I have a question concerning TreeViews and their Nodes in C#.
What I currently try to do. I have a TreeView and next to it a TableLayoutPanel. When I click of the Nodes, I want to call a specific Method and display the Data
in the TableLayoutPanel. Displaying the data works fine, but my problem is that I dont know exactly how to determine what Node/ChildNode has been selected.
I have a TreeView that looks like this
Root1
R1Child1
R1Child2
Root2
R2Child1
R2Child2
Root3
R3Child1
R3Child2
I currently handle this by an AfterSelect Method and just check the selected Node for the Text.
private void treeHardware_AfterSelect(object sender, TreeViewEventArgs e)
{
if (e.Node.Text == SysInfo.CPU.Name)
{
deleteRows();
initFixedRows();
updateTableCPU();
}
else if (e.Node.Text == ramNameIdent)
{
deleteRows();
initFixedRows();
updateTableRAM(e.Node.Index);
}
else if (e.Node.Text == "Memory")
{
deleteRows();
initFixedRows();
loadRAMDetails(0);
loadRAMOverview();
}
else if( e.Node.Text == "Mainboard")
{
deleteRows();
initFixedRows();
updateTableMainboard();
}
else
{
Console.WriteLine("ERROR");
}
}
In my Opinion this is a very unpractical way to check what Node has been clicked, because it just checks Strings, and it isnt very effective..
Next Problem, for Memory Node. I display all installed Physical Memories and add each of them as a ChildNode. Now when I click one of them, it should display the Data of the selected Memory in my TableLayoutPanel. But It always just shows the "last" one.
Hope hat you understand what I mean...
If not, just ask for more Information :-)
Cheers,
Consti
Use the Tag Property , put an ID in the tag property that is unique for every node
Good day all. I am trying to accomplish the following:
In a C# WinForm I am having a ComboBox.
In a local data-base I have some "groups" that after execution become folder in "D://" ( they are five )
After that in all the folders I have some files ( the number varies )
I do not know how to populate the ComboBox with the names of those files, and after that when pressing a button I need to interact with the name selected in the ComboBox.
I have absolutely no idea on how to do that. I do not beg for any code ( altho it will be well received ) I just want the guideline ( do "this" first they you can do "that" and at the end you do "that" ) and I will do all the rest. It is just I can not figure that out. Thank you all !
First get the names of the files that is something like this:
string[] files=Directory.GetFiles("//path");
Now you have an array of all file names in the specific folder given above. Now take this string and populate it to the combo box that is something like this.
foreach(string file in files){
comboBox1.Items.add(file);
}
After that you have to create the event behind the combo box. If you drag-drooped combo box, then you can make its event by going to properties. Then code something like this behind the item select event behind combo box.
protected void combobox(bla bla)
{
if(comboBox1.SelectedItem == "An item")
//Do whatever
//it maybe selectedItem or selectedText or something like this
}
I code roughly so it may contain some errors.
Based on the help given I have done:
public string seltest = null;
string group1 = GroupsDBForm.gone;
string[] tests1 =
Directory.GetFiles("D:\\Riddler\\groups\\" + group1).Select(path => Path.GetFileName(path)).ToArray();
foreach (string t1 in tests1)
{
test_list.Items.Add(group1+"\\"+t1);
}
private void begin_test_btn_Click(object sender, EventArgs e)
{
seltest = "D:\\Riddler\\groups\\" + test_list.Text;
Do_Test_Form DoTest = new Do_Test_Form();
DoTest.ShowPath = seltest;
DoTest.MdiParent = this.ParentForm;
DoTest.Show();
}
( Those are the parts of the project connected to the issue, and because they are connected to other parts is might be lessunderstandeble what are the other names mentioned )
I know it is far from the best code but it works. I post it if this help another person with a close to this issue !
Thank you again Jamil!
I have a ListBox control populated with branches of a large retail chain. The staff using the system have to log in to the relevant branch, and I would like them to be able to search the ListBox to find their branch.
I have created an event handler for when text in the search box changes, and attempted to use code sound on StackOverflow already:
private int lastMatch = 0;
private void txtSearch_TextChanged(object sender, EventArgs e)
{
int x = 0;
string match = txtSearch.Text;
if (txtSearch.Text.Length != 0)
{
bool found = true;
while (found)
{
if (lbBranches.Items.Count == x)
{
lbBranches.SetSelected(lastMatch, true);
found = false;
}
else
{
lbBranches.SetSelected(x, true);
match = lbBranches.SelectedValue.ToString();
if (match.Contains(txtSearch.Text))
{
lastMatch = x;
found = false;
}
x++;
}
}
}
}
When I compile and start typing into the search box, I get this error:
Object reference not set to an instance of an object.
The line in question is:
match = lbBranches.SelectedValue.ToString();
I have no idea what could be wrong there, anyone got an idea?
