C# Discussion Boards - CodeProject

OriginalGriff20-Dec-18 8:20

20-Dec-18 8:20

You can't, not at all.
When you loop in any UI control event handler, the thread that handles them all is busy running the loop until the event handler method exits - which it never does because it is sitting in your loop!

Loops in event handlers are - with exceptions - a bad idea, and loops in UI handlers are a very bad idea because they prevent any other event being recognized and processed because the only thread which is allowed to access UI controls (called the "UI thread") is permanently busy processing a single event.

If you want to use any form of user input to terminate a loop, the loop must be running on a different thread - which means you manually starting another thread and setting the loop running. That's not difficult to do (the BackgroundWorker Class (System.ComponentModel) | Microsoft Docs[^] makes it pretty painless and provides a simple way for your new thread to report progress / results to the user) but it is an operation that you have to start yourself, the system will not do it for you!

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Re: Kill execute function

OriginalGriff20-Dec-18 6:06

OriginalGriff

20-Dec-18 6:06

You can't kill "a method" from outside. You can kill the thread it is being executed on, but ... you can't tell that the thread is executing the function!

What you need is a semaphore that is checked in the method instead of the while(true), and signaled elsewhere in your app to indicate the method should exit when ready.

See here: How to: Create and Terminate Threads (C# Programming Guide) | Microsoft Docs[^]

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c# listview Update problem

MatrixRatrix20-Dec-18 2:29

MatrixRatrix

20-Dec-18 2:29

Hello,

I am new on C#, and I have a problem.

O make a form1 with listview,and i polulate this listview whit some Items.

Then I make another form2 with a button, just for count the items on Listview.

I create one function on Form1:

public void UpdatePart()
{

    MessageBox.Show(listView1.Items.Count.ToString());


}

In form2 I create a Button:

private void button1_Click(object sender, EventArgs e)
{
    Form1 a = new Form1();


    a.UpdatePart();
}

So, this count return always 0, but the listview on form1 is not empty, If I call
the same function but on the same form1, the code work and return the items numbers on listview.

What is rong ?

Thanks

Re: c# listview Update problem

Richard Deeming20-Dec-18 2:36

Richard Deeming

20-Dec-18 2:36

MatrixRatrix wrote:

private void button1_Click(object sender, EventArgs e)
{
    Form1 a = new Form1();
    a.UpdatePart();
}

Read that code again. You create a new, empty instance of Form1, and call the UpdatePart method on that instance. Since the new, empty instance doesn't have any items in the list, it will always display 0.

You need to call the method on the existing instance of Form1.

Transferring information between two forms, Part 1: Parent to Child[^]
Transferring information between two forms, Part 2: Child to Parent[^]
Transferring information between two forms, Part 3: Child to Child[^]

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Re: c# listview Update problem

MatrixRatrix20-Dec-18 2:49

MatrixRatrix

20-Dec-18 2:49

Thank you, I will check Smile | :)

Re: c# listview Update problem

BillWoodruff20-Dec-18 2:51

BillWoodruff

20-Dec-18 2:51

In addition to following Richard Deeming's excellent advice, see this recent answer to a similar problem: [^]

«Where is the Life we have lost in living? Where is the wisdom we have lost in knowledge? Where is the knowledge we have lost in information?» T. S. Elliot

KKSPANDICEO19-Dec-18 1:18

KKSPANDICEO

19-Dec-18 1:18

I HAVE BEEN CREATED THE INTERNET DOWNLOAD MANAGER.
I AM USING METHOD FOR FILEDOWNLOADASYN

HOW TO CREATE PAUSE,RESTART PROGRAM SIR?

Re: C#

OriginalGriff19-Dec-18 1:19

OriginalGriff

19-Dec-18 1:19

DON'T SHOUT. Using all capitals is considered shouting on the internet, and rude (using all lower case is considered childish). Use proper capitalization if you want to be taken seriously.

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Re: C#

Pete O'Hanlon19-Dec-18 3:02

Pete O'Hanlon

19-Dec-18 3:02

Are you using WebClient.DownloadFileAsync? If so, you can't pause and then restart from that point. You would have to cancel the existing download and then start again with a new one.

This space for rent

Re: C#

pkfox19-Dec-18 23:17

pkfox

19-Dec-18 23:17

Easy , turn your caps lock off - simples

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Message Closed

18-Dec-18 20:08

Member 14094444

18-Dec-18 20:08

Message Closed

modified 8-Jan-19 9:42am.

Re: How To Convert Image To Binary And Get Result In Text Box

Richard MacCutchan18-Dec-18 21:11

Richard MacCutchan

18-Dec-18 21:11

What is the problem?

Re: How To Convert Image To Binary And Get Result In Text Box

Eddy Vluggen19-Dec-18 0:40

Eddy Vluggen

19-Dec-18 0:40

A textbox is not meant to display "binary" code, and HEX-codes as your other post suggests are not a form of binary. There's quite some examples on how to convert a byte to hex in C#, but if you want the data in a nice transmittable form, you'd be better of converting it to Base64.

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Re: How To Convert Image To Binary And Get Result In Text Box

BillWoodruff19-Dec-18 16:20

BillWoodruff

19-Dec-18 16:20

Define "result:" exactly what type of information do you want to display in the TextBox ?

Don't use ArrayList: it's an older data structure that uses a lot of memory: use an array.

