Dewsoft Frontpage Tutorials

Lesson - 2 : Dialogs and Controls
2.3 :Writing a Dialog Box Class
When the resource is complete, bring up ClassWizard by choosing View, ClassWizard. ClassWizard recognizes that this new dialog box resource does not have a class associated with it and offers to build one for you, as shown in Figure 2.5. Leave the Create a New Class radio button selected, and click OK. The New Class dialog box appears, as shown in Figure 2.6. Fill in the classname as CSdiDialog and click OK. ClassWizard creates a new class, prepares the source file (SdiDialog.cpp) and header file (SdiDialog.h), and adds them to your project. FIG. 2.5 ClassWizard makes sure you don’t forget to create a class to go with your new dialog box resource. You connect the dialog box resources to your code with the Member Variables tab of ClassWizard, shown in Figure 2.7. Click IDC_CHECK1 and then click the Add Variable button. This brings up the Add Member Variable dialog box, shown in Figure 2.8. FIG. 2.6 Creating a dialog box class is simple with ClassWizard. FIG. 2.7 The Member Variables tab of ClassWizard connects dialog box controls to dialog box class member variables. A member variable in the new dialog box class can be connected to a control’s value or to the control. This sample demonstrates both kinds of connection. For IDC_CHECK1, fill in the variable name as m_check, and make sure that the Category drop-down box has Value selected. If you open the Variable Type drop-down box, you will see that the only possible choice is BOOL. Because a check box can be either selected or not selected, it can be connected only to a BOOL variable, which holds the value TRUE or FALSE. Click OK to complete the connection. FIG. 2.8 You choose the name for the member variable associated with each control. Here are the data types that go with each control type: Edit box. Usually a string but also can be other data types, including int, float, and long Check box. int Radio button. int List box. String Combo box. String Scrollbar. int Connect IDC_EDIT1 in the same way, to a member variable called m_edit of type CString as a Value. Connect IDC_LIST1 as a Control to a member variable called m_listbox of type CListBox. Connect IDC_RADIO_1, the first of the group of radio buttons, as a Value to an int member variable called m_radio. After you click OK to add the variable, ClassWizard offers, for some kinds of variables, the capability to validate the user’s data entry. For example, when an edit control is selected, a field under the variables list allows you to set the maximum number of characters the user can enter into the edit box (see Figure 2.9). Set it to 10 for m_edit. If the edit box is connected to a number (int or float), this area of ClassWizard is used to specify minimum or maximum values for the number entered by the user. The error messages asking the user to try again are generated automatically by MFC with no work on your part. FIG. 2.9 Enter a number in the Maximum Characters field to limit the length of a user’s entry.

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