Advanced MFC Programming

Chapter 5. Common Controls
command Layout | Tab order (or pressing CTRL+D keys). The Z-order of the controls can be reordered
by clicking them one by one according to the new sequence.
In the left-bottom corner of “Spin properties” property sheet, there is a combo box labeled
“Alignment”. This allows us to specify how the spin will be attached to its buddy window when being
displayed. If we select “Unattatched” style, the spin and the buddy control will be separated. Usually we
select either “Left” or “Right” style to attach the spin to the left or right side of the buddy control. In this
case, the size and position of the spin control in the dialog template has no effect on its real size and
position in the runtime, its layout will be decided according to the size and position of the buddy control.
Also, there is a “Set buddy integer” check box. If this style is set, the spin will automatically send out
message to its buddy control (must be an edit box) and cause it to display a series of integers when the
spin’s position is changed. By default, the integer contained in the edit box will increment or decrement
with a step of 1. If we want to customize this (For example, if we want to change the step or want to display
floating point numbers), we should uncheck this style and set the buddy’s text within the program.
Sample 5.1-1\CCtl demonstrates how to use spin control with edit control and set buddy automatically.
The sample is a standard dialog based application generated by Application Wizard, with all default
settings. The resource ID of the main dialog template is IDD_CCTL_DIALOG, which contains two spin
controls and two edit boxes. Both spins have “Auto buddy” and “Set buddy integer” styles. Also, their
alignment styles are set to “Right” (Figure 5-2).
Figure 5-2. Dialog template IDD_CCTRL_DIALOG
Without adding a single line of code, we can compile the project and execute it. The spin controls and
the edit controls will work together to let us select integers (Figure 5-3).
Figure 5-3. Sample 5-1\CCtrl
In MFC, spin control is implemented by class CSpinButtonCtrl. We need to call various member
functions of this class in order to customize the properties of the spin control. In sample 5.1-2\CCtl, the
control’s buddy is set by calling function CSpinButtonCtrl::SetBuddy(…) instead of using automatic
method. The best place to set a spin’s buddy is in the dialog box’s initialization stage. This corresponds to
calling function CDialog::OnInitDialog().
Sample 5.1-2\CCtl is based on sample 5.1-1\CCtl. Here, style “Auto buddy” is removed for two spin
controls. Also, some changes are nade to set the spin buddies manually.
There are two ways of accessing a specific spin: we can use a spin’s ID to call function
CWnd::GetDlgItem(…), which will return CWnd type pointer to the spin control; or we can add a
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