Study these links and code:

//https://stackoverflow.com/a/1668493/133321
//https://stackoverflow.com/a/221941/133321
public static byte[] ImageToByteAry(Image image, ImageFormat format)
{
    var stream = new System.IO.MemoryStream();
    image.Save(stream, format);
    stream.Position = 0;

    return stream.ToArray();
}

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DLL Snafu and debugging question

Super Lloyd18-Dec-18 12:23

Super Lloyd

18-Dec-18 12:23

I have this home project... at home.
It has lots of project.
I am also using Nuget to get some 3rd party library.
One of this Nuget package in particular contains 6 DLLs.
It is used in 4 projects... (a bit messy to update)

Now one of this DLLs has a nasty bug. Fortunately the source is on Github!

Is there an easy way for me to debug this single DLL with my project? Without having to mess up with my Nuget packages?

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Re: DLL Snafu and debugging question

Mycroft Holmes18-Dec-18 20:10

Mycroft Holmes

18-Dec-18 20:10

If you can download the source from Github you can reference the project directly - it may all fall apart if the other 5 DLLs are referencing (never had to attempt that) it internaly.

Never underestimate the power of human stupidity -
RAH
I'm old. I know stuff - JSOP

Re: DLL Snafu and debugging question

Super Lloyd19-Dec-18 3:47

Super Lloyd

19-Dec-18 3:47

Oh.. it turns out I can remove the DLL reference without removing the Nuget package!
After that I can reference the project and Bob is your uncle! Smile | :)

Well.. just gonna continue testing my app until I meet this error again, sweet, thanks! Smile | :)

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How is it possible that after I log in to a website which uses CAPTCHA, my WPF application take some input from me and fill some fields of that website for me?

Member 1409226217-Dec-18 0:38

Member 14092262

17-Dec-18 0:38

so basically I want my 3rd party program (which will be created using c# on WPF) be an interface between the user and that site. Using WebBrowser class I wanna load the login page and after the user logged in(and passed CAPTCHA), he/she will fill some fields in the program, and the program will use those data to fill the website fields.

after the user logged in to that website how can my program use his/her cookies to be able to access his/her profile to fill its fields?

Re: How is it possible that after I log in to a website which uses CAPTCHA, my WPF application take some input from me and fill some fields of that website for me?

OriginalGriff17-Dec-18 1:58

OriginalGriff

17-Dec-18 1:58

It's quite possible that you can't - the info doesn't have to be stored in cookies, it can be stored in the Session which is entirely server based.

And even if you can, I'm not sure it's something we should be involved in: sites add CAPTCHA to prevent apps from accessing an entire site and / or submitting data automatically, and what you are asking is effectively bypassing that.

If you have a genuine need, then contact the site admins and ask them: they may give you a simple method (or tell you to go to hell).

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Image on Windowsform ListBox

picasso215-Dec-18 7:57

picasso2

15-Dec-18 7:57

Can anyone help me understand this. not too much luck finding anything in google?
using the following code to display a image in a button works fine
button1.Image = global::AppInfo.Properties.Resources.MyImage;

But if I trying to display the image on a windows Form listbox, it does not work
listBox3.Items.Add(global::AppInfo.Properties.Resources.MyImage);
This only displays "System.Drawing.Bitmap" text
many thanks in advanced

Re: Image on Windowsform ListBox

Dave Kreskowiak15-Dec-18 10:13

Dave Kreskowiak

15-Dec-18 10:13

It's because the ListBox control doesn't render images on it's own.

You have to custom draw each item in the ListBox yourself. See ListBox.DrawItem Event (System.Windows.Forms) | Microsoft Docs[^]

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Re: Image on Windowsform ListBox

Eddy Vluggen15-Dec-18 10:14

Eddy Vluggen

15-Dec-18 10:14

If you add it to a listbox as an item, it will try to find a string-representation of your object. The thing it is displaying means it is working, and correctly. If you want images TO the items, try the Listbox.ImageList. There's an example on MSDN.

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If you can't read my code, try converting it here[^]
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Re: Image on Windowsform ListBox

BillWoodruff15-Dec-18 10:18

BillWoodruff

15-Dec-18 10:18

You may get more helpful replies here if you describe what the bitmaps you want to display are ... are they icons; do they vary in size, etc. ?

Start here: [^] and figure out:

1. would using a ListView or DatagridView be a better choice

... if not ...

2. would the facility to use an 'ImageList with the ListView do what you want

... if not ...

3. are you willing to take on drawing the graphics yourself ... sub-classing the ListView and owner-drawing ... see: [^]

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Is it possible to call a control event inside another event?

Member 1097549714-Dec-18 21:10

Member 10975497

14-Dec-18 21:10

I have an event right:

private void dataGridView1_SelectionChanged (object sender, EventArgs e)
             {
 
             }

I would like to trigger an event when it is made:

  private void dataGridView1_RowContextMenuStripNeeded (object sender, DataGridViewRowContextMenuStripNeededEventArgs e)
         {
 
}

Simply that the RowContex event worked with SelectionChanged ...
I searched the Internet and these mean me on average: |

If you can, it can be an example of how to do it?

Re: Is it possible to call a control event inside another event?

OriginalGriff14-Dec-18 21:23

OriginalGriff

14-Dec-18 21:23

It's not a good idea, or even really necessary.
Instead of messing about trying to force events to occur, put the code in your event handler inside a separate method and call it from both locations. That way, you don't need to "force" events to happen (which is rarely a good idea) and you reduce the code in your event handler which is a good idea from a style POV.

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