McBasic™ 0.7.881 · Build 881 · 10 min read

Controls · Visual control

CommandButton

Turn an explicit user action into a bound BASIC event.

41 properties17 events1 methodsDefault: Click

Build the CommandButton lesson Properties Events Methods

Use it in a Form#

The name belongs in txtName.Text; the result belongs in lblGreeting.Caption. A Click handler is the bridge between them. Trimming before testing length rejects whitespace-only input. The details window has its own public DisplayName field: set that value before calling Show so its Shown handler can render it.

Add CommandButton to its intended parent and name it cmdGreet for this example:

Property	Example value
`Caption`	`"Greet"`

A complete handler from Forms/frmMain.bas. The linked lesson includes its surrounding controls, declarations and helpers.

Forms/frmMain.bas

Private Sub cmdGreet_Click()
    Dim name As String
    name = Trim$(txtName.Text)

    If Len(name) = 0 Then
        lblGreeting.Caption = "Enter a name."
        Exit Sub
    End If

    lblGreeting.Caption = "Hello, " & name
End Sub

Properties#

Contract defaults are shown below. Where a new control has a different Designer starting value, that value is listed separately.

`Left`

DoubleDefault: 0

Horizontal position in device-independent points, relative to the parent container.

Range: -100000 to 100000.

`Top`

DoubleDefault: 0

Vertical position in device-independent points, relative to the parent container.

Range: -100000 to 100000.

`Width`

DoubleDefault: 120

Control width in device-independent points.

Range: 0 to 100000.

Designer starting value: 140.

`Height`

DoubleDefault: 32

Control height in device-independent points.

Range: 0 to 100000.

`MinWidth`

DoubleDefault: 0

Minimum control width in device-independent points; 0 lets the parent layout choose.

Range: 0 to 100000.

`MinHeight`

DoubleDefault: 0

Minimum control height in device-independent points; 0 lets the parent layout choose.

Range: 0 to 100000.

`MaxWidth`

DoubleDefault: 100000

Maximum control width in device-independent points.

Range: 0 to 100000.

`MaxHeight`

DoubleDefault: 100000

Maximum control height in device-independent points.

Range: 0 to 100000.

`TabIndex`

LongDefault: 0

Keyboard navigation order within the parent container; lower values come first.

Range: 0 to 100000.

`ZIndex`

LongDefault: 0

Stacking order among sibling controls; larger values appear in front. Equal values preserve document order.

Range: -100000 to 100000.

`Anchor`

StringDefault: "Left,Top"Not in InspectorNot serialized

Edges kept at their authored distance when the parent resizes. Use a comma-separated combination of Left, Top, Right and Bottom; Dock overrides the effective anchor without deleting it.

`Dock`

StringDefault: "None"

Automatic placement within the parent: None, Left, Top, Right, Bottom or Fill. Dock overrides effective Anchor layout without deleting the stored anchors.

`Visible`

BooleanDefault: True

Whether the control is shown in the running application.

`Enabled`

BooleanDefault: True

Whether the control accepts user interaction in the running application.

`HitTestVisible`

BooleanDefault: True

Whether the running control participates in pointer hit testing. The control remains selectable in the Designer.

`AllowDrop`

BooleanDefault: False

Whether this running control accepts application drag-and-drop operations; Designer movement is separate.

`DragMode`

LongDefault: 0

VB control drag: 0 Manual (code starts a drag with the Drag method) or 1 Automatic (a left-button press starts a drag, and the control raises no Click, MouseDown or MouseUp for that press).

Range: 0 to 1.

`DragIcon`

StringDefault: ""

Case-insensitive name of a declared project image resource shown under the pointer while this control is dragged; empty shows a grey outline of the control.

`TabStop`

BooleanDefault: True

Whether Tab navigation can move focus to this CommandButton.

`Caption`

StringDefault: ""

Text displayed by the control.

Designer starting value: "CommandButton".

`WordWrap`

BooleanDefault: False

Wraps the displayed caption within the available control width; false keeps a single line.

`TextTrimming`

StringDefault: "None"

Overflow behavior for an unwrapped caption: None, CharacterEllipsis or WordEllipsis.

`Padding`

StringDefault: "8,4,8,4"

Inner spacing around the caption as one non-negative DIP value or Left,Top,Right,Bottom.

`Default`

BooleanDefault: FalseNot serialized

Whether Enter invokes this CommandButton. Setting True supersedes the previous default button on the Form.

`Cancel`

BooleanDefault: FalseNot serialized

Whether Escape invokes this CommandButton. Setting True supersedes the previous cancel button on the Form.

`Font`

StringDefault: ""

Font as Family|Size or Family|Size|Regular/Bold|Normal/Italic, size 6–96 DIP. Empty uses the theme font; System uses the theme family.

`ForeColor`

StringDefault: ""

Text color as #RRGGBB. Empty uses the current macOS theme color.

`BackColor`

StringDefault: ""

Background color as #RRGGBB. Empty uses the current macOS theme color.

`Margin`

StringDefault: "0"

External spacing as one non-negative DIP value or Left,Top,Right,Bottom.

`Cursor`

StringDefault: "Default"

Pointer shown over the control: Default, Arrow, Hand, IBeam, Cross, Wait, Help, SizeAll, SizeNS, SizeWE, SizeNWSE, SizeNESW or NotAllowed.

`Opacity`

DoubleDefault: 1

Visual opacity from 0 (transparent) to 1 (opaque).

Range: 0 to 1.

`DesignLocked`

BooleanDefault: FalseDesigner only

Prevents movement and resizing in the Designer without changing runtime interaction.

`AccessibleDescription`

StringDefault: ""

Additional help text announced by assistive technology.

`AutomationId`

StringDefault: ""

Stable automation identifier; empty uses the component Name.

`AccessibleName`

StringDefault: ""

Name announced by assistive technology. Empty uses the stable control Name.

`AccessibleRole`

StringDefault: "Auto"

Accessibility role override. Auto preserves the native semantic role; explicit values use the corresponding platform automation role.

`ToolTipText`

StringDefault: ""

Help text shown when the pointer rests over the running control; empty disables the tooltip.

`Tag`

StringDefault: ""

Application-defined text associated with this control; McBasic™ does not interpret it.

`Picture`

StringDefault: ""

Name of a declared project image resource shown with the Caption (never enlarged; shrunk to fit). Empty shows the Caption only. Assigning an undeclared or unreadable image in code raises error 481.

`PictureAlignment`

StringDefault: "Left"

Where the Picture sits relative to the Caption: Left (the macOS default), Top, Right or Bottom.

`Index`

LongDefault: -1Read only in BASICDesigner Index row

Position of this control in its control array, 0 to 32767. Several controls share one name only when every one of them has an Index. Absent from the layout, and -1 in code, when the control is not in an array.

Designer values: 0 to 32767. Clear the dedicated Index row for a non-array control; BASIC then reads -1.

Events and parameters#

Replace control with the object’s Name when creating a handler. ByRef arguments may be changed by your handler; ByVal arguments report an input value.