// TortoiseGit - a Windows shell extension for easy version control

// Copyright (C) 2003-2010, 2020 - TortoiseSVN

// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software Foundation,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//

#pragma once

class CClipboardHelper
{
public:
	CClipboardHelper() : bClipBoardOpen(false) {}
	~CClipboardHelper();
	bool Open(HWND hOwningWnd);
	static HGLOBAL GlobalAlloc(SIZE_T dwBytes);
private:
	bool bClipBoardOpen;
};

inline CClipboardHelper::~CClipboardHelper()
{
	if (bClipBoardOpen)
		CloseClipboard();
}

inline bool CClipboardHelper::Open(HWND hOwningWnd)
{
	// OpenClipboard may fail if another application has opened the clipboard.
	// Try up to 8 times, with an initial delay of 1 ms and an exponential back off
	// for a maximum total delay of 127 ms (1+2+4+8+16+32+64).
	const int tries = 8;
	for (int attempt = 0; attempt < tries; ++attempt)
	{
		if (attempt > 0)
			::Sleep(1 << (attempt - 1));
		bClipBoardOpen = (OpenClipboard(hOwningWnd) != 0);
		if (bClipBoardOpen)
			return true;
	}
	return false;
}

inline HGLOBAL CClipboardHelper::GlobalAlloc(SIZE_T dwBytes)
{
	return ::GlobalAlloc(GMEM_MOVEABLE, dwBytes);
}
