CListBox::DrawItem

项目
03/01/2013

调用由结构，当所有者描述的可视方面是列表框更改。

virtual void DrawItem(
   LPDRAWITEMSTRUCT lpDrawItemStruct 
);

参数

lpDrawItemStruct
对包含有关所需的绘图的类型的信息 DRAWITEMSTRUCT framework的较长的指针。

备注

DRAWITEMSTRUCT 结构的 itemAction 和 itemState 成员定义要执行的绘制事件。

默认情况下，此成员函数不执行任何操作。重写该成员函数的实现所有者描述 CListBox 对象的绘图。此成员函数终止之前，应用程序应恢复为显示上下文中选择的所有图形设备接口(GDI)对象提供了在 lpDrawItemStruct。

为 DRAWITEMSTRUCT 结构的声明参见 CWnd::OnDrawItem。

示例

// CMyODListBox is my owner-drawn list box derived from CListBox. This 
// example draws an item's text centered vertically and horizontally. The 
// list box control was created with the following code:
//   m_myODListBox.Create(
//      WS_CHILD|WS_VISIBLE|WS_BORDER|WS_HSCROLL|WS_VSCROLL|
//      LBS_SORT|LBS_MULTIPLESEL|LBS_OWNERDRAWVARIABLE|LBS_WANTKEYBOARDINPUT,
//      CRect(10,250,200,450), pParentWnd, IDC_MYODLISTBOX);
//
void CMyODListBox::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct)
{
   ASSERT(lpDrawItemStruct->CtlType == ODT_LISTBOX);
   LPCTSTR lpszText = (LPCTSTR) lpDrawItemStruct->itemData;
   ASSERT(lpszText != NULL);
   CDC dc;

   dc.Attach(lpDrawItemStruct->hDC);

   // Save these value to restore them when done drawing.
   COLORREF crOldTextColor = dc.GetTextColor();
   COLORREF crOldBkColor = dc.GetBkColor();

   // If this item is selected, set the background color 
   // and the text color to appropriate values. Also, erase
   // rect by filling it with the background color.
   if ((lpDrawItemStruct->itemAction | ODA_SELECT) &&
      (lpDrawItemStruct->itemState & ODS_SELECTED))
   {
      dc.SetTextColor(::GetSysColor(COLOR_HIGHLIGHTTEXT));
      dc.SetBkColor(::GetSysColor(COLOR_HIGHLIGHT));
      dc.FillSolidRect(&lpDrawItemStruct->rcItem, 
         ::GetSysColor(COLOR_HIGHLIGHT));
   }
   else
   {
      dc.FillSolidRect(&lpDrawItemStruct->rcItem, crOldBkColor);
   }

   // If this item has the focus, draw a red frame around the
   // item's rect.
   if ((lpDrawItemStruct->itemAction | ODA_FOCUS) &&
      (lpDrawItemStruct->itemState & ODS_FOCUS))
   {
      CBrush br(RGB(255, 0, 0));
      dc.FrameRect(&lpDrawItemStruct->rcItem, &br);
   }

   // Draw the text.
   dc.DrawText(
      lpszText,
      (int)_tcslen(lpszText),
      &lpDrawItemStruct->rcItem,
      DT_CENTER|DT_SINGLELINE|DT_VCENTER);

   // Reset the background color and the text color back to their
   // original values.
   dc.SetTextColor(crOldTextColor);
   dc.SetBkColor(crOldBkColor);

   dc.Detach();
}