I am trying to create a dialog where the user selects a node in a TreeView so that he can save some data to that node.
The tree itself is created in a separate control (that is used for browsing/opening content of nodes) and my idea is that i should use that tree in my save control.
My constructor looks like this:
public FrmSaveToRepository(TreeView tree)
{
InitializeComponent();
this.treeView = tree;
}
but when the form holding the control pops up the treeView is empty. Did i miss a step?
I open my form with this code:
var frm = new FrmSaveToRepository(tree);
frm.Show();
Right so the correct way to add the old nodes to the new tree is:
public FrmSaveToRepository(TreeView tree)
{
InitializeComponent();
foreach (TreeNode node in tree.Nodes)
{
this.treeView1.Nodes.Add(node.Clone() as TreeNode);
}
}
but that still means that all the events and handlers have to be implemented separately in the new tree.
Related
Here i am trying to show the last selected node after reload of treeview but the selected node is always null. I am able to find the tree node from the treeview node collection but not able to assign it to tree view. Please suggeest:
public void LoadTreeViewData()
{
treeView.Nodes.Clear();// Clear any existing items
treeView.BeginUpdate(); // prevent overhead and flicker
LoadBaseNodes();//Populate all nodes
treeView.EndUpdate();
treeView.Refresh();
treeView.ExpandAll();
if (!string.IsNullOrEmpty(m_oSelectedNode_NAME))
{
TreeNode[] treeNodes = treeView.FlattenTree()
.Cast<TreeNode>()
.Where(r => Convert.ToDecimal(r.Tag) == Convert.ToDecimal(m_oSelectedNode_NAME))
.ToArray();
treeView.SelectedNode = treeNodes[0];
treeView.Focus();
}
}
This problem is happening because i am trying to Update the selected node inside the Tree view after label edit event. I put a timer inside After label edit to resolve the issue and set the Selected node it works for me.
var tnm = new Timer() { Enabled = true, Interval = 30 };
tnm.Tick += delegate {
SetSelectioNode();
tnm.Dispose();
};
At the moment I have a hardcoded treeview in a winform set up with the following code:
private void Form1_Load_1(object sender, EventArgs e)
{
TreeNode _leftCameraNode = new TreeNode("LeftCamera");
TreeNode _rightCameraNode = new TreeNode("RightCamera");
TreeNode[] stereoCameraArray = new TreeNode[] { _leftCameraNode, _rightCameraNode };
TreeNode _screenNode = new TreeNode("Screen");
TreeNode _cameraNode = new TreeNode("Camera", stereoCameraArray);
TreeNode[] headNodeArray = new TreeNode[] { _cameraNode };
TreeNode _headNode = new TreeNode("HeadNode", headNodeArray);
TreeNode[] centreNodeArray = new TreeNode[] { _screenNode, _headNode };
TreeNode _centreNode = new TreeNode("CentreNode", centreNodeArray);
// root node
TreeNode[] inmoRootNodeArray = new TreeNode[] { _centreNode };
TreeNode treeNode = new TreeNode("Main Node", inmoRootNodeArray);
treeView1.Nodes.Add(treeNode);
}
This works fine, however it is very limiting in its functionality. What I really want this to do is be populated from a list of nodes that I've set up and filled out with information that I'm getting from a bunch of text boxes on my form.
For example, I create a new list of screens (child of my node class) like so:
public List<HV_Screen> _screenList = new List<HV_Screen>();
Then I fill out my list with the data entered from my text box like this:
if (_selectedNode > -1)
{
Node n = _nodeList[_nodeList.Count - 1];
n.Name = _screenName;
}
I've been looking around on the net and on stackoverflow but I can't find anything to help me out with dynamically creating my treeview, so I was wondering if anyone would be able to point me in the right direction and help me out in how to do this?
The reason I want to do this is because, say I have 3 different instances of my screen, I want my treeview to show this, Then if I change the name in screen1 to MYSCREEN, I want my treeview to show this. But, should I click screen2, the treeview will still show the default name. Then, when I click back on screen1, its new name MYSCREEN will still be there on display.
I hope that makes sence.
Edit
Following on from a comment here is a screenshot of my current GUI:
The tree structure there has all be hard coded in with the code above. This takes in no information from my class screen class.
