虚拟列表的注意事项

来源：互联网发布：重装系统怎么保留软件编辑：程序博客网时间：2024/04/24 18:32

树控件中使用虚拟列表

插入时使用

    TVITEM tvItem;
    ZeroMemory(&tvItem, sizeof(tvItem));
    tvItem.mask = TVIF_TEXT | TVIF_IMAGE |TVIF_CHILDREN |TVIF_SELECTEDIMAGE | TVIF_PARAM;
    tvItem.pszText = lpsfi.szDisplayName;
    tvItem.cchTextMax = lstrlen(lpsfi.szDisplayName);
    tvItem.iImage = lpsfi.iIcon;
    tvItem.cChildren = lpsfi.dwAttributes & SFGAO_HASSUBFOLDER ? I_CHILDRENCALLBACK : 0;
    tvItem.iSelectedImage = lpsfi.iIcon;
    tvItem.lParam = FALSE;

    TV_INSERTSTRUCT tvis;
    tvis.item = tvItem;
    tvis.hParent = hItem;
    HTREEITEM hChild = InsertItem(&tvis);
然后

void CExpTree::OnGetdispinfo(NMHDR* pNMHDR, LRESULT* pResult)
{
TV_DISPINFO* pTVDispInfo = (TV_DISPINFO*)pNMHDR;
TVITEM *pitem = &(pTVDispInfo)->item;
if (pitem->mask & TVIF_CHILDREN && pitem->hItem != NULL )
{
pitem->cChildren = 1;
}
*pResult = 0;
}

展开时

void CExpTree::OnItemexpanding(NMHDR* pNMHDR, LRESULT* pResult)
{
static bool bfirst = 1;

NM_TREEVIEW* pNMTreeView = (NM_TREEVIEW*)pNMHDR;
if(pNMHDR->code == TVN_ITEMEXPANDING && bfirst == 0)
{
  NM_TREEVIEW* pNMTreeView = (NM_TREEVIEW*)pNMHDR;
  // TODO: Add your control notification handler code here
  HTREEITEM hItemNew = pNMTreeView->itemNew.hItem;

  if(hItemNew != NULL &&
   pNMTreeView->action == TVE_EXPAND &&
   lpMalloc != NULL
   )
  {

   SetRedraw(FALSE);
   this->LockWindowUpdate();
   //     DeleteTree(hItemNew);
   InsertChildItem(hItemNew);
   UnlockWindowUpdate();
   SetRedraw(TRUE);
  }
}
bfirst = 0;
*pResult = 0;
}

展开后

void CExpTree::OnItemexpanded(NMHDR* pNMHDR, LRESULT* pResult)
{
if (pNMHDR->code == TVN_ITEMEXPANDED)
{
  NM_TREEVIEW* pNMTreeView = (NM_TREEVIEW*)pNMHDR;
  // TODO: Add your control notification handler code here
  HTREEITEM hItemNew = pNMTreeView->itemNew.hItem;
  if(hItemNew != NULL && pNMTreeView->action == TVE_COLLAPSE && lpMalloc != NULL)
   //  && pNMTreeView->itemNew.lParam == PARENT_NODE)
  {
   Expand(hItemNew ,TVE_COLLAPSE);
  }
}

*pResult = 0;
}

而列表控件的虚列表的使用为

插入时
void CUploadDlg::Add2SelList(int nItem)
{
CString strFileName = m_PicList.GetItemText(nItem, 0);
CString strFile = m_PicList.m_strDir + "//" + strFileName;
if(find(m_vFile.begin(), m_vFile.end(), strFile) != m_vFile.end())
return;

m_nTotalSize += GetFileSize(strFile);
if(m_nTotalSize > TOTALSIZE)
  return;
CProgressCtrl *pProg = (CProgressCtrl*)GetDlgItem(IDC_PROGRESS);
pProg->SetPos((float)m_nTotalSize / TOTALSIZE * 100);
CString str;
str.Format("可用空间%dM,已选择上传%0.2fK",TOTALSIZE / 1024 /1024,(float)m_nTotalSize/1024);
SetDlgItemText(IDC_TOTAL, str);
int nIndex = m_SelList.GetItemCount();
m_SelectImgList.SetImageCount(nIndex + 1);
m_SelList.InsertItem(nIndex,strFileName, I_IMAGECALLBACK );
m_vFile.push_back(strFile);
}
然后
void CUploadDlg::OnGetdispinfoImagelist(NMHDR* pNMHDR, LRESULT* pResult)
{
LV_DISPINFO* pDispInfo = (LV_DISPINFO*)pNMHDR;
// TODO: Add your control notification handler code here
LV_ITEM *pItem = &(pDispInfo)->item;
if(pItem->mask & LVIF_IMAGE)
{
  if(pItem->iImage == -1)
  {
   pItem->mask |= LVIF_DI_SETITEM ;
   pItem->iImage = pItem-> iItem;
   m_PicList.ReplaceImage(m_SelectImgList, pItem->iItem,
    m_vFile[pItem->iItem]);

}
}
*pResult = 0;
}

注意差别，列表控件中使用了
pItem->mask |= LVIF_DI_SETITEM ;

这样使系统在本次请求后保存数据，不会再次发送这个ITEM的请求，

否则的话会刷新一次就请求一次，导致显示很慢。

而树控件里面还未找到相应的解决办法，是一直在GetDispInfo在。