139 lines
3.5 KiB
Plaintext
139 lines
3.5 KiB
Plaintext
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/*--------------------------------------------------------------------------*
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*
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* Microsoft Windows
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* Copyright (C) Microsoft Corporation, 1992 - 000
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*
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* File: guidhelp.inl
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*
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* Contents:
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*
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* History: 13-Apr-2000 jeffro Created
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*
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*--------------------------------------------------------------------------*/
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#pragma once
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#include "xmlbase.h" // for CXMLBinary
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/*+-------------------------------------------------------------------------*
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* ExtractString
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*
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* Gets string data representing the given clipboard format from the data
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* object. StringType must be a type that can accept assignment from
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* LPCTSTR (WTL::CString, CStr, tstring, etc.)
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*
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* Many (many!) implementations of IDataObject::GetDataHere incorrectly call
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* CreateStreamOnHGlobal using the HGLOBAL we get them (calling it is
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* incorrect because GetDataHere is specifically forbidden from reallocating
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* the medium that is given to it, which the IStream implementation returned
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* from CreateStreamOnHGlobal will do if it needs more room).
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*
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* We would be more robust if we used TYMED_STREAM in preference to
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* TYMED_HGLOBAL, if the snap-in supported it.
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*--------------------------------------------------------------------------*/
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template<class StringType>
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HRESULT ExtractString (
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IDataObject* piDataObject,
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CLIPFORMAT cfClipFormat,
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StringType& str)
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{
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DECLARE_SC (sc, _T("ExtractString"));
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sc = ScCheckPointers (piDataObject);
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if (sc)
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return (sc.ToHr());
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/*
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* clear out the output
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*/
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str = _T("");
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FORMATETC formatetc = {cfClipFormat, NULL, DVASPECT_CONTENT, -1, TYMED_HGLOBAL};
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STGMEDIUM stgmedium = {TYMED_HGLOBAL, NULL};
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CXMLBinary xmlBin;
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/*
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* 1024 isn't a random number. It must be (at least) this large to
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* maintain compatibility with buggy snap-ins.
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*/
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const int cchGrow = 1024;
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int cchBuffer = 0;
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/*
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* to enter the loop the first time
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*/
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sc = STG_E_MEDIUMFULL;
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while (sc == STG_E_MEDIUMFULL)
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{
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/*
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* increase the buffer size
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*/
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cchBuffer += cchGrow;
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const int cbBuffer = cchBuffer * sizeof(WCHAR);
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/*
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* Allocate a buffer for the string. In the reallocation case,
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* it is safe to store the return value from GlobalReAlloc in
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* stgmedium.hGlobal because the original handle is also held
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* in autoGlobal
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*/
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if (cchBuffer == cchGrow)
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sc = xmlBin.ScAlloc (cbBuffer, true /* fZeroInit */);
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else
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sc = xmlBin.ScRealloc (cbBuffer, true /* fZeroInit */);
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if (sc)
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return (sc.ToHr());
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/*
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* get the HGLOBAL out of the CXMLBinary
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*/
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stgmedium.hGlobal = xmlBin.GetHandle();
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sc = ScCheckPointers (stgmedium.hGlobal, E_UNEXPECTED);
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if (sc)
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return (sc.ToHr());
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/*
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* get the string from the data object
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*/
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sc = piDataObject->GetDataHere (&formatetc, &stgmedium);
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// don't check for error here, it'll be checked at the top of the loop
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}
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/*
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* this will handle all non-STG_E_MEDIUMFULL errors from
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* IDataObject::GetDataHere
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*/
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if (sc)
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{
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// don't trace these errors
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SC scTemp = sc;
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sc.Clear();
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return scTemp.ToHr();
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}
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/*
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* lock down the returned data in preparation for copying
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*/
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CXMLBinaryLock lock (xmlBin);
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LPWSTR pchBuffer = NULL;
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sc = lock.ScLock (&pchBuffer);
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if (sc)
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return (sc.ToHr());
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/*
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* Copy the string. The termination isn't unjustified paranoia.
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* Many implementations of IDataObject::GetDataHere don't terminate
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* their strings.
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*/
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USES_CONVERSION;
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pchBuffer[cchBuffer-1] = 0;
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str = W2CT (pchBuffer);
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return (sc.ToHr());
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}
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