Advanced MFC Programming

Chapter 1. Tool Bar and Dialog Bar
box’s parent window needs to be set to m_wndColorButton. Here, since the combo box variable is
embedded in the parent window’s class, we need to use this pointer to indicate the parent window.
Function CColorBar::ShowComboBox() and CColorBar::HideComboBox() change the combo box to
the button and vice versa. They should be called just before the default layout is about to be carried out:
BOOL CColorBar::ShowComboBox()
{
CRect rect;
SetButtonInfo(2, ID_BUTTON_BLUE, TBBS_SEPARATOR, 150);
if(m_wndComboBox.m_hWnd != NULL)
{
m_wndComboBox.ShowWindow(SW_SHOW);
}
}
return TRUE;
BOOL CColorBar::HideComboBox()
{
SetButtonInfo(2, ID_BUTTON_BLUE, TBBS_BUTTON, 2);
if(m_wndComboBox.m_hWnd != NULL)m_wndComboBox.ShowWindow(SW_HIDE);
}
return TRUE;
Finally, function CalcDynamicLayout(…) is overridden as follows:
CSize CColorBar::CalcDynamicLayout(int nLength, DWORD dwMode)
{
if(dwMode & LM_HORZDOCK)ShowComboBox();
else HideComboBox();
}
return CToolBar::CalcDynamicLayout(nLength, dwMode);
Before calling the base class version of this function, we examine LM_HORZDOCK bit of dwMode
parameter, if it is set, we call function CColorBar::ShowComboBox() to change the button to the combo
box. If not, we call function CColorBar::HideComboBox() to change the combo box back to the default
button.
It is relatively easy to use this class: we just need to include the header file of CColorBar class in file
“MainFrm.h”, then change the prototype of m_wndColorBar from CToolBar to CColorBar. Because the
combo box is embedded in CColorBar class, we need to remove variable wndComboBox declared in the
previous section. In function CMainFrame::OnCreate(), instead of creating the combo box by ourselves,
we can just call the member function of CColorBar. Here is how the combo box is created using this new
method:
……
……
m_wndColorButton.AddComboBox();
m_wndColorButton.ShowComboBox();
We can see that the original five statements have been reduced to two statements.
Now we can compile and execute the sample again to see the behavior of the combo box.
1.8. Dialog Bar
As we have noticed, the limitation of the tool bar is that when we design a tool bar from resource, only
bitmap buttons with the same size can be included. If we try to modify the size of one bitmap button, the
size of all other buttons will be automatically adjusted. If we want to include controls other than buttons,
we need to write code to add them dynamically.
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