DROPSRC.CPP

/* 
* DROPSRC.CPP
* Patron Chapter 24
*
* Implementation of a DropSource object.
*
* Copyright (c)1993-1995 Microsoft Corporation, All Rights Reserved
*
* Kraig Brockschmidt, Microsoft
* Internet : kraigb@microsoft.com
* Compuserve: >INTERNET:kraigb@microsoft.com
*/


#include "patron.h"


/*
* CDropSource::CDropSource
* CDropSource::~CDropSource
*
* Constructor Parameters:
* None
*/

CDropSource::CDropSource(void)
{
m_cRef=0;
return;
}

CDropSource::~CDropSource(void)
{
return;
}




/*
* CDropSource::QueryInterface
* CDropSource::AddRef
* CDropSource::Release
*
* Purpose:
* IUnknown members for CDropSource object.
*/

STDMETHODIMP CDropSource::QueryInterface(REFIID riid, PPVOID ppv)
{
*ppv=NULL;

if (IID_IUnknown==riid || IID_IDropSource==riid)
*ppv=this;

if (NULL!=*ppv)
{
((LPUNKNOWN)*ppv)->AddRef();
return NOERROR;
}

return ResultFromScode(E_NOINTERFACE);
}


STDMETHODIMP_(ULONG) CDropSource::AddRef(void)
{
return ++m_cRef;
}

STDMETHODIMP_(ULONG) CDropSource::Release(void)
{
if (0!=--m_cRef)
return m_cRef;

delete this;
return 0;
}





/*
* CDropSource::QueryDragContinue
*
* Purpose:
* Determines whether to continue a drag operation or cancel it.
*
* Parameters:
* fEsc BOOL indicating that the ESC key was pressed.
* grfKeyState DWORD providing states of keys and mouse buttons
*
* Return Value:
* HRESULT DRAGDROP_S_CANCEL to stop the drag,
* DRAGDROP_S_DROP to drop the data where it is,
* or NOERROR to continue.
*/

STDMETHODIMP CDropSource::QueryContinueDrag(BOOL fEsc, DWORD grfKeyState)
{
if (fEsc)
return ResultFromScode(DRAGDROP_S_CANCEL);

if (!(grfKeyState & MK_LBUTTON))
return ResultFromScode(DRAGDROP_S_DROP);

return NOERROR;
}






/*
* CDropSource::GiveFeedback
*
* Purpose:
* Provides cursor feedback to the user since the source task
* always has the mouse capture. We can also provide any other
* type of feedback above cursors if we so desire.
*
* Parameters:
* dwEffect DWORD effect flags returned from the last target
*
* Return Value:
* HRESULT NOERROR if you set a cursor yourself or
* DRAGDROP_S_USEDEFAULTCURSORS to let OLE do
* the work.
*/

STDMETHODIMP CDropSource::GiveFeedback(DWORD dwEffect)
{
return ResultFromScode(DRAGDROP_S_USEDEFAULTCURSORS);
}