CODEWITHSUNDEEP
c#wpfdatagrid
Alex Aparin
Alex Aparin

Reputation: 4512

How to use calculated columns in DataGrid without usage XAML?

I have DataGrid with 5 columns. Value of some column depends on other columns. how to create this dependency? I have tried to implement this structure, which fills data grid. But it was not updated in the case when other cells were eddited.

public class ColorItem
{
    //  Constructor
    /*
     *      ColorItem constructor
     *      Params: color name, color
     */
    public ColorItem(string color_name, Color color)
    {
        ItemName = color_name;
        RChanel = color.R;
        GChanel = color.G;
        BChanel = color.B;
    }

    //  Item name
    public string ItemName { get; set; }
    //  Item color (calculated item)
    public Brush ItemColor { get { return new SolidColorBrush(Color.FromRgb(RChanel, GChanel, BChanel)); } }
    //  Item r chanel
    public byte RChanel { get; set; }
    //  Item g chanel
    public byte GChanel { get; set; }
    //  Item b chanel
    public byte BChanel { get; set; }

}

Upvotes: 0

Views: 77

Answers (1)

Sinatr
Sinatr

Reputation: 21989

I don't think it's a good idea to use Brush in ViewModel (talking about MVVM), rather use multiconverter or e.g. Color + ColorToSolidBrushConverter.

But in any case you do not rise notification when you change property, so View doesn't know when to update.

Fixed version:

public class ColorItem : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged([CallerMemberName] string property = "") =>
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(property));

    public Brush ItemBrush => new SolidColorBrush(Color.FromRgb(R, G, B));

    byte _r;
    public byte R 
    {
        get { return _r; }
        set
        {
            _r = value;
            OnPropertyChanged(); // this will update bindings to R
            OnPropertyChanged(nameof(ItemBrush)); // this will update bindings to ItemBrush
        }
    }

    ... // same for G and B
}

Upvotes: 1

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