Exercise - Use StackLayout to build a user interface

10 minutes

In this exercise, you use nested StackLayout containers to arrange the views in your User Interface (UI). The first screenshot shows the layout implemented by the starter project, and the second one shows the layout for the completed project. Your job is to use StackLayout containers and LayoutOptions to turn the starter project into the completed version.

Screenshot showing the starter solution with all of the labels placed vertically in close proximity. Next to it, is the completed solution with controls aligned and positioned in a more intuitive manner.

Explore the starter solution

The starter solution contains a fully functional tip calculator app. Start by exploring the UI to understand what the app does.

Using Visual Studio, open the starter solution in the exercise2/TipCalculator folder in the repo that you cloned at the start of the previous exercise.
Build and run the app on your preferred operating system.
Enter a number into the text box and use the app to see how it works.
Experiment with the tip amount buttons and the slider.
When you're finished, close the app.

Open MainPage.xaml. Notice that all the views are placed into one VerticalStackLayout, as shown by the following XAML markup:

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:local="clr-namespace:TipCalculator"
         x:Class="TipCalculator.MainPage">
    <VerticalStackLayout>

        <Label Text="Bill" />
        <Entry x:Name="billInput" Placeholder="Enter Amount" Keyboard="Numeric" />

        <Label Text="Tip"   />
        <Label x:Name="tipOutput" Text="0.00" />

        <Label Text="Total" />
        <Label x:Name="totalOutput" Text="0.00" />

        <Label Text="Tip Percentage" />
        <Label x:Name="tipPercent" Text="15%" />
        <Slider x:Name="tipPercentSlider" Minimum="0" Maximum="100" Value="15" />

        <Button Text="15%" Clicked="OnNormalTip" />
        <Button Text="20%" Clicked="OnGenerousTip" />

        <Button x:Name="roundDown" Text="Round Down" />
        <Button x:Name="roundUp"   Text="Round Up" />

    </VerticalStackLayout>
</ContentPage>

Fix the UI

Now that you saw the app run, you can make it look better by adding HorizontalStackLayout containers. The goal is to make the app look like the screenshot at the start of the lab.

Open the MainPage.xaml file.
Add 40 units of padding and 10 units of spacing to the VerticalStackLayout:
```
<VerticalStackLayout Padding="40" Spacing="10">
```
Add a HorizontalStackLayout to group the Label that says Bill with the Entry field below it. Set the Spacing property to 10.
Set the WidthRequest of the Bill Label to 100 and the VerticalOptions property to Center. These changes ensure that the label is aligned vertically with the Entry field.
```
<HorizontalStackLayout Spacing="10">
    <Label Text="Bill" WidthRequest="100" VerticalOptions="Center"/>
    <Entry ... />
</HorizontalStackLayout>
```
Add another HorizontalStackLayout to group the Label that says Tip with the Label named tipOutput. Set the Spacing property to 10, and the Margin property to 0,20,0,0.

Set the WidthRequest of the Tip Label to 100

<HorizontalStackLayout Margin="0,20,0,0" Spacing="10">
    <Label Text="Tip" WidthRequest="100" />
    <Label .../>
</HorizontalStackLayout>

Use a HorizontalStackLayout to group the Label that says Total with the Label named totalOutput. Set the Spacing property to 10.

Set the WidthRequest of the Total Label to 100

<HorizontalStackLayout Spacing="10">
    <Label Text="Total" WidthRequest="100"  />
    <Label .../>
</HorizontalStackLayout>

Add another HorizontalStackLayout to group the Label that says Tip Percentage with the Label named tipPercent.
Set the VerticalOptions property of this HorizontalStackLayout to End and set the Spacing property to 10:

Set the WidthRequest of the Tip Percentage Label to 100

<HorizontalStackLayout VerticalOptions="End" Spacing="10">
    <Label Text="Tip Percentage" WidthRequest="100"/>
    <Label ... />
</HorizontalStackLayout>

Use a HorizontalStackLayout to group the Button with the caption 15% and the Button with the caption 20%.

Set the Margin property of this StackLayout to 0,20,0,0, and the Spacing property to 10:

<HorizontalStackLayout  Margin="0,20,0,0" Spacing="10">
    <Button Text="15%" ... />
    <Button Text="20%" ... />
</HorizontalStackLayout>

Add a final HorizontalStackLayout to group the Button with the caption Round Down and the Button with the caption Round Up.. Set the Margin property of this StackLayout to 0,20,0,0, and the Spacing property to 10:
```
<HorizontalStackLayout Margin="0,20,0,0" Spacing="10">
        <Button ... Text="Round Down" />
        <Button ... Text="Round Up" />
</HorizontalStackLayout>
```
On all four button controls, set the HorizontalOptions property to Center and the WidthRequest property to 150. For example:
```
<Button Text="15%" WidthRequest="150" HorizontalOptions="Center" ... />
```

The complete Extensible Application Markup Language (XAML) markup for the content page should look like this:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:TipCalculator"
             x:Class="TipCalculator.MainPage">

    <VerticalStackLayout Padding="40" Spacing="10">

        <HorizontalStackLayout Spacing="10">
            <Label Text="Bill" WidthRequest="100" VerticalOptions="Center" />
            <Entry x:Name="billInput" Placeholder="Enter Amount" Keyboard="Numeric" />
        </HorizontalStackLayout>

        <HorizontalStackLayout Margin="0,20,0,0" Spacing="10">
            <Label Text="Tip"  WidthRequest="100" />
            <Label x:Name="tipOutput" Text="0.00" />
        </HorizontalStackLayout>

        <HorizontalStackLayout Spacing="10">
            <Label Text="Total" WidthRequest="100"/>
            <Label x:Name="totalOutput" Text="0.00" />
        </HorizontalStackLayout>

        <HorizontalStackLayout VerticalOptions="End" Spacing="10">
            <Label Text="Tip Percentage" WidthRequest="100"/>
            <Label x:Name="tipPercent" Text="15%" />
        </HorizontalStackLayout>
        
        <Slider x:Name="tipPercentSlider" Minimum="0" Maximum="100" Value="15" />

        <HorizontalStackLayout Margin="0,20,0,0" Spacing="10">
            <Button Text="15%" Clicked="OnNormalTip" WidthRequest="150" HorizontalOptions="Center"/>
            <Button Text="20%" Clicked="OnGenerousTip"  WidthRequest="150" HorizontalOptions="Center"/>
        </HorizontalStackLayout>
        
        <HorizontalStackLayout Margin="0,20,0,0" Spacing="10">
            <Button x:Name="roundDown" Text="Round Down" WidthRequest="150" HorizontalOptions="Center"/>
            <Button x:Name="roundUp"   Text="Round Up" WidthRequest="150" HorizontalOptions="Center"/>
        </HorizontalStackLayout>

    </VerticalStackLayout>

</ContentPage>

Examine the results

Run the app again and look at the differences in the UI. Verify that the controls are aligned correctly, and are properly sized and spaced.

You used VerticalStackLayout and HorizontalStackLayout containers to improve the aesthetics of an existing UI. These layouts are the simplest layout panels, but are powerful enough to produce a reasonable UI.

Exercise - Use StackLayout to build a user interface

Explore the starter solution

Fix the UI

Examine the results

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