Form class

A Form is a top-level Win32 window that hosts the controls, menus, and drawing surface of a single twinBASIC user interface. Each form designed in the IDE becomes its own class derived from Form — its controls become members of that class, its event handlers become methods on it, and the file’s name becomes the class name. Code outside the form normally instantiates it implicitly through the global default-instance reference (MyForm.Show) or explicitly with New MyForm. The default property is Controls and the default event is Load.

' In Form1's code-behind:
Private Sub Form_Load()
    Caption = "Welcome"
    Me.MinWidth = 4000          ' twips, ≈ 2 inches
    Me.MinHeight = 3000
End Sub

Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
    If MsgBox("Quit?", vbYesNo) = vbNo Then Cancel = 1
End Sub

' In a startup module:
Sub Main()
    Form1.Show vbModal
End Sub

Lifecycle
Showing the form
Window appearance
Drawing surface
Controls and validation
Menus and pop-ups
Properties
Methods
Events

Lifecycle

A form goes through six distinct events from creation to destruction:

Event	When
Initialize	Before the underlying window exists. The form’s controls are not yet created.
Load	After the window and all controls have been created, before the form first appears.
Activate	When the form becomes the active window in the application.
Deactivate	When another form (or another application’s window) takes activation away.
QueryUnload	Before unload. Setting Cancel to non-zero keeps the form open.
Unload	After QueryUnload approves. Setting Cancel to non-zero keeps the form open.
Terminate	After the window has been destroyed and the class instance is released.

Closing a form goes through both QueryUnload and Unload, so either can veto. The UnloadMode argument of QueryUnload (QueryUnloadConstants) reports whether the user clicked the close button, code called Unload, Windows is shutting down, the MDI parent is closing, and so on.

Showing the form

Show makes the form visible. It accepts an optional FormShowConstants argument: vbModeless (default — the call returns immediately and the user can interact with other forms) or vbModal (the call blocks until the form is closed, and other forms in the application become unresponsive). MDI child forms cannot be shown modally; attempting to do so raises run-time error 404.

dlgOptions.Show vbModal, Me      ' modal, owned by the calling form

Hide and Close reverse the effect: Hide just clears Visible; Close runs the full unload sequence (QueryUnload then Unload then Terminate). The classic Unload <FormName> statement is the language-level equivalent of Close.

StartUpPosition (StartUpPositionConstants) is read at the first Show to decide where the form lands; afterwards the user (or code through Move and WindowState) controls position.

Window appearance

BorderStyle (FormBorderStyleConstants) chooses between sizable, fixed, dialog, tool, and borderless frames. Caption is the title-bar text. ControlBox, MaxButton, and MinButton toggle the system menu and resize buttons. Icon supplies the small/large icon used by the system menu, the taskbar, and Alt-Tab. WindowState (FormWindowStateConstants) reads or sets normal / minimised / maximised state at run time.

MinWidth, MinHeight, MaxWidth, and MaxHeight constrain the client area in twips during interactive resizing. Moveable decides whether the user can drag the form by its title bar; ShowInTaskbar decides whether the form shows up in the taskbar and Alt-Tab list.

Opacity and TransparencyKey drive Windows’ layered-window features for translucent forms and cut-out shapes.

Drawing surface

A Form is itself a graphics surface — code can draw lines, shapes, and text directly on it. The coordinate system is governed by ScaleMode (default vbTwips — the classic VB6 behaviour) and the ScaleLeft / ScaleTop / ScaleWidth / ScaleHeight properties, which together describe the form’s logical drawing rectangle. Setting ScaleMode to vbUser lets the four Scale* properties define an arbitrary rectangle; the Scale method does this in a single call.

The drawing primitives are Cls, Circle, Line, PSet, PaintPicture, and the Print statement (Form1.Print "Hello") — all use ForeColor, FillColor, FillStyle, DrawWidth, DrawMode, and DrawStyle for their pen and fill, and the form’s Font for text. The current pen position is tracked by CurrentX and CurrentY; TextWidth and TextHeight measure a string in the current font. ScaleX and ScaleY convert single coordinates between scale modes.

