DataGridVewTextBoxCell with Span Behaviour

Introduction

The standard System.Windows.Forms.DataGridView cells do not support merging the normal way. At some forums, developers advise the use of the CellPainting event of DataGridView. But this solution is not good if you need to realize complicated mergings. DataGridViewTextBoxCellEx supports spanning without any additional code.

Using the Code

To use DataGridViewTextBoxCellEx in a project, include the DataGridViewTextBoxCellEx.cs file, and then you can add DataGridViewTextBoxColumnEx in the columns editor of the DataGridView control.

Merging of cells is performed by setting the ColumnSpan and RowSpan properties of the left top DataGridViewTextBoxCellEx cell of the target region. For successful merging, all cells of the region must be of the DataGridViewTextBoxCellEx type.

var cell = (DataGridViewTextBoxCellEx)dataGridView1[0, 0];
cell.ColumnSpan = 3;
cell.RowSpan = 2;

As a result, the dataGridView1[0, 0] cell will occupy the region from (0, 0) to (2, 1) (see screenshot at the top). The merged cell will look as the top left cell of the region. And if you wish to address a merged cell, you need to address the top left cell of the merged region. The merged region will look and behave as a normal System.Windows.Forms.DataGridViewTextBoxCell. You can edit it the standard way (pressing F2, clicking or typing text).

DataGridViewTextBoxCellEx also has a property OwnerCell. For unmerged cells and for the left top cells of the merged regions, it is null. For other cells of the merged region, the property points to the left top cell.

History

11^th March, 2009: Initial post
9^th March, 2010: Article updated
21^st December, 2010: Demo and source files updated

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Sergey Semyonov

Software Developer
EKRA

Russian Federation

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Looks like what I want to do

Lee Belcher

15:17 22 Jan '12

Done a great deal of looking online for this functionality. Can this be used in Visual Basic 2010? I am pretty new to the .net world and I am not sure how to implement this in vb
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Re: Looks like what I want to do

Sergey Semyonov

21:10 22 Jan '12

Thank you. Yes, it can be used in VB. Just compile the sources (or take bin) and add the result assembly to references in your project.
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doublebuffering

xboxproject

2:16 19 Apr '11

Hello Sergey, i really like this project! I try to speed up my DataGridViews by enabling Double-Buffering, but sadly the DataGridViewTextBoxCellEx doesn't work with this - spanned cells don't paint correctly. I got thus far: using DataGridView.CreateGraphics() in Paint(...) should't be used, but still something is missing... Any idea?
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Re: doublebuffering

Sergey Semyonov

1:32 25 Apr '11

Hello. Whould you show your code, which doesn't work correctly?
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Re: doublebuffering

xboxproject

2:08 26 Apr '11

well, essentially i used the sample code from the zip

in DemoForm.cs i added:
SetDoubleBuffered(dataGridView1);
to the constructor

code for SetDoubleBuffered():

public static void SetDoubleBuffered(Control control)
{
    // set instance non-public property with name "DoubleBuffered" to true
    typeof(Control).InvokeMember("DoubleBuffered",
        BindingFlags.SetProperty | BindingFlags.Instance | BindingFlags.NonPublic,
        null, control, new object[] { true }
    );
}

(this has the same effect as deriving DataGridViewEx from DataGridView and setting this.Doublebuffered = true; in its contructor)

-> Effect: the spanned cells are incorrectly drawn, selection highlight is broken (use keyboard navigation for example)

i have a slightly adopted version of the sources, where i took some effort to overcome this, see
http://www.filedropper.com/spanneddatagridview[^]
(mainly changed some coding-style like braces)

best regards

Re: doublebuffering

Sergey Semyonov

5:30 27 Apr '11

Yes, you are right. DataGridView.CreateGraphics() in Paint() cause the problem. We should use buffer graphics, otherwise our painting will be corrupted, when buffer is applied. But using an instant graphics isn't a solution: we cant paint an expanded area.
I tried to use origin graphics and invalidate child cells in Paint(), this works, but hangs the app: Paint() is called very often. It's not good.
Now, I have not any good idea. I'm sorry.

