Re: Very Strange Behaviour (for me) ...... - C# Discussion Boards

5-Mar-15 22:06

Hi All

There is a strange behaviour in my code ...
I have a TextBox where i handle Doubleclick and call a simple form that contain a calendar so i can pick a date from it.

When TextBox_DoubleClik create the form i pass the TextBox to Form's costructor.
The form have ONLY the MonthCalendar control and haven't control box (no close with X).
If i click outside the form an handler on form's DEACTIVATE event call this.close().

When i change a date on MonthCalendar, an handler on monthcalendar's DATECHANGED set the selected date to property TEXT of my TextBox and in my intention the form should be closed ... but if use this.close() i have the run.time error: System.ObjectDisposedException (i think that the error is referred by monthcalendar why ?)

the other, and MOOORE strange, behaviour is that if i add a couple of messagebox.show(...) before this.close() the first messagebox is IGNORED and the Exception is disappeared!!!

Can Anyone halp me to solve this misteries ???

Below some pieces of code from my project:

NB: txtBase is my class derived by TextBox

// This is the code tha i used to call my datepickerform
private void txtBase_OnDoubleClick(object sender, EventArgs e){
txtBase sd = (txtBase) sender;
txtBaseDatePicker DP = new txtBaseDatePicker(sd);
DP.Show();
}

// This is main code of my form with mnthcalendar control
public partial class txtBaseDatePicker : Form
{
private TextBox txtDate;
public txtBaseDatePicker(TextBox TB):this(){
txtDate = TB;
}
public txtBaseDatePicker(){
InitializeComponent();
}
// Handler of event DateChanged of monthcalendar (cal)
// this.cal.DateChanged += new System.Windows.Forms.DateRangeEventHandler(this.CalDateSelected);
void CalDateSelected(object sender, DateRangeEventArgs e){
MonthCalendar s = (MonthCalendar) sender;

// This.Close() throw an exception ....
// but if i active the following two lines the exception disappeare and the first
// MessageBox doesn't work!
//MessageBox.Show("MSG 1 (Absorbed)");
//MessageBox.Show("MSG 2");
this.txtDate.Text = s.SelectionStart.ToString().Substring(0,10);
this.Close();
}

void TxtBaseDatePickerDeactivate(object sender, EventArgs e){
this.Close();
}

}

PS: I solved "temporarily" with a timer that after 200 ms call this.close() but i dislike this trick ... in italy i say "This is not his Mother"!

modified 6-Mar-15 4:29am.

Richard MacCutchan5-Mar-15 23:13

5-Mar-15 23:13

Why not just add a DateTimePicker[^] control to your main form? Also you should use ShowDialog for your child form (not Show) so that it closes automatically when it is finished.

Emanuele Bonin6-Mar-15 2:53

6-Mar-15 2:53

I don't use datetimepicker because i want use my txtbox class to accept any type of input.
I want that every txtBox (masked with date type) open & destroy it's own formpicker. I Call Show() method and not ShowModal() because i want that the form disappeard when the user click outside of the form.

ANYWAY ... my initial question haven't an answer ... why only adding two messagebox i can avoid an exception ?

Richard MacCutchan6-Mar-15 3:02

6-Mar-15 3:02

Emanuele Bonin wrote:
why only adding two messagebox i can avoid an exception ?

Not sure, but something is definitely wrong with your code.

Emanuele Bonin6-Mar-15 7:10

6-Mar-15 7:10

I'm not an expert and could be that i wrote something wrong.
This behaiour is very strange and the code is not complicated.
So i try to post below the complete code part to reproduce the problem.
What is wrong in my code ?

Is Wrong to create a form on the fly (local variable) pass to it a textbox so called it with Show() instead of ShowModal() ? This type of code is not acceppted to the garbage collector ?
Or there is some other problem ?

The below code is completed so is possible to reproduce the problem double cliccking on textbox and selecting a date.

using System;
using System.Windows.Forms;
using System.Drawing;

namespace TestDataPicker
{
internal sealed class Program
{
[STAThread]
private static void Main(string[] args)
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new MainForm());
}

}
public class MainForm : Form
{
public MainForm()
{
InitializeComponent();
}
void TextBox1DoubleClick(object sender, EventArgs e)
{
TextBox sd = sender as TextBox;
txtBaseDatePicker DP = new txtBaseDatePicker(sd);
DP.Location = sd.PointToScreen(Point.Empty + (Size)new Point(0, sd.Height));
DP.Show();
}

private System.ComponentModel.IContainer components = null;
private System.Windows.Forms.TextBox textBox1;

protected override void Dispose(bool disposing)
{
if (disposing) {
if (components != null) {
components.Dispose();
}
}
base.Dispose(disposing);
}

private void InitializeComponent()
{
this.textBox1 = new System.Windows.Forms.TextBox();
this.SuspendLayout();
this.textBox1.Location = new System.Drawing.Point(40, 54);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(144, 20);
this.textBox1.TabIndex = 0;
this.textBox1.DoubleClick += new System.EventHandler(this.TextBox1DoubleClick);
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(284, 262);
this.Controls.Add(this.textBox1);
this.Name = "MainForm";
this.Text = "testdatapicker";
this.ResumeLayout(false);
this.PerformLayout();

