Form Events and Capabilities VB6
Form Move Event
- Microsoft VB .NET has a form_move event, but Visual BASIC 6 does not.
- The Paint event won't detect a window being moved off the screen, but will get triggered when the window is moved back onto the screen. If AutoRedraw is enabled the Paint event is not fired at all.
- GotFocus/LostFocus Events are not triggered by the form.
- Form_MouseMove is fired when the mouse cursor is over the form, not including the title bar. However, dragging is done with the title bar.
Your options are:
Subclassing using WM_WINDOWPOSCHANGED
Subclassing can make the Visual Studio IDE unstable. The debugger does not work well when a new WindowProc is installed.
EventVB.dll Custom Functions
First add the EventVB.dll to your project references. It is not included with Visual Studio.
Option Explicit Dim WithEvents vbLink As EventVB.APIFunctions Dim WithEvents vbWnd As EventVB.ApiWindow Private Sub Form_Load() Set vbLink = New APIFunctions Set vbWnd = New ApiWindow vbWnd.hWnd = Me.hWnd '\\ Subclass this form vbLink.SubclassedWindows.Add vbWnd End Sub Private Sub vbWnd_Move(ByVal x As Long, ByVal y As Long, Cancel As Boolean) '\\ This event occurs when a drag-move completes: Debug.Print "Moved to " & x & "," & y End Sub Private Sub vbWnd_Moving(ByVal MoveEdges As EventVB.WindowSizingEdges, MoveRectangle As EventVB.APIRect) '\\ This event occurs during the drag-move With MoveRectangle Debug.Print "Moving to " & .Left & "," & .Top & " - " & .Right & "," & .Bottom End With End Sub
Open a Form From Another Form
Open the form called frmCompanies
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.
The Hide method of a form removes the form from the screen (makes it invisible), but the form still remains in memory.
frmCompanies.Hide Me.Hide Hide
You can load a form in memory and not display it.
Unload form from memory (which also closes it)
Private Sub Form_Unload(Cancel As Integer) If MsgBox("Are you sure you want to quit?", vbYesNo + vbQuestion, "Unload Test") = vbNo Then Cancel = 1 End If End Sub
From Dimensions and Twip Units
The default unit is the twip, which is 1/1440 of an inch for height, width, top, and left.
There are 15 twips per pixel.
Pixels to Twip:
W = W * Screen.TwipsPerPixelX H = H * Screen.TwipsPerPixelY
Twips to Pixel:
W = W / Screen.TwipsPerPixelX H = H / Screen.TwipsPerPixelY
- Width: Specifies the width of the control. The default unit is the twip, which is 1/1440 of an inch.
- Height: Specifies the height of the control. The default unit is the twip, which is 1/1440 of an inch.
- 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.
- 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.
- ScaleWidth: The width of the client area.
- ScaleHeight: The height of the client area.
- ScaleLeft: Coordinate horizontal of upper left client area.
- ScaleTop: Coordinate vertical of upper left client area.
Write to control on another form and display
Dim lblCaught As Label Set lblCaught = frmKaching.lblCaught frmKaching.WindowState = vbNormal lblCaught = "You've Been Naughty!" frmKaching.Show
Determine is a form has been loaded
The wrong way:
if form1.visible = true then
Due to the way an intrinsic variable instance works in VB, the line above will actually cause form1 to load. Forms are loaded automatically whenever referenced in code, whether loaded visibly or not.
Special thanks to a gentleman named Steve Gerrard who posted a correct sample script on another forum. His example works by going through a list of loaded forms and matching by the form name you are looking for.
Public Function FormIsLoaded(FormName As String) As Boolean Dim oFrm As Form For Each oFrm In Forms If oFrm.Name = FormName Then FormIsLoaded = True Exit For End If Next oFrm End Function
Prevent Partially Painted Windows
Sometimes when you display a form only some of the controls appear. After a pause the remaining controls appear. This does not have a professional look. This has become much less apparent in VB 5.0 because of dramatic improvements in screen painting.
frmPerson.Show vbModeless frmPerson.Refresh
The Refresh method will ensure that the form repainting is complete before executing any other code in the routine.