Advanced MFC Programming

Chapter 1. Tool Bar and Dialog Bar
CBarDoc::CBarDoc()
{
m_bBtnRed=FALSE;
m_bBtnGreen=FALSE;
m_bBtnBlue=FALSE;
m_bBtnYellow=FALSE;
}
Two types of message handlers (altogether eight member functions) are rewritten. The following
shows the implementation of two member functions for button ID_BUTTON_RED:
void CBarDoc::OnButtonRed()
{
m_bBtnRed=!m_bBtnRed;
}
void CBarDoc::OnUpdateButtonRed(CCmdUI* pCmdUI)
{
pCmdUI->SetRadio(m_bBtnRed);
}
If we execute the application at this point, we will see that the four color buttons behave like check
boxes.
Function CButton::SetButtonInfo(…)
Although this is a simple way to implement “check box” buttons, sometimes it is not efficient. Suppose
we have ten buttons that we expect to behave like check boxes, for every button we need to add a Boolean
type variable and implement a UPDATE_COMMAND_UI message handler. Although this is nothing difficult, it is
not the most efficient way of doing it.
Class CToolBar has a member function that can be used to set the button styles. The function allows us
to set button as a push button, separator, check box, or the start of a group of check boxes. We can also use
it to associate an image with a button contained in the tool bar. The following is the format of this function:
void CToolBar::SetButtonInfo(int nIndex, UINT nID, UINT nStyle, int iImage);
To use this function, we need to provide the information about the button, the style flags, and the
image information. Parameter nIndex indicates which button we are gong to customize. It is a zero-based
index, and button 0 is the left most button or separator on the tool bar (a separator is also considered a
button). Parameter nID specifies which command ID we want to associate with this button. Parameter
nStyle could be one of the following values, which indicates button’s style:
Flag
TBBS_BUTTON
TBBS_SEPARATOR
TBBS_CHECKBOX
TBBS_GROUP
TBBS_CHECKGROUP
Meaning
push button
separator
check box
start of a group
start of a check box group
The last parameter iImage indicates which image will be used to create the bitmap button. This is also
a zero-based number, which indicates the image index of the tool bar resource. In our case, the tool bar
resource contains four images, which are simply painted red, green, blue and yellow. The images are
indexed according to their sequence, which means the red image is image 0, the green image is image 1,
and so on.
When we create a tool bar resource, it seems that a button’s command ID and the associated image are
fixed from the beginning. Actually both of them can be modified through calling the above function. We
can assign any command ID and image to any button. Also, we can change a button to a separator. In a
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