Highlight cells if found

c#, datagrid, wpf

Solution

You can achieve that using `IMultiValueConverter` which will return true if Text lies within the range otherwise return false. `Based on the value returned by converter, change background color`.

Pass three parameters to converter:

- Actual Text value.

- Minimum value.

- Maximum value.

Converter

public class ItemExistInRangeConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType,
                          object parameter, CultureInfo culture)
    {
        bool itemsExistInRange = false;
        if (values.Length == 3)
        {
            int outputValue = int.MinValue;
            if (Int32.TryParse(values[0].ToString(), out outputValue))
            {
                int minValue = (int)values[1];
                int maxValue = (int)values[2];
                itemsExistInRange = minValue <= outputValue
                                     && outputValue <= maxValue;
            }
        }
        return itemsExistInRange;
    }

    public object[] ConvertBack(object value, Type[] targetTypes,
                                object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

XAML

<DataGrid.Resources>
    <local:ItemExistInRangeConverter x:Key="ItemExistInRangeConverter"/>
    <sys:Int32 x:Key="MinimumValue">1</sys:Int32>
    <sys:Int32 x:Key="MaximumValue">50</sys:Int32>
    <Style x:Key="BackgroundColourStyle" TargetType="{x:Type TextBlock}">
       <Style.Triggers>
          <DataTrigger Value="True">
             <DataTrigger.Binding>
                 <MultiBinding Converter="{StaticResource ItemExistInRangeConverter}">
                     <Binding Path="Text" RelativeSource="{RelativeSource Self}"/>
                     <Binding Source="{StaticResource MinimumValue}"/>
                     <Binding Source="{StaticResource MaximumValue}"/>
                 </MultiBinding>
             </DataTrigger.Binding>
             <Setter Property="Background" Value="LightGreen" />
          </DataTrigger>
        </Style.Triggers>
    </Style>
</DataGrid.Resources>

Make sure you add corresponding namespace at root level:

xmlns:local="clr-namespace:NamespaceOfConverter"
// Replace NamespaceOfConverter with namespace where converter resides.
xmlns:sys="clr-namespace:System;assembly=mscorlib"

UPDATE (In case want to find item in an array of numbers)

Assuming your array of numbers property exist in code behind or view model class.

First of all you need to `set ItemsSource of DataGrid to DataTable` instead of DataContext.

Second, `set DataContext of DataGrid to this from code behind or an instance of viewModel class`.

Also, to refresh GUI your class should implement INotifyPropertyChanged interface.

Now, assume you have a property say:

public int[] RangeNumbers { get; set; }

By default it will contain list of numbers which you want to highlight.

XAML will look like this:

<DataGrid.Resources>
    <local:ItemExistInRangeConverter x:Key="ItemExistInRangeConverter"/>
       <Style x:Key="BackgroundColourStyle" TargetType="{x:Type TextBlock}">
           <Style.Triggers>
              <DataTrigger Value="True">
                 <DataTrigger.Binding>
                    <MultiBinding Converter="{StaticResource ItemExistInRangeConverter}">
                       <Binding Path="Text" RelativeSource="{RelativeSource Self}"/>
                       <Binding Path="DataContext.RangeNumbers" 
                                RelativeSource="{RelativeSource FindAncestor,
                                                  AncestorType=DataGrid}"/>
                    </MultiBinding>
                 </DataTrigger.Binding>
               <Setter Property="Background" Value="LightGreen" />
            </DataTrigger>
        </Style.Triggers>
    </Style>
</DataGrid.Resources>

Converter code:

public class ItemExistInRangeConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType,
                          object parameter, CultureInfo culture)
    {
        bool itemsExistInRange = false;
        if (values.Length == 2)
        {
            int outputValue = int.MinValue;
            int[] rangeNumbers = (int[])values[1];
            if (rangeNumbers != null && 
                Int32.TryParse(values[0].ToString(), out outputValue))
            {
                itemsExistInRange = rangeNumbers.Contains(outputValue);
            }
        }
        return itemsExistInRange;
     }

     public object[] ConvertBack(object value, Type[] targetTypes,
                                 object parameter, CultureInfo culture)
     {
         throw new NotImplementedException();
     }
}

Now, items will be highlighted based on initial numbers in `RangeNumbers`. But suppose you update array afterwards, you need to raise property changed event so that GUI gets refreshed something like this:

RangeNumbers = new int[] { 23, 45, 47, 69 };
OnPropertyChanged("RangeNumbers");

Problem

Original source