McGraw-Hill/Irwin Programming in Visual Basic 6.0 © 2002 The McGraw-Hill Companies, Inc. All rights reserved. Update Edition Chapter 6 Multiple Forms

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 2 McGraw-Hill/Irwin Multiple Forms Multiple forms Show and Hide methods for forms Standard code modules Variable scope in multiform projects An About Box form Splash screen Set the startup form

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 3 McGraw-Hill/Irwin Multiple Forms Creating new forms Adding and removing forms Hide & Show methods Load & Unload statements Referring to objects in other forms –code in one form cannot “see” obj. in other forms –reference: FormName!ObjectName.property

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 4 McGraw-Hill/Irwin Multiple Forms First form is startup form. –By default, it is the first one created –You can set startup form in Project, Properties Create form: –Project, Add Form –Select form type You can add a form to project from existing form

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 5 McGraw-Hill/Irwin Adding/Removing Forms All the information in a form resides with the form: controls, properties, code, variables Add existing form: Project, Add Form and then click the existing tab Remove a form: Project, Remove File

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 6 McGraw-Hill/Irwin Hide and Show methods You display a form with the show method: frmAbout.Show General form is formname.Show –where style can be 1 (modal) or the default value 0 (nonmodal) User must respond to Modal form & cannot click another form in same project Hide a form: frmAbout. Hide

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 7 McGraw-Hill/Irwin Form Load & Activate Events The first time a form is displayed, it triggers a form load event followed by a form activate event Load calls the module into memory Activate occurs when the form receives control Subsequently, activate but not load events trigger when form is shown

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 8 McGraw-Hill/Irwin Unload/Load Statements (cont'd) Only time you might want to load a form is when you want to load a form but display it later. The Me keyword refers, always, to the currently active form: Unload Me Me.Hide

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 9 McGraw-Hill/Irwin Referring to Other Forms’ Objects You can refer to txtName in another form called frmSummary this way: frmSummary!txtName = … or frmSummary!txtName.Font.Name =... This implies that control names are unique within a form but need not be unique across forms.

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 10 McGraw-Hill/Irwin Standard Code Modules Public procedures are“visible” to all forms Public variables are visible to all forms SCM (Standard Code Module) has the extension.BAS Create SCM: Project, Add Module DIM variables in the code module are visible to all procedures in the module, but not to procedures in the form modules.

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 11 McGraw-Hill/Irwin Variables & Constants in Multi-form Projects Scope of variables: –Local: available inside a procedure –Static: inside procedure, but remembered –Module level: available anywhere in a form –Global: available across forms--anywhere Global variables declared with Public Variable prefix naming conventions: m for module, g for global Scope a variable as narrowly as possible

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 12 McGraw-Hill/Irwin An About Box Acts like a Windows Help|About box Often displays information about the programmers, designers, and so on An about box is simply a modal form with an OK button and label boxes displaying information You can use VB’s About Dialog template

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 13 McGraw-Hill/Irwin A Splash Screen Splash screen displays while product loads Create: Project, Add Form, then select Splash Screen Splash screen loads first instead of main form Place splash screen load statement in Sub Main procedure in Standard Code Module

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 14 McGraw-Hill/Irwin Setting the Startup Form/Proc. By default, the first form you create in a project is the startup form You can set the startup form in the Project Properties menu (Project menu)

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 15 McGraw-Hill/Irwin Hands on Programming Example Programming example is a multi-form Coffee Sales example with these forms: –Splash screen –Main form –Summary form –About box Main form called from splash screen

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 16 McGraw-Hill/Irwin Programming Hints Make form run maximized window by setting the WindowState form property to 2-Maximized In design time, close extra windows to maximize your view of form Clicking a form's Close button halts execution

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 17 McGraw-Hill/Irwin Summary (1) Projects can have unlimited # forms First form displayed is the startup form You can use forms from one project in another one Show/Hide are form methods Modal form requires a response; and, execution halts until response received

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 18 McGraw-Hill/Irwin Summary (2) Load statement loads forms but does not display them Me refers to currently active form Refer to object in another form with form name as prefix SCM contains public variables and public sub procedures that are global to project

Programming in Visual Basic 6.0 Update Edition © 2002 The McGraw-Hill Companies, Inc. All rights reserved. 19 McGraw-Hill/Irwin Summary (3) Public can appear only in the General Declarations section of a module—place it in Standard Code Module only by convention Static variables are local but with “memory” Program execution can begin in a sub procedure called Main located in Standard Code Module