Check Box

The check box control presents a Boolean value where the true value is represented using a check mark, and the false value is an empty box. The check box has an option to present a nullable Boolean, where the null value represents 'unknown' and is drawn as a shaded box.

Click interaction toggles the value in the sequence: checked, unchecked, unknown (if three-state).

Useful Properties

You will probably use these properties most often:

Property	Description
IsChecked	Sets the Boolean value.
IsThreeState	(Boolean) Sets the three state mode.

Examples

This is an example of two-state check boxes:

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="AvaloniaAppTemplate.MainWindow"
        Title="CheckBox sample">
    <StackPanel Margin="20">
        <CheckBox>Not checked by default</CheckBox>
        <CheckBox IsChecked="True">Checked by default</CheckBox>
    </StackPanel>
</Window>

Looks like this when running on Windows:

This is an example of a three-state checkbox:

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="AvaloniaAppTemplate.MainWindow"
        Title="CheckBox sample">
    <StackPanel Margin="20">
        <CheckBox IsThreeState="True" IsChecked="False">Not checked by default</CheckBox>
        <CheckBox IsThreeState="True" IsChecked="True">Checked by default</CheckBox>
        <CheckBox IsThreeState="True" IsChecked="{x:Null}">Unknown by default</CheckBox>
    </StackPanel>
</Window>

Looks like this when running on Windows:

More Information

For the complete API documentation about this control, see here.

View the source code on GitHub CheckBox.cs