Question

This question deals entirely with code and no XAML.

So I have this class, called Location:

public class Location
{
    public int id { get; set; }
    public double latitude { get; set; }
    public double longitude { get; set; }
    public string name { get; set; }
    public string type { get; set; }
    public bool isAnOption { get; set; }

    public Location(int newId, double newLatitude, double newLongitude, string newName, string newType)
    {
        id = newId;
        latitude = newLatitude;
        longitude = newLongitude;
        name = newName;
        type = newType;
        isAnOption = true;
    }

    public System.Windows.Shapes.Ellipse createIcon()
    {
        System.Windows.Shapes.Ellipse icon = new System.Windows.Shapes.Ellipse();
        SolidColorBrush brush;
        if (isAnOption)
        {
            brush = new SolidColorBrush(Colors.Blue);
        }
        else
        {
            brush = new SolidColorBrush(Colors.Red);
        }
        brush.Opacity = 0.5;
        icon.Fill = brush;
        icon.Height = icon.Width = 44;
        icon.HorizontalAlignment = HorizontalAlignment.Left;
        icon.VerticalAlignment = VerticalAlignment.Top;

        Thickness locationIconMarginThickness = new Thickness(0, 0, 0, 0);
        locationIconMarginThickness.Left = (longitude - 34.672852) / (35.046387 - 34.672852) * (8704) - 22;
        locationIconMarginThickness.Top = (32.045333 - latitude) / (32.045333 - 31.858897) * (5120) - 22;
        icon.Margin = locationIconMarginThickness;

        Label labelName = new Label();
        labelName.Content = name;

        StackPanel locationData = new StackPanel();
        locationData.Children.Add(labelName);

        ToolTip toolTip = new ToolTip();
        toolTip.Content = locationData;

        icon.ToolTip = toolTip;

        return icon;
    }
}

Pretty straight forward. Notice the createIcon method.

Now, in the MainWindow (it’s a WPF project), I declare List<Location> locations and fill it up with data.

At some point I put the “icons” on an existing GridScroller like so:

gridScroller.Children.Add(location.createIcon()); 

Now, the problem I have is I want to bind the property isAnOption of Location to the color of the brush of a corresponding icon’s brush’s color. In other words, when the property isAnOption of a certain object derived from Location is changed, I would like that change to reflect in the color of the ellipse that’s on the GridScroller.
Help please.

Thanks

Answer 1

First, your Location class would need to implement INotifyPropertyChanged, so any bindings that use isAnOption as a source will be notified when it is changed.

Then you can bind the Fill property to your property like so:

Binding binding = new Binding("isAnOption") {
    Source = this,
    Converter = new MyConverter(),
};
icon.SetBinding(Ellipse.FillProperty, binding);

Finally, MyConverter would be a custom IValueConverter that returns a Blue or Red brush based on the bool value passed.