}

}
public partial class txtBaseDatePicker : Form
{
private TextBox txtDate;
public txtBaseDatePicker(TextBox TB):this(){
txtDate = TB;
}
public txtBaseDatePicker(){
InitializeComponent();
}

void CalDateSelected(object sender, DateRangeEventArgs e){
MonthCalendar s = (MonthCalendar) sender;

this.txtDate.Text = s.SelectionStart.ToString().Substring(0,10);
/////////////////////////////////////////////////////////////////////////////////////////////////////
///// STRANGE BEHAVIOURS ///////////
//
//this.CloseForm.Enabled = true; // Enabling timer 200 millisecond that close form all OK!

// eliminating one messaebox raise an exception
MessageBox.Show("1"); // this message will be supressede
MessageBox.Show("2");
this.Close(); // <-- This raise an exception
///////////////////////////////////////////////////////////////////////////////////////////////////
}

void TxtBaseDatePickerDeactivate(object sender, EventArgs e){
this.Close();
}
void CloseFormTick(object sender, EventArgs e)
{
this.CloseForm.Enabled = false;
this.Close();
}
///

/// Designer variable used to keep track of non-visual components.
///

private System.ComponentModel.IContainer components = null;
private System.Windows.Forms.MonthCalendar cal;
private System.Windows.Forms.Timer CloseForm;

protected override void Dispose(bool disposing)
{
if (disposing) {
if (components != null) {
components.Dispose();
}
}
base.Dispose(disposing);
}

private void InitializeComponent()
{
this.components = new System.ComponentModel.Container();
this.cal = new System.Windows.Forms.MonthCalendar();
this.CloseForm = new System.Windows.Forms.Timer(this.components);
this.SuspendLayout();
this.cal.Location = new System.Drawing.Point(4, 2);
this.cal.Name = "cal";
this.cal.TabIndex = 0;
this.cal.DateChanged += new System.Windows.Forms.DateRangeEventHandler(this.CalDateSelected);
this.CloseForm.Interval = 200;
this.CloseForm.Tick += new System.EventHandler(this.CloseFormTick);
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(255)))), ((int)(((byte)(255)))), ((int)(((byte)(192)))));
this.ClientSize = new System.Drawing.Size(232, 169);
this.ControlBox = false;
this.Controls.Add(this.cal);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
this.MaximizeBox = false;
this.MinimizeBox = false;
this.Name = "txtBaseDatePicker";
this.ShowIcon = false;
this.ShowInTaskbar = false;
this.Deactivate += new System.EventHandler(this.TxtBaseDatePickerDeactivate);
this.ResumeLayout(false);
}

}

}

manchanx6-Mar-15 3:22

manchanx

6-Mar-15 3:22

I assume that Close() causes an OnDeactivate-Event if the Form was active at that point. So the first call to Close() in CalDateSelected(..) will dispose the Form and then due to the pending OnDeactivate-Event Close() gets called a second time in TxtBaseDatePickerDeactivate(..). If this assumption is correct, it should work if you unsubscribe from the OnDeactivate-Event (this.OnDeactivate -= TxtBaseDatePickerDeactivate) in CalDateSelected(..) before calling Close().

Emanuele Bonin6-Mar-15 7:36

6-Mar-15 7:36

I've noticed this behaviour ... closing form call deactivate .... but even if i suppress the Close () in deactivation the problem persist.
I tryed to unsubscribe ... but nothing ... no cigar i'm sorry 8) ...I suspect that the problem is inside MonthCalendarControl.

The only way to close after assign the date actually is use a Timer that after 200 ms call this.close ... i think that this de-link the close to the calnedar event.

BillWoodruff6-Mar-15 4:51

BillWoodruff

6-Mar-15 4:51

imho your design is doing a lot of unnecessary work, and you can simplify this easily; if you ask here, I'll show you another way to do so.

One way to increase the encapsulation of your objects is to expose/transmit only the "minimum" that clients of those objects need to have.

You pass an entire TextBox into your Form with a MonthCalendar. I propose to you that you don't need to pass anything to the Form with MonthCalendar.

