How to get width of list control in MFC application in pixels? - c++

Question

I'm writing a dialog based MFC application on Visual Studio 2017 in C++.
I've added an option for the user to maximize\minimize the window. As the user resizes the dialog I want to adjust the sizes of the controls. In the app there's a list control as shown in the picture below, which adjusts to the new size of the window.
before maximizing the window - the width of each column is adjusted to the list width:
after maximizing the window:
My problem is that I'm having trouble to adjust it's columns to the new size. I've seen some posts on the subject, but unfortunately I still couldn't solve the problem. I want the columns to be about the same size and to fill the whole window.
what I've tried:
1. method 1 - the problem was that the last column was much bigger than the others
void CEditableListControlDlg::OnSize(UINT nType, int cx, int cy) {
if (m_bUseWMSize) {
// adjust column width to window
for (int i = 0; i < m_EditableList.GetHeaderCtrl()->GetItemCount(); ++i) {
m_EditableList.SetColumnWidth(i, LVSCW_AUTOSIZE_USEHEADER);
}
}
m_bUseWMSize = true;
}
the variable m_bUseWMSize can be ignored - it's just a flag so I won't execute the code when the dialog is created. I've also tried switching the flage LVSCW_AUTOSIZE_USEHEADER inside SetColumnWidth to LVSCW_AUTOSIZE, but it didn't help either.
After using method 1 the list looks like this after maximizing the dialog:
2. method 2 - the problem was that the columns width wasn't affected. I think it's because the width variable has a value of 2147483647 and even if I divide it by 11 (the number of columns) it's still too big
void CEditableListControlDlg::OnSize(UINT nType, int cx, int cy) {
if (m_bUseWMSize) {
RECT rect;
m_EditableList.GetViewRect(&rect);
int width = abs(rect.left - rect.right);
int nCol = 11;
// adjust column width to window
for (int i = 0; i < m_EditableList.GetHeaderCtrl()->GetItemCount(); ++i) {
m_EditableList.SetColumnWidth(i, width/nCol);
}
}
m_bUseWMSize = true;
}
3. method 3 - I've tried to retrieve the width of the list in pixels and divide it by the number of columns. the problem was the the columns width was too small because the value of size.cx is 512
void CEditableListControlDlg::OnSize(UINT nType, int cx, int cy) {
if (m_bUseWMSize) {
CSize cz;
CSize size = m_EditableList.ApproximateViewRect(cz, -1);
int nCol = 11;
// adjust column width to window
for (int i = 0; i < m_EditableList.GetHeaderCtrl()->GetItemCount(); ++i) {
m_EditableList.SetColumnWidth(i, size.cx/11);
}
}
m_bUseWMSize = true;
}
relevant documentations:
SetColumnWidth Function
RECT struct
CSize struct
Functions ApproximateViewRect and GetViewRect
Thank you.

Answer 1

The easy option is to let the control do it for you :-). There is a special value you can pass (LVSCW_AUTOSIZE_USEHEADER) when sending an LVM_SETCOLUMNWIDTH message to the control, as per the following documentation topic:
https://learn.microsoft.com/en-us/windows/win32/controls/lvm-setcolumnwidth
Also referenced in that SetColumnWidth function link you mentioned in your post.

Answer 2

You could refer to the following code. Maybe it can help you.
bool CMFCApplication4Dlg::AdjustColumnWidth(CListCtrl* m_acclist)
{
CHeaderCtrl* pHeaderCtrl = m_acclist->GetHeaderCtrl();
int n = m_acclist->GetColumnWidth();
int nColumnCount = pHeaderCtrl->GetItemCount();
for (int i = 0; i < nColumnCount; i++)
{
m_acclist->SetColumnWidth(i, LVSCW_AUTOSIZE);
int nColumnWidth = m_acclist->GetColumnWidth(i);
m_acclist->SetColumnWidth(i, LVSCW_AUTOSIZE_USEHEADER);
int nHeaderWidth = m_acclist->GetColumnWidth(i);
m_acclist->SetColumnWidth(i, nColumnWidth > nHeaderWidth ? nColumnWidth : nHeaderWidth);
}
return true;
}

Answer 3

Because LVSCW_AUTOSIZE_USEHEADER will resize last column to the remaining width, it won't help you since you want to evenly distribute total width across all columns.
Similar to your method 2 you could try the following:
For each column cycle through all rows including the header and use CListCtrl::GetStringWidth to get text width in pixels. Store the maximum width of each column
Sum up all these max widths
Get width of control client rectangle with GetClientRect. If scrollbar is present subtract it with ::GetSystemMetrics (SM_CXVSCROLL)
Subtract result of 2 from 3 and divide by number of columns. Add result to each of max widths obtained in 1
Use SetColumnWidth to assign new width for each column