Windows Forms

Re: ListBox does not update when DataSource is changed

31-May-13 5:41

Dave Kreskowiak wrote:
Then quit bitching...

Your discourse is not civil, but constant.

Eddy Vluggen31-May-13 6:29

Re: ListBox does not update when DataSource is changed

31-May-13 6:29

Let it go. It's like looking at a game who will have the last word on a subject.

FWIW; Linux/Mono would react exactly the same.

Eddy Vluggen31-May-13 6:27

Re: ListBox does not update when DataSource is changed

31-May-13 6:27

rbsbscrp wrote:
Me, I think this is a horrible and terribly primitive solution and design.

Microsoft had the same idea; that's why the threaded version of the timer isn't in the WinForms designer-toolbox. The Timer from the toolbox simply raises events on the GUI-thread. No syncing required.

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

rbsbscrp31-May-13 7:22

Re: ListBox does not update when DataSource is changed

31-May-13 7:22

Hmmmmm... I am using a System.Windows.Forms.Timer. Isn't that the one you are referring to that doesn't use a separate thread? Okay, now I'm confused. My code works if i execute it from a button. It works if I invoke it thru a delegate. Other than that nothing happens.

Eddy Vluggen31-May-13 7:30

Re: ListBox does not update when DataSource is changed

31-May-13 7:30

Let me add to the confusion; there's not two, but three[^] timers available.

So, which timer is it? Smile | :)

..and there's a picture in that article of a second timer in the toolbox. Nice to see my previous post invalidated that quickly.

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

rbsbscrp31-May-13 7:39

Re: ListBox does not update when DataSource is changed

31-May-13 7:39

Wow, wonderful article.

Again, the timer that I'm using is the System.Windows.Forms.Timer one (I'm cut&pasting this from the <class>.Designer.cs file - and I don't see any other timers)

Thx for the article. I'll look at all this in a bit.

Eddy Vluggen31-May-13 8:32

Re: ListBox does not update when DataSource is changed

31-May-13 8:32

rbsbscrp wrote:
the timer that I'm using is the System.Windows.Forms.Timer one

That one runs on the UI thread, and doesn't need any invocations to update controls created.

using System;
using System.Windows.Forms;
using System.Threading;
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            Thread.CurrentThread.Name = "UI Thread";
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            Text = String.Format("{0}, {1}", Thread.CurrentThread.Name, Environment.TickCount);
            // Thread.Sleep(1000); Try resizing after uncommenting this
        }
    }
}

The timer is based on the Windows message-pump;

// System.Windows.Forms.Timer.TimerNativeWindow
protected override void WndProc(ref Message m)
{
	if (m.Msg == 275)
	{
		if ((int)m.WParam == this._timerID)
		{
			this._owner.OnTick(EventArgs.Empty);
			return;
		}
	}
	else
	{
		if (m.Msg == 16)
		{
			this.StopTimer(true, m.HWnd);
			return;
		}
	}
	base.WndProc(ref m);
}

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

TnTinMn6-Jun-13 9:08

TnTinMn

6-Jun-13 9:08

I know that this is a bit late, but have you ever considered using the BindingList(Of T) Class[^] instead? It will notify any changes to the list so that the bound control can take action.

Re: ListBox does not update when DataSource is changed

rbsbscrp6-Jun-13 12:38

Re: ListBox does not update when DataSource is changed

6-Jun-13 12:38

I'm not familiar with BindingList. I took a quick look at the link but am unsure of its benefit here. Thx for the heads up, though.

TnTinMn6-Jun-13 13:26

TnTinMn

6-Jun-13 13:26

Perhaps I misunderstood your problem, I thought that it was that the ListBox was not automatically reflecting changes to the underlying DataSource List. The BindingList raises events that would cause the ListBox to update automatically when the List changes.

Here is a simple example. New WinForm project with two buttons and two ListBoxes. Clicking Button1 adds items to the underlying lists, but only the ListBox with the BindingList as the DataSource is update. Clicking Button2 tells ListBox1 to Refresh it's data.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        List<int> L1 = new List<int>();
        BindingList<int> L2 = new BindingList<int>();
        private void Form1_Load(object sender, EventArgs e)
        {
            L1.Add(1);
            L1.Add(2);
            L2.Add(11);
            L2.Add(22);
            listBox1.DataSource = L1;
            listBox2.DataSource = L2;
            this.button1.Click += new System.EventHandler(this.button1_Click);
            this.button2.Click += new System.EventHandler(this.button2_Click);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            L1.Add(3);  // adds a value to L1, but listBox1 does not display it until the binding is refresshed
            L2.Add(33); // adds a value to L2 and listBox2 is automatically refreshed to display it
        }

        private void button2_Click(object sender, EventArgs e)
        {
            // tell listBox1 to refresh the data
            ((CurrencyManager)this.BindingContext[L1]).Refresh();
        }
    }
}

