WTL：如何繪製ComboBox

首先給大家介紹一個csdn博客關於ComboBox的組成和如何繪製的介紹。

http://blog.csdn.net/fengbangyue/article/details/5222124

我要繪製的是drop list模式的ComboBox。

直接上代碼：

//下拉列表框
class ComboBox : public CWindowImpl<ComboBox,CComboBox>,public COwnerDraw<ComboBox>
{
public:
	BEGIN_MSG_MAP(ComboBox)
		MSG_WM_ERASEBKGND(OnEraseBkgnd)
		MSG_WM_PAINT(OnPaint)
		CHAIN_MSG_MAP_ALT(COwnerDraw<ComboBox>,1)
		DEFAULT_REFLECTION_HANDLER()
	END_MSG_MAP()
	BOOL OnEraseBkgnd(CDCHandle dc)
	{	
		return TRUE;
	}
	void OnPaint(CDCHandle)	//繪製那個按鈕
	{
		CPaintDC dc(m_hWnd);
		CRect rc;
		GetClientRect(&rc);
		HBRUSH hBrush = CreateSolidBrush(RGB(200,200,250));
		dc.FillRect(&rc,hBrush);

		TCHAR str[255];
		GetWindowTextW(str,255);
		if(CString(str).IsEmpty() == FALSE)
		{
			CFont font;
			font.CreatePointFont(110,L"華文行楷");
			dc.SelectFont(font);
			dc.SetBkMode(TRANSPARENT);
			rc.left += 5;
			dc.DrawTextW(str,-1,&rc,DT_VCENTER | DT_SINGLELINE | DT_LEFT);
		}	
		DeleteObject(hBrush);
	}
	void DrawItem(LPDRAWITEMSTRUCT lpdis)
	{
		//ATLTRACE("ComboBox::DrawItem\r\n");
		int index = lpdis->itemID;
		if(index < 0)
			return;
		CDCHandle dc(lpdis->hDC);
		CRect rc = lpdis->rcItem;
		TCHAR sz[255] = { 0 };
		GetLBText(index,sz);

		if(lpdis->itemState & ODS_SELECTED)
		{
			dc.Draw3dRect(&rc,RGB(0,0,255),RGB(0,0,255));
			dc.SetTextColor(RGB(200,0,0));
		}
		else
		{
			HBRUSH hBrush = CreateSolidBrush(RGB(255,255,255));
			dc.FillRect(&rc,hBrush);
			dc.SetTextColor(RGB(0,0,0));
			DeleteObject(hBrush);
		}
		dc.SetBkMode(TRANSPARENT);
		rc.left += 5;
		dc.DrawTextW(sz,-1,&rc,DT_VCENTER | DT_SINGLELINE | DT_LEFT);		
	}
	void MeasureItem(LPMEASUREITEMSTRUCT lpmis)
	{
		//ATLTRACE("ComboBox::MeasureItem\r\n");
		if(lpmis->itemID < 0)	//是按鈕
			lpmis->itemHeight = 25;	//如果是子類化，改動無效
		else
			lpmis->itemHeight = 25;
	}
};

效果如下：