Datagridview Checkbox Select All

Though .Net allows to include Checkboxes in a datagridview,selection of all the checkboxes in a single column at once is always a tough task.I found it very tough initially.

Today I shall help you include a top Checkbox,clicking on which selection of all the checkboxes under that is possible.

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);
}
}

This class needs to be included to the project to get the Header Checkbox feature.

Then the checkbox need to be added to the datagridview as a DatagridViewCheckBoxColumn.
Then we assign the header to it.
The header is assigned an event with the help of which we can uncheck or check all the checkboxes.

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;
}

In the checkbox header clicked event,any conditions might be added to select only the needed rows..

I hope you'll have a good time working with the new header for checkboxes. :)