CDCHandle谨慎使用

LRESULT OnPaint(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)
{
  //HDC hdc = (HDC)wParam
  CPaintDC dc(m_hWnd);
  DoPaint(dc);

  bHandled = FALSE;
  return 0;
}

void DoPaint(CPaintDC& dc)
{

  CDCHandle _dc;
  HDC hdcDestop = ::GetDC(NULL);
  _dc.CreateCompatibleDC(hdcDestop);
  _dc.SelectBitmap(bitmap);

  dc.StretchBlt(rect.left, rect.top, rect.right, rect.bottom, _dc, 0, 0, 20, 20, SRCCOPY);

::ReleaseDC(NULL, hdcDestop);
_dc.DeleteDC();
}

如果此时没有 _dc.DeleteDC(); 那么重新事件后界面会成空白

dc使用原则.

Create用Delete

Get用Release

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