Dial Control

Dial Control shows how to create a Control that can be used as a Dial using Windows App SDK.

Step 1

Follow Setup and Start on how to get Setup and Install what you need for Visual Studio 2022 and Windows App SDK.

Step 2

Then in Visual Studio within Solution Explorer for the Solution, right click on the Project shown below the Solution and then select Add then New Item…

Step 3

Then in Add New Item from the C# Items list, select WinUI and then select User Control (WinUI 3) from the list next to this, then type in the name of Dial.xaml and then Click on Add.

Step 4

Step 5

In the XAML for Dial.xaml there will be some XAML for a Grid, below Grid, type the following XAML:

<Grid Name="DialGrid" Loaded="Load">
    <ContentPresenter Content="{x:Bind Face}"/>
    <ContentPresenter Content="{x:Bind Knob}" 
        RenderTransformOrigin="0.5,0.5">
        <ContentPresenter.RenderTransform>
            <TransformGroup>
                <RotateTransform x:Name="DialValue" />
            </TransformGroup>
        </ContentPresenter.RenderTransform>
    </ContentPresenter>
</Grid>
                                    

This XAML contains a Grid with a Loaded event handler of Load along with a ContentPresenter for the Face and Knob of the Dial which also has a RotateTransform to show the correct indicator for the Dial.

Step 6

Step 7

You will now be in the View for the Code of Dial.xaml.cs, type the following Code below the end of the Constructor of public Dial() { ... }:

private bool _hasCapture = false;

// Dependancy Properties 

// Properties

// GetRotation, GetAngle & SetPosition Methods

// Load Method                                        
                                    

The class for Dial represents the User Control for the Dial and includes a bool that will be used to know when the Dial is being interacted with.

Step 8

While still in the class of Dial after Comment of // Dependency Properties type the following Dependency Properties:

public static readonly DependencyProperty ValueProperty =
DependencyProperty.Register(nameof(Value), typeof(double),
typeof(Dial), null);

public static readonly DependencyProperty MinimumProperty =
DependencyProperty.Register(nameof(Minimum), typeof(double),
typeof(Dial), null);

public static readonly DependencyProperty MaximumProperty =
DependencyProperty.Register(nameof(Maximum), typeof(double),
typeof(Dial), null);

public static readonly DependencyProperty KnobProperty =
DependencyProperty.Register(nameof(Knob), typeof(UIElement),
typeof(Dial), null);

public static readonly DependencyProperty FaceProperty =
DependencyProperty.Register(nameof(Face), typeof(UIElement),
typeof(Dial), null);
                                    

There will also be some Errors as these refer to Properties that will be added in the next step.

These Dependency Properties refer to various Properties of the Dial that can be customised for the User Control.

Step 9

While still in the class of Dial after Comment of // Properties Method type the following Properties:

public double Value
{
    get { return (double)GetValue(ValueProperty); }
    set { SetValue(ValueProperty, value); }
}

public double Minimum
{
    get { return (double)GetValue(MinimumProperty); }
    set { SetValue(MinimumProperty, value); }
}

public double Maximum
{
    get { return (double)GetValue(MaximumProperty); }
    set { SetValue(MaximumProperty, value); }
}

public UIElement Knob
{
    get { return (UIElement)GetValue(KnobProperty); }
    set { SetValue(KnobProperty, value); }
}

public UIElement Face
{
    get { return (UIElement)GetValue(FaceProperty); }
    set { SetValue(FaceProperty, value); }
}
                                    

Any Errors should now be resolved, if you continue to get them check any previous steps to see if you have missed anything.

These Properties are for values for the User Control such as the Minimum or Maximum values for the Dial.