Re: ListBox does not update when DataSource is changed

Chirag Baroliya R24-May-13 2:25

Chirag Baroliya R

24-May-13 2:25

Try This :

public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
List<KeyValuePair<int, string>> data = new List<KeyValuePair<int, string>>();

KeyValuePair<int, string> item;

for (int i = 1; i < 10; i++)
{
item = new KeyValuePair<int, string>(i, "Item " + i.ToString());
data.Add(item);

}

listBox1.DataSource = data;
listBox1.DisplayMember = "Value";
listBox1.ValueMember = "Key";

}

private void button1_Click(object sender, EventArgs e)
{
KeyValuePair<int, string> item = new KeyValuePair<int,string>(11,"Item 11");

List<KeyValuePair<int, string>> data = (List<KeyValuePair<int, string>>)listBox1.DataSource;
data.Add(item);

listBox1.DataSource = null;
listBox1.DataSource = data;

}
}

Re: ListBox does not update when DataSource is changed

rbsbscrp24-May-13 20:11

Binding a DataGridView column to a nullable property, using a ComboBox bound to a non-nullable property.

24-May-13 20:11

Kuel. I like that you can use a List<> of Key/Values for a ListBox. Did not know that. Then can use the DataMember, ValueMember flexibility. Thx. However...

You are executing the update from a button_click Method - thus the code is executed on the UI thread - thus it will work. My problem is that I am executing from a timer handler - because I need the update at regular intervals (taking samples) - thus the handler is on a different thread and thus, when executed, silently does absolutely nothing.

Thx for the code. Educational. (and 'yes' I got it working)

Brady Kelly14-May-13 21:20

Brady Kelly

14-May-13 21:20

I have two objects, PriceRule and WeekDay, and PriceRule has a DayId column I have bound to a ComboBox column in a DataGridView. When I load the grid, if DayId is null, the combo is blank, but as soon as I drop the combo down, I have to select a day. No problem, I can inject an extra empty string day into the combo's data source, but the Id property of WeekDay is not nullable, so I need to do something as clumsy and stupid as insert a false day with Id of -1.

How do I catch this -1 and make it null before saving, and vice versa, catch a null DayId and make it -1 when loading?

Is there no other way to do what is a bloody common task that MS clearly isn't capable of handling themselves?

Control hide/show(should be post here, right?)

kenmaMoon23-Apr-13 21:20

kenmaMoon

23-Apr-13 21:20

I'm creating an user control like treeView, in this control, I want to put a button to let my user control hide/show in Owner form.

how could I do?

thanks

Richard MacCutchan23-Apr-13 21:57

Richard MacCutchan

23-Apr-13 21:57

You already posted this question at http://www.codeproject.com/Messages/4548577/Control-hide-show.aspx[^]. Please choose one forum only and stick to it.

Use the best guess

kenmaMoon23-Apr-13 22:00

kenmaMoon

23-Apr-13 22:00

Just delete it in C# forum

Richard MacCutchan23-Apr-13 22:42

Richard MacCutchan

23-Apr-13 22:42

I don't have authority to do that; but it's important that you read and follow http://www.codeproject.com/Messages/3137519/Forum-Guidelines-PLEASE-READ.aspx[^].

Use the best guess

Eddy Vluggen23-Apr-13 22:50

23-Apr-13 22:50

kenmaMoon wrote:
how could I do?

Toggle the Visible property?

The problem is a logical one; if you hide the control containing the button to toggle visibility, the user will not be able to make it visible again, as the button that toggles it is invisible too.

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

kenmaMoon23-Apr-13 22:55

kenmaMoon

23-Apr-13 22:55

thanks for your reply.

yes, but the button is in the userControl, next time I want the user control shown by click the button.

Eddy Vluggen24-Apr-13 6:29

C# Winform controls not drawing

24-Apr-13 6:29

kenmaMoon wrote:
yes, but the button is in the userControl, next time I want the user control shown by click the button.

Re-read what I wrote; the button will be invisible if you hide the container it's in. You cannot click an invisible button.

Either put the button somewhere else and have it toggle the Visible property, or put the button somewhere on location (0,0) and resize the control to shrink to the size of the button.

Third, best option; throw the button and the control you wish to show/hide on a new usercontrol.

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

Member 783446019-Apr-13 7:01

Member 7834460

19-Apr-13 7:01

I am working on a heavily used winform C# application.

I have a user control, that has 3 textboxes and it can contain another user control. user can add n number of main user control on the form. due to this, if the user adds more than 20 controls, after the 20th control, the UI doesnt show anything. It is not giving any exception, its simply not drawing the controls? My application is not exceeding GDI objects

Also the textbox is using WPF textbox.

All suggestions welcome. Thanks.

Re: C# Winform controls not drawing

Eddy Vluggen22-Apr-13 8:52