; |
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97 err = output.Replace(iFs, outputFile, EFileStream | EFileWrite | EFileShareExclusive); |
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98 if(err != KErrNone) |
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99 { |
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100 INFO_PRINTF1(KCreateFileError); |
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101 User::Leave(err); |
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102 } |
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103 |
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104 |
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105 //input file |
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106 |
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107 |
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108 _LIT(KInputFileLocation, "c:\\private\\E80000B7\\zip\\input\\output.gz"); |
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109 TFileName inputFile(KInputFileLocation); |
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110 |
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111 CEZGZipToFile *decompressor = CEZGZipToFile::NewLC(iFs, inputFile, output); |
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112 |
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113 while(decompressor->InflateL()) |
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114 { |
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115 } |
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116 |
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117 output.Close(); |
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118 iFS.Close(); |
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119 ; |
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120 }</codeblock> </postreq> |
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121 </taskbody></task> |