Step 10

While still in the class of Dial after Comment of // GetRotation, GetAngle & SetPosition Methods type the following Methods:

private double GetRotation(double width, double height, Point point)
{
    double radius = width / 2;
    Point centre = new(radius, height / 2);
    double triangleTop = Math.Sqrt(Math.Pow(point.X - centre.X, 2)
        + Math.Pow(centre.Y - point.Y, 2));
    double triangleHeight = (point.Y > centre.Y) ?
        point.Y - centre.Y : centre.Y - point.Y;
    return triangleHeight * Math.Sin(90) / triangleTop * 100;
}

private double GetAngle(Point point)
{
    double diameter = DialGrid.ActualWidth;
    double height = DialGrid.ActualHeight;
    double radius = diameter / 2;
    double rotation = GetRotation(diameter, height, point);
    if ((point.X > radius) && (point.Y <= radius))
    {
        rotation = 90.0 + (90.0 - rotation);
    }
    else if ((point.X > radius) && (point.Y > radius))
    {
        rotation = 180.0 + rotation;
    }
    else if ((point.X < radius) && (point.Y > radius))
    {
        rotation = 270.0 + (90.0 - rotation);
    }
    return rotation;
}

private void SetPosition(double rotation)
{
    if (Minimum >= 0 && Maximum > 0 && Minimum < 360 && Maximum <= 360)
    {
        if (rotation < Minimum) { rotation = Minimum; }
        if (rotation > Maximum) { rotation = Maximum; }
    }
    DialValue.Angle = rotation;
    Value = rotation;
}
                                    

These Methods will be used to determine the rotation for the Dial with GetRotation which will be used to set the angle with GetAngle and SetPosition will be used to constrain the angle as needed for the Dial.

Step 12

While still in the class of Dial after Comment of // Load Method type the following Method:

private void Load(object sender, RoutedEventArgs e)
{
    if (Minimum > 0 && Minimum < 360) 
        SetPosition(Minimum);
    DialGrid.PointerReleased += (object sender, PointerRoutedEventArgs e) =>
        _hasCapture = false;
    DialGrid.PointerPressed += (object sender, PointerRoutedEventArgs e) =>
    {
        _hasCapture = true;
        SetPosition(GetAngle(e.GetCurrentPoint(DialGrid).Position));
    };
    DialGrid.PointerMoved += (object sender, PointerRoutedEventArgs e) =>
    {
        if (_hasCapture)
            SetPosition(GetAngle(e.GetCurrentPoint(DialGrid).Position));
    };
    DialGrid.PointerExited += (object sender, PointerRoutedEventArgs e) =>
        _hasCapture = false;
}
                                    

Load will be used to set up the Event Handlers for the Dial for when the mouse is released or pressed and when the mouse is moved or leaves the Dial.

Step 12

Step 13

In the XAML for MainWindow.xaml there will be some XAML for a StackPanel, this should be Removed:

<StackPanel Orientation="Horizontal" 
HorizontalAlignment="Center" VerticalAlignment="Center">
    <Button x:Name="myButton" Click="myButton_Click">Click Me</Button>
</StackPanel>
                                    

Step 14

While still in the XAML for MainWindow.xaml above </Window>, type in the following XAML:

<local:Dial x:Name="Dial" Height="300" Width="300" Minimum="90.0" Maximum="275.0">
    <local:Dial.Face>
        <Ellipse Fill="{ThemeResource SystemControlHighlightAccentBrush}"/>
    </local:Dial.Face>
    <local:Dial.Knob>
        <Rectangle Height="40" Width="150" Margin="5,0,145,0" 
            RadiusX="20" RadiusY="20"  
            Fill="{ThemeResource SystemControlBackgroundAltHighBrush}"/>
    </local:Dial.Knob>
</local:Dial>
                                    

This XAML contains the User Control of Dial with the Face and Knob set along with other Properties such as the Minimum and Maximum values.

Step 15

Step 16

In the Code for MainWindow.xaml.cs there be a Method of myButton_Click(...) this should be Removed by removing the following:

private void myButton_Click(object sender, RoutedEventArgs e)
{
    myButton.Content = "Clicked";
}                                        
                                    

Step 17

Step 18

Once running you will see the Dial Control displayed, then you can rotate it to set the Value for the Dial.

Step 19