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WPF : Grid Control

Tutorial by:Manisha Dubey      Date: 2016-07-11 04:38:36

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The Grid is probably the most complex of the panel types. A Grid can contain multiple rows and columns. You define a height for each of the rows and a width for each of the columns, in either an absolute amount of pixels, in a percentage of the available space or as auto, where the row or column will automatically adjust its size depending on the content. Use the Grid when the other panels doesn't do the job, e.g. when you need multiple columns and often in combination with the other panels.

In its most basic form, the Grid will simply take all of the controls you put into it, stretch them to use the maximum available space and place it on top of each other:

<Window x:Class="WpfTutorialSamples.Panels.Grid"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Grid" Height="300" Width="300">
    <Grid>
		<Button>Button 1</Button>
		<Button>Button 2</Button>
	</Grid>
</Window>
A simple Grid

As you can see, the last control gets the top position, which in this case means that you can't even see the first button. Not terribly useful for most situations though, so let's try dividing the space, which is what the grid does so well. We do that by using ColumnDefinitions and RowDefinitions. In the first example, we'll stick to columns:

<Window x:Class="WpfTutorialSamples.Panels.Grid"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Grid" Height="300" Width="300">
    <Grid>
		<Grid.ColumnDefinitions>
			<ColumnDefinition Width="*" />
			<ColumnDefinition Width="*" />
		</Grid.ColumnDefinitions>
		<Button>Button 1</Button>
		<Button Grid.Column="1">Button 2</Button>
	</Grid>
</Window>
A Grid divided into two columns

In this example, we have simply divided the available space into two columns, which will share the space equally, using a "star width" (this will be explained later). On the second button, I use a so-called Attached property to place the button in the second column (0 is the first column, 1 is the second and so on). I could have used this property on the first button as well, but it automatically gets assigned to the first column and the first row, which is exactly what we want here.

As you can see, the controls take up all the available space, which is the default behavior when the grid arranges its child controls. It does this by setting the HorizontalAlignment and VerticalAlignment on its child controls to Stretch.

In some situations you may want them to only take up the space they need though and/or control how they are placed in the Grid. The easiest way to do this is to set the HorizontalAlignment and VerticalAlignment directly on the controls you wish to manipulate. Here's a modified version of the above example:

<Window x:Class="WpfTutorialSamples.Panels.Grid"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Grid" Height="300" Width="300">
    <Grid>
		<Grid.ColumnDefinitions>
			<ColumnDefinition Width="*" />
			<ColumnDefinition Width="*" />
		</Grid.ColumnDefinitions>		
		<Button VerticalAlignment="Top" HorizontalAlignment="Center">Button 1</Button>
		<Button Grid.Column="1" VerticalAlignment="Center" HorizontalAlignment="Right">Button 2</Button>
	</Grid>
</Window>
A Grid divided into two columns with custom alignment on the child controls

As you can see from the resulting screenshot, the first button is now placed in the top and centered. The second button is placed in the middle, aligned to the right.



Grid - Rows & columns

In the last chapter, we introduced you to the great Grid panel and showed you a couple of basic examples on how to use it. In this chapter we will do some more advanced layouts, as this is where the Grid really shines. First of all, let's throw in more columns and even some rows, for a true tabular layout:

<Window x:Class="WpfTutorialSamples.Panels.TabularGrid"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="TabularGrid" Height="300" Width="300">
    <Grid>
		<Grid.ColumnDefinitions>
			<ColumnDefinition Width="2*" />
			<ColumnDefinition Width="1*" />
			<ColumnDefinition Width="1*" />
		</Grid.ColumnDefinitions>
		<Grid.RowDefinitions>
			<RowDefinition Height="2*" />
			<RowDefinition Height="1*" />
			<RowDefinition Height="1*" />
		</Grid.RowDefinitions>
		<Button>Button 1</Button>
		<Button Grid.Column="1">Button 2</Button>
		<Button Grid.Column="2">Button 3</Button>
		<Button Grid.Row="1">Button 4</Button>
		<Button Grid.Column="1" Grid.Row="1">Button 5</Button>
		<Button Grid.Column="2" Grid.Row="1">Button 6</Button>
		<Button Grid.Row="2">Button 7</Button>
		<Button Grid.Column="1" Grid.Row="2">Button 8</Button>
		<Button Grid.Column="2" Grid.Row="2">Button 9</Button>
	</Grid>
</Window>
A Grid with several columns and rows, creating a tabular layout

A total of nine buttons, each placed in their own cell in a grid containing three rows and three columns. We once again use a star based width, but this time we assign a number as well - the first row and the first column has a width of 2*, which basically means that it uses twice the amount of space as the rows and columns with a width of 1* (or just * - that's the same).

You will also notice that I use the Attached properties Grid.Row and Grid.Column to place the controls in the grid, and once again you will notice that I have omitted these properties on the controls where I want to use either the first row or the first column (or both). This is essentially the same as specifying a zero. This saves a bit of typing, but you might prefer to assign them anyway for a better overview - that's totally up to you!



