CComboBoxEx 调试断言失败：afxcmn2.inl 第 334 行

Question

Please note that I have found that I need to add COMBOBOXEXITEM values much like LVITEM based on this book: Image Lists and ComboBoxEx Controls | Programming Windows with MFC, Second Edition (flylib.com)

FYI, I am getting the above error on the SetImageList call:

// Add color icons to combobox
for (int nCount = 0; nCount < m_colorBarTemplateFiles.GetCount(); nCount++) {
    CBitmap colorTemplateBitmap;
    const CString fname = colorBarTemplateDirectory + "\\" + m_colorBarTemplateImageFileNames[nCount];
    HANDLE colorTemplateImageHandle = LoadImage(0, fname, IMAGE_BITMAP, 16, 16, LR_LOADFROMFILE);
    colorTemplateBitmap.FromHandle((HBITMAP)colorTemplateImageHandle);
    m_colorBarTemplateImages.Add(&colorTemplateBitmap, (COLORREF)0xFFFFFF);
}
SetImageList(&m_colorBarTemplateImages);

In the book I link, the author writes this code (BTW, I have purchased the book which will hopefully come with the CD, but it won't arrive for another 3 weeks):

m_il.Create (IDB_IMAGES, 16, 1, RGB (255, 0, 255));         
SetImageList (&m_il); 

But unfortunately, on the website the code does not have an *.rc file:

So I don't know how he sets up IDB_IMAGES . As far as I understand, the IDB_IMAGES is a big bitmap that is partitioned out into different icons, but it is not clear to met how to set that up in MFC.

This is afxcmn2.inl Line 334:

_AFXCMN_INLINE CImageList* CComboBoxEx::SetImageList(_In_ CImageList* pImageList)
    { ASSERT(::IsWindow(m_hWnd)); return CImageList::FromHandle((HIMAGELIST) ::SendMessage(m_hWnd, CBEM_SETIMAGELIST, 0, (LPARAM)pImageList->GetSafeHandle())); }

So somehow I am not creating the handle properly. I have also checked out other posts like:

visual c++ - How to add Images to CListCtrl in MFC - Stack Overflow

ccombobox - MFC CComboBoxEx icon update issue - Stack Overflow

CImageList Class | Microsoft Docs

CComboBoxEx Class | Microsoft Docs

Do you have any suggestions? TIA.

UPDATE:

Please note that I just learned that I need to be able to add these colors dynamically at runtime so it turns out I won't be able to work with *.rc files and CBitmap s. Instead, I'll have to research adding a colored region to the ComboBoxEx in OnPaint or OnDraw somehow using using something like this:

    COLORREF itemColor = colorArray[subitem][item];
    CRect rect;
    GetSubItemRect(item, subitem, LVIR_LABEL, rect);
    CDC* pDc = GetDC();
    pDc->FillRect(rect, &CBrush(itemColor));
    ReleaseDC(pDc);

So I'll keep you posted on what I figure out.

Answer 1

This is how I ended up adding a color swatch to the combobox dynamically without using *.rc files or *.bmp files. In the parent windows class OnCreate function where a key argument is CBS_OWNERDRAWFIXED which causes the DrawItem function to be called every time the combobox is opened by the user:

int ParentToolbarWindow::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    // ...
    CRect rect;
    int toolbarButtonIndex = 0;
    wndToolBar.GetItemRect(toolbarButtonIndex, &rect);
    CSize colorSwatchSize = pDC->GetTextExtent("1234567");
    rect.left = rect.right;
    rect.right = rect.left + colorSwatchSize.cx + 60;
    if (!wndToolBar.cmbColor.Create(WS_CHILD | WS_VISIBLE | CBS_DROPDOWN | WS_VSCROLL | CBS_HASSTRINGS | CBS_OWNERDRAWFIXED,
        rect, &wndToolBar, IDC_COMBO_XLINE)) {
    // error message...
        return -1;
    }
    // ...
    UpdateCombobox();
    // ...
}

void ParentToolbarWindow::UpdateCombobox()
{
    wndToolBar.cmbColor.ResetContent();
    // Get input value CStringArray "colorSwatchNames" for combobox...

    for (int i = 0; i < colorSwatchNames.GetCount(); i++) {
        if (wndToolBar.cmbColor.AddString(colorSwatchNames[i]) == CB_ERR || wndToolBar.cmbColor.AddString(colorSwatchNames[i]) == CB_ERRSPACE) {
            AfxMessageBox("Error setting up combo");
            break;
        }       
    }
 
   wndToolBar.cmbColor.SetCurSel(0);
}

Here is where I actually draw the color swatch along with the text:

void CColorCombo::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct)
{
    // ...
    CRect itemRect(lpDrawItemStruct->rcItem);
    CRect blockRect(itemRect);
    // ... setup rect sizes and other setup steps

    // Draw color swatch as columns, each one pixel wide where inputColors is CStringArray
    for (int i = 0; i < inputColors.GetCount(); i++) {
        CString inputColorLine = inputColors[i];
        // read and tokenize inputColors into inputColorLine...
        int red = atoi(inputColorLine[0]);
        int green = atoi(inputColorLine[1]);
        int blue = atoi(inputColorLine[2]);

        COLORREF color = RGB(red, green, blue);
        CPen* pen = new CPen(PS_SOLID, 1, color);
        dc.SelectObject(pen);
        dc.MoveTo(blockRect.left + i, blockRect.top);
        dc.LineTo(blockRect.left + i, blockRect.bottom);
        if (pen != NULL) delete pen;
    }    
}