Applies to: Nevron Chart for .NET
How to create a custom axis view that updates the Y axis range?
Often, there is a requirement to have custom axis view that updates the Y axis range to match the range of data points currently visible on chart the x axis. This feature is useful when you are building charts with zooming and scrolling that show only a partial view of the data on the x axis.
The following code example shows how to create a custom axis view that updates the Y axis range to match the range of data points currently visible on the x axis:
[C#]
using System;
using System.Windows.Forms;
using Nevron.Chart;
using Nevron.Chart.WinForm;
using Nevron.GraphicsCore;
...
/// <summary>
/// Configures the axis to display the range of the content that scales on it
/// </summary>
[Serializable]
public partial class NCustomAxisView : NRangeAxisView
{
#region Constructors
/// <summary>
/// Constructor
/// </summary>
/// <param name="chartControl"></param>
public NCustomAxisView(NChartControl chartControl)
{
m_ChartControl = chartControl;
}
#endregion
#region Overrides
/// <summary>
/// Obtains the Y range displayed by the axis given the current X content range
/// </summary>
/// <param name="range"></param>
/// <param name="isZoomed"></param>
/// <returns></returns>
public override NRange1DD GetViewRange(NRange1DD range, ref bool isZoomed)
{
NChart chart = (NChart)this.ProvideReference(typeof(NChart));
// recalculate the x axis - this ensures the RulerRange is valid
chart.Axis(StandardAxis.PrimaryX).CalculateAxis(m_ChartControl.View.Context);
NRange1DD xRange = chart.Axis(StandardAxis.PrimaryX).Scale.RulerRange;
NLineSeries line = chart.Series[0] as NLineSeries;
if (line.Values.Count == 0)
return range;
// then compute min / max
bool hasMinMax = false;
double min = 0;
double max = 0;
for (int i = 0; i < line.Values.Count; i++)
{
if (!xRange.Contains((double)line.XValues[i]))
continue;
double value = (double)line.Values[i];
if (hasMinMax)
{
max = Math.Max(max, value);
min = Math.Min(min, value);
}
else
{
max = value;
min = value;
hasMinMax = true;
}
}
isZoomed = hasMinMax;
if (hasMinMax)
{
range = new NRange1DD(min, max);
}
// return the computed range
return range;
}
#endregion
#region Fields
NChartControl m_ChartControl;
#endregion
}
private void Form1_Load(object sender, EventArgs e)
{
NCartesianChart chart = (NCartesianChart)nChartControl1.Charts[0];
// configure chart
chart.BoundsMode = BoundsMode.Stretch;
chart.Axis(StandardAxis.PrimaryX).ScrollBar.Visible = true;
// install custom axis view
chart.Axis(StandardAxis.PrimaryY).View = new NCustomAxisView(nChartControl1);
// add dummy data
NLineSeries line = new NLineSeries();
line.UseXValues = true;
line.DataLabelStyle.Visible = false;
for (int i = 0; i < 200; i++)
{
line.Values.Add(Math.Sin(2 * Math.PI * i / 200.0));
line.XValues.Add(i);
}
chart.Series.Add(line);
// configure interactivity
NRangeSelection rs = new NRangeSelection();
rs.VerticalValueSnapper = new NAxisRulerMinMaxSnapper();
chart.RangeSelections.Add(rs);
nChartControl1.Controller.Tools.Add(new NSelectorTool());
nChartControl1.Controller.Tools.Add(new NAxisScrollTool());
nChartControl1.Controller.Tools.Add(new NDataZoomTool());
}
[VB.NET]
Imports System
Imports System.Windows.Forms
Imports Nevron.Chart
Imports Nevron.Chart.WinForm
Imports Nevron.GraphicsCore
…
''' <summary>
''' Configures the axis to display the range of the content that scales on it
''' </summary>
<Serializable()> _
Partial Public Class NCustomAxisView
Inherits NRangeAxisView
#Region "Constructors"
''' <summary>
''' Constructor
''' </summary>
''' <param name="chartControl"></param>
Public Sub New(chartControl As NChartControl)
m_ChartControl = chartControl
End Sub
#End Region
#Region "Overrides"
''' <summary>
''' Obtains the Y range displayed by the axis given the current X content range
''' </summary>
''' <param name="range"></param>
''' <param name="isZoomed"></param>
''' <returns></returns>
Public Overrides Function GetViewRange(range As NRange1DD, ByRef isZoomed As Boolean) As NRange1DD
Dim chart As NChart = DirectCast(Me.ProvideReference(GetType(NChart)), NChart)
' recalculate the x axis - this ensures the RulerRange is valid
chart.Axis(StandardAxis.PrimaryX).CalculateAxis(m_ChartControl.View.Context)
Dim xRange As NRange1DD = chart.Axis(StandardAxis.PrimaryX).Scale.RulerRange
Dim line As NLineSeries = TryCast(chart.Series(0), NLineSeries)
If line.Values.Count = 0 Then
Return range
End If
' then compute min / max
Dim hasMinMax As Boolean = False
Dim min As Double = 0
Dim max As Double = 0
For i As Integer = 0 To line.Values.Count - 1
If Not xRange.Contains(CDbl(line.XValues(i))) Then
Continue For
End If
Dim value As Double = CDbl(line.Values(i))
If hasMinMax Then
max = Math.Max(max, value)
min = Math.Min(min, value)
Else
max = value
min = value
hasMinMax = True
End If
Next
isZoomed = hasMinMax
If hasMinMax Then
range = New NRange1DD(min, max)
End If
' return the computed range
Return range
End Function
#End Region
#Region "Fields"
Private m_ChartControl As NChartControl
#End Region
End Class
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
Dim chart As NCartesianChart = DirectCast(NChartControl1.Charts(0), NCartesianChart)
' configure chart
chart.BoundsMode = BoundsMode.Stretch
chart.Axis(StandardAxis.PrimaryX).ScrollBar.Visible = True
' install custom axis view
chart.Axis(StandardAxis.PrimaryY).View = New NCustomAxisView(NChartControl1)
' add dummy data
Dim line As New NLineSeries()
line.UseXValues = True
line.DataLabelStyle.Visible = False
For i As Integer = 0 To 199
line.Values.Add(Math.Sin(2 * Math.PI * i / 200.0))
line.XValues.Add(i)
Next
chart.Series.Add(line)
' configure interactivity
Dim rs As New NRangeSelection()
rs.VerticalValueSnapper = New NAxisRulerMinMaxSnapper()
chart.RangeSelections.Add(rs)
NChartControl1.Controller.Tools.Add(New NSelectorTool())
NChartControl1.Controller.Tools.Add(New NAxisScrollTool())
NChartControl1.Controller.Tools.Add(New NDataZoomTool())
End Sub
Article ID: 219, Created On: 5/16/2012, Modified: 5/16/2012