AutoRedraw controls whether drawn output persists across paints: when False (default), the Paint event must redraw on every invalidation; when True, the form keeps an off-screen buffer that survives invalidations and the Paint event is suppressed. Setting Picture puts a bitmap behind the drawing layer; Image returns the rendered combined surface as a StdPicture.

Private Sub Form_Paint()
    Me.ScaleMode = vbPixels
    Me.ForeColor = vbBlue
    Me.DrawWidth = 3
    Me.Line (10, 10)-(120, 80), , B          ' rectangle
    Me.CurrentX = 16 : Me.CurrentY = 16
    Me.Print "Hello, twinBASIC"
End Sub

Controls and validation

Controls is a collection of every control on the form, indexable by name or zero-based position. Form is also enumerable directly — For Each ctrl In Form1 yields the same items as For Each ctrl In Form1.Controls. Count is shorthand for Controls.Count. ActiveControl returns the currently focused child, or Nothing when no control on this form has the focus.

KeyPreview routes keystrokes to the form’s KeyDown, KeyUp, and KeyPress events before the focused control sees them — useful for application-wide hotkey handling. ValidateControls explicitly fires the active control’s Validate event from code; it raises run-time error 380 if the validation handler sets Cancel.

Menus and pop-ups

Menu structures designed at form-design time appear automatically in the form’s title bar. PopUpMenu displays one of those menus as a context-menu pop-up at a specified location, raising the menu’s Click event when the user picks an item.

Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If Button = vbRightButton Then PopUpMenu mnuContext
End Sub

Properties

ActiveControl

The control on this form that currently has the input focus, as a Control object, or Nothing when no control on this form is focused. Read-only.

AlwaysShowKeyboardCues

When True, the form always shows underlines on access-key characters in Captions and menu items, instead of only displaying them after the user presses Alt. Boolean, read-only at run time. Set at design time.

Appearance

Determines how the control’s border is drawn by the OS. A member of AppearanceConstants: vbAppearFlat or vbAppear3d (default).

Note

Retained for VB6 compatibility; the property has no observable effect on a form.

AutoRedraw

Whether drawing performed on the form persists across invalidations. Boolean, default False.

When False, drawing primitives — Cls, Circle, Line, PSet, PaintPicture, and Print — paint directly to the screen and the form must redraw them in its Paint event whenever the affected area is invalidated. When True, the form keeps an off-screen bitmap, drawing primitives paint into it (and immediately to the screen), the bitmap survives invalidations, and the Paint event is suppressed. Reading Image returns this bitmap.

BackColor

The background colour of the form’s client area, as an OLE_COLOR. Defaults to the system 3-D face colour. Used as the fill colour for Cls and as the canvas behind Picture.

BorderStyle

The window-frame style. A member of FormBorderStyleConstants: vbBSNone, vbFixedSingle, vbSizable (default), vbFixedDialog, vbFixedToolWindow, vbSizableToolWindow, vbSizableNoTitleBar (new in twinBASIC), or vbSizableToolWindowNoTitleBar (new in twinBASIC). Run-time changes are accepted but only take effect after another change to the window — typically reassigning Caption.

Caption

The title-bar text. String.

Syntax: object.Caption [ = string ]

Setting Caption updates the title bar immediately and re-syncs the title-bar style flags (so it can revive a title bar that was hidden because the previous Caption was empty).

ClipControls

Whether child controls are clipped out of the form’s drawing region during paint. Boolean, default True. Read-only at run time — set at design time.

ControlBox

Whether the form’s title bar shows the system menu (and, with it, the close button). Boolean, default True. Setting it at run time re-syncs the title-bar style flags.

Controls

The collection of every control hosted by this form, indexable by control name or zero-based position. Default property. Read-only — controls are added to the collection by the runtime, not by user code.

