The WPF DataGrid is a very flexible tool, however in its current state certain simple tasks can prove to be rather tricky. A fairly common task when working with DataGrid is detecting which row, or cell a user has clicked on, or whether they clicked a column header. You might expect this information to be readily available in the form of events, after all, the Windows Forms DataGridView has CellClicked and ColumnHeaderMouseClick events (among many others). However, sadly this is not the case. In order to implement this behaviour you have to understand the visual tree of the DataGrid and how it can be navigated.
Let’s say for example you wanted to find the DataGrid item (cell, row, header) that was clicked when the right mouse button is released. Firstly, we add an event handler for the mouse click in our code-behind:
XAML:
<dg:DataGrid Name="DataGrid" MouseRightButtonUp="DataGrid_MouseRightButtonUp"/>
C#:
private void DataGrid_MouseRightButtonUp(object sender, MouseButtonEventArgs e) { }
The above event is a ‘bubbling’ event, which means that it it started on the element that was originally clicked (for example a TextBlock which renders the cell’s value within a DataGridCell), then bubbled up the logical tree until it reaches our event handler in the Window. The e.OriginalSource property gives us access to the element that initiated this event.
The problem is that while we have access to the lement which was clicked on, this element is part of the control or data template of the element that we are really interested, the cell or header. The WPF rich-content model means that our cells could contain all sorts of visual element, therefore we have no way of guessing exactly what e.OriginalSource will be. However, the one thing of which we can be certain is that this element is a child of the element which we are interested in.
If you place a bearkpoint within yoru event handler, you can then use the excellent Mole debug visualiser to locate the clicked element within the visual tree as illustrated below:
As you can see, the visual tree is a complex beast! I have highlighted the items of interest:
- The TextBlock, which is the element I clicked on, which is e.OriginalSource parameter.
- The DataGridCell, the cell which was clicked on.
- The DataGridRow which the cell belongs to.
- And finally, the DataGrid.
Therefore, in order to locate the cell and row that was clicked on we must navigate up the Visual Tree, searching by type:
private void DataGrid_MouseRightButtonUp(object sender, MouseButtonEventArgs e) { DependencyObject dep = (DependencyObject)e.OriginalSource; // iteratively traverse the visual tree while ((dep != null) && !(dep is DataGridCell) && !(dep is DataGridColumnHeader)) { dep = VisualTreeHelper.GetParent(dep); } if (dep == null) return; if (dep is DataGridColumnHeader) { DataGridColumnHeader columnHeader = dep as DataGridColumnHeader; // do something } if (dep is DataGridCell) { DataGridCell cell = dep as DataGridCell; // do something } }
Fantastic, we have now have our header and cell. All that’s left to do is extract the cell’s row and column indices, and cell value. Wait a minute … where are the cell.RowIndex and cell.ColumnIndex properties? It looks like there’s more work to be done.
Once we have navigated up the tree to the DataGridCell, we can continue our journey upwards to obtain the DataGridRow:
if (dep is DataGridCell) { DataGridCell cell = dep as DataGridCell; // navigate further up the tree while ((dep != null) && !(dep is DataGridRow)) { dep = VisualTreeHelper.GetParent(dep); } DataGridRow row = dep as DataGridRow; }
Does the DataGridRow have a RowIndex property? I think you can guess the answer to that question.
The DataGrid is an ItemsControl – WPF users are probably most familiar with the ListView which is also an ItemsControl whcih has a number of similarities with the DataGrid. In the ItemsControl terminology, the DataGridRow is an ItemContainer and the DataGrid has an ItemContainerGenerator associated with it for generating the rows. I don’t want to go into the details of how ItemContainers work, Dr. WPF has a good series on the ItemsControl for those who are interested. The following code can be used to determine the index of a row:
private int FindRowIndex(DataGridRow row) { DataGrid dataGrid = ItemsControl.ItemsControlFromItemContainer(row) as DataGrid; int index = dataGrid.ItemContainerGenerator. IndexFromContainer(row); return index; }
Now that we have the row index, the column index is thankfully a little easier to locate, cell.Column.DisplayIndex does the trick. The final piece of information which we might like is the cell value. Is there a cell.Value properly? don’t make me laugh!
