RDirectScreenAccess Class Reference

class RDirectScreenAccess : public MWsClientClass

The interface between an application that directly accesses the screen and the window server.

Note that most applications that need to access the screen directly should use CDirectScreenAccess instead. RDirectScreenAccess only needs to be used directly by applications without access to an active scheduler.

Inherits from

Public Member Functions
RDirectScreenAccess()
RDirectScreenAccess(RWsSession &)
IMPORT_C voidCancel()
IMPORT_C voidClose()
IMPORT_C voidCompleted()
IMPORT_C TIntConstruct()
IMPORT_C TIntConstruct(TBool)
IMPORT_C TIntRequest(RRegion *&, TRequestStatus &, const RWindowBase &)
Inherited Functions
MWsClientClass::AddToBitmapArray(const TInt)const
MWsClientClass::AsyncRequest(TRequestStatus &,TUint)const
MWsClientClass::CachedWindowSize(TSize &)const
MWsClientClass::DestroyWindowNativeSizeCacheEntry()
MWsClientClass::DestroyWindowSizeCacheEntry()
MWsClientClass::EnableWindowNativeSizeCacheL()
MWsClientClass::MWsClientClass()
MWsClientClass::MWsClientClass(RWsBuffer *)
MWsClientClass::MarkWindowSizeCacheDirty()
MWsClientClass::RefreshWindowSizeCache(const TSize &)const
MWsClientClass::SetWindowNativeSize(const TSize &)const
MWsClientClass::WindowNativeSize(TSize &)const
MWsClientClass::WindowNativeSizeCacheEnabled()const
MWsClientClass::WindowSizeCacheEnabled()const
MWsClientClass::Write(TUint)const
MWsClientClass::Write(const TAny *,TInt,TUint)const
MWsClientClass::Write(const TAny *,TInt,const TAny *,TInt,TUint)const
MWsClientClass::WriteInt(TInt,TUint)const
MWsClientClass::WritePoint(const TPoint &,TUint)const
MWsClientClass::WriteRect(const TRect &,TUint)const
MWsClientClass::WriteReply(TUint,const TIpcArgs *)const
MWsClientClass::WriteReply(const TAny *,TInt,TUint,const TIpcArgs *)const
MWsClientClass::WriteReply(const TAny *,TInt,const TAny *,TInt,TUint,const TIpcArgs *)const
MWsClientClass::WriteReplyByProvidingRemoteReadAccess(const TAny *,TInt,const TReadDescriptorType &,TUint)const
MWsClientClass::WriteReplyInt(TInt,TUint,const TIpcArgs *)const
MWsClientClass::WriteReplyIntP(TInt,const TWriteDescriptorType &,TUint)const
MWsClientClass::WriteReplyP(const TAny *,TInt,const TAny *,TInt,const TWriteDescriptorType &,TUint)const
MWsClientClass::WriteReplyP(const TAny *,TInt,const TWriteDescriptorType &,TUint)const
MWsClientClass::WriteReplyP(const TWriteDescriptorType &,TUint)const
MWsClientClass::WriteSize(const TSize &,TUint)const
MWsClientClass::WsHandle()const
Public Member Enumerations
enumTPriority { EPriorityVeryHigh = 2000 }
enumTTerminationReasons { ETerminateCancel, ETerminateRegion, ETerminateScreenMode, ETerminateRotation }
Private Attributes
TRequestStatus *iDummyRequest
CDsaMsgQueue *iMsgQueue
RWsSession *iWs
RThread iWsThread
Inherited Attributes
MWsClientClass::iBuffer
MWsClientClass::iWsHandle

Constructor & Destructor Documentation

RDirectScreenAccess()

IMPORT_CRDirectScreenAccess()

Default constructor.

Developers should use the other constructor overload instead.

RDirectScreenAccess(RWsSession &)

IMPORT_CRDirectScreenAccess(RWsSession &aWs)

C++ constructor with a connected window server session.

Construct() must be called to complete construction.

Parameters

RWsSession & aWsConnected session with the window server.

