How to optimize pixel scrolling in the WinForms GridControl?

2 mins read

Optimize the pixel scrolling

The Grid's base class pixel scrolling is not optimized for large row scenarios. In the derived WinForms GridControl, you have to override a couple of virtual methods to make it perform well and use binary tree structures to quickly get the row index for an absolute pixel position and vice versa.

Solution:

The following steps are given to optimize the pixel scrolling:

Step 1: Create a Custom derived GridControl and override the following methods for optimized vertical scrolling.

RowIndexToVScrollPixelPos(int rowIndex)
VScrollPixelPosToRowIndex(int pixelPos, out int rowIndex, out int pixelDelta)
GetVScrollPixelHeight

public class DerivedGridControl : GridControl
{
    // Gets the Scroll Position for the pixel scrolling of a row.
    public override int RowIndexToVScrollPixelPos(int rowIndex)
    {
        // Takes separate height for the column headers into account.
        rowIndex = Math.Min(rowIndex, Model.RowCount);
        if (rowIndex > 0)
            return (rowIndex - 1) * Model.Rows.DefaultSize + Model.RowHeights[0];
        else
            return Model.RowHeights[0];
    }

    // Gets the value for the vertical pixel Position.
    public override int GetVScrollPixelHeight()
    {
        // Checks the number of rows in the Grid.
        if (Model.RowCount == 0)
            return 0;

        // Returns the vertical pixel position.
        return (Model.RowCount - 1) * Model.Rows.DefaultSize + Model.RowHeights[0];
    }

    // Gets the row and pixel Delta to the scroll position of the row for the specified scroll position.
    public override void VScrollPixelPosToRowIndex(int pixelPos, out int rowIndex, out int pixelDelta)
    {
        if (pixelPos < pixelPos - Model.RowHeights[0])
        {
            rowIndex = 0;
            pixelDelta = pixelPos;
        }

        rowIndex = (pixelPos - Model.RowHeights[0]) / Model.Rows.DefaultSize + 1;
        pixelDelta = (pixelPos - Model.RowHeights[0]) % Model.Rows.DefaultSize;
    }
}

Public Class DerivedGridControl
    Inherits GridControl

    'Gets the Scroll Position for the pixel scrolling of a row.
    Public Overrides Function RowIndexToVScrollPixelPos(rowIndex As Integer) As Integer
        rowIndex = Math.Min(rowIndex, Me.Model.RowCount)
        If rowIndex > 0 Then
            Return (rowIndex - 1) * Me.Model.Rows.DefaultSize + Me.Model.RowHeights(0)
        Else
            Return Me.Model.RowHeights(0)
        End If
    End Function

    'Gets the value for the vertical pixel Position.
    Public Overrides Function GetVScrollPixelHeight() As Integer
        If Me.Model.RowCount = 0 Then
            Return 0
        End If
        Return (Me.Model.RowCount - 1) * Me.Model.Rows.DefaultSize + Me.Model.RowHeights(0)
    End Function

    'Gets the row and pixel Delta to the scroll position of the row for the specified scroll position.
    Public Overrides Sub VScrollPixelPosToRowIndex(pixelPos As Integer, ByRef rowIndex As Integer, ByRef pixelDelta As Integer)
        If pixelPos < pixelPos - Me.Model.RowHeights(0) Then
            rowIndex = 0
            pixelDelta = pixelPos
            Return
        End If
        rowIndex = (pixelPos - Me.Model.RowHeights(0)) \ Me.Model.Rows.DefaultSize + 1
        pixelDelta = (pixelPos - Me.Model.RowHeights(0)) Mod Me.Model.Rows.DefaultSize
    End Sub
End Class

Step 2: Assign the new custom control to the GridControl.

this.gridControl1 = new VscrollOptimization.DerivedGridControl();

Me.gridControl1 = New VscrollOptimization.DerivedGridControl()

Step 3: Set the VScrollPixel property to true.

//Sets VScrollPixce value to true to enable pixel scrolling.
this.gridControl1.VScrollPixel = true;

'Sets VScrollPixce value to true to enable pixel scrolling.
Me.gridControl1.VScrollPixel = True

The following screenshot displays the vertical scrolling optimization in the GridControl.

Vertical scrolling optimization

Figure 1: Vertical scrolling optimization

Samples:

C#: OptimizePixcelScrolling-C#2064456570.zip

VB: OptimizePixcelScrolling-VB-1952192200.zip

Conclusion

I hope you enjoyed learning about how to optimize pixel scrolling in the WinForms GridControl.

You can refer to WinForms GridControl feature tour page to know about its other groundbreaking feature representations and WinForms GridControl documentation, and how to quickly get started for configuration specifications.

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How to optimize pixel scrolling in the WinForms GridControl?

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