KB/books/PresentDataDataGridView/Noyes_c06_img_2.jpg' alt='C# Datagrid Checkbox Column' title='C# Datagrid Checkbox Column' />Customizing the Data. Grid. View to support expandingcollapsing ala Tree. Grid. View Mark Rideouts Blog. One of the first things that I wanted to customize with the Data. Grid. View is to make it support hierarchical data. Datagridview Checkbox Value' title='Datagridview Checkbox Value' />DataGridView with hierarchical data binding. In the normal datagridview this field is shown as checkbox. The TreeGridView by Mark Rideout heres the link is a great control. It allows us to display related data in a hierarchical form a tree, but I needed it to be. If you read my first blog post youll find out that Im not a developer anymore. Even though Im not a developer I still like to take features and customize them to do something really cool. As far as the Data. Grid. View goes, customizing it to support hierarchical data is a much larger task since the structure of the DGV doesnt lend itself to having different column sets, so, I decided Id settled for a tree like structure. Think of a Tree. View combined with a List. View and that is basically what I wanted to go with. NOTE This code is not supported by Microsoft and is provided as is. This code it not meant to show best practices, but just showing a concept. NOTE This control is written to require Visual Styles to be enabled on your computer. Youll need to modify it if you want to run the Tree. Grid. View without visual styles. Some people have been able to modify the code to run without Visual Styles. Datagridview Column Data TypeSee this post for details. Original Code http www. Here is a picture Anyway. The basic part of creating a Data. Grid. View that can expand and collapse is to dynamically add and remove rows. That was the easy part. Datagridview Column ValuetypeTo make this really usable and extendable, I decided to add a lot code and make this easier to use. Here are some details Design. I wanted to ensure that the design of the Tree. Grid. View supported normal Tree. View type properties and features, so creating necessary classes to create the tree view experience wa necessary see object model for more details. Custom Painting Painting an image in a cell is easy, but ensuring that the text from the Data. Grid. View. Text. Box. Cell didnt overlap the image took a bit of work. Differences Between the Windows Forms DataGridView. Multiple column types The DataGridView control. DataGridView control is the hierarchical display. The attached project shows how to display data which is both tabular and hierarchical in. A checkbox. Its. The rowstate for the selected row in a child. Using the Padding feature of the Data. Grid. View. Cell. Style, I add padding to the left side of the cell to account for the text and the indentation. This padding affects the painting and behavior of the text box cell, so editing a text cell correctly positions the editing control. SitingUnsiting a node Since I dont want to set padding and styling except when a node is actually displayed. When the node is displayed or in the grid, it is sited. When the node is sited I set all the necessary properties. Unbound Since expanding and collapsing is based upon dynamically adding and removing rows from the grid, I decided that unbound mode would be the best way to go with this. Ive hidden the databinding properties and the virtual mode property since this doesnt support those features. Edit Mode One thing that I had to deal with is that double clicking a cell enters edit mode. This double click occurs regardless of the padding, so double click on the symbol causes the control to enter edit mode. Edit also enters if you single click on a cell that already has focus. So, to deal with this I turn edit mode to be enabled only through programmatic means. I have code to handle the F2 key to enter edit mode. There are other ways to solve this, but I went with the F2 approach. Object model structure. Tree. Grid. Node Just like a tree view, I wanted to have the concept of a node. I made the nodes class derive from a Data. Grid. View. Row since a node in the list is the same as a row, just with a bit more info. Here are some properties Nodes Again, like the treeview, a node has children, so there is a Nodes property that returns child nodes. One of the challenges in coding this is to know when a node is actually a row or when it is just a node. A node is a row when it is in the grid, otherwise it is just a node. Is. Sited A node is sited when it is contained in the grid as a row. The Sited property is true in this case. There are a set of protected virtual methods on the Tree. Grid. View class Site. Node and Un. Site. Node. Image. Index Image index for the nodes image. Only used when an Image. List is associated with the Tree. Grid. View. Image Image associated with the node. Sets or gets the image. When an Image. List is associated with the Tree. Grid. View and an Image. Index is set then this returns an image from the Image. List. You can set the Image property to an image if you arent using an Image. List. Cells Returns the cells for the given node. This wasnt easy to do since accessing the cells for a node or row when the node isnt sited. Using the Data. Grid. Views Create. Cells method I can get the correct cells collection when the node isnt in the grid. Tree. Grid. CellColumn This is a special Data. Grid. View cell that derives from the Data. Grid. View. Text. Box. Cell. The main thing that this custom cell class does is to customize the cell drawing to make it look like a tree node. That means that it draws the nodes image and the icons and the tree lines. The custom cell also is where a node detects when you click the mouse to expand or collapse a node. NOTE A lot more work can be done to correctly detect that the mouse is directly over the image. Right now Im not doing that. Tree. Grid. View This class derives from the Data. Grid. View control. Many things are done in this class. Nodes are sitedunsited in the grid as actual rows. Somce Data. Grid. One Piece Episode 377 Sub Indo. View Properties are hidden since they do not apply. Here are some properties Virtual. Nodes One of the common things done with a normal Tree. View is to dynamically add child nodes when the user is expanding the parent. With the normal Tree. View usres add temp child nodes to get the sign and support expanding, then remove the temp node later. With the Virtual. Nodes property, the Tree. Grid. View always displays a sign next to a node, even if the node doesnt have any children. Then, by handling the Expanding event you can dynamically add child nodes. Image. List Image. List associated with the Tree. Anna Polina Nurse Dorcel. Grid. View. Nodes Identifies the root nodes. Show. Lines Determines if the Tree. Grid. View shows lines between nodes. Current. Node Identifies the node that has focus. Here are some events Expanding Again, like the treeview, this event occurs before a node is starting to expand. You can add nodes in this event to fill in more details of a child node collection. When the Virtual. Nodes property is true, the Tree. Grid. View will display the node with a sign next to it even when it doesnt have any children. Handling the Expanding event is where you would dynamically add new child nodes. Expanded After a node is expanded. Collapsing Before a node is being collapsed. Collapsed After a node has been collapsed. Ive included a simple test app that creates a news group reader looking list that supports expanding and collapsing. Let me know what you think and how youve used this in your project mark.