wpf-11115-controls-and-libraries-charts-suite-chart-control-examples-end-user-interaction-how-to-create-a-movable-legend-at-runtime.md
This example shows how to provide the capability for end-users to move a chart’s legend at runtime.
For this, you need to assign a TranslateTransform object (named legendTransform) to the Legend.RenderTransform property. This allows you to control and modify a legend position.
Before changing a legend position, you should handle the ChartControl.MouseLeftButtonDown and ChartControl.MouseLeftButtonUp events to make sure that a legend has been dragged by a mouse. After that, it becomes possible to calculate a distance by which a legendTransform object should be moved. To accomplish this task, handle the ChartControl.MouseMove event.
<Window x:Class="scratch.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:dxc="http://schemas.devexpress.com/winfx/2008/xaml/charts"
Title="MainWindow" Height="350" Width="525" >
<Grid>
<dxc:ChartControl Name="chartControl1" MouseMove="chart_MouseMove"
MouseLeftButtonDown="chart_MouseLeftButtonDown"
MouseLeftButtonUp="chart_MouseLeftButtonUp">
<dxc:ChartControl.Diagram>
<dxc:XYDiagram2D>
<dxc:XYDiagram2D.Series>
<dxc:BarSideBySideSeries2D ColorEach="True">
<dxc:BarSideBySideSeries2D.LegendPointOptions>
<dxc:PointOptions PointView="Argument"/>
</dxc:BarSideBySideSeries2D.LegendPointOptions>
<dxc:BarSideBySideSeries2D.Points>
<dxc:SeriesPoint Argument ="A" Value="1"/>
<dxc:SeriesPoint Argument ="B" Value="2"/>
<dxc:SeriesPoint Argument ="C" Value="3"/>
<dxc:SeriesPoint Argument ="D" Value="4"/>
<dxc:SeriesPoint Argument ="E" Value="5"/>
<dxc:SeriesPoint Argument ="F" Value="4"/>
<dxc:SeriesPoint Argument ="G" Value="3"/>
<dxc:SeriesPoint Argument ="H" Value="2"/>
</dxc:BarSideBySideSeries2D.Points>
</dxc:BarSideBySideSeries2D>
</dxc:XYDiagram2D.Series>
</dxc:XYDiagram2D>
</dxc:ChartControl.Diagram>
<dxc:ChartControl.Legend>
<dxc:Legend x:Name="legend" Visibility="Visible">
<dxc:Legend.RenderTransform>
<TranslateTransform x:Name="legendTransform"/>
</dxc:Legend.RenderTransform>
</dxc:Legend>
</dxc:ChartControl.Legend>
</dxc:ChartControl>
</Grid>
</Window>
using System.Windows;
using System.Windows.Input;
using DevExpress.Xpf.Charts;
namespace scratch {
public partial class MainWindow : Window {
Point clickPosition { set; get; }
Point startDragging;
public bool isDragging { set; get; }
public MainWindow() {
InitializeComponent();
}
void chart_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) {
startDragging = e.GetPosition(chartControl1);
ChartHitInfo hitInfo = chartControl1.CalcHitInfo(startDragging);
isDragging = hitInfo != null && hitInfo.InLegend;
((UIElement)sender).CaptureMouse();
}
void chart_MouseLeftButtonUp(object sender, MouseButtonEventArgs e) {
((UIElement)sender).ReleaseMouseCapture();
isDragging = false;
}
void chart_MouseMove(object sender, MouseEventArgs e) {
if (e.LeftButton == MouseButtonState.Pressed && isDragging) {
Point endDragging = e.GetPosition(chartControl1);
Point inLegendPosition = e.GetPosition(legend);
if (inLegendPosition.X < 0)
inLegendPosition.X = 0;
else if (inLegendPosition.X > legend.ActualWidth)
inLegendPosition.X = legend.ActualWidth;
if (inLegendPosition.Y < 0)
inLegendPosition.Y = 0;
else if (inLegendPosition.Y > legend.ActualHeight)
inLegendPosition.Y = legend.ActualHeight;
if (endDragging.X - inLegendPosition.X > 0 &&
endDragging.X + legend.ActualWidth - inLegendPosition.X < chartControl1.ActualWidth)
legendTransform.X += endDragging.X - startDragging.X;
if (endDragging.Y - inLegendPosition.Y > 0 &&
endDragging.Y + legend.ActualHeight - inLegendPosition.Y < chartControl1.ActualHeight)
legendTransform.Y += endDragging.Y - startDragging.Y;
startDragging = endDragging;
}
}
}
}
Imports Microsoft.VisualBasic
Imports System.Windows
Imports System.Windows.Input
Imports DevExpress.Xpf.Charts
Namespace scratch
Partial Public Class MainWindow
Inherits Window
Private privateclickPosition As Point
Private Property clickPosition() As Point
Get
Return privateclickPosition
End Get
Set(ByVal value As Point)
privateclickPosition = value
End Set
End Property
Private startDragging As Point
Private privateisDragging As Boolean
Public Property isDragging() As Boolean
Get
Return privateisDragging
End Get
Set(ByVal value As Boolean)
privateisDragging = value
End Set
End Property
Public Sub New()
InitializeComponent()
End Sub
Private Sub chart_MouseLeftButtonDown(ByVal sender As Object, ByVal e As MouseButtonEventArgs)
startDragging = e.GetPosition(chartControl1)
Dim hitInfo As ChartHitInfo = chartControl1.CalcHitInfo(startDragging)
isDragging = hitInfo IsNot Nothing AndAlso hitInfo.InLegend
CType(sender, UIElement).CaptureMouse()
End Sub
Private Sub chart_MouseLeftButtonUp(ByVal sender As Object, ByVal e As MouseButtonEventArgs)
CType(sender, UIElement).ReleaseMouseCapture()
isDragging = False
End Sub
Private Sub chart_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs)
If e.LeftButton = MouseButtonState.Pressed AndAlso isDragging Then
Dim endDragging As Point = e.GetPosition(chartControl1)
Dim inLegendPosition As Point = e.GetPosition(legend)
If inLegendPosition.X < 0 Then
inLegendPosition.X = 0
ElseIf inLegendPosition.X > legend.ActualWidth Then
inLegendPosition.X = legend.ActualWidth
End If
If inLegendPosition.Y < 0 Then
inLegendPosition.Y = 0
ElseIf inLegendPosition.Y > legend.ActualHeight Then
inLegendPosition.Y = legend.ActualHeight
End If
If endDragging.X - inLegendPosition.X > 0 AndAlso endDragging.X + legend.ActualWidth - inLegendPosition.X < chartControl1.ActualWidth Then
legendTransform.X += endDragging.X - startDragging.X
End If
If endDragging.Y - inLegendPosition.Y > 0 AndAlso endDragging.Y + legend.ActualHeight - inLegendPosition.Y < chartControl1.ActualHeight Then
legendTransform.Y += endDragging.Y - startDragging.Y
End If
startDragging = endDragging
End If
End Sub
End Class
End Namespace