CheckMark class

A CheckMark is a windowless control that draws a single check glyph --- checked, unchecked, or grey --- that scales to fill its rectangle. Unlike CheckBox, it has no caption, no font, and cannot take focus or receive keyboard input; it is essentially the box from a check-box rendered at whatever size the layout requires. This makes it especially useful inside reports and other dense layouts where the fixed-size system check would look out of place, but it is also available on a Form or UserControl.

The default property is Value and the default event is Click.

Private Sub Form_Load()
    Check1.Value = vbUnchecked
End Sub

Private Sub Check1_Click()
    Debug.Print "Check is now: " & Check1.Value
End Sub

Three-state behaviour

Value is typed as CheckBoxConstants:

Constant	Value	Meaning
vbUnchecked	0	The check is cleared.
vbChecked	1	The check is selected.
vbGrayed	2	The check is in an indeterminate (grey) state.

A user click toggles Value between vbChecked and vbUnchecked only. The grey state is reachable from code --- assign vbGrayed to Value to display it.

Check1.Value = vbGrayed     ' show the indeterminate state

Drawing modes

VisualStyles selects how the glyph is rendered:

• VisualStyles = False (default) --- drawn with the GDI DrawFrameControl primitive. Honours Appearance: vbAppear3d uses the classic raised/sunken look, vbAppearFlat uses a single-pixel outline. A disabled check, or one in the vbGrayed state, is drawn over the dotted three-state pattern.
• VisualStyles = True --- drawn through the OS theme engine (UXTHEME), so the glyph uses the current visual-style theme. Appearance is ignored in this mode.

Background

BackStyle controls whether the rectangle behind the glyph is filled before the glyph is drawn:

• vbBFTransparent (default) --- only the glyph is painted; whatever the container draws shows through.
• vbBFOpaque --- the rectangle is filled with BackColor first.

Properties

Anchors

The Anchors object that determines which sides of the control follow the corresponding sides of its container as the container is resized. Read-only --- set the individual sides through the returned object.

Appearance

How the glyph is shaded when VisualStyles is False. A member of AppearanceConstants: vbAppear3d (default) or vbAppearFlat. Ignored when VisualStyles is True.

BackColor

The background colour, as an OLE_COLOR. Defaults to the system 3-D face colour. Used only when BackStyle is vbBFOpaque.

BackStyle

Whether the control fills its rectangle before drawing the glyph. A member of BackFillStyleConstants: vbBFTransparent (default) or vbBFOpaque.

Container

The immediate container (a Form, Frame, PictureBox, or other container control) that hosts this CheckMark. Assigning a new value with Set moves the control to a different container.

ControlType

A read-only ControlTypeConstants value identifying this control as a check mark. Always vbCheckMark.

Dock

Whether the control fills one edge of, or the entire interior of, its container. A member of DockModeConstants, default vbDockNone.

DragIcon

A StdPicture used as the mouse cursor while the control is being drag-and-dropped (see Drag and DragMode).

DragMode

Whether the control should drag itself when the user holds the mouse over it. A member of DragModeConstants: vbManual (0, default --- call Drag from code) or vbAutomatic (1).

Enabled

Determines whether the control reacts to mouse input. A disabled CheckMark still shows its current value but is drawn dimmed and ignores clicks. Boolean, default True.

Height

The control's height, in twips by default (or in the container's ScaleMode units). Single.

Index

When the control is part of a control array, the Long zero-based index of this instance within the array. Reading Index on a control that is not part of an array raises run-time error 343 (Object not an array). Read-only at run time.

Left

The horizontal distance from the left edge of the container to the left edge of the control. Single.

MouseIcon

A StdPicture used as the mouse cursor when MousePointer is vbCustom and the pointer is over the control.

MousePointer

The mouse cursor shown when the pointer is over the control. A member of MousePointerConstants.

Name

The unique design-time name of the control on its parent form. Read-only at run time.

Parent

A reference to the Form (or UserControl) that contains this control. Read-only.

TabIndex

INFO

Reserved for compatibility with VB6; not currently implemented in twinBASIC. The control is not focusable, so the property has no effect at run time.

Tag

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

ToolTipText

A multi-line String displayed as a tooltip when the user hovers over the control.

Top

The vertical distance from the top of the container to the top of the control. Single.

Value

The current state of the check. Default property.

Syntax: object.Value [ = value ]

value

A member of CheckBoxConstants: vbUnchecked (0), vbChecked (1), or vbGrayed (2).

A user click toggles Value between vbChecked and vbUnchecked only; vbGrayed is settable from code.

Visible

Whether the control is shown. Boolean, default True.

VisualStyles

When True, the glyph is drawn through the OS theme engine; when False (default), it is drawn with DrawFrameControl and obeys Appearance. Boolean.

WhatsThisHelpID

A Long identifying a "What's This?" help-pop-up topic in the application's help file. See ShowWhatsThis.

Width

The control's width. Single.

Methods

Drag

Begins, completes, or cancels a manual drag-and-drop operation. Typically called from a MouseDown handler when DragMode is vbManual.

Syntax: object.Drag [ Action ]

Action

optional A member of DragConstants: vbCancel (0), vbBeginDrag (1, default), or vbEndDrag (2).

Move

Repositions and optionally resizes the control 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 control, raising the OLEStartDrag event so the application can populate the DataObject.

Syntax: object.OLEDrag

Refresh

Forces an immediate repaint of the control.

Syntax: object.Refresh

ShowWhatsThis

Displays the topic identified by WhatsThisHelpID as a "What's This?" pop-up.

Syntax: object.ShowWhatsThis

ZOrder

Brings the control to the front or back of its sibling stack.

Syntax: object.ZOrder [ Position ]

Position

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

Events

Click

Raised when the user clicks the control with the left mouse button --- after Value has toggled between vbChecked and vbUnchecked. Default event.

Syntax: object_Click( )

DblClick

Raised when the user double-clicks the control.

Syntax: object_DblClick( )

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 )

MouseDown

Raised when the user presses any mouse button over the control.

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

MouseMove

Raised when the cursor moves over the control.

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 control.

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

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 )