这里的问题是WM_CTLCOLOR
消息被发送到parent组合控件的窗口(可能是对话框),而不是控件本身;另外,在组合的下拉“列表框”部分的情况下,不会发送此消息(因为对话框不需要绘制它,除非控件已被激活)。
我实现你想要的方法是通过使控件所有者绘制,然后(手动)绘制列表中的每个项目。
首先,您需要添加CBS_OWNERDRAWFIXED
风格到你的控制.rc
/.rc2
脚本;像这样,对于一个典型的组合:
COMBOBOX IDC_IGONG, 224, 68, 52,120,
CBS_DROPDOWNLIST | CBS_HASSTRINGS | CBS_OWNERDRAWFIXED | WS_VSCROLL | WS_TABSTOP
然后,您需要添加ON_WM_DRAWITEM()
到您的对话框类的消息映射,并覆盖它的OnDrawItem()
成员。请注意,该消息发送一次每一个项目在下拉列表中,当用户操作使列表可见时:
void MyDialog::OnDrawItem(int nIDCtl, DRAWITEMSTRUCT *pDIS)
{
switch (pDIS->CtlType) { // You can switch on the ID if it's only one combo!
case ODT_COMBOBOX:
DrawDropDownBox(this, nIDCtl, pDIS);
break;
default:
CDialogEx::OnDrawItem(nIDCtl, pDIS);
break;
}
}
The DrawDropDownBox()
完成所有艰苦的工作:
void MyDialog::DrawDropDownBox(CWnd *box, int nID, DRAWITEMSTRUCT *pDIS)
{
CComboBox *pCBC = dynamic_cast<CMyComboBoxEx *>(box->GetDlgItem(nID));
if (pCBC == nullptr) return; // Skip if we can't get handle to the control
CDC *pDC = CDC::FromHandle(pDIS->hDC);
wchar_t buffer[4096]; // Or just char if you ain't using Unicode
if (pCBC->GetLBText(int(pDIS->itemID), buffer) == CB_ERR) return; // Maybe called during WM_DELETEITEM
int dcSave = pDC->SaveDC(); // Save DC state for later restoration
CPen pen(PS_SOLID, 0, ListColor); // ListColor is COLORREF for your desired b/g
if (pDIS->itemState & ODS_DISABLED) {
pDC->SelectStockObject(NULL_PEN);
pDC->SelectObject(BackBrush); // A CBrush for disabled: defined/created elsewhere
pDC->SetBkMode(TRANSPARENT);
}
else {
pDC->SelectObject(&pen);
pDC->SelectObject(ListBrush); // A CBrush that draws your desired b/g
pDC->SetBkMode(OPAQUE);
}
CRect rc(pDIS->rcItem); pDC->Rectangle(&rc); // This draws the b/g
if (pDIS->itemState & ODS_DISABLED) {
pDC->SetTextColor(GetSysColor(COLOR_GRAYTEXT));
}
else if (pDIS->itemState & ODS_SELECTED) { // Use Windows defaults if selected...
pDC->SetTextColor(GetSysColor(COLOR_HIGHLIGHTTEXT));
pDC->SetBkColor(GetSysColor(COLOR_HIGHLIGHT));
}
else {
pDC->SetTextColor(GetSysColor(COLOR_WINDOWTEXT));
pDC->SetBkColor(ListColor); // Custom b/g color
}
unsigned format = DT_SINGLELINE | DT_VCENTER; // You desired text alignment
pDC->DrawText(CString(buffer), rc, format);
pDC->RestoreDC(dcSave); // Restore DC's saved state...
pDC->Detach(); // ...then 'release it'
return;
}
显示的代码处理禁用的组合和列表中选定的项目;如果您想简化操作,您可以跳过其中一些。
请随时要求进一步解释和/或澄清。