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<!DOCTYPE task

  PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">

<task id="GUID-84922B27-FDCF-56FD-91ED-5E0BFE3ED0E4" xml:lang="en"><title>Compressing

and Decompressing File - Zip Format </title><shortdesc>The Zip Compression Library, EZLib provides stream and file compression

and decompression functionality for the Symbian platforms. The files can be

compressed to two formats namely zip and gzip. Compression and Decompression

are performed iteratively, till the completion of required task. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>

<context id="GUID-BE620F4A-6D23-5832-8C2A-4B9C75F6BF12"/>

<steps id="GUID-0DE92899-962B-5E18-9378-EB7B6C78E7BD">

<step id="GUID-414B561B-4BCA-5D6F-A744-3944D0EBDBE2"><cmd>Pass the input and

output files as parameters to construct an instance of <xref href="GUID-A54D8675-1874-3B4F-816D-001A235C0F9C.dita"><apiname>CEZFileBufferManager</apiname></xref>.

This returns a pointer to <xref href="GUID-A54D8675-1874-3B4F-816D-001A235C0F9C.dita"><apiname>CEZFileBufferManager</apiname></xref> (input buffer). </cmd>

<info> <xref href="GUID-A54D8675-1874-3B4F-816D-001A235C0F9C.dita"><apiname>CEZFileBufferManager</apiname></xref> provides functions that accept

and converts the data into buffers for <xref href="GUID-B90BA6D6-72A2-3EB8-B8EF-CD5408107A9E.dita"><apiname>MEZBufferManager</apiname></xref> class

to manage it internally. </info>

</step>

<step id="GUID-BA8CC59E-FD6B-5ACA-A516-EBFFB5316D30"><cmd/>

<info>Pass the input buffer and other compression parameters to the object

of the <xref href="GUID-AEF8BCC8-6B24-3D59-AD3A-17B5203B3AA5.dita"><apiname>CEZCompressor</apiname></xref> class. </info>

</step>

<step id="GUID-BD4E38F1-78A7-5ED3-83D7-6C56EE7122DD"><cmd/>

<info>Use <xref href="GUID-AEF8BCC8-6B24-3D59-AD3A-17B5203B3AA5.dita#GUID-AEF8BCC8-6B24-3D59-AD3A-17B5203B3AA5/GUID-03E4E3A2-3830-3209-9D7B-A2238B5AF219"><apiname>CEZCompressor::DeflateL()</apiname></xref> to compress the file. </info>

</step>

</steps>

<example><p>The following code demonstrates a compression procedure. </p><codeblock xml:space="preserve">/*

 * Compresses the file into a zip file using the EZlib component. 

 * It is assumed that the input and output file names are contained in a 

 * provided ini file.

 */

void CEZlibEZipTests::DoEZlibDeflateL()

    {

RFs iFs;

 iFS.connect();

    //Open input file

_LIT(KInputFileLocation, "c:\\private\\E80000B7\\zip\\input\\input.doc");

TFileName inputFile(KInputFileLocation);

    RFile input;

    err = input.Open(iFs, inputFile, EFileStream | EFileRead | EFileShareExclusive);

    if(err != KErrNone)

        {

        INFO_PRINTF1(KOpenFileError);

        User::Leave(err);

        }   

    //open output file

_LIT(KOutputFileLocation, "c:\\private\\E80000B7\\zip\\input\\output.zip");

TFileName outputFile(KOutputFileLocation);

    RFile output;

    err = output.Replace(iFs, outputFile, EFileStream | EFileWrite | EFileShareExclusive);

    if(err != KErrNone)

        {

        INFO_PRINTF1(KCreateFileError);

        User::Leave(err);

        }   

    CEZFileBufferManager *bufferManager = CEZFileBufferManager::NewLC(input, output);   

    CEZCompressor *compressor = CEZCompressor::NewLC(*bufferManager, aLevel, aWindowBits, aMemLevel, aStrategy);

    while(compressor->DeflateL())

        {       

        }   

     output.Close(); 

input.Close();

 iFS.Close();

    }

</codeblock></example>

<postreq><p>The decompression of a <filepath>.zip</filepath> file can be achieved

through the following the steps: </p> <ol id="GUID-468D2F53-B015-5DAB-96A7-08DBE8101773">

<li id="GUID-23A8B3BC-0C23-503A-969A-EAD80BBDA3ED"><p>Pass the

input and output files as parameters to construct an instance of <xref href="GUID-A54D8675-1874-3B4F-816D-001A235C0F9C.dita"><apiname>CEZFileBufferManager</apiname></xref>.

This returns a pointer to <xref href="GUID-A54D8675-1874-3B4F-816D-001A235C0F9C.dita"><apiname>CEZFileBufferManager</apiname></xref> ( buffer). </p> </li>

<li id="GUID-60335F30-42FF-57A1-8457-ADFAE6C34E76"><p>Pass the buffer to the

object of the <xref href="GUID-BC3CEC02-B747-38FB-8B35-E7390DB06E35.dita"><apiname>CEZDecompressor</apiname></xref> class. </p> </li>

<li id="GUID-969C35D8-AAB8-5875-9DA9-B80D0F402EB1"><p> <xref href="GUID-BC3CEC02-B747-38FB-8B35-E7390DB06E35.dita#GUID-BC3CEC02-B747-38FB-8B35-E7390DB06E35/GUID-0AC99B66-412B-3CCF-84DA-D7BC0F0D32B2"><apiname>CEZDecompressor::InflateL()</apiname></xref> is

called repeatedly until the decompression is complete. </p> </li>

</ol> <p>The following code demonstrates the decompression procedure. </p> <codeblock id="GUID-4A0A0D64-939C-587F-B9C7-F34B8F934E25" xml:space="preserve">/* Decompresses the file contained in a Zip file using the EZlib component. 

 * It is assumed that the input and output file names are contained in a 

 * provided ini file.

 */

void CEZlibEZipTests::DoEZlibInflateL()

    {

RFs iFs;

 iFS.connect();

//Open input file

_LIT(KInputFileLocation, "c:\\private\\E80000B7\\zip\\input\\output.zip");

TFileName inputFile(KInputFileLocation);

    RFile input;

    err = input.Open(iRfs, inputFile, EFileStream | EFileRead | EFileShareExclusive);

    if(err != KErrNone)

        {

        INFO_PRINTF1(KOpenFileError);

        User::Leave(err);

        }    

    //open output file

_LIT(KOutputFile, "c:\\private\\E80000B7\\zip\\input\\input.doc");

TFileName outputFile(KOutputFile);

    RFile output;

    err = output.Replace(iFs, outputFile, EFileStream | EFileWrite | EFileShareExclusive);

    if(err != KErrNone)

        {

        INFO_PRINTF1(KCreateFileError);

        User::Leave(err);

        }    

CEZFileBufferManager *bufferManager = CEZFileBufferManager::NewLC(input, Output);    

CEZDecompressor *decompressor = CEZDecompressor::NewLC(*bufferManager, aWindowBits);

    while(decompressor->InflateL())

        {        

        }    

output.Close();

        input.Close();

    ifs.Close();

    }</codeblock> </postreq>