Silverlight: Delete content of a specific cell in a grid

Question

I have a grid and I need to dynamically replace a control that resides in one of the cells. I don't know in terms of syntax to pinpoint the grid cell, as where do I put in the row and column number so I can delete whatever is in it.

Answer 1

If you know the cell and row that the control lives in, you can use a LINQ statement to grab it.

Here's a LINQ statement that will get the first control that is in column 3, row 4.

var control = (from d in grid.Children
               where Grid.GetColumn(d as FrameworkElement) == 3 
                  && Grid.GetRow(d as FrameworkElement) == 4
               select d).FirstOrDefault();

Answer 2

You could iterate the children of the grid checking their row and column values using the Grid.GetRow and Grid.GetColumn methods and replace the targeted content when the values match. Here's a sample tested in WPF, but should work in Silverlight:

    <Grid x:Name="SampleGrid">
    <Grid.RowDefinitions>
        <RowDefinition />
        <RowDefinition />
        <RowDefinition />
        <RowDefinition />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition />
        <ColumnDefinition />
        <ColumnDefinition />
    </Grid.ColumnDefinitions>
    <Rectangle Fill="Red" Width="20" Height="20" Grid.Row="0" Grid.Column="0" />
    <Rectangle Fill="Orange" Width="20" Height="20" Grid.Row="0" Grid.Column="1" />
    <Rectangle Fill="Yellow" Width="20" Height="20" Grid.Row="0" Grid.Column="2" />
    <Rectangle Fill="Green" Width="20" Height="20" Grid.Row="1" Grid.Column="0" />
    <Rectangle Fill="Blue" Width="20" Height="20" Grid.Row="1" Grid.Column="1" />
    <Rectangle Fill="Indigo" Width="20" Height="20" Grid.Row="1" Grid.Column="2" />
    <Rectangle Fill="Violet" Width="20" Height="20" Grid.Row="2" Grid.Column="0" />
    <Rectangle Fill="Black" Width="20" Height="20" Grid.Row="2" Grid.Column="1" />
    <Rectangle Fill="Gray" Width="20" Height="20" Grid.Row="2" Grid.Column="2" />
    <Button Grid.Row="3" Grid.ColumnSpan="3" Margin="10" x:Name="Swap" Click="Swap_Click" Content="Swap"/>
</Grid>

In the event handler:

    private void Swap_Click(object sender, RoutedEventArgs e)
    {
        Ellipse newEllipse = new Ellipse() { Fill = new SolidColorBrush(Colors.PaleGoldenrod), Width = 20d, Height = 20d };
        for (int childIndex = 0; childIndex < this.SampleGrid.Children.Count; childIndex++)
        {
            UIElement child = this.SampleGrid.Children[childIndex];
            if (Grid.GetColumn(child) == 2 && Grid.GetRow(child) == 2)
            {
                this.SampleGrid.Children.Remove(child);
                Grid.SetRow(newEllipse, 2);
                Grid.SetColumn(newEllipse, 2);
                this.SampleGrid.Children.Add(newEllipse);
            }
        }

    }