Now, my HV_Screen class looks as follows:
private string WIDTH;
private string HEIGHT;
public string Width
{
get { return WIDTH; }
set { WIDTH = value; }
}
public string Height
{
get { return HEIGHT; }
set { HEIGHT = value; }
}
public override List<XmlElement> GenerateXML(XmlDocument _xmlDoc)
{
List<XmlElement> elementList = new List<XmlElement>();
XmlElement _screenName = _xmlDoc.CreateElement("ScreenName");
_screenName.SetAttribute("Name", name.ToString());
_screenName.InnerText = name.ToString();
elementList.Add(_screenName);
XmlElement _screenTag = _xmlDoc.CreateElement("ScreenTag");
_screenTag.SetAttribute("Tag", tag.ToString());
_screenTag.InnerText = tag.ToString();
elementList.Add(_screenTag);
XmlElement _localPosition = _xmlDoc.CreateElement("LocalPosition");
_localPosition.SetAttribute("X", XPOS.ToString());
_localPosition.SetAttribute("Y", YPOS.ToString());
_localPosition.SetAttribute("Z", ZPOS.ToString());
_localPosition.InnerText = WorldPos.ToString();
elementList.Add(_localPosition);
XmlElement _orientation = _xmlDoc.CreateElement("Orientation");
_orientation.SetAttribute("Yaw", YAW.ToString());
_orientation.SetAttribute("Pitch", PITCH.ToString());
_orientation.SetAttribute("Roll", ROLL.ToString());
_orientation.InnerText = Orientation.ToString();
elementList.Add(_orientation);
XmlElement _width = _xmlDoc.CreateElement("Width");
_width.SetAttribute("Width", WIDTH.ToString());
_width.InnerText = WIDTH.ToString();
elementList.Add(_width);
XmlElement _height = _xmlDoc.CreateElement("Height");
_height.SetAttribute("Height", HEIGHT.ToString());
_height.InnerText = HEIGHT.ToString();
elementList.Add(_height);
return elementList;
}
Nothing too major. This simply takes in the information and writes it to an xml file. I plan on doing this for each of my Node children. So, if I was to have a camera class, it would have its own generate XML function and write it out from there. My base class (node) simply has a bunch of getters and setters for things like name, tag etc.
With the way the code is set up at the moment, I can add in new nodes. First I must select the root node I want to branch from, then I fill out the information associated with it. So in that screen shot, if I was to select Main Node and then hit the Add button, Sample Name would now be a child of Main Node. However, if I was to select Sample and Name and change it, nothing would happen.
This way is also hard coded in to only relate to my screen class. In theory, I could simply turn a lot of different text boxes on and off but this would be really bad practise. And I'm pretty sure it will have an impact on my programs performance.
So again, what I want is one Name text box that will be in charge of filling out the name for every object that requires a name. Then, I wish to take the name I entered and have it fill out the treeview. Once I select it, I want my selected node to fill out the textboxes with all of the associated text I put in for it. But, should I change the name of my selected node, it will also change the name in the tree structure.
Again, sorry if that is confusing. I'm pretty beat at the moment.
This question already has answers here:
ASP.NET TreeView and loading data on demand
(2 answers)
Closed 6 years ago.
I have a treeview I'm using to display a directory structure. I am trying to reduce load times by loading sub nodes on node expansion. Is there a way to do this?
Below is the code I'm currently using to populate the treeview:
protected void Page_Load(object sender, EventArgs e) {
BuildTree(Request.QueryString["path"]);
}
private void BuildTree(string dirPath)
{
//get root directory
System.IO.DirectoryInfo rootDir = new System.IO.DirectoryInfo(dirPath);
//create and add the root node to the tree view
TreeNode rootNode = new TreeNode(rootDir.Name, rootDir.FullName);
TreeView1.Nodes.Add(rootNode);
//begin recursively traversing the directory structure
TraverseTree(rootDir, rootNode);
}
private void TraverseTree(System.IO.DirectoryInfo currentDir, TreeNode currentNode)
{
//loop through each sub-directory in the current one
foreach (System.IO.DirectoryInfo dir in currentDir.GetDirectories())
{
//create node and add to the tree view
TreeNode node = new TreeNode(dir.Name, dir.FullName);
currentNode.ChildNodes.Add(node);
//recursively call same method to go down the next level of the tree
TraverseTree(dir, node);
}
foreach (System.IO.FileInfo file in currentDir.GetFiles())
{
TreeNode node = new TreeNode(file.Name, file.FullName);
currentNode.ChildNodes.Add(node);
}
}
For loading the nodes on demand, meaning that the children of a node will be loaded only when the parent node is expanded. Do the following steps:
1 - Set the TreeView.ExpandDepth to 0. This eliminates the expansion of the added TreeNode objects in the TreeView and shows the expansion symbol [+] next to each TreeNode that has the TreeNode.PopulateOnDemand property set to true.
2- Set the TreeNode.PopulateOnDemand to True for each branch TreeNode. When the TreeNode.ChildNodes collection is empty, the expansion symbol [+] will be showed only next to TreeNode objects that has TreeNode.PopulateOnDemand property set to true.
3- Handle the TreeView.TreeNodePopulate event to poulate branch nodes on expansion. This event will be fired when a TreeNode - with the TreeNode.PopulateOnDemand set to true - has been expanded right before the TreeView.TreeNodeExpanded event gets fired.
