Hello, I'm developing a Windows Form Control which is indeed a ListBox. My idea is that if you created a new ObservableCollection then it will .Clear() the existing one inside the ListBox class. This works fine, but when I am using CollectionChanged and trying to remove ALL labels off of the form - it doesn't.
What's suppose to happen is that the first ObservableCollection is created using two values, and then a second ObservableCollection is created using one value. When the latter is created, it is suppose to remove all elements in the ObservableCollection inside the ListBox class. As stated, that works - but when the CollectionChanged event is thrown, I call RemoveAllItems which is suppose to loop through all labels and remove them.
Remember when I said only two values are there at first? It detects 2 controls inside the control itself - that should be good, right? Well, it removes only ONE. Then of course the value on the latter ObservableCollection created is then added so you end up with 2 items in the ListBox - nuh'h! Should be only one.
Here is the Form in which I am using the ListBox control on.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Collections.ObjectModel;
namespace ControlTesting
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
this.flexibleListBox1.ItemCollection = new ObservableCollection<string>()
{"foo", "hello"
};
this.flexibleListBox1.ItemCollection = new ObservableCollection<string>()
{"bar"
};
}
private void flexibleListBox1_itemDoubleClicked(Label Sender)
{
MessageBox.Show(this.flexibleListBox1.getSelectedItem().Text);
}
}
}
Here is the relevant part to the ListBox class
using System;
using System.Collections.Specialized;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing;
using System.ComponentModel;
using System.Globalization;
namespace FlexibleListBox
{
public class FlexibleListBox : UserControl
{
private ObservableCollection<String> itemCollection = new ObservableCollection<String>();
public ObservableCollection<String> ItemCollection
{
get
{
return this.itemCollection;
}
set
{
this.itemCollection.Clear();
foreach (string v in value)
{
this.itemCollection.Add(v);
}
}
}
public FlexibleListBox()
{
this.AutoScroll = true;
this.itemCollection.CollectionChanged += this.itemCollectionChanged;
}
private void itemCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
switch (e.Action)
{
case System.Collections.Specialized.NotifyCollectionChangedAction.Add:
if (e.NewItems != null)
{
foreach (string item in e.NewItems)
{
this.addItem(item);
}
}
break;
case System.Collections.Specialized.NotifyCollectionChangedAction.Reset:
this.removeAllItems();
break;
default:
break;
}
}
private void addItem(string text)
{
Label label = new Label();
label.Visible = false;
label.Tag = label.Text = text;
label.TextAlign = ContentAlignment.MiddleLeft;
this.Controls.Add(label);
label.MouseEnter += this.item_MouseEnter;
label.MouseLeave += this.item_MouseLeave;
label.MouseClick += this.item_MouseClick;
label.MouseDoubleClick += this.item_MouseDoubleClick;
this.Invalidate();
}
private void removeAllItems()
{
foreach (Label label in this.Controls)
{
this.Controls.Remove(label);
}
}
}
}
In case the above doesn't give you enough information of what's happening, here is the entire ListBox class.
using System;
using System.Collections.Specialized;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing;
using System.ComponentModel;
using System.Globalization;
namespace FlexibleListBox
{
public class FlexibleListBox : UserControl
{
public delegate void itemDoubleClickedDelegate(Label Sender);
public event itemDoubleClickedDelegate itemDoubleClicked;
private int x = 0, y = 0;
private Color itemBackColor = Color.White;
private Color itemForeColor = Color.Black;
private Color itemHoverBackColor = SystemColors.Control;
private Color itemHoverForeColor = Color.Black;
private Color itemActiveBackColor = Color.FromArgb(0, 149, 204);
private Color itemActiveForeColor = Color.White;
private int itemHeight = 10;
private Padding itemPadding = new Padding(0);
private Label activeItem;
private ObservableCollection<String> itemCollection = new ObservableCollection<String>();
public Color ItemBackColor
{
get
{
return this.itemBackColor;
}
set
{
this.itemBackColor = value;
this.Invalidate();
}
}
public Color ItemForeColor
{
get
{
return this.itemForeColor;
}
set
{
this.itemForeColor = value;
