WPF Grid change ColumnSpan on MinWidth

Question

let's say I have a grid with 4 columns. Every column takes the same amount of width

-> 100% / 4cols = 25%.

The 3rd column has a TextBlock or any other control in it. Now, when I resize the Width of the Window and the column gets to a minimum value , I want the TextBlock to use ColumnSpan="2" else the TextBlock would be too small. I hope you guys understand what I mean. I tried so many things but I didn't even come close to what I want because I'm pretty new to WPF . For example setting the minWidth so it doesn't get too small doesn't work because at some point the controls will still be hidden inside the grid column. I don't have any useful xaml for you, unless you just want the grid layout. Maybe a Grid is not the right thing i want? The other layouts didn't seem right for this purpose. Any help is appreciated.

Answer 1

You could handle the SizeChanged event of the Grid or the window and programmaticlly set the Grid.ColumnSpan attached property of the TextBlock whenever the grid/window shrinks below a pre-defined minimum width. Please refer to the following sample code.

private void Grid_SizeChanged(object sender, SizeChangedEventArgs e)
{
    const double MinWidth = 200;
    Grid grid = (Grid)sender;
    if (grid.ActualWidth < MinWidth)
        Grid.SetColumnSpan(textBlock, 2);
    else
        Grid.SetColumnSpan(textBlock, 1);
}

XAML:

<Window x:Class="WpfApp1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d"
        Title="MainWindow" Height="300" Width="300">
    <Grid SizeChanged="Grid_SizeChanged">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="25*" />
            <ColumnDefinition Width="25*" />
            <ColumnDefinition Width="25*" />
            <ColumnDefinition Width="25*" />
        </Grid.ColumnDefinitions>
        <TextBlock Background="Yellow" Text="1" />
        <TextBlock Background="Green" Text="2" Grid.Column="1" />
        <TextBlock Background="Red" Text="4" Grid.Column="3"  />
        <TextBlock x:Name="textBlock" Background="Blue" Text="3" Grid.Column="2" Grid.ColumnSpan="2" />
    </Grid>
</Window>

If you decrease the width of the window, the blue TextBlock streches across the third and fourth columns.