Multiple Forms Standard Code Modules

1
Multiple FormsStandard Code Modules
chapter
SIX
2
Multiple Forms in Project
Project
Form1
Form2
3
Multiple Forms in Project

• Forms
• have scope - one form cannot see code in another
  (unless it is declared Public)
• reusable - have frm extension and can be used in
  other projects
• Startup form
• first form a project displays
• Creating
• Add Form under Project
• New or Existing

4
Multiple Forms in Project

• Project Menu Add Form choose type
• Project Menu Remove Form
• highlighted form in project explorer will be
  removed

5
Loading Forms

• Forms are loaded the first time shown
• A Form Load Event occurs when form loaded -once
  only, unless forms are unloaded and then loaded
  again.
• A Form Activate Event occurs each time a form is
  shown subsequently
• discuss use of these two events

6
Explicitly Loading/Unloading a Form

• Load frmName - will load a form, but not show it
• Unload frmName - will remove a form from memory
• use when form will no longer be used by program
  (i.e. startup or splash screen form)
• Unload Me
• Me is variable referring to current form

7
Showing Forms

• Show Method
• FormName.Show style
• style vbModal (user must respond to form -
  click etc.
• Important - NO OTHER CODE in PROGRAM will be
  executed until response and form hidden or
  unloaded
• style vbModeless (user can switch to other
  forms in project)
• Code in project after Show will continue to be
  executed
• frmAbout.Show vbModal
• frmSummary.Show vbModeless

8
Hiding Forms

• Hide Method
• Used to remove form from screen (remains in
  memory)
• Generic FormName.Hide
• frmAbout.Hide
• Me.Hide

9
Referring to Objects on Other Forms

• Generic frmName.ObjectName.Property
• So could I set up properties (ie label captions)
  before I showed a form?
• What does this do in terms of scope of variables
  used in display?
• VERY IMPORTANT - review Guidelines on page 216
  for declaring variables and constants

10
Standard Code Modules

• A file with a .BAS Extension
• Not associated with a particular form - contains
  only VB Code (no form/objects)
• Has a general declarations section and same
  structure as any form module
• Procedures and Functions that need to be used by
  multiple forms could reside in code module
  (define as Public)

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Standard Code Modules (2)

• Often contains a Sub Main Procedure which could
  start up the project (rather than a particular
  form)
• A Splash screen could be shown via the Sub Main
  Procedure and the next form could be explicitly
  loaded while the flash shows
• Sub Main ()
• frmSplash.Show vbModeless
• Load frmMain
• End Sub

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Standard Code Modules (3)

• Must set SubMain as start up form (defaults to
  first form in project)
• Project Menu Project Properties
• (Startup Form Drop Down -
• Choose Startup Form or Sub Main)