The following method determines the property binding for the cells column, then extracts the value from the data items associated with the row:
private object ExtractBoundValue(DataGridRow row, DataGridCell cell) { // find the column that this cell belongs to DataGridBoundColumn col = cell.Column as DataGridBoundColumn; // find the property that this column is bound to Binding binding = col.Binding as Binding; string boundPropertyName = binding.Path.Path; // find the object that is related to this row object data = row.Item; // extract the property value PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(data); PropertyDescriptor property = properties[boundPropertyName]; object value = property.GetValue(data); return value; }
Putting it all together, this blog post has a small smaple application which displays the header index and value, or cell’s row/column indices and value in response to a right mouse click:
The sample project can be download, wpfdatagridmouseclicks, changing the file extension from .doc to .zip.
Regards, Colin E.
@grix,
Try posting your question in the Silverlight forums:
http://forums.silverlight.net/forums/
Colin E.
Hi,
Need to detect editing a cell and bind to a command in a mvvm pattern.
Can be done?
Thanks for your time
Thanks George – a useful addition.
I was trying to find the row number of the selected DataGrid item. This article was the closest thing I could find by searching. The problem was I use a context menu (not a mouse click) to initiate the routine that needs to know the row number. After a day of experimenting, I finally came up with this code that seems to be the simplest method to determine the row number.
DataRowView prop = (DataRowView)myDataGrid.SelectedValue;
DataRow rowData =(DataRow)prop.Row;
int selectedRow = _myDataTable.Rows.IndexOf(rowData);
myDataGrid is the grid name. _myDataTable is the name of the datatable to fills the grid.
Hope this helps someone else.
That’s a simple one … WPF != WinForms
Why can’t you do it similar to the .Net way?
see:
http://blog.bitlinkit.com/post/Right-Click-and-Auto-Row-Select-with-a-
ContextMenuStrip.aspx
extract:
foreach (DataGridViewRow s in dataGridView1.SelectedRows)
s.Selected = false;
DataGridView.HitTestInfo hit = dataGridView1.HitTest(e.X, e.Y);
dataGridView1.Rows[hit.RowIndex].Selected = true;
dataGridView1.CurrentCell= dataGridView1.Rows[hit.RowIndex].Cells[hit.ColumnIndex];
contextMenuStrip1.Show(dataGridView1, new Point(e.X,e.Y) );
Sorry Sukumar, I do not have time to answer queries such as this. However, if you post to the WPF Toolkit forums I am sure someone will help you out:
http://wpf.codeplex.com/Thread/List.aspx
Colin E.
I am using your code for getting row value from datagrid, but I would like the same thing happening with mouse doubleclick event, not with mouse right click event.
the dep value after execution of this statement “DependencyObject dep = (DependencyObject)e.OriginalSource;” shows ’system.windows.controls.textblock’ for both events that when I doubleclick the row and when I right click the row
But after execution of following statement:
dep = VisualTreeHelper.GetParent(dep);
dep value is ‘null for mouse doubleclick event and
dep value is presenter(it’s parent element) for mouse right click event.
Can you help me? Thanks.