last question for this fabulous control :-)

gertdebusser

0:53 16 Dec '10

I have some little-big problem with a spannedcolumn Spanned over 4 cells, with - datagridview autosizerowmode = allcells - column.DefaultCellStyle.WrapMode = true when the text (take a page of text for example) is inside the cell, it adds empty lines at the bottom for a certain amount. if you don't use spaces it does not add the lines. Any idea? or do you need more code?
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Re: last question for this fabulous control :-)

Sergey Semyonov

4:18 16 Dec '10

Hi.
Yes, you're right, there is a problem. Here a code fixing the problem (not tested completely).

        
public class DataGridViewTextBoxCellEx: DataGridViewTextBoxCell, ISpannedCell
{
    ......
        protected override Size GetPreferredSize(Graphics graphics, DataGridViewCellStyle cellStyle, int rowIndex, Size constraintSize)
        {
            var size = base.GetPreferredSize(graphics, cellStyle, rowIndex, constraintSize);
            if (OwnerCell != null) return size;
            var grid = DataGridView;
            var height = size.Height - Enumerable.Range(RowIndex + 1, RowSpan - 1)
                                           .Select(index => grid.Rows[index].Height)
                                           .Sum();
            return new Size(size.Width, height);
        }
    ......
}

Place the method into DataGridViewTextBoxCellEx class (or other).
Later I publish this changes.

Re: last question for this fabulous control :-)

Sergey Semyonov

3:08 21 Dec '10

I'm sorry for misunderstanding your question in the previous reply. This problem is a problem/feature of `DataGridViewTextBoxCell` (you may test it) which I use, so I cant fix it in the near future. I hope, I've answered to the question correctly now.
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double question

gertdebusser

0:31 9 Nov '10

Question 1 :

When you use the CellPainting event of the datagridview... to change the cell color depending on a value, this occurs correctly EXCEPT for the spanned cells... any idea?

Question 2 :

How to bind the grid to a datasource so that every cell is of type datagridtextboxcolumnEX? after a standard bind , these are regular datacolumns....?

Kindly regards
Gert De Busser
Belgium .

example Question 1 :

Private Sub grdResult_CellPainting(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellPaintingEventArgs) Handles grdResult.CellPainting
Try
If e.RowIndex >= 0 Then

If e.ColumnIndex = ResultaatKolom Then
If grdResult.Rows(e.RowIndex).Cells(ResultaatKolom).ReadOnly = False Then
e.CellStyle.BackColor = Color.Cornsilk
e.CellStyle.ForeColor = Color.Black

Else
e.CellStyle.BackColor = Color.White
e.CellStyle.ForeColor = Color.Black
End If
Else
e.CellStyle.BackColor = Color.White
e.CellStyle.ForeColor = Color.Black
End If
End If
Catch ex As Exception
MsgBox(ex.InnerException.ToString & ex.Message.ToString)
End Try

End Sub
Private Sub SetReadOnly()
Dim row As DataGridViewRow
For Each row In grdResult.Rows
Dim c As SpannedDataGridView.DataGridViewTextBoxCellEx
For Each c In row.Cells
If c.ColumnIndex = ResultaatKolom Then
If c.Value.ToString.Contains("0") Then
If AlleVeldenInvullen = True Then
c.ReadOnly = False

Else
c.ReadOnly = True
End If
DirectCast(c, SpannedDataGridView.DataGridViewTextBoxCellEx).ColumnSpan = 2
Else
c.ReadOnly = False
DirectCast(c, SpannedDataGridView.DataGridViewTextBoxCellEx).ColumnSpan = 1
End If

Else
c.ReadOnly = True
DirectCast(c, SpannedDataGridView.DataGridViewTextBoxCellEx).ColumnSpan = 1
End If
Next
grdResult.InvalidateRow(row.Index)
Next

grdResult.Refresh()

