I'd like to programmatically emulate a click on a node in a TreeView control. There's no clickable method as far I can see (something corresponding to other controls) and I guess that I need to go for the currently selected node.
So I've tried the following:
christmasTreeView.SelectedNode. ???
However, intellisense gave me no hint on what to call in order to fire a clickety-click on the node. How can it be done?
You can do something like:
// find the node you want to select and make it the SelectedNode
christmasTreeView.SelectedNode = christmasTreeView.Nodes[1]; // <-- the index you need
// Now trigger a select
christmasTreeView.Select();
// or
//christmasTreeView.Focus();
This will fire:
private void christmasTreeView_AfterSelect(object sender, TreeViewEventArgs e) {
// awesome
}
Possible approach (not very smooth, though).
TreeNode preSelected = ChristmasTreeView.SelectedNode;
ChristmasTreeView.SelectedNode = null;
ChristmasTreeView.SelectedNode = preSelected;
ChristmasTreeView.Select();
Your main issue is that a Windows Forms TreeNode does not derive from a Control like a TreeView does (or, for example, a Button). It's much closer to a "model" class, meaning that it's primarily concerned with the hierarchical organization of your data. Although some of the presentational abstraction is leaked in properties like Color, Bounds, Handle and similar, a TreeNode doesn't know how to paint itself, nor how to handle click events.
On the other hand, a TreeView is an actual Control, meaning you can derive from it and be able to override its protected OnClick method, like shown in the example you linked.
If you want to follow that path, you could create your derived TreeView class from it and override the protected OnNodeMouseClick method. This method is specific to the TreeView and called by its WndProc method when a certain node is clicked.
But having read your comments to other answers, it seems that this is not what you really need to do to accomplish your goal.
You need to use event handler for TreeView.NodeMouseClick.
This Event got parameter which You can call in Your EventHandler like below:
void MyTreeview_NodeMouseClick(object sender,
TreeNodeMouseClickEventArgs e)
{
// do something with e.Node
}
Related
I am building a searchable TreeView (treeView1), which will remove any TreeNode that do not contain the search keyword. However, I would like to reset the tree back to its original structure on the click of a button. I am storing the original treeview in a variable before the search is performed.
TreeView originalTreeView = new TreeView();
originalTreeView = treeView1;
I then perform the search, which is likely to remove some TreeNodes.
treeView1.searchTree(keyword);
Then, when I click the Reset button, I would like treeView1 to once again show the full originalTreeView, which is what I cannot figure out how to do.
private void resetBtn_Click(object sender, EventArgs e) {
treeView1 = originalTreeView;
}
This code does nothing (the listener is OK). Is it possible to do something like this, or do I have to populate the tree all over again every time?
Your code are assign the reference to originalTreeView only, but not copy/clone as a new object (backup).
Please try this Copy all treeView parent and children to another treeView c# WinForms
For a project I am doing, I'm trying to create 16 panels onto a WinForm, via two for loops. Then once those panels have been placed on the form loadup, I'm trying to have a MouseClick event for each panel. Only problem is accessing them. The panels are placed properly onto the winform, but I have no way of accessing them. I tried putting them into a List, but everytime I add them the list turns out to be empty. This is my code:
Anyone have suggestions toward a solution?
To start off, the list is always empty because it was declared static, I would guess that if you just made it a private member, then the list will work as expected (since you will be trying to access it outside of a static context). In any case, I would do something like this:
Well, first thing's first, I would create a dictionary like this:
Dictionary<string, Panel> formsPanels; // Initialize in form's constructors
Then, I would register each panel's mouse click event within the for loop(s) (i.e. panel.MouseClick += new EventHandler(eventMethod)), and assign each panel an unique name (I would use something like panel1, panel2, etc), then add that panel to the formsPanels using its name as the key. Then within the event, you can query which panel was clicked using something like this:
public void MouseClick(object sender, EventArgs e)
{
var panel = sender as Panel;
if(panel == null) // check if the sender is a panel
return;
// Your Code
}
I didn't verify any issues within my code, so I apologize for any errors that occur. In any case, hope that helps.
