RResourceFile Class Reference

#include <barsc.h>

class RResourceFile

Public Member Functions
	RResourceFile()
IMPORT_C HBufC8 *	AllocReadL(TInt)
IMPORT_C HBufC8 *	AllocReadLC(TInt)
IMPORT_C void	Close()
IMPORT_C void	ConfirmSignatureL(TInt)
IMPORT_C void	ConfirmSignatureL()
TInt	Offset()
IMPORT_C void	OpenL(RFs &, const TDesC &)
IMPORT_C void	OpenL(RFs &, const TDesC &, TUint, TInt)
IMPORT_C TBool	OwnsResourceId(TInt)
IMPORT_C TBool	OwnsResourceIdL(TInt)
IMPORT_C void	ReadL(TDes8 &, TInt)
IMPORT_C TInt	SignatureL()
IMPORT_C TUidType	UidType()

Detailed Description

Accesses a resource file and reads the resource data into a buffer.

Interpretation of the data is achieved using the TResourceReader class.

RResourceFile instance behaviour when some problem occurs - it panics. Or asserts, if the used method is not "L" method.

Expected behaviour when assignment operator or copy constructor is called: The class doesn't have assignment operator and copy constructor, so the compiler generated ones will be used. The heap buffers used by the source class instance will be shared with the destination class instance.

Expected behaviour when the RResourceFile instance is about to be destroyed: The class doesn't have destructor so compiler generated one will be used. Always call Close() to free allocated by the instance resources.

Constructor & Destructor Documentation

RResourceFile ( )

IMPORT_C

RResourceFile

(

)

Constructs a default resource file object.

Member Function Documentation

AllocReadL ( TInt )

IMPORT_C HBufC8 *

AllocReadL

(

TInt

aResourceId

)

const

Reads a resource into a heap descriptor and returns a pointer to that descriptor.

A heap descriptor of appropriate length is allocated for the resource. Ownership of the heap descriptor passes to the caller who must destroy it when it is no longer needed.

The search for the resource uses the following algorithm:

A resource id in the range 1 to 4095 is looked up in this resource file. The function leaves if there is no matching resource.

If the resource id is greater than 4095, then the most significant 20 bits of the resource id is treated as an offset and the least significant 12 bits is treated as the real resource id. If the offset matches the offset value defined for this file, then the resource is looked up in this resource file using the real resource id (i.e. the least significant 12 bits). If the offset does not match, then the function leaves.

Note, do not call this function until a call to ConfirmSignatureL() has completed successfully.

See also: RResourceFile::Offset() TBafPanic for panic codes.

Parameters
aResourceId	The numeric id of the resource to be read.

Return Value: Pointer to an 8 bit heap descriptor containing the resource.

Leave Codes
KErrNotFound	- there is no resource with aResourceId in the file.

Panic Codes
If	the file is corrupted - the method will panic in debug mode.

AllocReadLC ( TInt )

IMPORT_C HBufC8 *

AllocReadLC

(

TInt

aResourceId

)

const

Reads a resource into a heap descriptor, returns a pointer to that descriptor and pushes the pointer onto the cleanup stack.

A heap descriptor of appropriate length is allocated for the resource. Ownership of the heap descriptor passes to the caller who must destroy it and pop its pointer off the cleanup stack when it is no longer needed.

The search for the resource uses the following algorithm:

A resource id in the range 1 to 4095 is looked up in this resource file. The function leaves if there is no matching resource.

Note, do not call this function until a call to ConfirmSignatureL() has completed successfully.

See also: RResourceFile::Offset() TBafPanic for panic codes.

Parameters
aResourceId	The numeric id of the resource to be read.

Return Value: Pointer to a heap descriptor containing the resource.

Leave Codes
KErrNotFound	- there is no resource with aResourceId in the file.

Panic Codes
If	the file is corrupted - the method will panic in debug mode.

Close ( )

IMPORT_C void

(

)

Closes the resource file reader. This function is called after finishing reading all resources.

ConfirmSignatureL ( TInt )

IMPORT_C void

ConfirmSignatureL

(

TInt

aSignature

)

Initialises the offset value from the first resource.

The function assumes that the first resource in the file consists of two 32-bit integers. The first integer contains the version number and the second is a self-referencing link whose value is the offset for the resources in the file, plus 1.This function must be called before calling Offset(), AllocReadL(), AllocReadLC() or ReadL().

See also: TBafPanic for panic codes.

Parameters
aSignature	This argument value is not used by the function.

Leave Codes
KErrCorrupt	- wrong size of the first resource in the file. Probably the file is corrupted.

Panic Codes
If	the file is corrupted - the method will panic in debug mode.

ConfirmSignatureL ( )

IMPORT_C void

ConfirmSignatureL

(

)

Initialises the offset value from the first resource.