this.Invalidate();
}
}
public Color ItemHoverBackColor
{
get
{
return this.itemHoverBackColor;
}
set
{
this.itemHoverBackColor = value;
this.Invalidate();
}
}
public Color ItemHoverForeColor
{
get
{
return this.itemHoverForeColor;
}
set
{
this.itemHoverForeColor = value;
this.Invalidate();
}
}
public Color ItemActiveBackColor
{
get
{
return this.itemActiveBackColor;
}
set
{
this.itemActiveBackColor = value;
this.Invalidate();
}
}
public Color ItemActiveForeColor
{
get
{
return this.itemActiveForeColor;
}
set
{
this.itemActiveForeColor = value;
this.Invalidate();
}
}
public int ItemHeight
{
get
{
return this.itemHeight;
}
set
{
this.itemHeight = value;
this.Invalidate();
}
}
public Padding ItemPadding
{
get
{
return this.itemPadding;
}
set
{
this.itemPadding = value;
this.Invalidate();
}
}
public ObservableCollection<String> ItemCollection
{
get
{
return this.itemCollection;
}
set
{
this.itemCollection.Clear();
foreach (string v in value)
{
this.itemCollection.Add(v);
}
}
}
public FlexibleListBox()
{
this.AutoScroll = true;
this.itemCollection.CollectionChanged += this.itemCollectionChanged;
foreach (string item in this.itemCollection)
{
this.addItem(item);
}
}
public Label getSelectedItem()
{
return this.activeItem;
}
private void item_MouseEnter(object sender, EventArgs e)
{
if ((Label)sender != this.activeItem)
{
((Label)sender).BackColor = (this.itemHoverBackColor);
((Label)sender).ForeColor = (this.itemHoverForeColor);
}
}
private void item_MouseLeave(object sender, EventArgs e)
{
if ((Label)sender != this.activeItem)
{
((Label)sender).BackColor = (this.itemBackColor);
((Label)sender).ForeColor = (this.itemForeColor);
}
}
private void item_MouseClick(object sender, MouseEventArgs e)
{
switch (e.Button)
{
case MouseButtons.Left:
foreach (Label label in this.Controls)
{
label.BackColor = (this.itemBackColor);
label.ForeColor = (this.itemForeColor);
}
this.activeItem = (Label)sender;
this.activeItem.BackColor = (this.itemActiveBackColor);
this.activeItem.ForeColor = (this.itemActiveForeColor);
break;
}
}
private void item_MouseDoubleClick(object sender, MouseEventArgs e)
{
switch (e.Button)
{
case MouseButtons.Left:
this.itemDoubleClicked((Label)sender);
break;
}
}
private void itemCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
switch (e.Action)
{
case System.Collections.Specialized.NotifyCollectionChangedAction.Add:
if (e.NewItems != null)
{
foreach (string item in e.NewItems)
{
this.addItem(item);
}
}
break;
case System.Collections.Specialized.NotifyCollectionChangedAction.Remove:
if (e.OldItems != null)
{
foreach (string item in e.OldItems)
{
this.removeItem(item);
}
}
break;
case System.Collections.Specialized.NotifyCollectionChangedAction.Reset:
this.removeAllItems();
break;
default:
break;
}
}
private void addItem(string text)
{
Label label = new Label();
label.Visible = false;
label.Tag = label.Text = text;
label.TextAlign = ContentAlignment.MiddleLeft;
this.Controls.Add(label);
label.MouseEnter += this.item_MouseEnter;
label.MouseLeave += this.item_MouseLeave;
label.MouseClick += this.item_MouseClick;
label.MouseDoubleClick += this.item_MouseDoubleClick;
this.Invalidate();
}
private void removeItem(string text)
{
foreach (Label label in this.Controls)
{
if (label.Text == text)
{
this.Controls.Remove(label);
break;
}
}
}
private void removeAllItems()
{
foreach (Control label in this.Controls)
{
if (label is Label)
{
this.Controls.Remove(label);
}
}
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
this.y = 0;
foreach (Label label in this.Controls)
{
label.BackColor = (this.itemBackColor);
label.ForeColor = (this.itemForeColor);
label.Width = this.Width;
label.Padding = this.itemPadding;
label.Height = this.itemHeight + (this.itemPadding.Top + this.itemPadding.Bottom);
label.Location = new Point(x, y);
label.Visible = true;
this.y += label.Height;
}
if (this.VerticalScroll.Visible)
{
foreach (Label l in this.Controls)
{
l.Width = this.Width - SystemInformation.VerticalScrollBarWidth;
}
}
}
}
}
Are you able to help me? As a quick summary, in the form that uses the ListBox I create two ObservableCollections, the first with 2 values the second with only 1 value. The output on the ListBox is "Hello" and "Bar" when it should be just "Bar"... it isn't removing my labels properly - but it is removing from the ObservableCollection defined in the ListBox class.