Need a faster DataGridView bulk edit method

Question

Hello all,

This is what I'm currently using to implement a "Check all" feature on a bound DataGridView:

int max = ((DataTable)dataGridRes.DataSource).Rows.Count;
for (int i = 0; i < max; i++)
{
    if(((DataTable)dataGridRes.DataSource).Rows[i].Field<long>(0) == 0)
        ((DataTable)dataGridRes.DataSource).Rows[i].SetField(0, 1);
}

However this code is hopelessly slow. On a 625 row DataTable it takes aprox 5 seconds to complete on my computer. Very unacceptable.

What am I doing wrong? What better way can I use to do bulk edits on a DataGridView?

Answer 1

Second try.

1. You are casting way too many times
2. You are doing an if statement that doesn't matter

try something like:

foreach(DataRow r in ((DataTable)dataGridRes.DataSource).Rows)
{
    r.SetField(0, 1);
}

Answer 2

This blog has what you need: DataGridView CheckBox Select All

Code posted for posterity:

public delegate void CheckBoxClickedHandler(bool state);
public class DataGridViewCheckBoxHeaderCellEventArgs : EventArgs
{
    bool _bChecked;
    public DataGridViewCheckBoxHeaderCellEventArgs(bool bChecked)
    {
     _bChecked = bChecked;
    }
    public bool Checked
    {
     get { return _bChecked; }
    }
}

class DatagridViewCheckBoxHeaderCell : DataGridViewColumnHeaderCell
{
    Point checkBoxLocation;
    Size checkBoxSize;
    bool _checked = false;
    Point _cellLocation = new Point();
    System.Windows.Forms.VisualStyles.CheckBoxState _cbState =
     System.Windows.Forms.VisualStyles.CheckBoxState.UncheckedNormal;

    public event CheckBoxClickedHandler OnCheckBoxClicked;

    public DatagridViewCheckBoxHeaderCell()
    {
    }

    protected override void Paint(System.Drawing.Graphics graphics,
     System.Drawing.Rectangle clipBounds,
     System.Drawing.Rectangle cellBounds,
     int rowIndex,
     DataGridViewElementStates dataGridViewElementState,
     object value,
     object formattedValue,
     string errorText,
     DataGridViewCellStyle cellStyle,
     DataGridViewAdvancedBorderStyle advancedBorderStyle,
     DataGridViewPaintParts paintParts)
    {
     base.Paint(graphics, clipBounds, cellBounds, rowIndex,
      dataGridViewElementState, value,
      formattedValue, errorText, cellStyle,
      advancedBorderStyle, paintParts);

     Point p = new Point();

     Size s = CheckBoxRenderer.GetGlyphSize(graphics,
      System.Windows.Forms.VisualStyles.CheckBoxState.UncheckedNormal);

     p.X = cellBounds.Location.X +
      (cellBounds.Width / 2) - (s.Width / 2);
     p.Y = cellBounds.Location.Y +
      (cellBounds.Height / 2) - (s.Height / 2);

      _cellLocation = cellBounds.Location;
      checkBoxLocation = p;
      checkBoxSize = s;
     if (_checked)
      _cbState = System.Windows.Forms.VisualStyles.
      CheckBoxState.CheckedNormal;
     else
      _cbState = System.Windows.Forms.VisualStyles.
      CheckBoxState.UncheckedNormal;
      CheckBoxRenderer.DrawCheckBox
      (graphics, checkBoxLocation, _cbState);
    }

    protected override void OnMouseClick(DataGridViewCellMouseEventArgs e)
    {
     Point p = new Point(e.X + _cellLocation.X, e.Y + _cellLocation.Y);
     if (p.X >= checkBoxLocation.X && p.X <=
      checkBoxLocation.X + checkBoxSize.Width
      && p.Y >= checkBoxLocation.Y && p.Y <=
      checkBoxLocation.Y + checkBoxSize.Height)
     {
     _checked = !_checked;
     if (OnCheckBoxClicked != null)
     {
      OnCheckBoxClicked(_checked);
      this.DataGridView.InvalidateCell(this);
     }
    }
    base.OnMouseClick(e);
  }
}

The code to add the checkbox to header and the corresponding event code is given below.

private void FormatGrid()
{
    DataView dv = new DataView();
    dv.Table = _loginDs.Tables[0];

    DataGridViewCheckBoxColumn chkbox = new DataGridViewCheckBoxColumn();
    DatagridViewCheckBoxHeaderCell chkHeader = new DatagridViewCheckBoxHeaderCell();
    chkbox.HeaderCell = chkHeader;
    chkHeader.OnCheckBoxClicked += new CheckBoxClickedHandler(chkHeader_OnCheckBoxClicked);
    _chkBoxGrid.Columns.Add(chkbox);

    DataGridViewTextBoxColumn uname = new DataGridViewTextBoxColumn();
    uname.HeaderText = "user";
    uname.Name = "username";
    uname.DataPropertyName = "username";
    _chkBoxGrid.Columns.Add(uname);

    _chkBoxGrid.DataSource = dv;
}

void chkHeader_OnCheckBoxClicked(bool state)
{
    foreach (DataGridViewRow row in _chkBoxGrid.Rows)
        row.Cells[0].Value = state;

}

Answer 3

When editing multiple rows or columns in a DataTable, call BeginLoadData 1st and then call EndLoadData when you're done.

Answer 4

I found a way to speed it up to an acceptable performance. Essentially unbind the control, do the update on the DataTable and rebind it.

DataTable dt = (DataTable)dataGridRes.DataSource;
dataGridRes.DataSource = null;

for (int i = 0; i < dt.Rows.Count; i++)
    dt.Rows[i].SetField(0, 1);

dataGridRes.DataSource = dt;