将文本设置为大量数据后，Edit Control 的空闲堆？

Question

我在提取大量数据到 CEditView 然后设置回少量数据后，在任务管理器中查看我的进程。我注意到提交大小保持很大。然后我使用 VMMMap 也看到了它，所以我在 VS2017 诊断工具中做了“内存使用情况”。我看到它最终来自 ::SetWindowText() 调用。所以这显然在堆上分配了一个大缓冲区，但是当我将它设置回少量时，分配保持很大。问题是，有没有办法让 Edit Control 释放它不需要的内存以减少文本量以减少提交的内存？比如说，我可以在设置新文本之前释放它，它会根据需要分配？

谢谢！！

Answer 1

  // From within CEditView
  
  // based on an answer RbMm using EM_GETHANDLE/EM_SETHANDLE and further
  // from 
 
  // reduce size to 64K if larger than that and not needed
  #define EDITctrlLimitSize 65536  
 
  // check if we should reduce size of buffer
  HLOCAL horgmem = (HLOCAL) SendMessage(EM_GETHANDLE,0,0);
  SIZE_T sizeused=LocalSize(horgmem);
 
  int cbCh = sizeof(TCHAR) > 1 ? sizeof(TCHAR) : IsUsingComCtlV6() ? sizeof(WCHAR) : sizeof(char);
  if (sizeused > EDITctrlLimitSize && (string.GetLength()*cbCh) < EDITctrlLimitSize) {
    // EM_GETHANDLE says to not change the data, yet EM_SETHANDLE tells you to
    // get the handle then LocalFree it, so why not just LocalReAlloc it and set
    // again.
    HLOCAL hnewmem=(HLOCAL) LocalReAlloc(horgmem, EDITctrlLimitSize, LMEM_MOVEABLE);
    if (hnewmem) {
      // zero full buffer because seems like good thing to do
      LPVOID pnewmem=LocalLock(hnewmem);
      if (pnewmem) {
        memset(pnewmem, 0, EDITctrlLimitSize);
        LocalUnlock(hnewmem);
      }

      // viola - process memory reduced.
      SendMessage(EM_SETHANDLE, (WPARAM) hnewmem, 0);
    }
  }

将文本设置为大量数据后，Edit Control 的空闲堆？

Free Heap of Edit Control after setting the text to a large amount of data?

winapi

memory-management

comctl32