KernelDragTarget Class Reference

An instantiation of this class is created by each entity which wishes to provide a 'destination' to which the mouse can go to complete a drag. KernelDragTargets are used as a base class from which to derive drag targets for KERNEL entities (usually a DialogOp and optional Gadget ID). More...

#include <dragtrgt.h>

Inheritance diagram for KernelDragTarget:

List of all members.


Public Member Functions
	KernelDragTarget (DialogOp *TheDialog, CGadgetID TheGadget=NULL)
	Constructs a KernelDragTarget, AND REGISTERS it with the current DragManagerOp This is used as a drag target for entities existing in the kernel (usually DialogOps).
virtual BOOL	IsAKernelObject (void)
	Virtual method to determine if a given DragTarget is of the Kernel or Winoil 'gender'.
Protected Member Functions
virtual BOOL	ProcessEvent (DragEventType Event, DragInformation pDragInfo, OilCoord pMousePos, KeyPress *pKeyPress)
	To process a drag-specific event. By default this method does nothing, just returning FALSE so that the event is left unclaimed, and is thus passed on to other interested drag targets.
virtual void	GetTargetAreaInfo (DialogOp *ReturnedDialog, CGadgetID ReturnedGadget)
	Kernel method for determining target-area information.
Protected Attributes
DialogOp *	TargetDialog
CGadgetID	TargetGadget
Friends
class	DragManagerOp

Detailed Description

Author:: Jason_Williams (Xara Group Ltd) <camelotdev@xara.com>

Date:: 2/1/95

Notes: Drag targets are destructed automatically when a drag finishes by the drag manager with which they were registered.

To remove a drag target at any time, destruct it - it automatically deregisters and cleans up.

See also:: DragManagerOp::StartDrag; DragInformation; DragTarget

Documentation: Docs.doc

Definition at line 300 of file dragtrgt.h.

Constructor & Destructor Documentation

KernelDragTarget::KernelDragTarget ( DialogOp * TheDialog,

CGadgetID TheGadget = NULL

)

Constructs a KernelDragTarget, AND REGISTERS it with the current DragManagerOp This is used as a drag target for entities existing in the kernel (usually DialogOps).

Author:
Jason_Williams (Xara Group Ltd) <camelotdev@xara.com>

Date:
3/1/95

Parameters:

TheDialog - NULL (see Notes), or the kernel DialogOp providing the drag target [INPUTS] TheGadget - NULL (see Notes), or the ID of the gadget within that dialogue which is the drag target area.

Notes: If both parameters are NULL, then this DragTarget is not associated with any particular area of the screen, and will recieve all drag events (that are not claimed by another such global event processor). It is not expected that kernel drag processors will be used in this way
If TheGadget is NULL, then the entire dialogue client area will be considered the target area. Otherwise, only that gadget is used as the target.

See also:
OilDragTarget::OilDragTarget; DragManagerOp

Returns:
Errors: In debug builds, an ERROR3 will occur if there is no active drag manager (no drag occurring), and the DragTarget will probably appear as a memory leak (as the Drag manager is normally responsible for deleting the drag targets registered with it)
Documentation: Docs.doc
Definition at line 396 of file dragtrgt.cpp.
00397 { 00398 TargetDialog = TheDialog; 00399 TargetGadget = TheGadget; 00400 00401 // PORTNOTE("other", "Removed DragManagerOp usage") 00402 //#ifndef EXCLUDE_FROM_XARALX 00403 // Register this drag target automatically with the system 00404 DragManagerOp *DragMan = DragManagerOp::GetCurrentManager(); 00405 if (DragMan != NULL) 00406 DragMan->RegisterTarget(this, (TheDialog == NULL)); 00407 #ifdef _DEBUG 00408 else 00409 ERROR3("There is no active drag (when attempting to create a DragTarget)"); 00410 #endif 00411 //#endif 00412 }

Member Function Documentation

void KernelDragTarget::GetTargetAreaInfo ( DialogOp ** ReturnedDialog,

CGadgetID * ReturnedGadget

) [protected, virtual]

Kernel method for determining target-area information.

Author:
Jason_Williams (Xara Group Ltd) <camelotdev@xara.com>

Date:
10/1/95

Parameters:

ReturnedDialog - Filled in with a pointer to the dialogop of the target area [OUTPUTS] ReturnedGadget - Filled in with the gadget containing the target area

Documentation: Docs.doc
Reimplemented from DragTarget.
Definition at line 495 of file dragtrgt.cpp.
00496 { 00497 *ReturnedDialog = TargetDialog; 00498 *ReturnedGadget = TargetGadget; 00499 }

BOOL KernelDragTarget::IsAKernelObject ( void ) [virtual]

Virtual method to determine if a given DragTarget is of the Kernel or Winoil 'gender'.

Author:
Jason_Williams (Xara Group Ltd) <camelotdev@xara.com>

Date:
3/1/95

Returns:
TRUE (This is a kernel object, not a winoil one)
Notes: Don't override this! Derive from KernelDragTarget or OilDragTarget
Documentation: Docs.doc
Reimplemented from DragTarget.
Definition at line 434 of file dragtrgt.cpp.
00435 { 00436 return(TRUE); 00437 }

BOOL KernelDragTarget::ProcessEvent ( DragEventType Event,

DragInformation * pDragInfo,

OilCoord * pMousePos,

KeyPress * pKeyPress

) [protected, virtual]

To process a drag-specific event. By default this method does nothing, just returning FALSE so that the event is left unclaimed, and is thus passed on to other interested drag targets.

Author:
Jason_Williams (Xara Group Ltd) <camelotdev@xara.com>

Date:
9/1/95

Parameters:

Event - Specifies what type of event has occurred [INPUTS] pDragInfo - Specifies a descriptor describing the currently active drag pMousePos - Specifies the last known mouse coordinates, in terms of OilCoords (Millipoint offsets within the drag target window/gadget) pKeyPress - NULL, or a pointer to the key pressed (for KEYPRESS events)

Notes: Each derived DragTarget class should override this method to handle events in a manner appropriate for the target.
BE VERY CAREFUL to only override the kernel parts of this interface!

See also:
keyword DragEventType
Documentation: Docs.doc
Reimplemented from DragTarget.
Reimplemented in ColEditorDragTarget, SGNameDragTarget, SGBitmapDragTarget, SGColourDragTarget, SGScrollDragTarget, SGListDragTarget, SGClipartDragTarget, SGFillsDragTarget, SGNameDragTarget, SGFontsDragTarget, and SGLineDragTarget.
Definition at line 470 of file dragtrgt.cpp.
00472 { 00473 return(FALSE); // We do not claim the event 00474 }