User interface: – The user interface is perhaps the most important part of visual basic application. It is certainly the most visible. To users, the interface is the application, they probably are not aware of the code that is executing behind the scenes. No matter how much time and effort we put into writing and optimizing our code, the usability of our application depends upon the interface.
When we design an application, a number of decision need to be made regarding the interface.
- (i) Should be use the single document or multiple document style.
- (ii) How many different forms we will need.
- (iii) What command will our menus include, and will be use tool bars to duplicate menu function. What about dialog boxes to interact with the user?
- (iv) How much assistance do we need to provide.
Before we began designing the user interface, we need to thing about the purpose of the application. The design for a primary application that will be constant use should be different from one that is used occasionally for short periods of time. An application with the primary purpose of displaying information has different requirement that one used together information. Visual basic support to types of interface style. They are –
- (i) Single document interface (SDI)
- (ii) Multiple document interface (MDI)
Single document interface (SDI): – A single document interface application contains single data window. Examples of SDI application are notepad and WordPad. Both application is included with Microsoft window. In notepad or WordPad, we can open only one document at a time. If second window will open, previous window closed automatically.
A SDI application usually does not content a window menu on its menu bar because we cannot move between data window. When the use open a new data file, the data replaces the data currently shown in the open window.
Multiple document interface (MDI): – The multiple document interface allows us to create an application that maintains multiple form with in a single container form. Application such as MS-Word, MS-Excel, etc. are MDI application.
A MDI document allows the user to display multiple document at the same time, with each document displayed in its own window. Document and child window are content in parent window, which provide a work space for all the child windows is the application. Each individual window is confined to the area of the excel parent window. When we minimize excel, all of the document window are minimized as well, only the parent window icon appear in the taskbar. A child form is an ordinary form that it has its MDI child properties set to true. Our application can include many MDI child forms of similar or different types.
At run time, child forms are displayed. Within the workspace of MDI parent form when a child form is minimized, its icon appears with in the workspace of the MDI form instead of the taskbar. Our application can also include standard non-MDI forms that are not content in the MDI form.