The function tests to catch cases where the first resource is not an RSS_SIGNATURE. It assumes that the first resource in the file consists of two 32-bit integers. The first integer contains the version number and the second is a self-referencing link whose value is the offset for the resources in the file, plus 1.This function must be called before calling Offset(), AllocReadL(), AllocReadLC() or ReadL().

See also: TBafPanic for panic codes.

Leave Codes
KErrCorrupt	- wrong size of the first resource in the file. Probably the file is corrupted.

Panic Codes
If	the file is corrupted - the method will panic in debug mode.

Offset ( )

TInt

Offset

(

)

const [inline]

Returns the offset value defined for this resource file.

This function must not be called until a call to ConfirmSignatureL() has completed successfully, otherwise the value returned by this function may be meaningless.

Return Value: The offset value defined for this resource file.

OpenL ( RFs &, const TDesC & )

IMPORT_C void	OpenL	(	RFs &	aFs,
			const TDesC &	aName
		)

Opens the resource file reader.

The resource file reader must be opened before reading resources or checking the signature of the resource file. This function initially closes the resource-file object if it is currently open. If a leave occurs during the function, the object is reverted to its closed state.

See also: TBafPanic for panic codes.

Parameters
aFs	Handle to a file server session.
aName	File to open as a resource file

Leave Codes
The	function leaves if the named file cannot be opened or the header record at the beginning of the file cannot be read.

Panic Codes
If	the file is corrupted - the method will panic in debug mode.

OpenL ( RFs &, const TDesC &, TUint, TInt )

IMPORT_C void	OpenL	(	RFs &	aFs,
			const TDesC &	aName,
			TUint	aFileOffset,
			TInt	aFileSize
		)

Opens the resource file reader.

See also: TBafPanic for panic codes.

Parameters
aFs	Handle to a file server session
aName	File to open as a resource file
aFileOffset	Resource file section offset from the beginning of the file.
aFileSize	Resource file section size.

Leave Codes
Function	leaves if the named file cannot be opened or the header record at the beginning of the file cannot be read.

Panic Codes
If	the file is corrupted - the method will panic in debug mode.

OwnsResourceId ( TInt )

IMPORT_C TBool

OwnsResourceId

(

TInt

aResourceId

)

const

Tests whether the resource file owns the specified resource id.

The resource file owns the resource id if the most significant 20 bits of the resource id are zero or match the offset value as returned from a call to the DeprecatedInterface is deprecated because it is unsafe as it may leave. Offset() member function.

Parameters
aResourceId	The resource id to test or if the resource id is not out of range.

Return Value: True, if the resource file owns the id, false otherwise.

OwnsResourceIdL ( TInt )

IMPORT_C TBool

OwnsResourceIdL

(

TInt

aResourceId

)

const

Tests whether the resource file owns the specified resource id.

The resource file owns the resource id if the most significant 20 bits of the resource id are zero or match the offset value as returned from a call to the Offset() member function or if the resource id is not out of range.

See also: TBafPanic for panic codes.

Parameters
aResourceId	The resource id to test.

Return Value: True, if the resource file owns the id, false otherwise.

Panic Codes
If	the file is corrupted - the method will panic in debug mode.

ReadL ( TDes8 &, TInt )

IMPORT_C void	ReadL	(	TDes8 &	aDes,
			TInt	aResourceId
		)	const

Reads a resource specified by resource id into the specified descriptor.

The descriptor must be long enough to contain the entire resource

The search for the resource uses the following algorithm:

A resource id in the range 1 to 4095 is looked up in this resource file. The function leaves if there is no matching resource.

Note, do not call this function until a call to ConfirmSignatureL() has completed successfully.

See also: TBafPanic for panic codes.

Parameters
aDes	On return, contains the resource that has been read. The function leaves if the descriptor is not long enough to contain the entire resource.
aResourceId	The numeric id of the resource to be read.

Leave Codes
The	function leaves if this resource id is not in this resource file.

Panic Codes
If	the file is corrupted - the method will panic in debug mode.

SignatureL ( )

IMPORT_C TInt

SignatureL

(

)

const

Returns this resource file's version number.

The function assumes that the first resource in the file consists of two 32-bit integers. The first integer contains the version number.

See also: RResourceFile::ConfirmSignatureL() TBafPanic for panic codes.

Return Value: The version number.

Leave Codes
KErrCorrupt	Wrong size of the first resource in the file. Probably the file is corrupted.

Panic Codes
If	the file is corrupted - the method will panic in debug mode.

UidType ( )

IMPORT_C TUidType

UidType

(

)

const

Retrieve the UID tuple of the opened resource file.

Pre-condition: OpenL() has been called successfully.

See also: TBafPanic for panic codes.

Return Value: The UIDs of the loaded resource file.

Panic Codes
If	the file is not opened or class data members initialization fails - the method will panic always.