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Editor/XT/Include/XTDropSource.h

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+// XTDropSource.h : header file
+//
+// This file is a part of the Xtreme Toolkit for MFC.
+// <20>1998-2003 Codejock Software, All Rights Reserved.
+//
+// This source code can only be used under the terms and conditions 
+// outlined in the accompanying license agreement.
+//
+// support@codejock.com
+// http://www.codejock.com
+//
+//////////////////////////////////////////////////////////////////////
+
+#ifndef __XTDROPSOURCE_H__
+#define __XTDROPSOURCE_H__
+
+#if _MSC_VER > 1000
+#pragma once
+#endif // _MSC_VER > 1000
+
+// NUMBERED LIST:
+
+//////////////////////////////////////////////////////////////////////
+// Summary: CXTDropSource class is derived from IDropSource.  It is used by the
+//			shell list control to provide drag-and-drop operations in your application. 
+//
+//			It contains methods used in any application used as a data source in
+//			a drag-and-drop operation. The data source application in a drag-and-drop
+//			operation is responsible for: 
+//			[ol]
+//			[li]Determining the data being dragged based on the user's selection.[/li]
+//			[li]Initiating the drag-and-drop operation based on the user's mouse actions. [/li]
+//			[li]Generating some of the visual feedback during the drag-and-drop operation, such
+//			as setting the cursor and highlighting the data selected for the
+//			drag-and-drop operation.[/li]
+//			[li]Canceling or completing the drag-and-drop operation based on the
+//			user's mouse actions.[/li]
+//			[li]Performing any action on the original data caused by the drop operation,
+//			such as deleting the data on a drag move.[/li]
+//			[/ol]
+//			CXTDropSource contains the methods for generating visual feedback to
+//			the end user and for canceling or completing the drag-and-drop operation.
+//			You also need to call the DoDragDrop, RegisterDragDrop, and RevokeDragDrop
+//			functions in drag-and-drop operations.
+class _XT_EXT_CLASS CXTDropSource : public IDropSource
+{
+protected:
+	
+	UINT m_uiRefCount; // Indicates the current reference count.
+
+public: 
+	// Summary: Constructs a CXTDropSource object.
+	CXTDropSource();
+	
+	// Summary: Destroys a CXTDropSource object, handles clean up and de-allocation.
+	~CXTDropSource();
+
+	//////////////////////////////////////////////////////////////////////
+	// IUnknown Interface Members
+	//////////////////////////////////////////////////////////////////////
+
+	// Input:	riid - Identifier of the interface being requested. 
+	//			ppReturn - Address of the pointer variable that receives the interface pointer
+	//			requested in 'riid'. Upon successful return, 'ppReturn' contains
+	//			the requested interface pointer to the object. If the object does
+	//			not support the interface specified in 'riid', 'ppReturn' is set to NULL. 
+	// Returns: A pointer to an interface if successful, otherwise returns NULL.
+	// Summary:	The QueryInterface method gives a client access to other interfaces
+	//			on an object. For any one object, a specific query for the IUnknown
+	//			interface on any of the object's interfaces must always return the
+	//			same pointer value. This allows a client to determine whether two pointers
+	//			point to the same component by calling QueryInterface on both, and comparing
+	//			the results. It is specifically not the case that queries for interfaces
+	//			(even the same interface through the same pointer) must return the
+	//			same pointer value.
+	STDMETHODIMP QueryInterface(REFIID riid, LPVOID* ppReturn);
+
+	// Returns: A ULONG value that represents the new reference count.  The return value can be an 
+	//			integer from 1 to n, the value of the new reference count. This information
+	//			is meant to be used for diagnostic and testing purposes only, because, in certain 
+	//			situations, the value may be unstable.
+	// Summary:	The AddRef method increments the reference count for an interface on
+	//			an object.  It should be called for every new copy of a pointer to
+	//			an interface on a given object.  
+	STDMETHODIMP_(ULONG) AddRef(void);
+
+	// Returns: A ULONG value that represents the resulting value of the reference count,
+	//			which is used for diagnostic and testing purposes only. 
+	// Summary:	This method decrements the reference count for the calling interface
+	//			on a object. If the reference count on the object falls to 0, the object
+	//			is freed from memory. 
+	STDMETHODIMP_(ULONG) Release(void);
+
+	//////////////////////////////////////////////////////////////////////
+	// IDropSource Interface Members
+	//////////////////////////////////////////////////////////////////////
+
+	// BULLETED LIST:
+
+	// Input:	bEsc - Specifies whether the ESC key has been pressed since the previous
+	//			call to QueryContinueDrag, or to DoDragDrop if this is the first call
+	//			to QueryContinueDrag.  A TRUE value indicates the end user has pressed
+	//			the escape key.  A FALSE value indicates it has not been pressed. 
+	//			dwKeyState - Current state of the keyboard modifier keys on the keyboard. Valid
+	//			values can be a combination of any of the flags MK_CONTROL, MK_SHIFT,
+	//			MK_ALT, MK_BUTTON, MK_LBUTTON, MK_MBUTTON, and MK_RBUTTON. 
+	// Returns: An HRESULT value.
+	// Summary:	This method determines whether a drag-and-drop operation should be
+	//			continued, canceled, or completed.  You do not call this method directly.
+	//			The OLE DoDragDrop function calls this method during a drag-and-drop
+	//			operation.  This method supports the standard return values E_UNEXPECTED
+	//			and E_OUTOFMEMORY, as well as the following:
+	//			[ul]
+	//			[li]<b>S_OK</b> Drag operation should continue. This result occurs if no
+	//			errors are detected, the mouse button starting the drag-and-drop
+	//			operation has not been released, and the ESC key has not been detected.[/li]
+	//			[li]<b>DRAGDROP_S_DROP</b> Drop operation should occur completing the drag
+	//			operation. This result occurs if DWORD indicates that the key that
+	//			started the drag-and-drop operation has been released.[/li]
+	//			[li]<b>DRAGDROP_S_CANCEL</b> Drag operation should be canceled with no drop
+	//			operation occurring. This result occurs if BOOL is TRUE, indicating
+	//			the ESC key has been pressed.[/li]
+	//			[/ul]
+	STDMETHODIMP QueryContinueDrag(BOOL bEsc,DWORD dwKeyState);
+	
+	// BULLETED LIST:
+
+	// Input:	DWORD - Effect of a drop operation.
+	// Returns: An HRESULT value.
+	// Summary:	This method enables a source application to give visual feedback to
+	//			the end user during a drag-and-drop operation by providing the DoDragDrop
+	//			function with an enumeration value specifying the visual effect. This
+	//			method supports the standard return values E_INVALIDARG, E_UNEXPECTED,
+	//			and E_OUTOFMEMORY, as well as the following: 
+	//			[ul]
+	//			[li]<b>S_OK</b> Method completed its task successfully, using the cursor
+	//			set by the source application.[/li]
+	//			[li]<b>DRAGDROP_S_USEDEFAULTCURSORS</b> Successful completion of the method,
+	//			and requests OLE to update the cursor using the OLE-provided default
+	//			cursors.[/li]
+	//			[/ul]
+	STDMETHODIMP GiveFeedback(DWORD);
+};
+
+//////////////////////////////////////////////////////////////////////
+
+#endif // __XTDROPSOURCE_H__