Dim ctrl As Control
For Each ctrl In Me.Controls
    ctrl.Enabled = False
Next

Count

The number of controls in Controls, as a Long. Read-only. Equivalent to Me.Controls.Count.

ControlType

A read-only ControlTypeConstants value identifying this control as a form. Always vbForm.

CurrentX

The horizontal pen position, in ScaleMode units, used by drawing primitives that omit a starting coordinate (for example, Print and the rectangle form of Line). Double.

CurrentY

The vertical pen position, in ScaleMode units, used by drawing primitives that omit a starting coordinate. Double.

DpiScaleFactorX

The horizontal DPI scale factor of the monitor the form is currently on, as a Double. 1.0 at 96 DPI, 1.25 at 120 DPI, 1.5 at 144 DPI, and so on. Read-only.

DpiScaleFactorY

The vertical DPI scale factor of the monitor the form is currently on. Currently always equal to DpiScaleFactorX. Read-only.

DrawMode

The raster operation that drawing primitives apply when combining the pen with the destination. A member of DrawModeConstants: vbCopyPen (default) is normal opaque drawing; other values produce XOR, AND, NOT, and other pixel-mixing effects.

DrawStyle

The pen line pattern used by drawing primitives. A member of DrawStyleConstants: vbSolid (default), vbDash, vbDot, vbDashDot, vbDashDotDot, vbInvisible, or vbInsideSolid.

DrawWidth

The pen width in pixels for drawing primitives. Long, default 1. Widths greater than 1 force DrawStyle back to vbSolid (a Win32 GDI limitation).

Enabled

Determines whether the form accepts user input. A disabled form ignores keyboard and mouse input and dims its controls. Boolean, default True.

FillColor

The fill colour for closed shapes drawn by Circle and the rectangle form of Line. OLE_COLOR, default 0 (black). Used only when FillStyle is not vbFSTransparent.

FillStyle

The fill pattern for closed shapes. A member of FillStyleConstants: vbFSSolid, vbFSTransparent (default), vbHorizontalLine, vbVerticalLine, vbUpwardDiagonal, vbDownwardDiagonal, vbCross, or vbDiagonalCross.

Font

The StdFont used by the Print statement and other text drawing on this form. The convenience properties FontName, FontSize, FontBold, FontItalic, FontStrikethru, and FontUnderline read or write the corresponding members of this object.

FontTransparent

When True (default), text drawn on the form has a transparent background, leaving the underlying drawing visible behind it. When False, text is drawn over an opaque rectangle filled with BackColor. Boolean.

ForeColor

The pen colour used by Circle, Line, PSet, and the text drawn by Print. OLE_COLOR.

hDC

The Win32 device context handle for the form, as a LongPtr. Read-only. Returns 0 when the underlying window has not yet been created. Useful for passing to GDI API calls.

HasDC

Whether the form keeps a private device context (CS_OWNDC) for its drawing surface. Boolean, default True. Read-only at run time — set at design time.

Height

The form’s outer height, in twips by default (or in the container’s ScaleMode units). Double. Setting it resizes the window. Constrained at run time by MinHeight and MaxHeight when those are non-zero.

HelpContextID

A Long identifying a topic in the application’s help file, retrieved when the user presses F1 while the form has focus.

hWnd

The Win32 window handle for the form, as a LongPtr. Read-only. Useful for passing to API functions.

Icon

The icon shown on the title bar, in the taskbar, and in Alt-Tab. A StdPicture of type vbPicTypeIcon. Assigning a non-icon picture clears the icon to the default Windows application icon.

Image

Returns the rendered drawing surface as a StdPicture. Read-only. Most useful when AutoRedraw is True — the returned picture is the persistent off-screen buffer.

KeyPreview

When True, the form’s KeyDown, KeyUp, and KeyPress events fire before the focused control receives the same keystroke. Boolean, default False. Useful for application-wide hotkeys; events still fire on the focused control afterwards.

