Splitter Dialog

Environment: VC6 SP3, NT4 SP5

The CSplitterDialog class adds splitter capabilities to a dialog, much like the MFC
CSplitterWnd class does to a child frame.
Derive your CDialog-derived class from CSplitterDialog
and call InitDialog() from your OnInitDialog()

Here’s the prototype:

void CSplitterDialog::InitDialog( LPCTRLINFO pLeftCtrl, LPCTRLINFO pRightCtrl, UINT nPerc );

The first two parameters are pointers to CTRLINFO structure which describes the
controls (targets) managed by the splitter, the third is the initial horizontal dimension of the left control
(expressed in percentage of dialog’s total dimension).

If the dialog is resizable, the controls are automatically resized to keep the settings of the dialog.
It is also possible to define an area on the dialog surface not used by the target controls: at the left of left
control, at the right of right control and above or below each control (e.g. to add buttons or bitmaps on the dialog in
addition to target controls).
Target controls must belong to a CWnd-derived class
CTreeCtrl, CButton,
CEdit, CStatic, …)

Below are listed CTRLINFO structure members:

  • CWnd* m_pWnd: pointer to the control;
  • CSize m_sizeMin: specifies minimum allowable size of the control (pixels);
  • UINT m_nOffX: specifies offset (pixels) at the left of the control,
    for left control, or at the right of the control, for right control;
  • UINT m_nOffY: specifies offset (pixels) above or below the control;
  • UINT m_nHowY: specifies if m_nOffY
    is an offset above (CSplitterDialog::TOP) or below
    (CSplitterDialog::BOTTOM) the control.

How to use this class:

  • use resource editor to create a dialog with two target controls and additional controls if you need them.
    The target controls are resized and repositioned by CSplitterDialog::InitDialog();
    the other controls must be managed by the developer (place them in the free area – see the
    CTRLINFO structure previously described);
  • set the dialog style to resizable if you want a resizable dialog.
    Warning: the non-target controls, placed on the dialog, should be managed by developer during the resizing phase
    (i.e. should be correctly repositioned);
  • define the class that manage the dialog, must derive from CSplitterDialog;
  • add a member variable for each target control and add the
    WM_INITDIALOG message map with Class Wizard, for example:
    CListCtrl m_ctrlLeft;
    CTreeCtrl m_ctrlRight;
  • in your OnInitDialog() override initialize
    CTRLINFO structure for each target control and call

Thanks to Matteo Benzoni and Diego Perrotta


Download demo project – 33 Kb
Download source – 4 Kb

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