Windows Forms Chart Plotting Minor Grid Lines with a Log Scale

[Bruce Barker]

It appears that there are no methods to plot minor grid lines. It can be accomplished using the ChartAreaPaint event. The code below shows an example.

 

Private

Sub _BubblePlot_ChartAreaPaint(sender As Object, e As System.Windows.Forms.PaintEventArgs) Handles _BubblePlot.ChartAreaPaint

Dim YMin As Double, YMax As Double, XMin As Double, XMax As Double, MaxStop As Double

Dim GridLoc As Double, _Increment As Double

Dim _Pen As Pen = New Pen(System.Drawing.Color.FromArgb(175, 129, 115, 27))

　

If (_BubblePlot.PrimaryYAxis.ValueType = ChartValueType.Logarithmic) Then 'Include Minor Gridlines for Y Axis (Horizontal)

Dim ptLeft As Point, ptRight As Point

YMin = _BubblePlot.PrimaryYAxis.Range.Min

'Min, Max Values in Log Space

YMax = _BubblePlot.PrimaryYAxis.Range.Max

MaxStop = 10 ^ YMax

Dim LogIncrement As Integer = CInt(YMin)

_Increment = 10 ^ YMin

GridLoc = _Increment

'> Draw horizonal lines incrementing by _Increment for each log cycle

Do While GridLoc < MaxStop

For I As Integer = 1 To 9

GridLoc += _Increment

ptLeft = _BubblePlot.ChartArea.GetPointByValue(

New ChartPoint(_BubblePlot.PrimaryXAxis.Range.Min, GridLoc))

ptRight = _BubblePlot.ChartArea.GetPointByValue(

New ChartPoint(_BubblePlot.PrimaryXAxis.Range.Max, GridLoc))

e.Graphics.DrawLine(_Pen, ptLeft.X, ptLeft.Y, ptRight.X, ptRight.Y)

Next

_Increment *= 10

GridLoc = _Increment

Loop

End If

If (_BubblePlot.PrimaryXAxis.ValueType = ChartValueType.Logarithmic) Then 'Include Minor Gridlines for X Axis (Vertical)

Dim ptBottom As Point, ptTop As Point

XMin = _BubblePlot.PrimaryXAxis.Range.Min

'Min, Max Values in Log Space

XMax = _BubblePlot.PrimaryXAxis.Range.Max

MaxStop = 10 ^ YMax

Dim LogIncrement As Integer = CInt(XMin)

_Increment = 10 ^ XMin

GridLoc = _Increment

'> Draw horizonal lines incrementing by _Icrement for each log cycle

Do While GridLoc < MaxStop

For I As Integer = 1 To 9

GridLoc += _Increment

ptBottom = _BubblePlot.ChartArea.GetPointByValue(

New ChartPoint(GridLoc, _BubblePlot.PrimaryYAxis.Range.Min))

ptTop = _BubblePlot.ChartArea.GetPointByValue(

New ChartPoint(GridLoc, _BubblePlot.PrimaryXAxis.Range.Max))

e.Graphics.DrawLine(_Pen, ptBottom.X, ptBottom.Y, ptTop.X, ptTop.Y)

Next

_Increment *= 10

GridLoc = _Increment

Loop

End If

End Sub

[Vijayabharathi K]

Hi Bruce,

 Thanks for using Syncfusion products.

 We are having properties to plot the minor grid lines in logarithmic type chart. Please refer the below code snippet to achieve this,

 [C#]

this.chartControl1.PrimaryXAxis.ValueType = ChartValueType.Logarithmic;

            this.chartControl1.PrimaryXAxis.DrawMinorGrid = true;

            this.chartControl1.PrimaryXAxis.SmallTicksPerInterval = 3;

 Note: Please find the attachment screenshot for minor grid lines.

 Please let us know if any concerns.

 Regards,

Vijayabharathi

 

Screenshot_e83d19d5.zip