Add New Member Variables to Scribble

In addition to storing the current pen width in m_nPenWidth, class CScribbleDoc needs to keep track of whether the pen is currently thick or thin and how “thick” and “thin” are defined (in pixels). You do this by adding new data members for the thick and thin pen values. In Connecting a Class to a Dialog Box, in Scribble’s next lesson, you will add code to allow the user to define these values with a dialog box. For now, the default values will be hard coded.

To add the new data members

1. Use ClassView to jump to the class definition for CScribbleDoc.

   Locate the section labeled “// Attributes:”.

2. Right above this label, and after the protected keyword and the existing m_nPenWidth declaration, add the following code:

   BOOL    m_bThickPen;    // Thick currently selected or not
   UINT    m_nThinWidth;    // Current definition of thin
   UINT    m_nThickWidth;    // Current definition of thick
   

Tip   You could also right-click CScribbleDoc in ClassView and click Add Member Variable to add these three variables.

To hard code the values

1. Use ClassView to jump to InitDocument (in ScribbleDoc.cpp), and add the following code just before the call to ReplacePen:

   m_bThickPen = FALSE;
   m_nThinWidth = 2;     // Default thin pen is 2 pixels wide
   m_nThickWidth = 5;    // Default thick pen is 5 pixels wide
   

   The added code specifies that the pen is initially thin and defines the meanings of “thin” and “thick.”

2. Save your work in ScribbleDoc.h and ScribbleDoc.cpp.

ClassView displays icons for the new member variables in class CScribbleDoc.