Equally less-than-optimal, imho, would be to expose the entire MonthCalendar to the main Form.

imho, what is desired is that when your MonthCalendar's SelectionRange is changed, that it raise an Event ... which the Form with the TextBoxes has subscribed to, passing the SelectionRange, or whatever, back to the subscriber.

When the Form with TextBoxes gets the Event (callback), it can then easily insert whatever it has been passed (in the right form) in the current active TextBox.

Also, whether you use ShowDialog, or not, there's no need to create an instance of the Form with MonthCalendar every time you want to use it ! That's a total waste; it's so easy to re-use one instance of that Form.

«To kill an error's as good a service, sometimes better than, establishing new truth or fact.» Charles Darwin in "Prospero's Precepts"

Emanuele Bonin6-Mar-15 7:29

6-Mar-15 7:29

Quote:
You pass an entire TextBox into your Form with a MonthCalendar. I propose to you that you don't need to pass anything to the Form with MonthCalendar.

This choice was made because in my head the picker must disappear when user click outside of it so is necessary a modless form that can't return a value ...
The picker, in my head, should be static, i'm developing the ideas and design to create a Framework, initially i tryed in this mode ... but i can't explain to myself this problems.
Next step would be reuse (or use of a static datepicker).
Thanx for suggestion.

BillWoodruff6-Mar-15 13:20

BillWoodruff

6-Mar-15 13:20

Yes, if you want the Picker Form to disappear when you click outside it, it cannot be shown modally, that's understood.

But, to me that's a separate issue, entirely. You just hide the Picker Form when it fires its Deactivate Event, and that should not cause the behavior you describe.

A MonthCalender Control is an "object:" whether it is "static" or not is a result of how you declared your reference to an instance of that object.

In my view, if you recreate the Picker Form each time you want to use it, that's the opposite of "static." This is static:

// in main Form
private static PickerForm dtPicker = new dtPicker(); // show and hide as needed

Learning how to raise custom events, and create custom event arguments for use with them as needed, is an important part of your .NET toolkit.

If you want to see an example, just ask.

cheers, Bill

«To kill an error's as good a service, sometimes better than, establishing new truth or fact.» Charles Darwin in "Prospero's Precepts"

Emanuele Bonin6-Mar-15 20:57

6-Mar-15 20:57

Thankyou very much.
I know the concept that you describe, the problem is my my poor english.
My code is a first approach wrote without think to optimize the various aspect. Infact i'll change it. But my varoius question about my code (i posted the complete example) are born because the behaviour is very strange and i want to know why, indipendently from my intention. I can use many ways to avoid the problem ... but i want know why exist the problem.
Actually i don't know where my code is problematic or if there is a Bug in compiler ...
I try to repeat my last question using an example from my experience of ther language.
In VisualFoxPro when i declare a local variable and assign to it an object, the object is destroyed when the scope of variable id ended (unless the object haven't references to objects outside his scope). Now in my code i create an Obect Form with a local Scope to the dblclick event but i show it modless, this implies that after Show() the variable object Form reach his "out of scope", but form remain visible, so i can use it and pick my date. In VFP the form should be destroyed immediatly after show() caused by out of scope of object. My question is, the behaviour of DatePicker is correct or is a latency of garbage collector or some other things that i ignore ?
If i'm not clear please don't esitate to ask me again.

GF(256) Multiplication

Member 115029285-Mar-15 20:50

Member 11502928

5-Mar-15 20:50

what is code in C# to multiply two bytes in GF(256) with a given primitive polynomial i.e. X^8+x^6+^x^4+1

Richard MacCutchan5-Mar-15 21:08

5-Mar-15 21:08

See https://msdn.microsoft.com/en-us/library/6a71f45d(v=vs.71).aspx[^].

harold aptroot5-Mar-15 23:12

5-Mar-15 23:12

I'm sure that's going to be of absolutely zero help to OP.

Richard MacCutchan5-Mar-15 23:56

5-Mar-15 23:56

Perhaps you can offer something better.

harold aptroot6-Mar-15 0:04

6-Mar-15 0:04

Not really, because I don't know the answer. I do know it's not on that page.
Well, I know how to multiply in GF(2^k), using shifts and xors, but I'm not so sure about that remainder.

Richard MacCutchan6-Mar-15 0:15

6-Mar-15 0:15

I don't know the answer either, but given the lack of any useful detail in the question I pointed OP to the C# mathematical operators. If he comes back with something more concrete then I'll try a bit harder.

harold aptroot6-Mar-15 0:21

6-Mar-15 0:21

Seems pretty clear to me, multiply and take the remainder by the polynomial, all in GF(256). I've found the answer now so I guess I'll post that..

harold aptroot6-Mar-15 0:24