Using VCL TNumberBox Control

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The VCL TNumberBox control is a modern looking numeric input control, modeled after the Windows platform WinUI NumberBox control. The control supports the input of integer numbers, floating point numbers with a given set of decimal digits and proper formatting, and currency values.

The user can increase or decrease the value using arrow buttons or allow keys or mouse wheel, and also increase and decrease by a large value using Page Up and Page Down keys.

The component supports simple expression evaluation; if enabled, a user can input an expression like 40 + 2 and the control will replace it with the result.

The control supports computing inline calculations of basic equations such as multiplication, division, addition, and subtraction (allowing the use of parentheses). Notice that you can use the symbols + and - both as binary and unary operations, so you can type -23 or + 23, you can write 55+23 and 55-23, and even combine them as in 53++23 or 53--23, which is evaluated as 53 - (-23). thus, adds the two values.

The component includes an optional spin button, configured with the SpinButtonOptions Placement property, which can be compact, inline, or disabled, as you can see below:

List of TNumberBox Component Properties

The control supports VCL styling, is HighDPI-enabled, and has many additional properties to adjust visual style and behavior. This is a list of the control properties:

Mode: TNumberBoxMode	Defines in which mode control works and is based on the following enumeration: TNumberBoxMode = (nbmInteger, nbmFloat, nbmCurrency);
Value: Extended	Current Value
ValueInt: Integer	Current Value as Integer
ValueFloat: Extended	Current Value as Extended rounded using Decimal property
ValueCurrency: Extended	Current Value as Extended rounded with Decimal = 2
CurrencyString: String	Defines string for currency mode, which will be added at the end of display text
DisplayFormat: String	Defines custom text format
MinValue: Extended	Defines minimum value
MaxValue: Extended	Defines maximum value
Decimal: Byte	Defines the number of decimal digits
SmallStep: Extended	Defines the amount by which the Value property will change with spin button, Up/Down keys and mouse wheel
LargeStep: Extended	Defines the amount by which the Value property will change with Page Up/Page Down keys
AcceptExpressions: Boolean	Enables using expressions in control
SpinButtonOptions: TNumberBoxSpinButtonOptions	Defines options of spin button and is a data structure including sub-properties ButtonWidth, Placement, RepeatTimerInterval, ShowInlineDividers, and different arrow colors
UseNaNValue: Boolean	Uses NaN value with empty text
UseMouseWheel: Boolean	Enables changing Value with mouse wheel using SmallStep property
UseUpDownKeys: Boolean	Enables changing Value with Up/Downand Page Up/Page Down keys
Wrap: Boolean	Enables incrementing from the max value to the minimum one and reverse

List of TNumberBox Component Events

The component has the following events:

OnChangeValue: TNotifyEvent	Occurs if Value property is changed
OnEvaluateExpression: TNotifyEvent	Occurs when applying custom evaluation of expression using Text and Value properties
OnValidateChar: TNumberBoxValidateCharEvent	Custom validation of input char