CMPT 212 Object-Oriented Applications Design in C++ Spring 1998

Other Controls

• A check box control is used to set a boolean value.
  

• A static control is a control that neither receives nor generates messages.
  • A text box is a static control.
    

  • A group box is a static control. A group box draws a box, usually to visually group other controls.
    

• A radio button control is used to model mutually exclusive choices.
  

• A scrollbox control is used when items will not fit into the available space in the window.
  

Modeless Dialog Boxes

• A modeless dialog box allows the user to interact with the parent window while the dialog box is open.

• To create a modeless dialog box, we use CreateDialog instead of DialogBox.

• Unlike the modal dialog box, a modeless dialog box is not automatically visible. We must either:
  • explicitly show it using ShowWindow,
  • add WS_VISIBLE to the STYLE property of the dialog box in the resource file.

• To close a modeless dialog box, we call DestroyWindow instead of EndDialog.

• When our application receives messages, it must determine if they are for the parent window or the dialog box.
  • The function IsDialogMessage determines if a message is for a dialog box.
    • If the message is for the dialog box, the message is sent to the dialog box and IsDialogMessage returns a non-zero value.

    • Otherwise it returns zero.

  • Example:

       HWND hDlg;     // dialog box handle.
    
       int WINAPI WinMain(HINSTANCE hThisInst,
    		      HINSTANCE hPrevInst,
    		      LPSTR     lpszArgs,
    		      int       nWinMode) {
    
          MSG msg;
    
          ...
    
          while (GetMessage(&msg, NULL, 0)) {
    	 if (!IsDialogMessage(hDlg, &msg)) {
    	    TranslateMessage(&msg);
    	    DispatchMessage(&msg);
    	    }
             }
    
          ...
    
       }
    	       

Model/View/Controller Architecture

• The model/view/controller (MVC) architecture is a way of designing a GUI application.

• The data which a program uses can be displayed in various ways.
  • Spreadsheet data can be displayed in a table or in a graph.
  • A word processor may have the same document open in more than one window.

• The application stores the data in some format (the model) but has different ways of displaying it (the views).

• The controller portion of the application has two purposes:
  1. coordinates the user's interaction with views to update the model,
  2. ensures that the views show the latest updates of the model.

• MVC architecture:

• We can use callback functions to update the views then the model changes.
  • Each view registers a callback function with the controller.

  • When the model is changed, the controller will call each callback function so that the views are updated.

• The MVC architecture is useful in other types of applications, but is very appropriate for GUI applications.

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