Member Functions Documentation

Cancel()

IMPORT_C voidCancel()

Indicates to the window server that you have finished performing direct screen access.

Close()

IMPORT_C voidClose()

Calls Completed() then deletes the server side resource and sets the client's handle to it to NULL.

Completed()

IMPORT_C voidCompleted()

Indicates to the window server that you have responded to the completion of the request status passed to Request(), by stopping direct screen access.

Construct()

IMPORT_C TIntConstruct()

Second phase constructor.

Creates the server side resource and initialises the client's handle to it.

This function always causes a flush of the window server buffer.

panic
TW32Panic 17 in debug builds if called on an already constructed object.

Construct(TBool)

IMPORT_C TIntConstruct(TBoolaRegionTrackingOnly)

Second phase constructor. This is not supported in WSERV non NGA. It's available just when NGA is present.

Parameters

TBool aRegionTrackingOnly

Request(RRegion *&, TRequestStatus &, const RWindowBase &)

IMPORT_C TIntRequest(RRegion *&aRegion,
TRequestStatus &aStatus,
const RWindowBase &aWindow
)

Issues a request to the window server for permission to perform direct screen access on a window.

Direct access to the screen may be refused due to lack of memory or if the target window is completely obscured.

If direct access is allowed, the function passes back a clipping region which is the part of the screen the caller can draw to.

When direct screen access must stop, for instance because a dialog is to be displayed in front of the region where direct screen access is taking place, the window server completes the request. The recommended way to check for this is for aStatus to be the request status of an active object that will be run when the request completes, i.e. if Request() returns KErrNone, call SetActive(), and in the object's RunL(), you should immediately abort direct screen access.

While the DSA is in operation, it is strongly advised that the client should not make any call to WSERV that will affect the visible area of the window in which the DSA is taking place.

When WSERV tells the client that it needs to abort its DSA, it waits to receive the acknowledgment from the client that it has done so. However, it doesn't wait for ever, since the client may have entered some long running calculation or even an infinite loop. So WSERV also waits on a timer: if the timer expires before the client acknowledges, then WSERV continues; if, later on, WSERV gets notification from the client that it has aborted the DSA, then WSERV will invalidate the region in which the DSA was taking place, just in case there had been a conflict between the DSA and another client.

This function always causes a flush of the window server buffer.

Parameters

RRegion *& aRegionOn return, the clipping region that the caller can draw to. NULL if the function was not successful. If the target window is invisible or completely covered by other windows then the region will be empty.
TRequestStatus & aStatusA request status that is set to a completion code by the window server when direct screen access must stop.
const RWindowBase & aWindowThe window that you want to perform the direct screen access on. There must not already be direct access on this window or a panic occurs.

Member Enumerations Documentation

Enum TPriority

The priority of the active object that responds to notification that direct screen access must stop.

Enumerators

EPriorityVeryHigh = 2000

A suggested value for the priority of the active object that responds to notification from the window server that direct screen access must stop. This is also the value used by CDirectScreenAccess for this purpose.

Enum TTerminationReasons

Provides the reason why direct screen access must terminate. This enum is used in the MAbortDirectScreenAccess::AbortNow() and MDirectScreenAccess::Restart() functions.

The first value (ETerminateCancel) indicates that direct screen access is being terminated by the application. The final three values indicate that direct screen access is being terminated by the window server. Note that for users of CDirectScreenAccess, the termination code is not important because these issues are dealt with by CDirectScreenAccess::StartL().

Enumerators

ETerminateCancel

The application has finished direct screen access.

ETerminateRegion

A window is about to come in front of a part of the area that is being used for direct screen access.

ETerminateScreenMode

The screen's color depth (as enumerated by TDisplayMode) is about to change.

ETerminateRotation

The current screen mode (the combination of screen rotation and screen size) is about to change.

Member Data Documentation

TRequestStatus * iDummyRequest

TRequestStatus *iDummyRequest[private]

CDsaMsgQueue * iMsgQueue

CDsaMsgQueue *iMsgQueue[private]

RWsSession * iWs

RWsSession *iWs[private]

RThread iWsThread

RThread iWsThread[private]