Sorry Devi, I do not have time to answer queries such as this. However, if you post to teh WPF Toolkit forums I am sure someone will help you out:
http://wpf.codeplex.com/Thread/List.aspx
Colin E.
hi colin,
I want to add Image as a column to the DataGrid dynamically.I coded like this,But its not working am unable to see the Image in the datagrid column.Can u plz help me out..
string backgroundImagePath=”Resources\Hand.jpg”;
BitmapImage bitmapImage = new BitmapImage();
Uri objUri = new Uri(backgroundImagePath);
bitmapImage.SetValue(BitmapImage.UriSourceProperty, objUri);
FrameworkElementFactory factory1 = new FrameworkElementFactory(typeof(Image));
factory1.SetValue(Image.SourceProperty, bitmapImage);
DataTemplate cellTemplate1 = new DataTemplate();
cellTemplate1.VisualTree = factory1;
DataGridTemplateColumn col1 = new DataGridTemplateColumn();
col1.Header = “MyHeader”;
col1.CellTemplate = cellTemplate1;
dgDynamicColumns.Columns.Add(col1);
Thanks In advance,
Devi
Hi Sachin,
Sorry – not sure I can help. I would suggest trying the WPF Toolkit forums:
http://wpf.codeplex.com/Thread/List.aspx
Colin E.
Hi Colin,
I dont get default context menu (copy, cut, paste) to show up on datagrid row mouse right click. Context menu shows up when grid cell is double click which puts cell in edit mode. Any help would be greatly appreciated.
Thanks,
sachin
hi colin,
i want to change Border style to Datagrid with corner radius and all how can i do that.
Thanks in advance….
Saru
Hi Saru,
I would try posting to the codeplex WPF Toolkit forums with that question:
http://www.codeplex.com/wpf/Thread/List.aspx
Regards,
Colin E.
hi,
colin with your source code support i learned and implemented a lot in wpf datagrid.
Now my new problem is in my datagrid i am binding data dynamically i want to set RowBackground of each row with different color from code like for example in my datagrid will look like this
—————————————————————–
Category | Name | Year | Enter Value|
————————————-
Cat1 | | | |
————————————–
| S1 |2001 | |
————————————–
| s2 |2002 | |
————————————–
Cat2 | | | |
————————————–
i want to highlight Row with only Category and Want to give different Background color for EnterValue column how can we approach this
Hi Saru,
I think you will probably get the best feedback if you post your questions to the WPF DataGrid forums:
http://www.codeplex.com/wpf/Thread/List.aspx
Regards, Colin E.
Hi ur style property for datagrid worked fine for old version of Datagrid but now i downloaded newer version and there is no “DataGridColumnHeader” property. SO how to Allign Header text in center in new version datagrid.
And also one more question is for my requirement i want to show sun columns in a column like for example i have a column called “Share Of Market” in this column we have to show 2 sub columns SME and LME like think the below as column
—————–
Share Of Market |
—————-
SME | LME |
————-
| |
———————
Hi Kelvin,
I have not tried this before – sorry. However, it has been discussed in the WPF Toolkit forums a few times:
http://wpf.codeplex.com/Thread/List.aspx?SearchText=excel
Regards, Colin E.
Great article.
Is there any way to loop through all of the cells in a datagrid? I’m trying to make an Excel XML export routine for the WPF Toolkit datagrid similar to the Xceed Excel export routine.
@Jing,
Thanks for pointing those two methods out. Whether they are new additions, or I just missed them I am not sure!
I had a quick look at the implementation, and internally they use the same implementation i present here, walking the visual tree, and using
ItemsControl.ItemsControlFromItemContainer.Thanks, Colin E.
And to get the DataGridRow of a DataGridCell
maybe we can use
DataGridRow row = DataGridRow.GetRowContainingElement(cell);
Regards, Jing
Hi, I think in the current version of the toolkit, we can get row index by calling the row.GetIndex().
Regards, Jing
@Saru,
I would suggest you take your question to the WPF Toolkit forums:
http://www.codeplex.com/wpf/Thread/List.aspx
There are many people there who could help out.
