DataGridBoolColumn

[boB Taylor MCSD, MCDBA, MCSE]

I am trying to create the following behavior. I have a WinForm that contains a DataGrid, bound to a Dataset. One of the columns is a DataGridBoolColumn. When the grid is not selected (ie. no row currently selected) clicking on a check box only sets focus to the cell, but requires a second click to actually check (or uncheck) the control. I tried capturing the CurrentCellChanged event of the grid, and I am able to determine the row and col, but when I try to use the GetColValueAtRow and SetColValueAtRow functions, I am told that they are marked internal and I can't use them. I would hope that their would be a way to accomplish this?

[Clay Burch]

The DataGridBoolColumn does not fire a change event when the boolean value
changes. The FAQ referenced below derives this class and adds a change event
that includes a row & column & value in its EventArgs. This may give you
what you need for tracking the value of an active cell.

In regard to it taking 2 clicks if the cell is not active, I don't have a
tested solution for you. But I think this code in the Edit override of the
sample should flip the value on any initial click. You may way to try to
restrict the change to only when the mouse position is over the checkbox
bitmap (instead of a click anywhere in the cell).

protected override void Edit(System.Windows.Forms.CurrencyManager source,
int rowNum, System.Drawing.Rectangle bounds, bool readOnly, string
instantText, bool cellIsVisible)
{
saveValue = (bool) base.GetColumnValueAtRow(source, rowNum);

if(Control.MouseButtons == MouseButtons.Left)
{
saveValue = !saveValue;
base.SetColumnValueAtRow(source, rowNum,
saveValue);
//fire the event
if(BoolValueChanged != null)
{
BoolValueChangedEventArgs e = new
BoolValueChangedEventArgs(rowNum, _column, saveValue);
BoolValueChanged(this, e);
}
}
lockValue = true;
beingEdited = true;
saveRow = rowNum;

base.Edit(source, rowNum, bounds, readOnly, instantText, cellIsVisible);
}

================================================
The Windows Forms FAQ contains an entry entitled:

How can I catch the bool values changing in a DataGridBoolColumn?

http://www.syncfusion.com/faq/winforms/search/874.asp

[Clay Burch]

Here is some code that only switches on the first click if it hits the checkbox (not just the cell)

protected override void Edit(System.Windows.Forms.CurrencyManager source, int rowNum, System.Drawing.Rectangle bounds, bool readOnly, string instantText, bool cellIsVisible)
{
	saveValue = (bool) base.GetColumnValueAtRow(source, rowNum);
	if(Control.MouseButtons == MouseButtons.Left)
	{
		Point mousePos = this.DataGridTableStyle.DataGrid.PointToClient(Control.MousePosition);
		DataGrid dg = this.DataGridTableStyle.DataGrid;
		Rectangle rect = dg.GetCellBounds(dg.CurrentCell);
				
		//define the checkbox hit size somehow
		Size checkiconsize = new Size(20, 20);//SystemInformation.SmallIconSize; //however you want to define the hit-area
		//assume checkbox is centered
		rect = new Rectangle(rect.Left + (rect.Width- checkiconsize.Height) / 2,
				rect.Top + (rect.Height - checkiconsize.Height) / 2,
				checkiconsize.Width, checkiconsize.Height);
				
		if(rect.Contains(mousePos))
		{
			saveValue = !saveValue;
			base.SetColumnValueAtRow(source, rowNum, saveValue);
			//fire the event
			if(BoolValueChanged != null)
			{
				BoolValueChangedEventArgs e = new BoolValueChangedEventArgs(rowNum, _column, saveValue);
				BoolValueChanged(this, e);
			}
		}

		lockValue = true;
		beingEdited = true;
		saveRow = rowNum;

		base.Edit(source, rowNum,  bounds, readOnly, instantText, cellIsVisible);
	}
}

[boB Taylor MCSD, MCDBA, MCSE]

This is what I wound up with. I think it is simpler approach.

public class SingleClickDataGrid : DataGrid
{
public SingleClickDataGrid()
{
this.MouseDown += new System.Windows.Forms.MouseEventHandler(this.GridMouseDown);
}
public void GridMouseDown(object sender, MouseEventArgs e)
{
System.Windows.Forms.DataGrid.HitTestInfo hi;

// let's see where we clicked...
hi = HitTest(e.X,e.Y);

// If the user did not click on a cell, we don't care...
// we'll just pass on to the base class
if(hi.Type == System.Windows.Forms.DataGrid.HitTestType.Cell)
{

// Get the TableStyles collection
DataGridTableStyle dgt = TableStyles[0];

// Get the ColumnStyle for the selected column
DataGridColumnStyle myCol = dgt.GridColumnStyles[hi.Column];

// Is this a check box column?
// if not, we'll let the base class handle it
if(myCol.GetType() == typeof(DataGridBoolColumn))
{
// First part of the magic... select the row, so that the edit can happen
Select(hi.Row);
// Call the grid table style to start and end the edit
dgt.BeginEdit(myCol,hi.Row);
dgt.EndEdit(myCol,hi.Row,true);
}
}
}
}