WPF Slider Control in VB.NET

This article shows you how to use the Slider control available in WPF.
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Slider Control

The Slider element in XAML represents a WPF Slider control.

<Slider></Slider>

Slider Control Properties

The Width and Height property represent the width and the height of the control.  The Name property represents name of the control, which is a unique identifier of the control.  The Background property is used to set the background color of the control. The Minimum and Maximum properties represent the minimum and maximum values of the slider range.

The code snippet in Listing 1 creates a Slider control and sets its name, height, width, background, maximum, and minimum properties. .

<Slider Name="mcSlider" Width="300" Height="20"
        Background="Gray" Maximum="100" Minimum="0">           
</Slider>

Listing 1

The code snippet in Listing 1 generates output looks like Figure 1.

SliderImg1.jpg
Figure 1

The IsFocused property indicates whether the slider control has focus and IsDirectionReversed property represents the direction of increasing value. By default, the slider control sits on UI in horizontal direction. By using the Orientation property, a slider control can be placed vertically.

The code snippet in Listing 2 sets the orientation of a slider control vertical.

 <Slider Name="mcSlider" Width="300" Height="20"
        Background="Gray" Maximum="100" Minimum="0">           
</Slider>

Listing 1

The code snippet in Listing 2 generates output looks like Figure 2.

SliderImg2.jpg
Figure 2

The Application

Now we are going to create a real world application that will use Slider controls values to create a color from three values Red, Green, and Blue respectively. From these three values, we will create a color and fill an ellipse with that color.

First we create a UI page with one circle and three slider controls that looks like Figure 3.

SliderImg3.jpg

Figure 3

The code that generates Figure 3 is listed in Listing 2.

<Canvas Name="LayoutRoot" Background="LightGray" >
    <!-- Create an Ellipse -->
    <Ellipse Name="mcCircle" Width="200" Height="200"               
            Canvas.Left="60" Canvas.Top="20"
             Fill="Gray" Stroke="Black" StrokeThickness="2">           
    </Ellipse>

    <!-- Create Slider controls -->
    <Slider Name="RedSlider" Width="300" Height="20"
            Background="Red" Maximum="255" Minimum="0"              
            Canvas.Left="30" Canvas.Top="240"
            ValueChanged="RedSlider_ValueChanged"/>
    <Slider Name="GreenSlider" Width="300" Height="20"
            Background="Green" Maximum="255" Minimum="0"                
            Canvas.Left="30" Canvas.Top="270"
            ValueChanged="GreenSlider_ValueChanged"/>
    <Slider Name="BlueSlider" Width="300" Height="20"
            Background="Blue" Maximum="255" Minimum="0"               
            Canvas.Left="30" Canvas.Top="300"
            ValueChanged="BlueSlider_ValueChanged"/>
</Canvas>

Listing 2

Now, on the ValueChanged event of slider controls, we write the code listed in Listing 3. In this code, we simply create a Color from the values of the slider controls and create a brush with this color and fill the circle.

    Private Sub RedSlider_ValueChanged(ByVal sender As Object, ByVal e As RoutedPropertyChangedEventArgs(Of Double))
        UpdateCircleWithColors()
    End Sub

    Private Sub GreenSlider_ValueChanged(ByVal sender As Object, ByVal e As RoutedPropertyChangedEventArgs(Of Double))
        UpdateCircleWithColors()
    End Sub

    Private Sub BlueSlider_ValueChanged(ByVal sender As Object, ByVal e As RoutedPropertyChangedEventArgs(Of Double))
        UpdateCircleWithColors()
    End Sub

    Private Sub UpdateCircleWithColors()
        Dim clr As Color = Color.FromArgb(255, Convert.ToByte(RedSlider.Value), Convert.ToByte(GreenSlider.Value), Convert.ToByte(BlueSlider.Value))
        mcCircle.Fill = New SolidColorBrush(clr)
    End Sub

Listing 3

Now if you run the application and change slider values, you will see the fill color of circle changes accordingly. See Figure 4.

SliderImg4.jpg
Figure 4

Summary

In this article, I discussed how to create and use a Slider control available in WPF.  We also saw, how to create a real world application using slider controls.

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