Adding vertical gripper to dialog - mfc

Question

I am not sure what code to show you here. I have a CDialogEx derived resource in my MFC application:
It supports the dynamic resize layout controls so the user can resize the window. But I would like to add a vertical gripper (indicated in red) so the user can make the width of the names column larger.
I have done some research on this and all the articles are nearly 10 years old and don't factor in the newer dynamic resizing controls.
Having researched this more I see that the "resize gripper" term is not what I mean. That is the icon in the bottom right. I don't mean this.
I am sure you know what I mean though. Is it possible?

Answer 1

Adding a custom gripper control can be relatively easy. See CMySplitter class below.
But if all the controls are in one dialog, it will be very difficult reposition/resize individual controls one by one.
Ideally, use two child dialogs. Set the resize/reposition properties for individual controls in resource editor. Put the grip control in between the two dialogs and resize in response.
Class for gripper control:
#include <functional>
class CMySplitter : public CStatic
{
public:
class CPopup : public CWnd
{
public:
CMySplitter *parent;
int offset;
void OnMouseMove(UINT flag, CPoint pt);
void OnLButtonUp(UINT flag, CPoint pt);
DECLARE_MESSAGE_MAP()
};
std::function<void(int)> callback;
CRect boundary;
CPopup popup;
void OnLButtonDown(UINT flag, CPoint point);
void PreSubclassWindow();
void SetRange(int left, int right);
DECLARE_MESSAGE_MAP()
};
//create splitter control from a static control in dialog
void CMySplitter::PreSubclassWindow()
{
CStatic::PreSubclassWindow();
//modify static control's style (must have SS_NOTIFY)
SetWindowLongPtr(m_hWnd, GWL_STYLE, WS_VISIBLE | SS_GRAYRECT | WS_CHILD | SS_NOTIFY);
//create a popup window with transparency
static CString classname =
AfxRegisterWndClass(0, 0, (HBRUSH)GetStockObject(BLACK_BRUSH));
popup.CreateEx(WS_EX_LAYERED | WS_EX_PALETTEWINDOW | WS_EX_NOACTIVATE,
classname, NULL, WS_POPUP, CRect(0, 0, 0, 0), this, 0);
popup.SetLayeredWindowAttributes(0, 128, LWA_ALPHA);
popup.parent = this;
}
//when user click the static control, show a popup window
void CMySplitter::OnLButtonDown(UINT flag, CPoint pt)
{
CStatic::OnLButtonDown(flag, pt);
GetCursorPos(&pt);
CRect rc;
GetWindowRect(&rc);
popup.offset = pt.x - rc.left;
popup.SetWindowPos(NULL, rc.left, rc.top, rc.Width(), rc.Height(), SWP_SHOWWINDOW);
popup.SetCapture();
}
//how far to the left and right the splitter can go
void CMySplitter::SetRange(int left_, int right_)
{
CRect rc;
GetParent()->GetWindowRect(&rc);
boundary.left = rc.left + left_;
boundary.right = rc.right - right_;
}
//move this popup window
void CMySplitter::CPopup::OnMouseMove(UINT flag, CPoint pt)
{
CWnd::OnMouseMove(flag, pt);
GetCursorPos(&pt);
CRect rc;
GetWindowRect(&rc);
int x = pt.x - offset;
if (x > parent->boundary.left && x < parent->boundary.right)
SetWindowPos(NULL, x, rc.top, 0, 0, SWP_NOSIZE);
}
//hide popup window, let the parent dialog know
void CMySplitter::CPopup::OnLButtonUp(UINT flag, CPoint pt)
{
CWnd::OnLButtonUp(flag, pt);
ReleaseCapture();
ShowWindow(SW_HIDE);
CRect rc;
GetWindowRect(&rc);
parent->callback(rc.left);
}
BEGIN_MESSAGE_MAP(CMySplitter::CPopup, CWnd)
ON_WM_CREATE()
ON_WM_LBUTTONDOWN()
ON_WM_LBUTTONUP()
ON_WM_MOUSEMOVE()
END_MESSAGE_MAP()
BEGIN_MESSAGE_MAP(CMySplitter, CWnd)
ON_WM_LBUTTONDOWN()
END_MESSAGE_MAP()
Usage:
Add a static control with IDC_STATIC1 to the dialog and use as follows.
The code below has a main dialog CMyDialog with IDD_DIALOG, normal dialog
It has two child dialogs, child1 and child2 with IDD_PAGE1 and IDD_PAGE2
IDD_PAGE1 and IDD_PAGE2 are dialog resources with "child" style (not popup)
class CMyDialog : public CDialogEx
{
public:
class CChild1 : public CDialogEx
{
};
class CChild2 : public CDialogEx
{
};
CChild1 child1;
CChild1 child2;
//respond to gripper resize
void respond(int position)
{
CRect rs;
m_splitter.GetWindowRect(&rs);
rs.MoveToX(position);
ScreenToClient(&rs);
CRect rc;
GetClientRect(&rc);
CRect r1(0, 0, rs.left, rc.bottom);
CRect r2(rs.right, 0, rc.right, rc.bottom);
child1.MoveWindow(r1, TRUE);
child2.MoveWindow(r2, TRUE);
m_splitter.MoveWindow(rs, TRUE);
m_splitter.Invalidate(TRUE);
}
CMySplitter m_splitter;
BOOL OnInitDialog()
{
CDialogEx::OnInitDialog();
child1.Create(IDD_PAGE1, this);
child2.Create(IDD_PAGE2, this);
m_splitter.SubclassDlgItem(IDC_STATIC1, this);
m_splitter.SetRange(50, 50);
m_splitter.callback = std::bind(&CMyDialog::respond, this, std::placeholders::_1);
//width for splitter
int dx = 10;
CRect rc;
GetClientRect(&rc);
CRect r1(0, 0, 200, rc.bottom);
CRect r2(r1.right + dx, 0, rc.right, rc.bottom);
CRect rs(r1.right, 10, r2.left, rc.bottom - 10);
child1.MoveWindow(r1);
child2.MoveWindow(r2);
m_splitter.MoveWindow(rs);
child1.ShowWindow(SW_SHOW);
child2.ShowWindow(SW_SHOW);
return TRUE;
}
...
};