Problems changing datagrid color using WPF C#

Question

I am using a datagrid and changing the color of the rows according to their conditions and I am performing this programmatically. follow the example as my datagrid is bound to a datatable I load information straight from the datatable

private void UpdateCor () {

gvDados.UpdateLayout ();
for (int i = 0; i <dt.Rows.Count; i ++)
{
      var rowContext = (DataGridRow) 
      gvDados.ItemContainerGenerator.ContainerFromIndex (i);

      if (rowContext! = null)
      {
            if (dt.Rows [i] ["situation"]. ToString (). Equals (1))
                     rowContext.Background = Brushes.Green;
            else
                     rowContext.Background = Brushes.Red;
      }
   }
}

With this I can update the color of my grid even though it is not the best method to be approached. my problem is this, whenever I use the scroll to go down or up the bar the colors become outdated. How do I prevent this from happening? that even when I roll the bar the colors stay fixed?

Answer 1

This is a similar question to this question . Can be done using datatrigger:

 <DataGrid ItemsSource="{Binding YourItemsSource}">
        <DataGrid.RowStyle>
            <Style TargetType="DataGridRow"> 
                <Style.Triggers>
                    <DataTrigger Binding="{Binding State}" Value="State1">
                        <Setter Property="Background" Value="Red"></Setter>
                    </DataTrigger>
                    <DataTrigger Binding="{Binding State}" Value="State2">
                        <Setter Property="Background" Value="Green"></Setter>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </DataGrid.RowStyle>
    </DataGrid>

Answer 2

Often, XAML is too simple to express more complicated conditions. I prefer to put the logic which values should use which colors into a converter. This leads to a simpler XAML and much greater flexibility for the converter in C#.

<datagrid.rowstyle>
  <style targettype="DataGridRow">
    <Setter Property="Background" Value="{Binding RelativeSource={RelativeSource Self},
      Path=Item.situation, Converter={StaticResource ValueToBackgroundConverter}}"/>
  </style>
</datagrid.rowstyle>

In C#:

class ValueToBackgroundConverter: IValueConverter {
  public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
    if (value is int) {
      int quantity = (int)value;
      if (quantity>=100) return Brushes.White;
      if (quantity>=10) return Brushes.WhiteSmoke;
      if (quantity>=0) return Brushes.LightGray;
      return Brushes.White; //quantity should not be below 0
    }
    //value is not an integer. Do not throw an exception
    // in the converter, but return something that is obviously wrong
    return Brushes.Yellow;
  }

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

Formatting the various parts of a WPF Datagrid is notoriously difficult and Microsoft is not providing the necessary information how to do it. Read my article Codeproject: Guide to WPF DataGrid formatting using binding to get a better understanding how to do it easily.