Method Initialize

ShellExtension/ShellExtension/WinMergeShell.cpp:148–231

Reads selected paths

/// Reads selected paths
HRESULT CWinMergeShell::Initialize(LPCITEMIDLIST pidlFolder,
		LPDATAOBJECT pDataObj, HKEY hProgID)
{
	HRESULT hr = E_INVALIDARG;

	std::vector<std::wstring> paths;

	// Files/folders selected normally from the explorer
	if (pDataObj)
	{
		FORMATETC fmt = {CF_HDROP, NULL, DVASPECT_CONTENT, -1, TYMED_HGLOBAL};
		STGMEDIUM stg = {TYMED_HGLOBAL};
		HDROP hDropInfo;

		// Look for CF_HDROP data in the data object.
		if (FAILED(pDataObj->GetData(&fmt, &stg)))
			// Nope! Return an "invalid argument" error back to Explorer.
			return E_INVALIDARG;

		// Get a pointer to the actual data.
		hDropInfo = (HDROP) GlobalLock(stg.hGlobal);

		// Make sure it worked.
		if (NULL == hDropInfo)
			return E_INVALIDARG;

		// Sanity check & make sure there is at least one filename.
		UINT uNumFilesDropped = DragQueryFile(hDropInfo, 0xFFFFFFFF, NULL, 0);

		if (uNumFilesDropped == 0)
		{
			GlobalUnlock(stg.hGlobal);
			ReleaseStgMedium(&stg);
			return E_INVALIDARG;
		}

		hr = S_OK;

		/// Max. filecount to select
		constexpr unsigned MaxFileCount = 3u;

		// Get all file names.
		for (UINT x = 0 ; x < (std::min)(MaxFileCount + 1, uNumFilesDropped); x++)
		{
			// Get the number of bytes required by the file's full pathname
			UINT wPathnameSize = DragQueryFile(hDropInfo, x, NULL, 0);

			// Allocate memory to contain full pathname & zero byte
			wPathnameSize += 1;
			LPTSTR npszFile = (TCHAR *) new TCHAR[wPathnameSize];

			// If not enough memory, skip this one
			if (npszFile == NULL)
				continue;

			// Copy the pathname into the buffer
			DragQueryFile(hDropInfo, x, npszFile, wPathnameSize);