I'm using DevExpree XtraTreeList Control, I want to randomly Set one of the first levels nodes to be the first node in the Tree, nothing helpful shown in the TreeList Control's Methods nor in the TreeListNode Methods,
Please Advice.
Edit: My Code
private void btnSetMaster_ButtonClick(object sender, DevExpress.XtraEditors.Controls.ButtonPressedEventArgs e)
{
//Load reprot
if (treeLstRprtDS.FocusedNode != null)
{
treeLstRprtDS.SetNodeIndex(treeLstRprtDS.FocusedNode,0);
//Get selected underlying object
ReportDataSource rprtDataSourceSelected =
(ReportDataSource)treeLstRprtDS.GetDataRecordByNode(treeLstRprtDS.FocusedNode);
theReport.SetReportDataSourceAsMaster(rprtDataSourceSelected);
}
}
Edit:
Note: working on bound mode
Solution:
I implemented the CompareNodeValues Event for the XtrTreeList Control
Read here...
and then forced the tree to do sorting using Column.SortIndex Read here...
Do you wish to scroll the TreeList so that a certain node to be the top one? If so, use the TreeList's TopVisibleNodeIndex property. If you need a certain node to be the first one, you should sort the TreeList within its CompareNodeValues event handler.
It sounds like you're looking for the SetNodeIndex method.
I have a button in my user control which should be used to remove the user control from its parent container. This is the way I have coded it today.
private void RemoveRoleButton_Click(object sender, RoutedEventArgs e)
{
if (ConfirmRoleRemoval())
{
Panel parentPanel = (Panel)this.Parent;
parentPanel.Children.Remove(this);
}
}
private bool ConfirmRoleRemoval()
{
return MessageBox.Show("Are you sure [...]
}
Is it normal to do it this way in WPF?
Yes, it looks fine to me. As Mike Hillberg writes in his blog:
An element doesn’t actually pick its logical parent; instead, a parent “adopts” children.
Thus, it makes sense that "removing" a child is also done through the object model of the parent.
As a side note: You might want to consider throwing a "nice" exception (or even disabling the button) when the parent is not a Panel (rather than waiting for the InvalidCastException).
I have a WinForms ListView, obviously containing ListViewItems. I'd like to be able to attach a click event to each item, instead of to the entire ListView (and then trying to figure out what item was clicked). The reason for this is that I need to perform a different action based on which item was selected. The ListViewItem class seems to be very limited in this regard. Is there any way to do what I want, or am I forced to use the ListView.Click event?
I would still use the ListView Click event.
A trick I've used in these situations is to use the Tag property of a ListViewItem. It's great for storing per item data and you can put anything in it.
It may make sense to subclass ListViewItem and use virtual dispatch to select the appropriate behavior based on the selected ListViewItem in the appropriate ListView event.
E.g. (uncompiled)
public abstract class MyItems : ListViewItem
{
public abstract DoOperation();
}
public class MyItemA : MyItems
{
public override DoOperation()
{ /* whatever a */ }
}
public class MyItemB : MyItems
{
public override DoOperation()
{ /* whatever b */ }
}
// in ListView event
MyItems item = (MyItems)this.SelectedItem;
item.DoOperation();
As others have mentioned, it may also make sense to use the appropriate Tag property. Which technique you go for really depends on what your action is (and therefore where it belongs, architecturally). I assumed the subclass made more sense because you're looking for a click on a listview item, and that (to me) seems more likely to be presentation-layer b/c you're overriding some standard control behavior (which would normally just select an item) as opposed to doing something in response to behavior.
In most use cases, a ListViewItem is a representation in the UI of some object, and what you're trying to do is execute a method of the object that the ListViewItem represents when the user clicks on it. For the sake of simplicity and maintainability, you want as few things to sit between the user's mouse-click and the actual method being executed.