Regards, Colin E.
hi,thanks for ur reply but its not working for me i dont have property like u gave in style x:Key so i modified like this but its not wrking
please correct me
Thank you,
sarada
Try the following style:
<Style x:Key="HeaderStyle" TargetType="{x:Type dg:DataGridColumnHeader}"> <Setter Property="HorizontalContentAlignment" Value="Center"/> </Style> <dg:DataGrid ColumnHeaderStyle="{StaticResource HeaderStyle}"/>Regards, Colin E.
hi,
ur post is very useful. i have one question i’m using the WPF Datagrid in my application by default the column header text is alligned left but i want to show the column header text in center.How to do this any ideas plz help me out its urgent.
Thanks,
Saru.
Tom, Sorry – I haven’t played much with the combo box column. I would try directing this comment to the WPF toolkit forums:
http://www.codeplex.com/wpf/Thread/List.aspx
Regards, Colin E.
Tullio,
To extract values for a single column, I presume this value is bound to a specific property of your dataobject? In ExtractBoundValue notice the following lines:
// find the object that is related to this row
object data = row.Item;
Once you have the bound object, you can do what you like. You can cast it to the correct type and manipulate it directly:
Person person = data as Person;
string voiced = person.VoicedBy;
i.e. this will always extract the VoicedByProperty of the item bound to the row that was clicked.
Hope this makes sense!
Regards, Colin E.
Hi Colin,
I am studing your example … great but a bit difficult for me (I am a beginner).
I need a method to obtain data just for one particular column, if I select the row 3 I want to see the data in cell [3, 3], in the same way, if I select the row 4 I want to see the data in cell [4, 3].
Exist a easier way to obtain my data? I have to modify your example?
Anyway, great example
Tullio
Colin,
Your ExtractBoundValue method works for the DataGridTextColumn which inherits from DataGridBoundColumn which implements the Binding property. But the DataGridComboBoxColumn inherits from DataGridColumn which does not have the Binding property. Instead the DataGridComboBoxColumn implements SelectedValueBinding, SelectedItemBinding, and TextBinding. Yikes.
Short of hard codeing as switch statement based on the type of column (which will only get harder with the DataGridTemplateColumn), do you know a way to find the bound property name on these other columns?
Thanks,
Tom
Hey Colin,
Really great stuff! Keep it up.
Colin,
another one that falls into this context: how can I catch the event that is fired when a checkbox in a checkbox column is clicked (with left button/or by pressing space or other accelerators) ?
Regards
Klaus
yepp, thanks, thats what I meant
Regards
Klaus
Hi Klaus,
Have you tried the sample application associated with this post? When you right click on a column header it should output the column index and the property which the column is bound to. e.g.
“Header clicked [1] = Forename”
Is that what you wanted?
[ ---- edit ----]
Hang on … did you mean the row header?
If so, simply navigate up the visual tree to the row in the same way that you do for the cell. Try the following code snippet in the sample application:
DependencyObject dep = (DependencyObject)e.OriginalSource;
while ((dep != null) && !(dep is DataGridCell) &&
!(dep is DataGridColumnHeader) && !(dep is DataGridRowHeader))
{
dep = VisualTreeHelper.GetParent(dep);
}
if (dep == null)
return;
if (dep is DataGridRowHeader)
{
DataGridRowHeader rowHeader = dep as DataGridRowHeader;
// navigate further up the tree
while ((dep != null) && !(dep is DataGridRow))
{
dep = VisualTreeHelper.GetParent(dep);
}
if (dep == null)
return;
DataGridRow row = dep as DataGridRow;
int rowIndex = FindRowIndex(row);
ClickedItemDisplay.Text = string.Format(
“Row header clicked [{0}]“,
rowIndex);
}
Colin E.
Hi Colin
could you help me out to get the same info for right clicking on a column header?
Thanks
Klaus
Very use ful article . I was on research in this for past few days . To get the controls inside datatemplate in a grid cell, i think we can use this way
ContentPresenter objPresent = Mygrid.Columns[ColumnNumber].GetCellContent(e.Row) as ContentPresenter;
DependencyObject objdep = objPresent.ContentTemplate.LoadContent();
from this dependancy object , we can access the control