Grid - Units

So far we have mostly used the star width/height, which specifies that a row or a column should take up a certain percentage of the combined space. However, there are two other ways of specifying the width or height of a column or a row: Absolute units and the Auto width/height. Let's try creating a Grid where we mix these:

<Window x:Class="WpfTutorialSamples.Panels.GridUnits"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="GridUnits" Height="200" Width="400">
	<Grid>
		<Grid.ColumnDefinitions>
			<ColumnDefinition Width="1*" />
			<ColumnDefinition Width="Auto" />
			<ColumnDefinition Width="100" />
		</Grid.ColumnDefinitions>
		<Button>Button 1</Button>
		<Button Grid.Column="1">Button 2 with long text</Button>
		<Button Grid.Column="2">Button 3</Button>
	</Grid>
</Window>
A Grid with columns of varying widths

In this example, the first button has a star width, the second one has its width set to Auto and the last one has a static width of 100 pixels.

The result can be seen on the screenshot, where the second button only takes exactly the amount of space it needs to render its longer text, the third button takes exactly the 100 pixels it was promised and the first button, with the variable width, takes the rest.

In a Grid where one or several columns (or rows) have a variable (star) width, they automatically get to share the width/height not already used by the columns/rows which uses an absolute or Auto width/height. This becomes more obvious when we resize the window:

A Grid with columns of varying widths, resized to a smaller size A Grid with columns of varying widths, resized to a larger size

On the first screenshot, you will see that the Grid reserves the space for the last two buttons, even though it means that the first one doesn't get all the space it needs to render properly. On the second screenshot, you will see the last two buttons keeping the exact same amount of space, leaving the surplus space to the first button.

This can be a very useful technique when designing a wide range of dialogs. For instance, consider a simple contact form where the user enters a name, an e-mail address and a comment. The first two fields will usually have a fixed height, while the last one might as well take up as much space as possible, leaving room to type a longer comment. In the next chapter, we will try building a contact form, using the grid and rows and columns of different heights and widths.



Grid - Spanning

The default Grid behavior is that each control takes up one cell, but sometimes you want a certain control to take up more rows or columns. Fortunately the Grid makes this very easy, with the Attached properties ColumnSpan and RowSpan. The default value for this property is obviously 1, but you can specify a bigger number to make the control span more rows or columns.

Here's a very simple example, where we use the ColumnSpan property:

<Window x:Class="WpfTutorialSamples.Panels.GridColRowSpan"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="GridColRowSpan" Height="110" Width="300">
	<Grid>
		<Grid.ColumnDefinitions>			
			<ColumnDefinition Width="1*" />
			<ColumnDefinition Width="1*" />
		</Grid.ColumnDefinitions>
		<Grid.RowDefinitions>
			<RowDefinition Height="*" />
			<RowDefinition Height="*" />
		</Grid.RowDefinitions>
		<Button>Button 1</Button>
		<Button Grid.Column="1">Button 2</Button>
		<Button Grid.Row="1" Grid.ColumnSpan="2">Button 3</Button>
	</Grid>
</Window>
A Grid with column spanning applied to one of the controls

We just define two columns and two rows, all of them taking up their equal share of the place. The first two buttons just use the columns normally, but with the third button, we make it take up two columns of space on the second row, using the ColumnSpan attribute.

This is all so simple that we could have just used a combination of panels to achieve the same effect, but for just slightly more advanced cases, this is really useful. Let's try something which better shows how powerful this is:

<Window x:Class="WpfTutorialSamples.Panels.GridColRowSpanAdvanced"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="GridColRowSpanAdvanced" Height="300" Width="300">
    <Grid>
		<Grid.ColumnDefinitions>
			<ColumnDefinition Width="*" />
			<ColumnDefinition Width="*" />
			<ColumnDefinition Width="*" />
		</Grid.ColumnDefinitions>
		<Grid.RowDefinitions>
			<RowDefinition Height="*" />
			<RowDefinition Height="*" />
			<RowDefinition Height="*" />
		</Grid.RowDefinitions>
		<Button Grid.ColumnSpan="2">Button 1</Button>
		<Button Grid.Column="3">Button 2</Button>
		<Button Grid.Row="1">Button 3</Button>
		<Button Grid.Column="1" Grid.Row="1" Grid.RowSpan="2" Grid.ColumnSpan="2">Button 4</Button>
		<Button Grid.Column="0" Grid.Row="2">Button 5</Button>
	</Grid>
</Window>
A Grid with both column and row spanning applied to several child controls

With three columns and three rows we would normally have nine cells, but in this example, we use a combination of row and column spanning to fill all the available space with just five buttons. As you can see, a control can span either extra columns, extra rows or in the case of button 4: both.

So as you can see, spanning multiple columns and/or rows in a Grid is very easy. In a later article, we will use the spanning, along with all the other Grid techniques in a more practical example.



GridSplitter

As you saw in the previous articles, the Grid panel makes it very easy to divide up the available space into individual cells. Using column and row definitions, you can easily decide how much space each row or column should take up, but what if you want to allow the user to change this? This is where the GridSplitter control comes into play.