Thanks!
SelectedValue of the listbox will only return a value if you have specified the ValueMember property of the listbox to indicate a property from which you would like to read the value for the selected item. The property you want to use in this case is SelectedItem:
match = lbBranches.SelectedItem.ToString();
when the user is entering text it's possible that no value has been selected (hence the error) -- keep in mind that what is being entered by the user has no mandatory or direct association with selections in the controls listbox sub-element
it's possible what you're doing might be simpler to implement with a full combo-box control and I think some of the examples at MSDN could be very helpful for you as well
I am working on claim expenses application for the staff where I work. Part of the process contains a listview, part of a new requirement is that if an expense type is mileage the user will not be able to edit the item, only delete and resubmit as part of business rules and UK tax reasons etc.
Anyway, I want to be able to find a control in each item of the listview that has a certain text value.
I thought something like the following but this is not correct and I know why.
Label ExpenseTypeLabel = (Label)Expenses.FindControl("ExpenseTypeLabel");
string ExpenseType = (ExpenseTypeLabel.Text.ToString());
if (ExpenseType == "Mileage")
{
foreach (ListViewDataItem thisItem in Expenses.Items)
{
ImageButton btnEdit = (ImageButton)thisItem.FindControl("btnEdit");
btnEdit.Enabled = false;
}
}
The expenses are based on weekending and as the page loads it throws my excepion as It cannot bind to a particular individual control as there are many ExpenseTypeLabels associated with the expense for the current weekending (which loads first).
What I am trying to accomplish here is to find all ExpenseTypeLabels in both the item template and the alternating item template and disable the edit function of that expense item. FYI incase you're wondering the weekending is the expense, and the children are the individual expense items.
Could one of you lovely people please educate me on the best way to accomplish this?
Thanks
Matt
Binding order, and timing for accessing bound items, is extremely important; this is especially true when you have sub controls that have binding items also.
If you want to affect the the display for these bound controls, you can usually do it from the aspx end.
Create a link from the front end to a function on the server end, then pass it all the necessary parameters:
<asp:listview id='lstExpense'>
...
<asp:button id='btnEdit' enabled='<%#= isEnabled(((Expense)Container.DataItem).ExpenseType) %>' ...
...
<asp:listview>
On the server end, make a public function to return that value:
public boolean IsEnabled(string ExpenseType) {
return ('Mileage' != ExpenseType);
}
Best solution though, is to use jQuery. Not exaggerating, but you can accomplish all of that with something as simple as:
$('.rowClass').each(function() {
if ($(this).find('.expenseTypeClass').val() == 'Mileage'))
$(this).find('.btnEditClass').attr('disabled','disabled');
})
use OnItemDataBound event as follows
OnItemDataBound="Expenses_ItemDataBound"
protected void Expenses_ItemDataBound(object sender, ListViewItemEventArgs e)
{
if (e.Item.ItemType == ListViewItemType.DataItem)
{
Label ExpenseTypeLabel = (Label)e.Item.FindControl("ExpenseTypeLabel");
string ExpenseType = (ExpenseTypeLabel.Text.ToString());
if (ExpenseType == "Mileage")
{
// disable button
}
}
}
I have some items in a CheckedListBox, I want to disable the CheckBox of first item in it.
i.e. I want to disable the first item in the CheckedListBox, because I want to tell the user visually that option is not available.
Combining 2 of the above partial answers worked great for me.
Add your items to the list with:
myCheckedListBox.Items.Add(myItem, myState);
Where myState is CheckState.Indeterminate for items that should be disabled.
Then add an event handler to keep those items from being changed:
myCheckedListBox.ItemCheck += (s, e) => { if (e.CurrentValue == CheckState.Indeterminate) e.NewValue = CheckState.Indeterminate; };
This does not allow you to use 'Indeterminate' in this list for its normal purpose but it does give a look very similar to what one would expect for a disabled item and it provides the correct behavior!
Though this post is pretty old, the last added answer has been submitted in April this year,
and I hope this will help someone.
I was after something similar : a checked list box that behaves like
a lot of installers, which offer a list of options where some features are required and
thus are both checked and disabled.
Thanks to this post (Can I use a DrawItem event handler with a CheckedListBox?)
I managed to do that, subclassing a CheckedListBox control.
As the OP in the linked post states, in the CheckedListBox control the OnDrawItem event is never fired,
so subclassing is necessary.
It's very basic, but it works.
This is what it looks like (the CheckBox above is for comparison) :
NOTE: the disabled item is really disabled : clicking on it has no effects whatsoever (as far as I can tell).
