Advanced MFC Programming

Chapter 5. Common Controls
CSpinButtonCtrl type variable for the spin control (through using Class Wizard). The following code
fragment shows how the buddy of the two spin controls are set using the first method:
……
BOOL CCCtlDlg::OnInitDialog()
{
(
(CSpinButtonCtrl *)GetDlgItem(IDC_SPIN_VER)
)->SetBuddy(GetDlgItem(IDC_EDIT_VER));
(
(CSpinButtonCtrl *)GetDlgItem(IDC_SPIN_HOR)
)->SetBuddy(GetDlgItem(IDC_EDIT_HOR));
}
return TRUE;
Since CWnd::GetDigItem(…) returns a CWnd type pointer, we need to first cast it to CSpinButtonCtrl
type pointer in order to call any member function of class CSpinButtonCtrl. The only parameter that needs
to be passed to function CSpinButtonCtrl::SetBuddy(…) is a CWnd type pointer to the buddy control,
which can also be obtained by calling function CWnd::GetDlgItem(…).
Spin controls implemented in sample 5.1-2\CCtl behaves exactly the same with those implemented in
sample 5.1-1\CCtl.
5.2 Customizing the Properties of Spin Control
We can customize a spin control’s properties in function CDialog::OnInitDialog(). The following
three functions are the most commonly used ones for doing customization:
Function Name
Int CSpinButtonCtrl::SetBase
(
int nBase
);
Void CSpinButtonCtrl::SetRange
(
int nLower, int nUpper
);
int CSpinButtonCtrl::SetPos
(
int nPos
);
Description
We can use this function to set the base of a spin control. Parameter
nBase can be either 10 or 16, which will make the buddy window
display decimal or hexadecimal numbers respectively.
We can use this function to set the range of a spin control. The
default range is 100 to 0, so by default the number in the edit box
will be decremented when we press the upward arrow of a vertical
spin. To change this feature, we can call function
CSpinButtonCtrl::SetRange(…) to set its range to be from 0 to 100
(nLower=0, nUpper=100).
We can call this function to set the initial position of a spin control.
If we do not set it, the default position is 0.
Sample 5.2\CCtl is based on sample 5.1-1\CCtl. In this sample, the vertical spin is customized to
display hexadecimal integers, whose range is set from 0x0 to 0xC8 (0 to 200), and its initial position is set
to 0x64 (100). The horizontal spin still displays decimal integers, its range is from 50 to 0, and the initial
position is 25. The following portion of function CCCtlDlg::OnInitDialog() shows the newly added code:
……
BOOL CCCtlDlg::OnInitDialog()
{
(
(CSpinButtonCtrl *)GetDlgItem(IDC_SPIN_VER)
)->SetBuddy(GetDlgItem(IDC_EDIT_VER));
((CSpinButtonCtrl *)GetDlgItem(IDC_SPIN_VER))->SetRange(0, 200);
((CSpinButtonCtrl *)GetDlgItem(IDC_SPIN_VER))->SetBase(16);
((CSpinButtonCtrl *)GetDlgItem(IDC_SPIN_VER))->SetPos(100);
(
(CSpinButtonCtrl *)GetDlgItem(IDC_SPIN_HOR)
)->SetBuddy(GetDlgItem(IDC_EDIT_HOR));
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