Left

The horizontal position of the form’s outer rectangle, in twips (or the calling code’s ScaleMode units), measured from the left edge of the screen — or, for an MDI child, from the left edge of the MDI parent’s client area. Double.

LinkMode

Note

Reserved for compatibility with VB6’s DDE feature; not currently implemented in twinBASIC.

LinkTopic

Note

Reserved for compatibility with VB6’s DDE feature; not currently implemented in twinBASIC.

MaxButton

Whether the title bar shows the maximise button. Boolean, default True, read-only at run time. Set at design time.

MaxHeight

The maximum height of the form’s client area, in twips. Double, default 0 (no limit). Honoured during interactive resizing.

MaxWidth

The maximum width of the form’s client area, in twips. Double, default 0 (no limit). Honoured during interactive resizing.

MDIChild

When True, the form is hosted as a child inside an MDIForm. Boolean, read-only — set at design time. An MDI child form cannot be shown modally.

MinButton

Whether the title bar shows the minimise button. Boolean, default True, read-only at run time. Set at design time.

MinHeight

The minimum height of the form’s client area, in twips. Double, default 0 (no limit). Honoured during interactive resizing.

MinWidth

The minimum width of the form’s client area, in twips. Double, default 0 (no limit). Honoured during interactive resizing.

MouseIcon

A StdPicture used as the mouse cursor when MousePointer is vbCustom and the pointer is over the form (and not over a child control with its own setting).

MousePointer

The mouse cursor shown when the pointer is over the form (and not over a child control with its own setting). A member of MousePointerConstants.

Moveable

Whether the user can drag the form by its title bar. Boolean, default True.

Name

The unique design-time name of the form. Read-only at run time. Also the class name of the generated form class.

NegotiateMenus

Note

Reserved for compatibility with VB6’s ActiveX-document menu negotiation feature; not currently implemented in twinBASIC.

OLEDropMode

How the form responds to OLE drops. A restricted member of OLEDropConstants: vbOLEDropNone or vbOLEDropManual. Automatic-drop mode is not supported on a Form.

Opacity

The form’s opacity as a percentage (0–100, default 100). Values outside the range are clamped on Initialize. Values below 100 cause the form to become a layered window.

Palette

Note

Reserved for compatibility with VB6’s 256-colour palette feature; not currently implemented in twinBASIC.

PaletteMode

Note

Reserved for compatibility with VB6’s 256-colour palette feature; not currently implemented in twinBASIC.

Picture

A StdPicture drawn as the form’s background. Painted before any drawing primitives or child controls. Assigning Nothing removes the background.

PictureDpiScaling

When True, Picture is scaled by the current DPI factor before drawing. Boolean, default False.

RightToLeft

Note

Reserved for compatibility with VB6; not currently implemented in twinBASIC.

ScaleHeight

The height of the logical drawing rectangle, in ScaleMode units. Double. Setting it (or ScaleWidth, ScaleLeft, or ScaleTop) implicitly switches ScaleMode to vbUser.

ScaleLeft

The logical horizontal coordinate of the left edge of the form’s client area, in ScaleMode units. Double. Default 0.

ScaleMode

The unit of measurement used by CurrentX, CurrentY, the drawing primitives, TextWidth, and TextHeight. A member of ScaleModeConstants: vbTwips (default), vbPoints, vbPixels, vbCharacters, vbInches, vbMillimeters, vbCentimeters, or vbUser (the four Scale* properties define the rectangle).

ScaleTop

The logical vertical coordinate of the top edge of the form’s client area, in ScaleMode units. Double. Default 0.

ScaleWidth

The width of the logical drawing rectangle, in ScaleMode units. Double. Setting it implicitly switches ScaleMode to vbUser.

ShowInTaskbar

Whether the form appears in the Windows taskbar and Alt-Tab list. Boolean, default True. Read-only at run time — set at design time.

