Develop Reference

How to visible all items inside groupbox in c#

I have a windows form which include some textbox and labels.In my program I set all of them unvisible and when I press button it makes all of the labels and textbox visible with the code below and it works perfect.
List<Label> lbls = this.Controls.OfType<Label>().ToList();
foreach (var lbl in lbls)
{
if (lbl.Name.StartsWith("label"))
{
lbl.Visible = true;
}
}
List<TextBox> txts = this.Controls.OfType<TextBox>().ToList();
foreach (var txt in txts)
{
if (txt.Name.StartsWith("textBox"))
{
txt.Visible = true;
}
}
But when I put all of my labels and textboxes into groupbox.My code doesn't work.How can I do this?
Note: My groupbox is also unvisible and when I press button.
groupBox1.visible =true;
This code works and groupbox panel seems, but the code of labels and textboxes doesn't work.

Because you are working with the immediate child of Form here
List<Label> lbls = this.Controls.OfType<Label>().ToList();
Notice this that means your current form. so when you have controls outside in form it works,
But when you put them inside group box it won't be the immediate child anymore.
so use
List<Label> lbls = groupBox1.Controls.OfType<Label>().ToList();
This will give you access to immediate children of the group box.

You're better off creating a recursive method of your own. Try implementing something like this:
private void MakeControlsInvisible(Control container, params Type[] controlTypes)
{
foreach (Control control in container.Controls)
{
if (controlTypes.Contains(control.GetType()))
{
control.Visible = false;
}
if (control.Controls.Count > 0)
{
MakeControlsInvisible(control, controlTypes);
}
}
}
And then using it on whatever container you wish:
MakeControlsInvisible(this, typeof(Label), typeof(TextBox)); // Will make all labels and textboxes inside the entire form invisible.
MakeControlsInvisible(groupBox1, typeof(Label), typeof(TextBox));// Will make all labels and textboxes inside groupBox1 invisible.

How to hide specific item from a combo box in win forms

How can I hide specific number of items from a combo box. Code below will hide all the items instead. I couldn't find a way to perform this
string taskSelection = taskSelectionComboBox.Text;
string stateOfChild = stateOfChildComboBox.Text;
if (stateOfChild == "Awake")
{
taskSelectionComboBox.Hide();
}

you need to store the items you want then use remove method to delete them. you can use add to make them back.
// keep the items in a list
List<string> list = new List<string>();
list.Add("Awake");
// remove them from combobox
comboBox1.Items.Remove("Awake");
// if you want to add them again.
comboBox1.Items.Add(list[0]);

I would suggest you to look at DrawItem and MeasureItem events and just make your logic in it.
// this is crucial as it gives the the measurement and drawing capabilities
// to the item itself instead of a parent ( ComboBox )
taskSelectionComboBox.DrawMode = DrawMode.OwnerDrawVariable;
taskSelectionComboBox.DrawItem +=TaskSelectionDrawItem;
taskSelectionComboBox.MeasureItem += TaskSelectionMeasureItem;
Then inside of TaskSelectionMeasureItem method just set height to 0 :
void TaskSelectionMeasureItem(object sender, MeasureItemEventArgs e)
{
if(/* check if you want to draw item positioned on index e.Index */
!CanDraw(e.Index) // or whatever else to determine
)
e.ItemHeight = 0;
}
After that in the drawing method ( TaskSelectionDrawItem ) you can check for that again and either draw or not that particular element :
void TaskSelectionDrawItem(object sender, DrawItemEventArgs e)
{
if(CanDraw(e.Index))
{
Brush foregroundBrush = Brushes.Black;
e.DrawBackground();
e.Graphics.DrawString(
taskSelectionComboBox.Items[e.Index].ToString(),
e.Font,
foregroundBrush,
e.Bounds,
StringFormat.GenericDefault
);
e.DrawFocusRectangle();
}
}

Another approach will be using DataSource of combobox
var originalTasks = new List<string>
{
"One",
"Two",
"Three",
"Awake"
};
taskSelectionComboBox.DataSource = originalTasks;
Then you will hide items by re-assigning DataSource with only items you want to show
taskSelectionComboBox.DataSource = originalTasks.Where(item => item != "Awake").ToList();
An show all items back again
taskSelectionComboBox.DataSource = originalTasks;
This approach will work for any types of items.

