Question

I have a group of WPF CheckBoxes that have a Checked event handler that handles some logic when the user clicks on one of them. However, I also have a “Clear All” button that, when clicked, will clear all the checkboxes. If the user clicks on the “Clear All” button, I do NOT want the checkboxes to fire their Checked event. Is there a way of doing this?

Answer 1

Remove the event handler at the beginning of the in the Clear All button’s event handler and then re-add the event handler at the end of the Clear All button’s event handler.

Here’s a dirty sample:

XAML

<Window x:Class="UncheckedTest.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
    <Grid>
        <CheckBox Height="16" Margin="22,30,136,0" Name="checkBox1" VerticalAlignment="Top" 
                  Unchecked="checkBox1_Unchecked">CheckBox 1</CheckBox>
        <CheckBox Height="16" Margin="22,76,136,0" Name="checkBox2" VerticalAlignment="Top" 
                  Unchecked="checkBox2_Unchecked">CheckBox 2</CheckBox>
        <CheckBox Margin="22,0,136,121" Name="checkBox3" Height="16" VerticalAlignment="Bottom" 
                  Unchecked="checkBox3_Unchecked">CheckBox 3</CheckBox>
        <Button HorizontalAlignment="Right" Margin="0,118,37,121" Name="button1" Width="87" 
                Click="button1_Click">Uncheck All</Button>
        <TextBox Height="74" Margin="22,0,20,13" Name="textBox1" VerticalAlignment="Bottom" 
                 TextWrapping="Wrap" VerticalScrollBarVisibility="Visible" />
    </Grid>
</Window>

Code Behind

using System;
using System.Windows;

namespace UncheckedTest
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        private int i = 1;
        public Window1()
        {
            InitializeComponent();
        }

        void checkBox3_Unchecked(object sender, RoutedEventArgs e)
        {
            textBox1.Text = i++.ToString() + ". Checkbox 3 Unchecked." + Environment.NewLine + textBox1.Text;
        }

        void checkBox2_Unchecked(object sender, RoutedEventArgs e)
        {
            textBox1.Text = i++.ToString() + ". Checkbox 2 Unchecked." + Environment.NewLine + textBox1.Text;
        }

        void checkBox1_Unchecked(object sender, RoutedEventArgs e)
        {
            textBox1.Text = i++.ToString() + ". Checkbox 1 Unchecked." + Environment.NewLine + textBox1.Text;   
        }

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            checkBox1.Unchecked -= checkBox1_Unchecked;
            checkBox2.Unchecked -= checkBox2_Unchecked;
            checkBox3.Unchecked -= checkBox3_Unchecked;

            checkBox1.IsChecked = false;
            checkBox2.IsChecked = false;
            checkBox3.IsChecked = false;

            checkBox1.Unchecked += checkBox1_Unchecked;
            checkBox2.Unchecked += checkBox2_Unchecked;
            checkBox3.Unchecked += checkBox3_Unchecked;
        }
    }
}