StartUpPosition

How the form’s initial position is determined the first time it is shown. A member of StartUpPositionConstants: vbStartUpManual, vbStartUpOwner, vbStartUpScreen, or vbStartUpWindowsDefault (default). Read-only at run time — set at design time.

TabFocusAutoSelect

When True, a TextBox on this form whose own TabFocusAutoSelect is also True auto-selects its content when the focus enters it via the TAB key. Boolean, default False.

Tag

A free-form String the application can use to associate custom data with the form. Ignored by the framework.

Top

The vertical position of the form’s outer rectangle, in twips (or the calling code’s ScaleMode units), measured from the top edge of the screen — or, for an MDI child, from the top edge of the MDI parent’s client area. Double.

TopMost

Whether the form sits in the always-on-top z-order layer. Boolean, read-only at run time. Set at design time.

TransparencyKey

An OLE_COLOR that, when set, becomes fully transparent in the rendered form — clicks pass through to whatever is underneath, and the corresponding pixels do not paint. Default -1 disables the effect.

Visible

Whether the form is shown. Boolean, default True. Setting Visible to True when the form was hidden is equivalent to calling Show vbModeless; setting it to False is equivalent to calling Hide.

WhatsThisButton

When True, the title bar shows a “?” help button — but only when MinButton is False, MaxButton is False, ControlBox is True, and BorderStyle is not a tool-window style. Boolean.

WhatsThisHelp

When True, WhatsThisMode and the title-bar help button enter Windows’ “What’s This?” cursor mode. Boolean, default False.

Width

The form’s outer width, in twips by default (or in the container’s ScaleMode units). Double. Setting it resizes the window. Constrained at run time by MinWidth and MaxWidth when those are non-zero.

WindowState

The window’s normal/minimised/maximised state. A member of FormWindowStateConstants: vbNormal (0, default), vbMinimized (1), or vbMaximized (2). Setting it at run time updates the window placement immediately if the form is visible.

Methods

Circle

Draws a circle, ellipse, or arc on the form using ForeColor for the outline and FillColor/FillStyle for the interior.

Syntax: object.Circle [ Step ] ( X, Y ), Radius [, [ Color ] [, [ Start ] [, [ End ] [, Aspect ] ] ] ]

X, Y: required The centre, in ScaleMode units. Step makes the centre relative to (CurrentX, CurrentY).
Radius: required A Single giving the radius in ScaleMode units.
Color: optional An OLE_COLOR for the outline; defaults to ForeColor.
Start, End: optional Angles in radians, used to draw an arc rather than a full circle.
Aspect: optional Ratio of vertical to horizontal radius. 1.0 is circular; values away from 1.0 produce ellipses.

Cls

Clears any drawing performed by Circle, Line, PSet, PaintPicture, and Print, repaints BackColor, and resets CurrentX / CurrentY to 0. Does not affect the Picture backdrop or child controls.

Syntax: object.Cls

Close

Initiates the form’s unload sequence — QueryUnload, then Unload, then Terminate. Either of the first two events can cancel the close by setting Cancel to non-zero. Equivalent to the language statement Unload Me.

Syntax: object.Close

Hide

Hides the form without unloading it. The class instance and its controls are preserved; calling Show (or assigning Visible = True) brings it back. Equivalent to assigning Visible = False.

Syntax: object.Hide

Line

Draws a line, or a rectangle, on the form using ForeColor (or an explicit colour) and DrawWidth/DrawStyle.

Syntax: object.Line [ [ Step ] ( X1, Y1 ) ] -[ Step ] ( X2, Y2 ) [, [ Color ] [, B [ F ] ] ]

X1, Y1: optional The start point, in ScaleMode units. Step makes the point relative to (CurrentX, CurrentY). When omitted, drawing begins from the current pen position.
X2, Y2: required The end point, in ScaleMode units. Step makes the point relative to (X1, Y1).
Color: optional An OLE_COLOR for the line; defaults to ForeColor.
B: optional Draw a rectangle whose opposite corners are (X1, Y1) and (X2, Y2) instead of a line.
F: optional When combined with B, fill the rectangle with ForeColor instead of FillColor/FillStyle.