And this is the code :
public class CheckedListBoxDisabledItems : CheckedListBox {
private List<string> _checkedAndDisabledItems = new List<string>();
private List<int> _checkedAndDisabledIndexes = new List<int>();
public void CheckAndDisable(string item) {
_checkedAndDisabledItems.Add(item);
this.Refresh();
}
public void CheckAndDisable(int index) {
_checkedAndDisabledIndexes.Add(index);
this.Refresh();
}
protected override void OnDrawItem(DrawItemEventArgs e) {
string s = Items[e.Index].ToString();
if (_checkedAndDisabledItems.Contains(s) || _checkedAndDisabledIndexes.Contains(e.Index)) {
System.Windows.Forms.VisualStyles.CheckBoxState state = System.Windows.Forms.VisualStyles.CheckBoxState.CheckedDisabled;
Size glyphSize = CheckBoxRenderer.GetGlyphSize(e.Graphics, state);
CheckBoxRenderer.DrawCheckBox(
e.Graphics,
new Point(e.Bounds.X + 1, e.Bounds.Y + 1), // add one pixel to align the check gliph properly
new Rectangle(
new Point(e.Bounds.X + glyphSize.Width + 3, e.Bounds.Y), // add three pixels to align text properly
new Size(e.Bounds.Width - glyphSize.Width, e.Bounds.Height)),
s,
this.Font,
TextFormatFlags.Left, // text is centered by default
false,
state);
}
else {
base.OnDrawItem(e);
}
}
public void ClearDisabledItems() {
_checkedAndDisabledIndexes.Clear();
_checkedAndDisabledItems.Clear();
this.Refresh();
}
}
Use it like this:
checkedListBox.Items.Add("Larry");
checkedListBox.Items.Add("Curly");
checkedListBox.Items.Add("Moe");
// these lines are equivalent
checkedListBox.CheckAndDisable("Larry");
checkedListBox.CheckAndDisable(0);
Hope this can help someone.
Disabling items isn't a great idea, the user will have no good feedback that click the check box won't have any effect. You cannot use custom drawing to make it obvious. Best thing to do is to simply omit the item.
You can however easily defeat the user with the ItemCheck event:
private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e) {
if (e.Index == 0) e.NewValue = e.CurrentValue;
}
To disable any particular item use following:
checkedListBox1.SetItemCheckState(0, CheckState.Indeterminate);
SetItemCheckState takes index of item and CheckState Enum
Indeterminate is used to show shaded appearance
I know it has been a while, but I found this in my search for a list box and thought I would add it to the discussion.
If you have a listbox and want to disable all of the checkboxes so they cannot be clicked, but not disable the control so the user can still scroll etc. you can do this:
listbox.SelectionMode = SelectionMode.None
The CheckedListBox will not work in this way. CheckedListBox.Items is a collection of strings so they cannot be "disabled" as such.
Here are some discussions about possible solutions that might help you: here and here.
This works for me:
checkedListBox1.SelectionMode = SelectionMode.None;
Which means no items can be selected
None: No items can be selected.
For more info, you can check it here: SelectionMode Enumeration.
The solution is to use the event ItemChecking:
_myCheckedListBox.ItemChecking += (s, e) => e.Cancel = true;
This will cancel all the checking on every item, but you can always do more refined solution but testing the current .SelectedItem
Here's how I did it in a helpdesk application I wrote:
First, I made it so the check box was greyed out as I added it to the list during form load:
private void frmMain_Load(object sender, EventArgs e)
{
List<string> grpList = new List<string>();
ADSI objADSI = new ADSI();
grpList = objADSI.fetchGroups();
foreach (string group in grpList)
{
if (group == "SpecificGroupName")
{
chkLst.Items.Add(group, CheckState.Indeterminate);
}
else
{
chkLst.Items.Add(group);
}
}
Then I used an event so that when clicked it ensures it stays clicked:
private void chkLst_SelectedIndexChanged(object sender, EventArgs e)
{
if (chkLst.SelectedItem.ToString() == "SpecificGroupName")
{
chkLst.SetItemCheckState(chkLst.SelectedIndex, CheckState.Indeterminate);
}
}
The idea here is that on my form it's set so that the box checks on item click/select. This way I could kill two birds with one stone. I could keep this event from causing problems when the item is first checked and added during form load. Plus making it check on select allows me to use this event instead of the item checked event. Ultimately the idea is to keep it from messing up during the load.
You'll also notice that it doesn't matter what the index number is, that variable is unknown because in my app it's grabbing a list of groups from AD that exist in a specific OU.
As to whether this is a good idea or not, that's dependent on the situation. I have another app where the item to disable is dependent on another setting. In this app I just want the helpdesk to see that this group is required so they don't go removing them from it.
Try Below Code:
Private Sub CheckedListBox1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles CheckedListBox1.MouseUp
If (Condition) Then
Me.CheckedListBox1.SelectedIndex = -1
End If
End Sub
I think an alternative solution, is using Telerik components.
A RadListControl can give you that option: