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.
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();
};
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.
I have a TreeView and an associated ImageList. What are the steps to add images to the Parent and child nodes ?
All the nodes are being added from the code. Nothing is done from the Design.
public void fill_tree()
{
host_listbox_new.Items.Clear();
foreach (KeyValuePair<string, host_config> hlitem in host_list)
{
string sitem = hlitem.Key;
if (host_list[sitem].sessionOptions == null)
host_list[sitem].sessionOptions = new SessionOptions();
host_list[sitem].sessionOptions.Protocol = Protocol.Sftp;
host_list[sitem].sessionOptions.HostName = host_list[sitem].ip;
host_list[sitem].sessionOptions.UserName = host_list[sitem].username;
host_list[sitem].sessionOptions.Password = host_list[sitem].password;
host_list[sitem].sessionOptions.PortNumber = Convert.ToInt32(host_list[sitem].port);
//host_list[sitem].sessionOptions.SshHostKeyFingerprint = host_list[sitem].rsa;
if (treeView1.SelectedNode != null)
{
treeView1.SelectedNode.Nodes.Add(hlitem.Key.ToString());
}
else
{
treeView1.Nodes[0].Nodes.Add(hlitem.Key.ToString());
}
}
}
private void Parent_Load(object sender, EventArgs e)
{
read_process_config();
read_host_config();
host_listbox.Items.Clear();
treeView1.BeginUpdate();
treeView1.Nodes.Add("Servers");
fill_tree();
treeView1.EndUpdate();
treeView1.ExpandAll();
connect_server_bttn.Enabled = false;
}
i want to add items i.e child nodes to Server Parent node each of them having one image before them ( green image if hlitem.Value.connected is true. red image if hlitem.Value.connected is false)
But i have no idea about treeview or imagelist.
Can anyone help me about the whole thing?
The Add command returns a reference to the new Node. You can use it to style the Node.
Change your code to this:
if (treeView1.SelectedNode != null)
{
TreeNode tn =treeView1.SelectedNode.Nodes.Add(hlitem.Key.ToString());
tn.ImageIndex = yourIndex;
}
else
{
TreeNode tn =treeView1.Nodes[0].Nodes.Add(hlitem.Key.ToString());
tn.ImageIndex = yourIndex;
}
Or whatever logic you need to set the index.
If you need the parent node's index you could write:
tn.ImageIndex = tn.Parent.ImageIndex;
You may also want ot check out the other formats of the Add method. Some let you include the ImageIndex directly. You can also include the SelectedIndex; especially if you don't want that you should include it to prevent the Tree using its default SelectedIndex!
This will set the node to show the 2nd image, whether selected or not:
TreeNode tn =treeView1.Nodes[0].Nodes.Add(sitem, sitem, 1,1 );
Since you can't set a property of an object before you have created it, you can't set the Child nodes when you create the parent node. Instead you can use a simple function to do the changes:
void copyImgIndexToChildren(TreeNode tn)
{
if (tn.Nodes.Count > 0)
foreach (TreeNode cn in tn.Nodes) cn.ImageIndex = tn.ImageIndex;
}
void copyImgIndexToAllChildren(TreeNode tn)
{
if (tn.Nodes.Count > 0)
foreach (TreeNode cn in tn.Nodes)
{
cn.ImageIndex = tn.ImageIndex;
copyImgIndexToAllChildren(cn);
}
}
The first method changes the direct ChildNodes only , the 2nd recursively changes all levels below the starting node.
BTW: Is there a reason to use hlitem.Key.ToString() in your code instead of sitem?
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.
i need to clone an entire treeview to implement Undo\Redo actions. i try in different ways but it appears that directly isn't possible. I mean copying the entire treeview, save that copy in a list. Then when the Undo action is requested decrement a specific counter of levels of undo and replace the actual treeview with the treeview that exist in the index positions of the list. if I do redo the same happens but lvls is incremented so i recover what come next. Every time that a modifications occurs in the treeview i need to save that copy and increment the lvl counter
I think you should consider going about this a different way.
You don't need to store the entire TreeView in order to keep track of undos and redos. You only need to keep track of the changes:
If you add a node, the undo is to remove it, so you only need a reference to that node.
If you remove it, the undo is to add it, so you need a reference to the added node and the node it was added to.
If you delete a whole branch, then you need to store the branch and the node it was deleted from.
And so forth. I think you'll have better luck doing it this way than trying to store the entire tree. And I've done it this way in applications where I've implemented undo/redo.
Instead of cloning the treeview itself you could simply clone the TreeNodes (see TreeNode.Clone()). It seems like the important bit is the relationship between the nodes, so this would probably work for you (I say "probably" because I haven't actually done this myself, so I can't tell you if there are any caveats to be wary of).
Consider implementing Command pattern (GoF):
Put your actions logic into classes
which implement common ICommand
{Do(); Undo();} interface.
On each user action you create object
of command requested and initialize
it with context parameters like new
and old filename.
Call Do(), put object into stack of
completed commands.
Each command is supplied with
context, so by calling Undo() it can
reverse changes.
Consider moving files into temporary
folder instead of removals.
Also, for a quick linear undo/redo, another option is the Memento pattern using zip of file as memento.
This is my shot at it, no big objects being moved in memory:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using System.Drawing;
namespace treeundoredo
{
static class Program
{
static TreeNode GetNode(string id, TreeNodeCollection root)
{
foreach (TreeNode node in root)
if (node.Text == id)
return node;
else
{
var subnode = GetNode(id, node.Nodes);
if (subnode != null)
return subnode;
}
return null;
}
[STAThread]
static void Main()
{
// list of (node, parent)
List<KeyValuePair<string, string>> undo = new List<KeyValuePair<string, string>>(), redo = new List<KeyValuePair<string, string>>();
Random rng = new Random();
TreeView Tree = new TreeView() { Size = new Size(200, 250) };
Tree.Nodes.Add("Root");
Tree.NodeMouseClick += (s, e) => { undo.Add(new KeyValuePair<string, string>(e.Node.Nodes.Add(rng.Next().ToString()).Text, e.Node.Text)); Tree.ExpandAll(); redo.Clear(); };
Button Undo = new Button() { Text = "Undo", Left = 205 };
Undo.Click += (s, e) => { if (undo.Count > 0) { var kvp = undo[undo.Count - 1]; GetNode(kvp.Key, Tree.Nodes).Remove(); redo.Add(kvp); undo.Remove(kvp); } };
Button Redo = new Button() { Text = "Redo", Left = 205, Top = 50 };
Redo.Click += (s, e) => { if (redo.Count > 0) { var kvp = redo[redo.Count - 1]; GetNode(kvp.Value, Tree.Nodes).Nodes.Add(kvp.Key); redo.Remove(kvp); undo.Add(kvp); Tree.ExpandAll(); } };
Form frm = new Form();
frm.Controls.AddRange(new Control[] { Tree, Undo, Redo });
Application.Run(frm);
}
}
}