Move

Repositions and optionally resizes the form in a single call.

Syntax: object.Move Left [, Top [, Width [, Height ] ] ]

Left: required A Single giving the new horizontal position.
Top, Width, Height: optional New values for the corresponding properties. Omitted values are left unchanged.

OLEDrag

Initiates an OLE drag operation from the form, raising the OLEStartDrag event so the application can populate the DataObject.

Syntax: object.OLEDrag

PaintPicture

Draws a StdPicture onto the form, with optional scaling and raster operations.

Syntax: object.PaintPicture Picture, X1, Y1 [, Width1 [, Height1 [, X2 [, Y2 [, Width2 [, Height2 [, Opcode [, StretchQuality ] ] ] ] ] ] ] ]

Picture: required A StdPicture to draw.
X1, Y1: required The destination upper-left corner, in ScaleMode units.
Width1, Height1: optional Destination size; defaults to the picture’s natural size.
X2, Y2, Width2, Height2: optional The source rectangle within the picture; defaults to the whole picture.
Opcode: optional A raster-operation code (member of RasterOpConstants). Defaults to vbSrcCopy.
StretchQuality: optional The interpolation method when scaling. Defaults to normal quality.

PopUpMenu

Displays a Menu as a context-menu pop-up at the specified location.

Syntax: object.PopUpMenu Menu [, Flags [, X [, Y [, DefaultMenu ] ] ] ]

Menu: required The Menu control to display. The menu must already exist on the form (or its MDI parent).
Flags: optional A combination of MenuControlConstants controlling alignment and which mouse buttons trigger the menu items.
X, Y: optional The screen-relative position to anchor the menu at, in ScaleMode units. Defaults to the current mouse position.
DefaultMenu: optional The Menu sub-item to render in bold as the default action.

Point

Note

Reserved for compatibility with VB6; not currently implemented in twinBASIC. In VB6 this returns the OLE_COLOR of a single pixel of the drawing surface.

Syntax: object.Point( X, Y )

PrintForm

Sends a screen-shot of the form’s current visual state to the default printer through the Printer object.

Syntax: object.PrintForm [ ImplicitEndDoc [, OutputAtCurrentPosition ] ]

ImplicitEndDoc: optional When True (default), the print job is finalised before returning; when False, the form is sent as a page but the print job stays open for further output.
OutputAtCurrentPosition: optional When True, the form is rendered at the printer’s current pen position rather than at the page origin. Boolean, default False.

PSet

Sets a single pixel on the form to a specified colour.

Syntax: object.PSet [ Step ] ( X, Y ) [, Color ]

X, Y: required The pixel position, in ScaleMode units. Step makes the position relative to (CurrentX, CurrentY).
Color: optional An OLE_COLOR; defaults to ForeColor.

Refresh

Forces an immediate repaint of the form, raising Paint when AutoRedraw is False.

Syntax: object.Refresh

Scale

Sets the form’s logical drawing rectangle in a single call by assigning ScaleLeft, ScaleTop, ScaleWidth, and ScaleHeight. Switches ScaleMode to vbUser. Calling Scale with no arguments resets the rectangle to a 1-to-1 mapping with the client area in pixels.

Syntax: object.Scale [ ( X1, Y1 )-( X2, Y2 ) ]

X1, Y1: optional The logical coordinate at the top-left corner.
X2, Y2: optional The logical coordinate at the bottom-right corner.

ScaleX

Converts a horizontal length from one ScaleMode to another.

Syntax: object.ScaleX( Width [, FromScale [, ToScale ] ] )

Width: required A Single giving the source length.
FromScale, ToScale: optional Members of ScaleModeConstants. Default to the current ScaleMode when omitted.

ScaleY

Converts a vertical length from one ScaleMode to another.

