ChartControl.LegendItemChecked Event
Occurs when a legend item is checked in the legend checkbox.
Namespace: DevExpress.XtraCharts
Assembly: DevExpress.XtraCharts.v22.1.UI.dll
NuGet Package: DevExpress.Win.Charts
Declaration
Event Data
The LegendItemChecked event's data class is LegendItemCheckedEventArgs. The following properties provide information specific to this event:
Property | Description |
---|---|
CheckedElement | Gets a value that defines which chart element has been checked on a legend by a legend check box. |
NewCheckState | Gets a value that indicates the check state of a legend item after the ChartControl.LegendItemChecked event is handled. |
Remarks
The LegendItemChecked event is raised after the legend item has been checked in the legend checkbox by an end-user or in code by setting the CheckedInLegend property to true for the corresponding chart element.
Example
This example demonstrates how to show a series (Point, Line or Area), depending on the selection state of a custom radio button in the chart legend.
To accomplish this task, do the following:
Use the ChartControl.CustomDrawSeries (WebChartControl.CustomDrawSeries) event handler to create a custom appearance for radio buttons based on the color of a selected series.
To provide the capability for custom radio buttons to show (or hide) the series, use the LegendItemCheckedEventArgs.CheckedElement and SeriesBase.CheckedInLegend properties in the ChartControl.LegendItemChecked
(WebChartControl.LegendItemChecked) event.
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;
using DevExpress.XtraCharts;
namespace CustomCheckboxesInLegendViewAndBehavior {
public partial class mainForm : Form {
const int LegendRadioSide = 17;
const int LegendRadioInnerPointBoundsSide = 8;
const float LegendRadioWidth = 1.5f;
bool initializationFlag = false;
public mainForm() {
InitializeComponent();
chartControl.BeginInit();
{
chartControl.LegendItemChecked += OnLegendItemChecked;
chartControl.CustomDrawSeries += OnCustomDrawSeries;
chartControl.Legend.UseCheckBoxes = true;
chartControl.Series["Point"].CheckedInLegend = false;
chartControl.Series["Line"].CheckedInLegend = true;
chartControl.Series["Area"].CheckedInLegend = false;
}
chartControl.EndInit();
initializationFlag = false;
}
void OnLegendItemChecked(object sender, LegendItemCheckedEventArgs e) {
if (initializationFlag == true)
return;
initializationFlag = true;
{
Series checkedSeries = e.CheckedElement as Series;
if (checkedSeries == null)
throw new Exception("Expected series only");
foreach (Series series in chartControl.Series)
series.CheckedInLegend = false;
checkedSeries.CheckedInLegend = true;
chartControl.Titles[0].Text = checkedSeries.Name;
}
initializationFlag = false;
}
void OnCustomDrawSeries(object sender, CustomDrawSeriesEventArgs e) {
Bitmap bitmap = new Bitmap(LegendRadioSide, LegendRadioSide);
using (Graphics graphics = Graphics.FromImage(bitmap)) {
graphics.SmoothingMode = SmoothingMode.HighQuality;
Color seriesColor = GetSeriesColor(e.Series, chartControl);
using (Pen radioPen = new Pen(seriesColor, LegendRadioWidth)) {
int radioRadius = LegendRadioSide - 3;
Rectangle radioRectangle = new Rectangle(1, 1, radioRadius, radioRadius);
graphics.DrawEllipse(radioPen, radioRectangle);
}
if (e.Series.CheckedInLegend) {
using (Brush brush = new SolidBrush(seriesColor)) {
int coord = (LegendRadioSide - LegendRadioInnerPointBoundsSide) / 2;
Rectangle filledEllipseBounds = new Rectangle(coord, coord,
LegendRadioInnerPointBoundsSide, LegendRadioInnerPointBoundsSide);
graphics.FillEllipse(brush, filledEllipseBounds);
}
}
}
e.DisposeLegendMarkerImage = true;
e.LegendMarkerImage = bitmap;
}
Color GetSeriesColor(Series series, ChartControl chartControl) {
int seriesIndex = chartControl.Series.IndexOf(series);
string paletteName = chartControl.PaletteName;
Palette currentPalette = chartControl.PaletteRepository[paletteName];
PaletteEntry paletteEntryAccordingToSeries = currentPalette[seriesIndex];
Color result = paletteEntryAccordingToSeries.Color;
return result;
}
}
}
Related GitHub Examples
The following code snippet (auto-collected from DevExpress Examples) contains a reference to the LegendItemChecked event.
Note
The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.