Source: ASP.NET TreeView and loading data on demand
I have a treeview which represents filesystem, I have a New folder button, It works fine if the selected node has some child nodes, however when selected node does not have any child nodes it is not able to add a editable child node. I am using the following code:
tree.LabelEdit = true;
TreeNode node = new TreeNode("New Folder");
if(tree.SelectedNode.Nodes.Count>0)
tree.SelectedNode.Expand();
tree.SelectedNode.Nodes.Add(node);
if(tree.SelectedNode.Nodes.Count>0)
tree.SelectedNode.Expand();
node.BeginEdit();
Any ideas on whats going wrong?
Just change two lines in your code like that:
public Form1()
{
InitializeComponent();
tree.SelectedNode = tree.Nodes.Add("Hello", "Hello");
}
private void button1_Click(object sender, EventArgs e)
{
tree.LabelEdit = true;
TreeNode node = new TreeNode("New Folder");
tree.SelectedNode.Nodes.Add(node);
tree.SelectedNode.Expand();
node.BeginEdit();
}
Explanation: You cannot expand a node which hasn't child nodes. So you have to add the node before you expand the parent node.
I need to construct a huge treeview from a composite database table with Grouping.
Grouping is, what we see in SQL Server Management Studio Express. After a Database node, some fixed folders are shown (like, Database Diagrams, Tables, Views, Synonyms, Programmability and Security) and children are grouped in those folders.
Up to this point I have used AfterSelect event and handler to achieve this.
But the problem with AfterSelect is, before selecting the node, the viewer is not able to know whether there is any child available. This is because, the expandable plus sign is not visible.
I want to use BeforeExpand. But the problem with BeforeExpand is, it works if the children are already populated. In that case, when I click groups, nothing happens.
How to solve this?
So codes/web-link will be appreciated.
What I usually do is to add a "dummy child node" wherever there may be children that should be loaded in a lazy manner. This will make the parent have the plus sign, and then you can add code to the AfterExpand event where you do the following:
Check if there are are exactly one child, and if that child is the dummy node (you can use the Tag property to identify the dummy node)
If the dummy node is found, launch a search to get the children and add them to the parent node, finish it off by removing the dummy node.
I typically give the dummy node a text like "Loading data. Please wait..." or so, so that the user gets some info on what is going on.
Update
I put together a simple example:
public class TreeViewSample : Form
{
private TreeView _treeView;
public TreeViewSample()
{
this._treeView = new System.Windows.Forms.TreeView();
this._treeView.Location = new System.Drawing.Point(12, 12);
this._treeView.Size = new System.Drawing.Size(200, 400);
this._treeView.AfterExpand +=
new TreeViewEventHandler(TreeView_AfterExpand);
this.ClientSize = new System.Drawing.Size(224, 424);
this.Controls.Add(this._treeView);
this.Text = "TreeView Lazy Load Sample";
InitializeTreeView();
}
void TreeView_AfterExpand(object sender, TreeViewEventArgs e)
{
if (e.Node.Nodes.Count == 1 && e.Node.Nodes[0].Tag == "dummy")
{
// this node has not yet been populated, launch a thread
// to get the data
ThreadPool.QueueUserWorkItem(state =>
{
IEnumerable<SomeClass> childItems = GetData();
// load the data into the tree view (on the UI thread)
_treeView.BeginInvoke((Action)delegate
{
PopulateChildren(e.Node, childItems);
});
});
}
}
private void PopulateChildren(TreeNode parent, IEnumerable<SomeClass> childItems)
{
TreeNode child;
TreeNode dummy;
TreeNode originalDummyItem = parent.Nodes[0];
foreach (var item in childItems)
{
child = new TreeNode(item.Text);
dummy = new TreeNode("Loading. Please wait...");
dummy.Tag = "dummy";
child.Nodes.Add(dummy);
parent.Nodes.Add(child);
}
originalDummyItem.Remove();
}
private IEnumerable<SomeClass> GetData()
{
// simulate that this takes some time
Thread.Sleep(500);
return new List<SomeClass>
{
new SomeClass{Text = "One"},
new SomeClass{Text = "Two"},
new SomeClass{Text = "Three"}
};
}
private void InitializeTreeView()
{
TreeNode rootNode = new TreeNode("Root");
TreeNode dummyNode = new TreeNode("Loading. Please wait...");
dummyNode.Tag = "dummy";
rootNode.Nodes.Add(dummyNode);
_treeView.Nodes.Add(rootNode);
}
}
public class SomeClass
{
public string Text { get; set; }
}
It's standard behaviour for a tree to show a "+" in front of every folder/group, and the plus dissapears when clicked on if it's found to have no children, this saves the expensive "do you have children" check.
Alternatively you can provide this information if you have a cheap way of determining if a node has children. This question provides more information.