Based on the very neat method of my colleague Mateusz:
The items displayed in comboBox need not be text strings, but any objects having a ToString () method that outputs as an item.
We can introduce an additional Hidden property into such an object. Then, in the described methods, add recognition of this property and quite naturally eliminate the display of this item.
Replace
if (CanDraw(e.Index))
{
}
with
object item = combo.Items[e.Index];
var h = item.GetType().GetProperty("Hidden");
if (!(h == null) && h.GetValue(item).AsBool())
{
}

Allow a ListBox to overlap a TableLayoutPanel (C# .NET)

I have a form that contains a TableLayoutPanel with various controls and labels in it. One of them is a custom control that inherits from ComboBox that has extra auto-complete behavior (auto-completes on any text rather than just left to right). I didn't write the code for this control, so I'm not super familiar with how it works, but essentially upon clicking on the Combobox, it adds a ListBox below the ComboBox, within the same Panel of the TableLayoutPanel, that covers the normal drop down.
Unfortunately, the TableLayoutPanel prevents the ListBox from being fully visible when added, and only one item is shown. The goal is to get it to look like a normal ComboBox which would drop down to cover any controls below it.
Is there any way to allow a control that is in a TableLayoutPanel to overlap the TableLayoutPanel to get this to work as I want? I want to avoid any controls moving around due to the TableLayoutPanel growing to accommodate the ListBox.
Relevant code from the control:
void InitListControl()
{
if (listBoxChild == null)
{
// Find parent - or keep going up until you find the parent form
ComboParentForm = this.Parent;
if (ComboParentForm != null)
{
// Setup a messaage filter so we can listen to the keyboard
if (!MsgFilterActive)
{
Application.AddMessageFilter(this);
MsgFilterActive = true;
}
listBoxChild = listBoxChild = new ListBox();
listBoxChild.Visible = false;
listBoxChild.Click += listBox1_Click;
ComboParentForm.Controls.Add(listBoxChild);
ComboParentForm.Controls.SetChildIndex(listBoxChild, 0); // Put it at the front
}
}
}
void ComboListMatcher_TextChanged(object sender, EventArgs e)
{
if (IgnoreTextChange > 0)
{
IgnoreTextChange = 0;
return;
}
InitListControl();
if (listBoxChild == null)
return;
string SearchText = this.Text;
listBoxChild.Items.Clear();
// Don't show the list when nothing has been typed
if (!string.IsNullOrEmpty(SearchText))
{
foreach (string Item in this.Items)
{
if (Item != null && Item.ToLower().Contains(SearchText.ToLower()))
{
listBoxChild.Items.Add(Item);
listBoxChild.SelectedIndex = 0;
}
}
}
if (listBoxChild.Items.Count > 0)
{
Point PutItHere = new Point(this.Left, this.Bottom);
Control TheControlToMove = this;
PutItHere = this.Parent.PointToScreen(PutItHere);
TheControlToMove = listBoxChild;
PutItHere = ComboParentForm.PointToClient(PutItHere);
TheControlToMove.Anchor = ((System.Windows.Forms.AnchorStyles)
((System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right)));
TheControlToMove.BringToFront();
TheControlToMove.Show();
TheControlToMove.Left = PutItHere.X;
TheControlToMove.Top = PutItHere.Y;
TheControlToMove.Width = this.Width;
int TotalItemHeight = listBoxChild.ItemHeight * (listBoxChild.Items.Count + 1);
TheControlToMove.Height = Math.Min(ComboParentForm.ClientSize.Height - TheControlToMove.Top, TotalItemHeight);
}
else
HideTheList();
}
Images:
Desired behavior
Current behavior

Going on the suggestion from TaW, I came up with a tentative solution. This form isn't re-sizable but does auto-size so that it looks ok if the user changes their DPI in Windows.
To resolve this, I moved the control out of the TableLayoutPanel to an arbitrary position in the Parent of the TableLayoutPanel. On form loading, I summed the coordinates of the TableLayoutPanel and an empty panel in the cell that I wanted the control to be located on top of. This worked for my needs but it feels like a kludge.
The better solution is probably to use Control.PointToScreen and Control.PointToClient methods, however I wasn't able to get these methods to give me the correct coordinates.

How to loop through all textBox controls and change associated label color

foreach (Control c in this.Controls)
{
if (c is TextBox && c.Text.Length==0)
{
// [Associatedlabel].ForeColor = System.Drawing.Color.Red;
err = true;
}
instead of [Associatedlabel], I want to associate each textbox to label, so eventually all labels near the textbox that are empty will be red, how it can be done?
Thanks.

