Restriction or Validation in WPF Percent TextBox

18 Nov 20186 minutes to read

This section explains how to validate or restrict the WPF Percent TextBox control value.

Restrict the value within minimum and maximum value

The PercentValue of the WPF Percent TextBox can be restricted within the maximum and minimum limits. Once the percent value has reached the maximum or minimum value, the value will not exceed the limit. You can change the maximum and minimum limits by using the MinValue and MaxValue properties.

You can choose when to validate the maximum and minimum limits while changing the percent values by using the MinValidation and MaxValidation properties. The default value of both properties is OnKeyPress.

• OnKeyPress — When setting the MaxValidation or MinValidation to OnKeyPress, the percent value in the PercentTextBox will be validated shortly after pressing a key. So, it is not possible to provide any invalid input at all, and the percent value will not exceed the maximum and minimum limits.

• OnLostFocus - When MaxValidation or MinValidation is set to OnLostFocus, the percent value is validated when the WPF Percent TextBox loses focus. The control accepts any percent value while it has focus, and validation occurs only after focus is lost. If the value exceeds MaxValue or is less than MinValue, it is automatically reset to MaxValue or MinValue, respectively.

• MaxValueOnExceedMaxDigit - When you give input greater than the specified maximum limit, the MaxValueOnExceedMaxDigit property will decide whether to retain the old percent value or reset to the maximum limit. For example, if MaxValue is set to 100 and you are trying to input 200, PercentValue will be changed to 100 when MaxValueOnExceedMaxDigit is true. When MaxValueOnExceedMaxDigit is false, 20 will be retained and the last entered 0 will be ignored.

  MaxValueOnExceedMaxDigit property is enabled only when the MaxValidation is set to OnKeyPress.

• MinValueOnExceedMinDigit - When you give input less than the specified minimum limit, the MinValueOnExceedMinDigit property will decide whether to retain the old percent value or reset to the minimum limit. For example, if MinValue is set to 200 and the PercentValue is 205 and you are trying to change the percent value to 20, PercentValue will be changed to 200 when MinValueOnExceedMinDigit is true. When MinValueOnExceedMinDigit is false, the old percent value 205 will be retained.

  MinValueOnExceedMinDigit is enabled only when the MinValidation is set to OnKeyPress.

XAML

<syncfusion:PercentTextBox x:Name="percentTextBox" Width="150" MaxValue="100" MinValue="10"
                          MinValueOnExceedMinDigit="True" MaxValueOnExceedMaxDigit="True"
                          MinValidation="OnKeyPress" MaxValidation="OnLostFocus"/>

C#

PercentTextBox percentTextBox = new PercentTextBox();
percentTextBox.Width = 150;
percentTextBox.Height = 25;
percentTextBox.MinValue = 10;
percentTextBox.MaxValue =100;
percentTextBox.MinValidation = MinValidation.OnKeyPress;
percentTextBox.MaxValidation = MaxValidation.OnLostFocus;
percentTextBox.MinValueOnExceedMinDigit = true;
percentTextBox.MaxValueOnExceedMaxDigit = true;

MinValidation is set to OnKeyPress, so it will not allow entering a percent value less than the MinValue. If you try to enter a percent value less than the MinValue, then the MinValue will be set to the PercentValue property because MinValueOnExceedMinDigit is set to true.

MaxValidation is set to OnLostFocus, so the MaxValidation will be performed only on lost focus.

Restrict number of decimal digits

You can format the decimal digits in the PercentTextBox control using the PercentDecimalDigits property. You can restrict the decimal digits of the text within maximum and minimum limits in the PercentTextBox control using the MinPercentDecimalDigits and MaxPercentDecimalDigits properties. The default value of the MinPercentDecimalDigits, MaxPercentDecimalDigits, and DoubleDecimalDigits properties is -1 (unrestricted). DoubleDecimalDigits controls the decimal digits used to display the underlying double value when the control is not focused.

If the value of the MinPercentDecimalDigits property is greater than the value of the MaxPercentDecimalDigits property, the text of WPF Percent TextBox will be updated based on the value of the MinPercentDecimalDigits property.

XAML

<syncfusion:PercentTextBox PercentValue="125.32545" HorizontalAlignment="Center" VerticalAlignment="Center"
                            MaxPercentDecimalDigits="4"
                            MinPercentDecimalDigits="1" />

C#

PercentTextBox percentTextBox = new PercentTextBox();
percentTextBox.PercentValue = 125.32545;
percentTextBox.MaxPercentDecimalDigits = 4;
percentTextBox.MinPercentDecimalDigits = 1;

When the values of MinPercentDecimalDigits, MaxPercentDecimalDigits, and PercentDecimalDigits are specified, the PercentDecimalDigits property takes higher precedence and updates the text of the WPF Percent TextBox property.

XAML

<syncfusion:PercentTextBox PercentValue="125.32545" HorizontalAlignment="Center" VerticalAlignment="Center"
                            MaxPercentDecimalDigits="4"
                            MinPercentDecimalDigits="1" 
                            PercentDecimalDigits="3"
                            />

C#

PercentTextBox percentTextBox = new PercentTextBox();
percentTextBox.PercentValue = 125.32545;
percentTextBox.MaxPercentDecimalDigits = 4;
percentTextBox.MinPercentDecimalDigits = 1;
percentTextBox.PercentDecimalDigits = 3;

Read only mode

The WPF Percent TextBox does not allow user input or edits when the IsReadOnly property is set to true. The user can still select text and display the cursor on the WPF Percent TextBox by setting the IsReadOnlyCaretVisible property to true. However, the value can be changed programmatically in read-only mode.

XAML

<syncfusion:PercentTextBox x:Name="percentTextBox" IsReadOnly="True" PercentValue="10" IsReadOnlyCaretVisible="True"/>

C#

PercentTextBox percentTextBox = new PercentTextBox();
percentTextBox.PercentValue = 10;
percentTextBox.IsReadOnly = true;
percentTextBox.IsReadOnlyCaretVisible = true;