Categories: UI | Symbian C++ | How To | Code Examples

This page was last modified 00:13, 15 July 2008.

From Forum Nokia Wiki

Consider the following two scenarios

• We need a list of the recent URL's that the user entered OR
• We need a list of recent search keywords that the user entered.

There can be many more like this, these keywords/URL's/Files opened etc... can be sorted in the recent used order in an array.

The following class is very handy in such situations, not only it maintains a recent list it also stores it into a file so that the recent list is available the next time the application starts.

Header File

Recent.h

#ifndef 	__RECENT__H__
#define  	__RECENT__H__
class CRecent : public CBase
{
public:
	virtual ~CRecent();
	void ReadFromFileL();
	void WriteToFileL();
	CRecent();
	TInt RecentCount();
	void AppendToRecTitle(TDesC& aUrl);
	void RecentSelected(TInt aIndex, TDes& aRet);
	void  MoveArrayElementsL(TDesC& aUrl);
	TBool ResetAll();
	TBool ItemElseWhere(TDesC& aUrl);
	TBool ItemAtZeroth(TDesC& aUrl);
	void SetFile(TFileName& aFile);
private:
	void ConstructL();
private:
   CDesCArray *iRecent;
   TUint iRCount;
   TFileName iFile;
};
 
#endif

Cpp File

Recent.cpp

#include <bautils.h>
#include <s32file.h>
#include <eikspane.h>
#include <akntitle.h>
#include <avkon.hrh>
#include "Recent.h"
 
_LIT(KFile,".dat");
 
_LIT(KFormat,"%S");
const TInt KMax = 5;
 
CRecent::CRecent()
{
	iRecent = new (ELeave) CDesCArrayFlat(10);
		
}
 
void CRecent::SetFile(TFileName& aFile)
{
	iFile.Copy(aFile);
	iFile.Append(KFile);
	ReadFromFileL();
}
 
//clean up
CRecent::~CRecent()
{
	delete iRecent;
	
}
 
//read recent urls line by line from file
void CRecent::ReadFromFileL()
{
	RFs aFs;
	User::LeaveIfError(aFs.Connect());
	CleanupClosePushL(aFs);
	
	TBool iBool;
	iBool=BaflUtils::FileExists(aFs,iFile);
 
	if(iBool)
	{
		iRecent->Reset();
		
	
		TBuf<128> urlbuf;
		RFileReadStream fRead;
		User::LeaveIfError(fRead.Open(aFs,iFile, EFileRead));
		CleanupClosePushL(fRead);
		TInt count = fRead.ReadInt16L();
		iRCount=count;  //added now
		for(TInt i=0;i<count;i++)
		{
			HBufC *url = HBufC::NewL( fRead, KMaxTInt );
			iRecent->AppendL(url->Des());
			delete url;
		}
 
		CleanupStack::PopAndDestroy(&fRead);
	}
	else
	{
		iRCount = 0;
	}
 
	aFs.Close();
	CleanupStack::PopAndDestroy(&aFs);
}
 
//write files line by line to the file
void CRecent::WriteToFileL()
{
	RFs aFs;
	User::LeaveIfError(aFs.Connect());
	CleanupClosePushL(aFs);
	aFs.Delete(iFile);
	RFileWriteStream fWrite;
	User::LeaveIfError(fWrite.Create(aFs, iFile, EFileWrite));
	CleanupClosePushL(fWrite);
 
	fWrite.WriteInt16L( static_cast<TInt16>(iRecent->Count() ) ); 
	for(TInt i =0 ; i < iRecent->Count() ; i++)
	{
		fWrite << iRecent->MdcaPoint(i); // Warning, this _CAN_ leave
	}
	fWrite.CommitL();
	CleanupStack::PopAndDestroy(&fWrite);
	CleanupStack::PopAndDestroy(&aFs);
}
 
TInt CRecent::RecentCount()
{
	return iRCount;
}
 
//new file to list
void CRecent::AppendToRecTitle(TDesC& aUrl)
{
	//the first element is selected , dont do anything
	if(ItemAtZeroth(aUrl))
		return;
 
	//a file that already exists in the list , bring it to top
	if(ItemElseWhere(aUrl)) 
		return;
 
	//else  append to recent list
	if(iRecent->Count() == KMax)
		MoveArrayElementsL(aUrl);
	else
		iRCount++;
 
	iRecent->AppendL(aUrl);
	WriteToFileL();
	ReadFromFileL();
}
 
//a file that already exists in the list , bring it to top
TBool CRecent::ItemElseWhere(TDesC& aUrl)
{
	TBuf<128> iCompStr;
	TInt iIndex;
	TBool iFound;
	iFound = EFalse;
	for(TInt i=0; i < iRecent->Count();i++)
	{
		iCompStr.Zero();
		iCompStr.Copy(iRecent->MdcaPoint(i));
		TInt comp =iCompStr.Compare(aUrl);
		if(comp == 0)
		{			
			iFound=ETrue;
			iIndex = i;
			break;
		}
	}
	if(iFound)
	{
	
		TBuf<128> item;
		item.Copy(iRecent->MdcaPoint(iIndex));
		iRecent->Delete(iIndex);
		iRecent->AppendL(item);
		
		WriteToFileL();
		ReadFromFileL();
 
		return ETrue;
	}
	else
		return EFalse;
}
 
//item already is at the recent position or not
TBool CRecent::ItemAtZeroth(TDesC& aUrl)
{
	if(iRecent->Count() > 0 )
	{
		TBuf<128> iCompStr;
		if(iRecent->Count() == 1)
			iCompStr.Copy(iRecent->MdcaPoint(0));
		else
			iCompStr.Copy(iRecent->MdcaPoint(iRCount-1));
 
		TInt comp =iCompStr.Compare(aUrl);
		if(comp != 0)
			return EFalse;
		else
			return ETrue;
	}
	else
	{
		return EFalse;
	}
}
 
 
//return selected item
void  CRecent::RecentSelected(TInt aIndex, TDes& aRet)
{
	aRet.Copy(iRecent->MdcaPoint(aIndex));
}
 
//move elements in case of list full
void  CRecent::MoveArrayElementsL(TDesC& aUrl)
{
	TInt i;
	CDesCArrayFlat* iTempRecentUrls = new (ELeave) CDesCArrayFlat(10);
 
	for( i=1 ; i <= KMax-1 ; i++ )
	{
		iTempRecentUrls->AppendL(iRecent->MdcaPoint(i));
	}
		
	iRecent->Reset();
	
	for( i = 0 ; i <=KMax-2 ; i++)
	{
		iRecent->AppendL(iTempRecentUrls->MdcaPoint(i));
	}
 
	delete iTempRecentUrls;
}
 
//reset all
TBool CRecent::ResetAll()
{
	RFs aFs;
	User::LeaveIfError(aFs.Connect());
	CleanupClosePushL(aFs);
 
	TBool iBool;
	iBool=BaflUtils::FileExists(aFs, iFile);
	if(iBool)
	{	
		aFs.Delete(iFile);
		iRCount = 0 ;
		iRecent->Reset();
		CleanupStack::PopAndDestroy(&aFs);
		return ETrue;
	}
	CleanupStack::PopAndDestroy(&aFs);
	return EFalse;
}

PS: The url/search mentioned in the above scenarios are not the external applications data,like the browsers urls , all scenarios are for the same applications data.