src/Utils/ClipboardHelper.h

   1 // TortoiseGit - a Windows shell extension for easy version control
   2
   3 // Copyright (C) 2003-2010, 2020 - TortoiseSVN
   4
   5 // This program is free software; you can redistribute it and/or
   6 // modify it under the terms of the GNU General Public License
   7 // as published by the Free Software Foundation; either version 2
   8 // of the License, or (at your option) any later version.
   9
  10 // This program is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14
  15 // You should have received a copy of the GNU General Public License
  16 // along with this program; if not, write to the Free Software Foundation,
  17 // 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 //
  19
  20 #pragma once
  21
  22 class CClipboardHelper
  23 {
  24 public:
  25         CClipboardHelper() : bClipBoardOpen(false) {}
  26         ~CClipboardHelper();
  27         bool Open(HWND hOwningWnd);
  28         static HGLOBAL GlobalAlloc(SIZE_T dwBytes);
  29 private:
  30         bool bClipBoardOpen;
  31 };
  32
  33 inline CClipboardHelper::~CClipboardHelper()
  34 {
  35         if (bClipBoardOpen)
  36                 CloseClipboard();
  37 }
  38
  39 inline bool CClipboardHelper::Open(HWND hOwningWnd)
  40 {
  41         // OpenClipboard may fail if another application has opened the clipboard.
  42         // Try up to 8 times, with an initial delay of 1 ms and an exponential back off
  43         // for a maximum total delay of 127 ms (1+2+4+8+16+32+64).
  44         const int tries = 8;
  45         for (int attempt = 0; attempt < tries; ++attempt)
  46         {
  47                 if (attempt > 0)
  48                         ::Sleep(1 << (attempt - 1));
  49                 bClipBoardOpen = (OpenClipboard(hOwningWnd) != 0);
  50                 if (bClipBoardOpen)
  51                         return true;
  52         }
  53         return false;
  54 }
  55
  56 inline HGLOBAL CClipboardHelper::GlobalAlloc(SIZE_T dwBytes)
  57 {
  58         return ::GlobalAlloc(GMEM_MOVEABLE, dwBytes);
  59 }