Syntax: object.ScaleY( Height [, FromScale [, ToScale ] ] )

Height: required A Single giving the source length.
FromScale, ToScale: optional Members of ScaleModeConstants. Default to the current ScaleMode when omitted.

SetFocus

Activates the form and gives input focus to the control whose TabIndex is 0 (or to whichever control last held focus on this form).

Syntax: object.SetFocus

Show

Makes the form visible. Triggers Load on the first call.

Syntax: object.Show [ Modal [, OwnerForm ] ]

Modal: optional A member of FormShowConstants: vbModeless (0, default — the call returns immediately) or vbModal (1 — the call blocks until the form is closed and the user cannot interact with other forms).
OwnerForm: optional For modal shows, the form that is disabled while this form is up; defaults to the currently active form.

TextHeight

Returns the height that the given string would occupy when drawn with the form’s current Font, in ScaleMode units.

Syntax: object.TextHeight( Str )

Str: required A String to measure.

TextWidth

Returns the width that the given string would occupy when drawn with the form’s current Font, in ScaleMode units.

Syntax: object.TextWidth( Str )

Str: required A String to measure.

ValidateControls

Fires the Validate event of the currently active control on this form. If the handler sets Cancel to True, ValidateControls raises run-time error 380 (Invalid property value); the caller can wrap this with On Error to detect a failed validation. Useful for checking pending input before saving or closing.

Syntax: object.ValidateControls

WhatsThisMode

Enters Windows’ “What’s This?” cursor mode — the next click on a control raises that control’s help instead of activating it. WhatsThisHelp must be True.

Syntax: object.WhatsThisMode

ZOrder

Brings the form to the front or back of the top-level z-order.

Syntax: object.ZOrder [ Position ]

Position: optional A member of ZOrderConstants: vbBringToFront (0, default) or vbSendToBack (1).

Events

Activate

Raised when the form becomes the active window in the application — either after Load for the first show, or whenever it gains activation back from another window.

Syntax: object_Activate( )

Click

Raised when the user single-clicks the form’s client area (i.e. not over any child control).

Syntax: object_Click( )

DblClick

Raised when the user double-clicks the form’s client area.

Syntax: object_DblClick( )

Deactivate

Raised when another window in the application takes activation away from this form. Not raised when activation moves to a window in a different application.

Syntax: object_Deactivate( )

DPIChange

Raised when the form moves to a monitor with a different DPI scale, but only when the application is per-monitor DPI aware (PROCESS_PER_MONITOR_DPI_AWARE). The event’s NewDPI argument carries the new effective DPI; child controls re-scale themselves automatically. New in twinBASIC.

Syntax: object_DPIChange( NewDPI As Long )

DragDrop

Raised on the destination control when a manual drag operation ends over it.

Syntax: object_DragDrop( Source As Control, X As Single, Y As Single )

DragOver

Raised on the control under the cursor while a manual drag operation is in progress.

Syntax: object_DragOver( Source As Control, X As Single, Y As Single, State As Integer )

GotFocus

Raised when the form receives the input focus and no enabled child control of the form is in a position to take it instead. A form with no focusable child controls receives focus directly.

Syntax: object_GotFocus( )

Initialize

Raised once, before the underlying window is created and before any of the form’s child controls exist. Useful for setting initial values on form-level fields. The form’s controls cannot be referenced from this event.

Syntax: object_Initialize( )

KeyDown

Raised when the user presses any key. Fires on the focused control by default; with KeyPreview True, fires on the form first.

Syntax: object_KeyDown( KeyCode As Integer, Shift As Integer )

KeyPress

Raised when the user types a character that produces an ANSI keystroke. Fires on the focused control by default; with KeyPreview True, fires on the form first.

Syntax: object_KeyPress( KeyAscii As Integer )

KeyUp

Raised when the user releases a key. Fires on the focused control by default; with KeyPreview True, fires on the form first.