You can store the object in the ListViewItem's Tag property and then reference it in the Click event handler, but that results in code that's got some inherent weak points:
private void MyListView_Click(object sender, EventArgs e)
{
ListView l = (ListView)sender;
if (l.SelectedItem != null)
{
MyClass obj = l.SelectedItem.Tag as MyClass;
if (obj != null)
{
obj.Method();
}
}
}
That's a lot of casting and null-reference checking. And the really weak thing about this code is that if it turns out that Tag is null, or contains something other than a MyClass object, you don't really know where to look to find out where the problem is occurring.
Contrast it with code like this:
private void MyListView_Click(object sender, EventArgs e)
{
MyClass.ListViewClicked(sender as ListView);
}
When you're maintaining this code, you don't know how that ListViewClicked method is implemented, but at least you know where to look for it - in MyClass. And when you do, you'll see something like this:
public static void ListViewClicked(ListView listView)
{
if (listView.SelectedItem == null)
{
return;
}
if (ListViewItemLookup.ContainsKey(listView.SelectedItem))
{
ListViewItemLookup[listView.SelectedItem].Execute();
}
}
Well, that's interesting. Following the thread, how does that dictionary get populated? You find that in another method in MyClass:
private static Dictionary<ListViewItem, MyClass> ListViewItemLookup =
new Dictionary<ListViewItem, MyClass>();
public ListViewItem GetListViewItem()
{
ListViewItem item = new ListViewItem();
item.Text = SomeProperty;
// population of other ListViewItem columns goes here
ListViewItemLookup.Add(item, this);
return item;
}
(Reasonable people can disagree about whether or not it's appropriate for a class to be so closely tied to a specific form of its representation in the UI - there are those who would isolate these methods and this dictionary in a helper class instead of in MyClass itself, and depending on how hairy the rest of the problem is I might do it too.)
This approach solves a number of problems: it gives you a simple way of handling the ListView's Click event properly, which is what you asked for. But it also isolates the not-always-trivial process of creating the ListViewItem in the first place. It reduces the amount of code you'll have to move around if you refactor your form and move the ListView to another form. And it reduces the number of things that your form class needs to know about, which is generally a good thing.
Also, it's testable. Generally, the only way to test code in a UI event handler is through the UI. This approach lets you isolate all of the logic surrounding this part of the UI in something that you can unit test; the only thing you can't write a unit test for is a single line of code in the form.
I should point out that the other approach people have been suggesting - subclassing ListViewItem - is perfectly fine too. You put the logic I put in the GetListViewItem method in the class's constructor, make the MyClass instance a private property of the class, and expose a Click method that calls the method of MyClass. Pretty much the only reason I don't like it is that it still leaves you with a fair amount of code in your form that you can't really unit test:
ListView l = (ListView)sender;
if (l.SelectedItem != null)
{
MyClassListViewItem item = l.SelectedItem as MyClassListViewItem;
if (item != null)
{
item.MyClass.Method();
}
}
You might however have luck sticking a reference to a delegate or other handler in the tag field (assuming there is a tag property of a ListViewItem). You would still have to determine which ListViewItem is clicked, but you could then go straight to the tag instead of another decision structure.
You want to create a new class (or classes if there are various types), which inherits from ListViewItem, then populate your ListView with these objects (as long as they inherit from listview (even several levels of inheritence) The ListView control will take them).
Then add a click method to your custom class(es) and on the ItemClick event of your listView, just call the click method of the clicked item. (some casting may be needed)
Actually there is no way to use a ListViewItem. You have to use the ListView itself. By using the 'SelectedItems' property of the ListView you can access the selected ListViewItems.
One option is to override the ListViewItem class an implement the specific stuff in there. Then you can cast the selected item to the overridden one and perform the action.
I really don't understand the reason to do so instead of just using the regular ListView Click event, but if I were to do like you suggest I would assign an EventHandler delegate to the Tag property of each ListViewItem, then in the ListView Click event handler I would check if the ListViewItem.Tag <> null, and if so call the delegate.