TrackBarItem.Value Property

Gets or sets the item’s associated value.

Assembly : DevExpress.Web.v25.2.dll

Declaration

C#
VB.NET

csharp

[DefaultValue(null)]
public override object Value { get; set; }

<DefaultValue(Nothing)>
Public Overrides Property Value As Object

Property Value

Type	Default	Description
Object	null

An Object that specifies the item’s value.

Remarks

The Value property specifies a value associated with an item. To access the item value on the client side, use the ASPxClientTrackBar.GetItemValue method.

If the item’s TrackBarItem.ToolTip property is not specified, the Value property value is displayed within the value tooltip.

Note

For a track bar editor to function properly, values of all items in its ASPxTrackBar.Items collection should be unique. There should not be two or more items with the same value of the Value property.

Example

The code sample below demonstrates how you can use the ASPxTrackBar control in two ways. On the one hand, a user can easily choose the required value or item, on the other hand, you can show end-users the visual result of their actions.

In this example, an end-user can select a chemical element and see its melting point. Here we use two track bars. The first track bar is used to visualize melting points and looks like a thermometer scale. By design, an end-user cannot change its value directly, so the ASPxEdit.ReadOnly property for this track bar is enabled. The second track bar is used to select the required chemical element. All the defined elements are gathered to the ASPxTrackBar.Items collection. The ASPxClientTrackBar.PositionChanged event of the second track bar is handled to update the value of the first track bar.

The image below shows the result.

JS
ASPX

javascript

function OnPositionChanged(s, e) {
    updateItems(s);
}

function OnInit(s, e) {
    updateItems(s);
}

function updateItems(trackBar) {
    var trackBarValue = trackBar.GetValue();
    termometer.SetValue(trackBarValue);
}

aspx

<dx:ASPxTrackBar ID="ASPxTrackBar1" runat="server" ScalePosition="RightOrBottom" 
    Orientation="Vertical" ShowChangeButtons="False" 
    ShowDragHandles="False" Direction="Reversed" ReadOnly="True" 
    ValueType="System.String" ClientInstanceName="termometer" 
    MaxValue="-340" MinValue="-440" ScaleLabelFormatString="{0}°F" 
    Width="54px" ValueToolTipPosition="None" LargeTickEndValue="-340" 
    LargeTickStartValue="-440" Position="-440" PositionEnd="-440" PositionStart="-440" 
    >
    <ScaleStyle>
        <BackgroundImage ImageUrl="~/imgs/scale_background.png" />
    </ScaleStyle>
    <BarHighlightStyle>
        <BackgroundImage ImageUrl="~/imgs/barhighlight.png" Repeat="RepeatY" 
            HorizontalPosition="center" />
    </BarHighlightStyle>
    <TrackStyle>
        <BackgroundImage ImageUrl="~/imgs/track.png" Repeat="RepeatY" 
            HorizontalPosition="center" />
    </TrackStyle>
</dx:ASPxTrackBar>




<dx:ASPxTrackBar ID="ASPxTrackBar2" runat="server" LargeTickEndValue="4" 
    MaxValue="4" Step="1" ScalePosition="RightOrBottom" 
    ShowChangeButtons="False" ValueType="System.String" Position="0" 
    PositionStart="0" EnableAnimation="true" 
    ValueToolTipPosition="RightOrBottom" >
    <ClientSideEvents Init="OnInit" PositionChanged="OnPositionChanged" />
    <Items>
        <dx:TrackBarItem Text="H" ToolTip="Hydrogen" Value="-434" />
        <dx:TrackBarItem Text="Ne" ToolTip="Neon" Value="-414"/>
        <dx:TrackBarItem Text="O" ToolTip="Oxygen" Value="-367"/>
        <dx:TrackBarItem Text="F" ToolTip="Fluorine" Value="-362"/>
        <dx:TrackBarItem Text="N" ToolTip="Nitrogen" Value="-346"/>
    </Items>
    <ScaleStyle Font-Names="Arial" >
    </ScaleStyle>
</dx:ASPxTrackBar>