End Sub

Re: double question

Sergey Semyonov

2:18 9 Nov '10

Hi. A for Q1: Use `DataGridVeiw.CellFormatting` event to set colors. A for Q2: Set `DataGridVeiw.AutoGenerateColumns = false` before applying data source.
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Re: double question

gertdebusser

6:19 9 Nov '10

works perfect. Thx! cellformatting <> cellpainting ... sometimes strange.
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Re: double question

Sergey Semyonov

21:26 11 Nov '10

It's practice from documentation.
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Bug when frozen cells

CLOPEZ

18:52 8 Nov '10

Hi, first of all great work. I was checking your demo and when I set the first row to frozen it began to draw the cell overlaped, it seems that it looses the correct position of the cells. Regards
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Re: Bug when frozen cells

Sergey Semyonov

21:26 8 Nov '10

Hi. Thank you very much! Yes, you are right, it take place. But do you propose to froze whole spanned row when a part is frozen?
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Re: Bug when frozen cells

CLOPEZ

5:37 9 Nov '10

As a matter of fact yes, I believe that's probably one reason of the bug, however I believe it has something to do in the way the boundaries are calculated. Well it is not a must to have frozen cells in my application, and definitely having merging cells is need it. Eather way I will try to see how this can be fix and if I had the solution I will post it here. Thanks
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Re: Bug when frozen cells

Sergey Semyonov

21:27 11 Nov '10

It would be wonderful. Thanks.
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Bug with RTL ...

A7mad_

14:08 13 Jul '10

when i use right to left alignment, it becomes crazy DataGridView.. so how can i solve this ???
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Re: Bug with RTL ...

Sergey Semyonov

0:13 14 Jul '10

Thanks. I've fixed it and new release will be available soon. I'll tell you when it will.
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Re: Bug with RTL ...

Sergey Semyonov

22:29 15 Jul '10

New files are available now.
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First Row/Column Problem

Member 3038216

4:27 9 Mar '10

Great job! Thank you! I've found one bug though. I use DataGridView without row and column header. In this case, if spanned cells are in the first row (ColumnSpan) or first column (RowSpan), they don't paint properly. Any ideas? Gennadiy
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Re: First Row/Column Problem

Sergey Semyonov

7:03 10 Mar '10

Hi! Thanks for the bug report. I've found out that cells of first row(column) of `DataGridView` without header row(column) have different height(width). So, they did not paint correctly: bottom(right) parts remained not painted. I've fixed it, and a new version is available now.
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Re: First Row/Column Problem

Gennadiy, Erlangen

2:34 11 Mar '10

Thank you for quick reply. But your solution didn't work for me well. In my DataGridView data grid border width is 1pt, in your demo project border width is 2pt.

I've replaced your code

if (singleVerticalBorderAdded)
    clipBounds.Width++;
if (singleHorizontalBorderAdded)
    clipBounds.Height++;

with

            
if (singleVerticalBorderAdded)
{
    clipBounds.Width += 2;
    clipBounds.X--;
}
if (singleHorizontalBorderAdded)
{
    clipBounds.Height += 2;
    clipBounds.Y--;
}

and

if (singleVerticalBorderAdded)
    spannedCellBounds.Width++;
if (singleHorizontalBorderAdded)
    spannedCellBounds.Height++;

with

if (singleVerticalBorderAdded)
{
    spannedCellBounds.Width ++;
    spannedCellBounds.X--;
}
if (singleHorizontalBorderAdded)
{
    spannedCellBounds.Height ++;
    spannedCellBounds.Y--;
}

it works just fine.

Re: First Row/Column Problem

Sergey Semyonov

10:24 11 Mar '10

Very interesting... But I can't detect the border you mean (what property, where did you get 1pt and 2pt), and I can't model the bug scenario. Would you please explain it, or/and bring some code.
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