Syntax: object_KeyUp( KeyCode As Integer, Shift As Integer )

LinkClose

Note

Reserved for compatibility with VB6’s DDE feature; not currently raised in twinBASIC.

LinkError

Note

Reserved for compatibility with VB6’s DDE feature; not currently raised in twinBASIC.

LinkExecute

Note

Reserved for compatibility with VB6’s DDE feature; not currently raised in twinBASIC.

LinkOpen

Note

Reserved for compatibility with VB6’s DDE feature; not currently raised in twinBASIC.

Load

Raised after the form’s window and all controls have been created, just before the form first appears on screen. The classic place to populate controls, attach data sources, and perform any initialisation that needs the controls to exist. Default event.

Syntax: object_Load( )

LostFocus

Raised when the form loses the input focus.

Syntax: object_LostFocus( )

MouseDown

Raised when the user presses any mouse button over the form’s client area.

Syntax: object_MouseDown( Button As Integer, Shift As Integer, X As Single, Y As Single )

MouseMove

Raised when the cursor moves over the form’s client area.

Syntax: object_MouseMove( Button As Integer, Shift As Integer, X As Single, Y As Single )

MouseUp

Raised when the user releases a mouse button over the form’s client area.

Syntax: object_MouseUp( Button As Integer, Shift As Integer, X As Single, Y As Single )

MouseWheel

Raised when the mouse wheel turns over the form. New in twinBASIC.

Syntax: object_MouseWheel( Delta As Integer, Horizontal As Boolean )

OLECompleteDrag

Raised on the source control when the OLE drag operation finishes, indicating which effect (copy, move, none) the destination accepted.

Syntax: object_OLECompleteDrag( Effect As Long )

OLEDragDrop

Raised on the destination control when the user drops data on it.

Syntax: object_OLEDragDrop( Data As DataObject, Effect As Long, Button As Integer, Shift As Integer, X As Single, Y As Single )

OLEDragOver

Raised on the destination control while an OLE drag passes over it.

Syntax: object_OLEDragOver( Data As DataObject, Effect As Long, Button As Integer, Shift As Integer, X As Single, Y As Single, State As Integer )

OLEGiveFeedback

Raised on the source control during a drag so the application can adjust the cursor or other visual feedback.

Syntax: object_OLEGiveFeedback( Effect As Long, DefaultCursors As Boolean )

OLESetData

Raised on the source control when the destination requests data in a format that was registered but not yet supplied.

Syntax: object_OLESetData( Data As DataObject, DataFormat As Integer )

OLEStartDrag

Raised on the source control at the start of an OLE drag, so the application can populate the DataObject and choose the allowed effects.

Syntax: object_OLEStartDrag( Data As DataObject, AllowedEffects As Long )

Paint

Raised when an invalidated portion of the form needs to be redrawn. Suppressed when AutoRedraw is True — the form’s persistent off-screen buffer is blitted to the screen instead.

Syntax: object_Paint( )

QueryUnload

Raised before the form unloads, giving the application a chance to confirm or cancel the close. Setting Cancel to non-zero keeps the form open. Always raised before Unload.

Syntax: object_QueryUnload( Cancel As Integer, UnloadMode As Integer )

Cancel: Set to non-zero (any non-zero value, conventionally 1) to cancel the close.
UnloadMode: A member of QueryUnloadConstants identifying what triggered the close — the close button, code, Windows shutdown, the MDI parent, or the owner form.

Resize

Raised when the form is resized — by the user, by code, by the OS following a WindowState change, or by initial layout during the first show.

Syntax: object_Resize( )

Terminate

Raised after the form’s window has been destroyed and the class instance is about to be released. The controls are no longer accessible at this point.

Syntax: object_Terminate( )

Unload

Raised after QueryUnload approves and before the form’s window is destroyed. Setting Cancel to non-zero keeps the form open and prevents the unload.

Syntax: object_Unload( Cancel As Integer )

Cancel: Set to non-zero (any non-zero value, conventionally 1) to cancel the unload.