Difference between revisions of "The Basics of VB6"

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These notes can be organized later.   
 
These notes can be organized later.   
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=== Open a Form From Another Form ===
 
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Open the form called frmCompanies
 
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  frmCompanies.Show
 
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Open it so that the parent form cannot be clicked.  To suspend execution of the first form until after the second form is done with, add the keyword constant vbModal as an argument to the Show method.
 
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  frmCompanies.Show vbModal
 
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The Hide method of a form removes the form from the screen (makes it invisible), but the form still remains in memory.
 
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  frmCompanies.Hide
 
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  Me.Hide
 
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  Hide
 
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You can load a form in memory and not display it.
 
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  Load frmCompanies
 
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Unload form from memory (which also closes it)
 
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  Unload Me
 
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Example
 
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  Private Sub Form_Unload(Cancel As Integer)
 
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    If MsgBox("Are you sure you want to quit?", vbYesNo + vbQuestion, "Unload Test") = vbNo Then
 
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      Cancel = 1
 
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    End If
 
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  End Sub
 
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=== From Dimensions and Twip Units ===
 
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The default unit is the twip, which is 1/1440 of an inch for height, width, top, and left. 
 
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There are 15 twips per pixel.
 
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Pixels to Twip:
 
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  W = W * Screen.TwipsPerPixelX
 
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  H = H * Screen.TwipsPerPixelY
 
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Twips to Pixel:
 
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  W = W / Screen.TwipsPerPixelX
 
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  H = H / Screen.TwipsPerPixelY
 
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=== Resizing Forms ===
 
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* Width: Specifies the width of the control. The default unit is the twip, which is 1/1440 of an inch.
 
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* Height: Specifies the height of the control. The default unit is the twip, which is 1/1440 of an inch.
 
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* Left: Specifies the distance between the internal left edge of a control and the left edge of its containter.The default unit is the twip, which is 1/1440 of an inch.
 
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* Top: Specifies the distance between the internal top edge of a control and the top edge of its containter.The default unit is the twip, which is 1/1440 of an inch.
 
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<BR>
 
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* ScaleWidth: The width of the client area.
 
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* ScaleHeight: The height of the client area.
 
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* ScaleLeft:  Coordinate horizontal of upper left client area.
 
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* ScaleTop: Coordinate vertical of upper left client area.
 
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<BR>
 
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* ClientWidth:
 
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* ClientHeight:
 
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* ClientLeft:
 
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* ClientTop:
 
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=== TabStrip Control ===
 
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Tabs are not containers!  In design time you cannot just select a tab and drop a control on it, assigning a different control to each tab.  It just isn't how tabs work.
 
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You must trap the click event and determine which tab is being clicked.
 
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  Private Sub TabStrip1_Click()
 
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    SelectedTab = TabStrip1.SelectedItem.Index
 
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  End Sub
 
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Setting the default tab
 
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Private Sub Form_Load()
 
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  'default to first tab (note: indexing starts at 1 - this is how control is designed)
 
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  TabStrip1.Tabs(1).Selected = True
 
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End Sub
 
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Another Example
 
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  Private Sub TabStrip1_Click
 
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    TabFrame(TabStrip1.SelectedItem.Index-1).Zorder 0
 
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  End Sub
 
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Tabs That Are Containers:
 
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If you wish to use tabs that are containers, look at SStab, which is in the component Microsoft Tabbed Dialog Control 6.0 (SP5). The .OCX is TABCTL32.ocx.
 
  
 
=== Select Case (Switch) ===
 
=== Select Case (Switch) ===
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   End Select
 
   End Select
  
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=== Public Declarations ===
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Public strCurrentTool As String
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Public fMainForm As frmQAB
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Public cn As ADODB.Connection
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Public rsCompanies As ADODB.Recordset
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Public Const dbtContact = "contact"
  
  

Latest revision as of 10:55, 2 February 2008

These notes can be organized later.

Select Case (Switch)

CASE in Visual BASIC does not "fall through" like in C. 

 Select Case Button.Key
   Case "ListCache"
     mnuListCache_Click
   Case "Refresh"
     mnuRefresh_Click
   Case "simmode"
     cmdSimMode_Click
 End Select

 Select Case tcpClient.State
   Case 0
     tcpClient.RemoteHost = cboRemoteHost
     SessionConnect
   Case 7
     lblStatus.Caption = "Connected"
   Case 9
     lblStatus.Caption = "Connection Error"
 End Select

Case based on more than one condition 

 Select Case True
   Case strMessage Like "*OK*" And lblStatus.Caption = "Connected"
   blnReceivedAll = True
 Case strMessage Like "*OK*" And lblStatus.Caption = "retrieving."
   lblStatus.Caption = "retrieving.."
   blnReceivedAll = True
 Case Else
   Set LoopTime = New TimerClass: tmrDisconnect.Enabled = True
 End Select

Public Declarations

Public strCurrentTool As String

Public fMainForm As frmQAB

Public cn As ADODB.Connection

Public rsCompanies As ADODB.Recordset

Public Const dbtContact = "contact"


 

 

 

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