There is no fantastic way to find the label control back from the textbox. Using the form's GetChildAtPoint() method is something you can make easily work but are going to regret some day. Naming helps, like FooBarLabel matches FooBarTextBox. Now you can simply use the Controls collection to find the label back:
var label = (Label)this.Controls[box.Name.Replace("TextBox", "Label")];
But Winforms solves many problems by simple inheritance. Add a new class to your project and paste this code:
using System;
using System.Windows.Forms;
class LabeledTextBox : TextBox {
public Label Label { get; set; }
}
Compile and drop the new control from the top of the toolbox. Set the Label property in the designer, just pick it from the dropdown list. Boomshakalaka.

You can first manually set your TextBox's Tag property to these labels. Tag is meant to contain user-defined data, so you can place any object there. Then you can do simply:
foreach (Control c in this.Controls)
{
if (c is TextBox && c.Text.Length==0 && c.Tag is Label)
{
((Label)c.Tag).ForeColor = System.Drawing.Color.Red;
err = true;
}
}
This is the simplest solution, but a few more sophisticated exists though.
Creating a custom composite control consisting of a label, textbox and custom behavior;
Creating a control deriving from a textbox, which stores information about label it is connected with (as Hans Passant suggests)
Creating a Dictionary<TextBox, Label> or Dictionary<Control, Label>, which allows resolving such matters in runtime (variation on Steve's idea).

I suppose that you are using WinForms. In this environment you don't have any built-in functionality that associate a label to a textbox. So you need to build your own association.
This could be done creating a dictionary in the constructor of your code
public class MyForm : Form
{
private Dictionary<string, Label> assoc = new Dictionary<string, Label>();
public MyForm()
{
// Key=Name of the TextBox, Value=Label associated with that textbox
assoc.Add("textbox1", Label1);
assoc.Add("textbox2", Label2);
assoc.Add("textbox3", Label3);
}
}
.....
foreach (TextBox t in this.Controls.OfType<TextBox>())
{
if(t.Text.Length == 0)
{
assoc[t.Name].ForeColor = System.Drawing.Color.Red;
err = true;
}
else
assoc[t.Name].ForeColor = ??? system forecolor ???
}

How to access TabPages that are created in real-time?

Some inits done earlier in the code...
private List<System.Windows.Forms.TabPage> tab_pages = new List<System.Windows.Forms.TabPage>();
int tab_increment = 0;
Somewhere in the code, I create a bunch of tab pages in real-time.
for (i=0; i<5; i++)
{
tab_pages.Add( new System.Windows.Forms.TabPage() );
tab_pages[tab_increment].Location = new System.Drawing.Point(4, 22);
tab_pages[tab_increment].Name = 1 + tab_increment.ToString();
tab_pages[tab_increment].Size = new System.Drawing.Size(501, 281);
tab_pages[tab_increment].Text = tab_increment.ToString();
this.tabControl.Controls.Add(tab_pages[tab_increment]);
tab_increment += 1;
}
Now I would like to access elements that are these tab pages. Also let's pretend that I created different elements on each page (example, tabPage[0] a button, tabPage[1] a checkbox, etc), how do I access them knowing that everything was added dynamically?

Check this approach:
void Walk(Control control)
{
foreach (Control c in control.Controls)
{
//just walking through controls...
//...do something
//but remember, it could contain containers itself (say, groupbox or panel, etc.)...so, do a recursion
if (c.Controls.Count > 0)
Walk(c);
}
//or
foreach (Button btn in control.Controls.OfType<Button>())
{
//an example of how to walk through controls sub array of certain type
//this loop won't have a single iteration if this page contains no Buttons
//..so you can replace Button
//and have some certain code for different types of controls
}
}
And launch it for tabcontrol:
foreach (TabPage page in tabControl1.TabPages)
Walk(page);
I guess there is no special need to have separate collection of tabpages for one tabcontrol, as soon as it has TabPages property.
In the code above I used Enumerable.OfType Method to get a subcollection of controls of certain type.
As for your code, try this:
for (int i = 0; i < 5; i++)
{
this.tabControl.Controls.Add(new System.Windows.Forms.TabPage());
this.tabControl.TabPages[i].Text = i.ToString();
//...do whatever you need
//...
//besdies, I think, ther's no need in tab_increment...loop index works well enough
}

In order to add pages, I think that using
tabControl.TabPages.Add(new TabPage("Name"));
or in your case
this.tabControl.TabPages.Add(tab_pages[tab_increment]);
is more suitable.
In order to access them you could use
TabPage tp = tabControl.TabPages[i]; //where i is the index of your TabPage
and you can use TabPage.Controls.Add of the Controls property to add any Control on the TabPage like:
Button btn = new Button();
btn.Name = "Button name";
tp.Controls.Add(btn);

You can use the Controls property on the TabPage object. Each control in the collection is given to you as a Control, and it is up to you to cast them to the type that you want.