#1,052 – Making Two Columns in a Grid the Same Size

You can force two columns (or rows) in a Grid to always be the same size using the SharedSizeGroup property when defining the columns (or rows).

Below, we specify that the third column should auto-size and that the first and third columns should be the same size.  The first column will be sized to match the auto-sized third column.  We do the following:

  • Set Grid.IsSharedSizeScope property of the Grid to true
  • Set SharedSizeGroup property in the first and third ColumnDefinition elements to the same value (in this case it’s “A”)
        <Grid Name="myGrid" Grid.IsSharedSizeScope="True">
            <Grid.RowDefinitions>
                <RowDefinition/>
                <RowDefinition/>
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition SharedSizeGroup="A"/>
                <ColumnDefinition />
                <ColumnDefinition Width="Auto" SharedSizeGroup="A"/>
            </Grid.ColumnDefinitions>

            <Label Content="0,0" Background="Azure" />
            <Label Content="1,0" Background="Moccasin" Grid.Row="1" />
            <Label Content="Row 0 Col 2" Background="Lavender" Grid.Column="1" />
            <Label Content="Row 1 Col 2" Background="Honeydew" Grid.Row="1" Grid.Column="1" />
            <Label Content="Row 0 Col 3" Background="LightSalmon" Grid.Column="2" />
            <Label Content="Row 1 Col 3" Background="GreenYellow" Grid.Row="1" Grid.Column="2" />
        </Grid>

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#1,051 – How the GridSplitter Behaves when Cells Use Auto Sizing

If one or both columns on either size of a GridSplitter (in its own column) have a width set to Auto, the behavior is as follows (“proportional” refers to star sizing):

  • Both columns set to Auto: Left column changes size and is switched to Absolute sizing
  • Left column Auto, right column proportional: Both columns change size, left switches to Absolute, right remains at original proportion (e.g. “1*”)
  • Right column Auto, left column proportional: Both columns change size, right switches to Absolute, left remains at original proportion

In the example below, columns 0 and 2 surround a GridSplitter in column 1.  Columns 0 and 2 are set to Auto size (as is the column with the GridSplitter) and column 3 is set to proportional.

Initially, we see that both columns 0 and 2 are auto-sized.
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If we slide the GridSplitter to the right, column 0 changes size and switches to Absolute sizing.  Column 2 remains as Auto.

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#1,050 – How the GridSplitter Behaves when Cells Use Absolute Sizing

Recall that a GridSplitter in its own column and with its HorizontalAlignment set to Center will resize columns on either side of it.  In the example below, columns 0 and 2 are resized, but the width of column 3 is not changed.

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If one of the columns whose size is not changing as a result of using the GridSplitter has its size set to an absolute value, it will retain that value.  In the example below column 3 (far right) has an absolute width of 100.  The two columns whose size is changing are using star sizing and have had their relative sizes adjusted.

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If one of the columns being resized with the GridSplitter has an absolute size, moving the GridSplitter will change its size, but it will continue to have an absolute size.

Before resize:

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After resize:

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We can see that column 0 has an absolute size if we make the entire Grid wider.

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#1,049 – How the GridSplitter Behaves when Cells Use Star Sizing

Recall that a GridSplitter in its own column and with its HorizontalAlignment set to Center will resize columns on either side of it.  In the example below, columns 0 and 2 are resized, but the width of column 3 is not changed.

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If all of the content columns are sized using star sizing, the GridSplitter will leave them as star sized, but change the coefficients to match the final size after moving the GridSplitter.  We can see this by dumping out the column widths before and after our sizing operation.

Before resizing, columns 0, 2 and 3 are all “1*” (or just “*”).  They take up equal space.

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After resizing, the coefficients change.  Columns are still proportionally sized, but the proportions are different.

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We can verify that the columns are sized proportionally by resizing the entire Grid (containing window).  The columns retain their post-GridSplitter relative sizes.

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#1,048 – How to Set a GridSplitter’s Alignment Properties

The most common way to use a GridSplitter is to place it in its own auto-sized row or column.  In the example below, we want a vertical GridSplitter, so we place it in its own auto-sized column.

        <Grid Name="myGrid">
            <Grid.RowDefinitions>
                <RowDefinition/>
                <RowDefinition/>
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition />
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition />
                <ColumnDefinition />
            </Grid.ColumnDefinitions>

            <Label Content="Row 0 Col 0" Background="Azure" Grid.Row="0" Grid.Column="0" />
            <!-- more here -->

            <GridSplitter Grid.Column="1" Grid.RowSpan="2" Width="3" Background="Blue"
                      VerticalAlignment="Stretch" HorizontalAlignment="Center" />
        </Grid>

When a vertical GridSplitter is in its own column, you’ll want to set its VerticalAlignment to Stretch and its HorizontalAlignment to Center.  (A horizontal GridSplitter would reverse this).

With the HorizontalAlignment set to Center, the column containing the GridSplitter does not itself resize.  Moving the GridSplitter resizes the two columns on either side of it, which is what we want.

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#1,047 – Setting the Size of a Grid’s Rows or Columns from Code

There are three ways to set the size of a row or a column in a Grid:

  • Auto – set height/width to fit the size of the contained element
  • numeric value – explicitly set height/width to specified number of device independent units (1/96th in)
  • * or n* – distribute remaining space proportionately

You can set row or column sizes from code for all three of these methods.

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            // Set to Auto
            myGrid.RowDefinitions[0].Height = GridLength.Auto;

            // Set explicit size
            myGrid.RowDefinitions[1].Height = new GridLength(35.0, GridUnitType.Pixel);

            // Set star sizing (proportional)
            myGrid.RowDefinitions[2].Height = new GridLength(1.0, GridUnitType.Star);
            myGrid.RowDefinitions[3].Height = new GridLength(2.0, GridUnitType.Star);
        }

Before clicking the button, the row heights default to “*” (evenly spaced):
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After executing the code shown above, the Grid looks like this:
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#1,046 – Setting the Background Color of a Cell in a Grid

There are several different ways to set the background color of a cell within a Grid.  They include:

  • Setting the Background property of the element within a cell (e.g. a Label)
  • Including a Rectangle in the same cell as another element and setting its Fill property
  • Using a Border element and setting its Background property
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>

        <Label Grid.Row="0" Grid.Column="0" Content="Larry" Margin="5" Background="Lavender"/>
        <Label Grid.Row="0" Grid.Column="1" Content="Moe" Margin="5" />

        <Rectangle Grid.Row="1" Grid.Column="0" Fill="Bisque"/>
        <CheckBox Grid.Row="1" Grid.Column="0" Margin="5" Content="Nose Tweak"
                  VerticalAlignment="Center"/>

        <Border Grid.Row="1" Grid.Column="1"  Background="MediumSpringGreen"
                CornerRadius="5" Margin="5">
            <Button Grid.Row="1" Grid.Column="1" Margin="5" Content="Do Eye Poke"
                    VerticalAlignment="Center"/>
        </Border>
    </Grid>

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