The GridSplitter is used simply by adding it to a column or a row in a Grid, with the proper amount of space for it, e.g. 5 pixels. It will then allow the user to drag it from side to side or up and down, while changing the size of the column or row on each of the sides of it. Here's an example:

<Window x:Class="WpfTutorialSamples.Panels.GridSplitterSample"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="GridSplitterSample" Height="300" Width="300">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="5" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <TextBlock FontSize="55" HorizontalAlignment="Center" VerticalAlignment="Center" TextWrapping="Wrap">Left side</TextBlock>
        <GridSplitter Grid.Column="1" Width="5" HorizontalAlignment="Stretch" />
        <TextBlock Grid.Column="2" FontSize="55" HorizontalAlignment="Center" VerticalAlignment="Center" TextWrapping="Wrap">Right side</TextBlock>
    </Grid>
</Window>

A Grid panel with a GridSplitter control

A Grid panel with a GridSplitter control in action

As you can see, I've simply created a Grid with two equally wide columns, with a 5 pixel column in the middle. Each of the sides are just a TextBlock control to illustrate the point. As you can see from the screenshots, the GridSplitter is rendered as a dividing line between the two columns and as soon as the mouse is over it, the cursor is changed to reflect that it can be resized.

Horizontal GridSplitter

The GridSplitter is very easy to use and of course it supports horizontal splits as well. In fact, you hardly have to change anything to make it work horizontally instead of vertically, as the next example will show:

<Window x:Class="WpfTutorialSamples.Panels.GridSplitterHorizontalSample"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="GridSplitterHorizontalSample" Height="300" Width="300">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="5" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <TextBlock FontSize="55" HorizontalAlignment="Center" VerticalAlignment="Center" TextWrapping="Wrap">Top</TextBlock>
        <GridSplitter Grid.Row="1" Height="5" HorizontalAlignment="Stretch" />
        <TextBlock Grid.Row="2" FontSize="55" HorizontalAlignment="Center" VerticalAlignment="Center" TextWrapping="Wrap">Bottom</TextBlock>
    </Grid>
</Window>

A horizontal Grid panel with a GridSplitter control in action

As you can see, I simply changed the columns into rows and on the GridSplitter, I defined a Height instead of a Width. The GridSplitter figures out the rest on its own, but in case it doesn't, you can use the ResizeDirection property on it to force it into either Rows or Columns mode.



Using Grid: A contact form

In the last couple of chapters we went through a lot of theoretic information, each with some very theoretic examples. In this chapter we will combine what we have learned about the Grid so far, into an example that can be used in the real world: A simple contact form.

The good thing about the contact form is that it's just an example of a commonly used dialog - you can take the techniques used and apply them to almost any type of dialog that you need to create.

The first take on this task is very simple and will show you a very basic contact form. It uses three rows, two of them with Auto heights and the last one with star height, so it consumes the rest of the available space:

<Window x:Class="WpfTutorialSamples.Panels.GridContactForm"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="GridContactForm" Height="300" Width="300">
    <Grid>
		<Grid.RowDefinitions>
			<RowDefinition Height="Auto" />
			<RowDefinition Height="Auto" />
			<RowDefinition Height="*" />
		</Grid.RowDefinitions>		
		<TextBox>Name</TextBox>
		<TextBox Grid.Row="1">E-mail</TextBox>
		<TextBox Grid.Row="2" AcceptsReturn="True">Comment</TextBox>		
	</Grid>
</Window>
A simple contact form using the Grid

As you can see, the last TextBox simply takes up the remaining space, while the first two only takes up the space they require. Try resizing the window and you will see the comment TextBox resize with it.

In this very simple example, there are no labels to designate what each of the fields are for. Instead, the explanatory text is inside the TextBox, but this is not generally how a Windows dialog looks. Let's try improving the look and usability a bit:

<Window x:Class="WpfTutorialSamples.Panels.GridContactFormTake2"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="GridContactFormTake2" Height="300" Width="300">
	<Grid Margin="10">
		<Grid.ColumnDefinitions>
			<ColumnDefinition Width="Auto" />
			<ColumnDefinition Width="*" />
		</Grid.ColumnDefinitions>
		<Grid.RowDefinitions>
			<RowDefinition Height="Auto" />
			<RowDefinition Height="Auto" />
			<RowDefinition Height="*" />
		</Grid.RowDefinitions>
		<Label>Name: </Label>
		<TextBox Grid.Column="1" Margin="0,0,0,10" />
		<Label Grid.Row="1">E-mail: </Label>
		<TextBox Grid.Row="1" Grid.Column="1" Margin="0,0,0,10" />
		<Label Grid.Row="2">Comment: </Label>
		<TextBox Grid.Row="2" Grid.Column="1" AcceptsReturn="True" />
	</Grid>
</Window>
A simple contact form using the Grid - take two

But perhaps you're in a situation where the comment field is pretty self-explanatory? In that case, let's skip the label and use ColumnSpan to get even more space for the comment TextBox:

<TextBox Grid.ColumnSpan="2" Grid.Row="2" AcceptsReturn="True" />
A simple contact form using the Grid - take three

So as you can see, the Grid is a very powerful panel. Hopefully you can use all of these techniques when designing your own dialogs.

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