Advanced MFC Programming

Chapter 1. Tool Bar and Dialog Bar
However, because tool bar resource does not let us add controls other than buttons, dynamic method is
the only way we can pursue to implement combo box on the tool bar. The question here is: because the
buttons are positioned side by side, where can we put a combo box that will definitely take up a larger area?
To prevent the controls from interfering with each other, one control should not overlap another. So
first, we must find an inactive area on the tool bar where we could create the combo box.
On the tool bar, separator is an inactive control. If we click mouse on it, there will be no response. We
already know that we can call function CToolBar::SetButtonInfo(…) to change a button to a separator.
Also, when doing this, we can specify the width of the separator by using iImage parameter (when we pass
TBBS_SEPARATOR to nStyle parameter, the meaning of iImage parameter becomes the width of the
separator).
On top of the separator, we can create any controls using dynamic method.
Sample 1.6\Bar demonstrates how to add combo box to the tool bar. This sample is based upon sample
1.4\Bar. In the new sample, the third button (blue button) is changed to a combo box. The following lists
necessary steps of implementing this:
1) Change the blue button to a separator with a width of 150 after the tool bar is created. For this purpose,
the following statement is added to function CMainFrame::OnCreate(…):
m_wndColorButton.SetButtonInfo(2, ID_BUTTON_BLUE, TBBS_SEPARATOR, 150);
Here the first parameter indicates that we want to modify the third button. The second parameter is the
blue button’s resource ID. The fourth parameter specifies the width of the separator. If we compile and
execute the sample at this point, we will see that the blue button does not exist anymore. Instead, a
blank space with width of 150 is added between the third and fourth button. This is the place where we
will create the combo box.
2) Use CComboBox to declare a variable m_wndComboBox in class CMainFrame as follows:
……
……
class CMainFrame : public CFrameWnd
{
}
protected:
CStatusBar m_wndStatusBar;
CToolBar m_wndToolBar;
CToolBar m_wndColorButton;
CComboBox m_wndComboBox;
3) Use the newly declared variable to call function CComboBox::Create(…) in CMainFrame::OnCreate(…)
after the blue button has been changed to separator.
Function CComboBox::Create(…) has four parameters. We must specify combo box’s style, size &
position, parent window, along with the control ID in order to call this function. The following is the format
of this function:
BOOL CComboBox::Create(DWORD dwStyle, const RECT& rect, CWnd* pParentWnd, UINT nID);
We can use the first parameter to set the styles of a combo box. A combo box can have different styles,
in our sample, we just want to create a very basic drop down combo box (For other types of combo boxes,
see Chapter 5). The following code fragment shows how this function is called within CMainFrame::
OnCreate(…):
……
m_wndColorButton.SetButtonInfo(2, ID_BUTTON_BLUE, TBBS_SEPARATOR, 150);
m_wndColorButton.GetItemRect(2, rect);
rect.bottom=rect.top+150;
if(!m_wndComboBox.Create(WS_CHILD | CBS_DROPDOWN |
CBS_AUTOHSCROLL | WS_VSCROLL | CBS_HASSTRINGS,
rect, &m_wndColorButton, ID_BUTTON_BLUE))
{
return -1;
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