Re: BackgroundWorker and ProjessBar - C# Discussion Boards

naglbitur5-Dec-05 7:05

5-Dec-05 7:05

Hi, thanks for your help.
I still don´t know how to do this. How can I disable a menuItem when some other menuItem is selected? For instance, if menuItem5 is chosen then I want menuItem11 and menuItem12 to be disabled? How do I do that?
Thanks again for your help,

FJ

Re: Disabling MenuItems

mav.northwind5-Dec-05 7:18

mav.northwind

5-Dec-05 7:18

private void menuItem5_Clicked(object sender, EventArgs e)
{
  menuItem11.Enabled = false;
  menuItem12.Enabled = false;
}

that's as explicit as I can put it...

mav

Re: Disabling MenuItems

naglbitur6-Dec-05 2:06

naglbitur

6-Dec-05 2:06

Hi.
This is very clear!! Vielen Dank!
Take care,

FJ

Re: Disabling MenuItems

André Ziegler5-Dec-05 4:04

André Ziegler

5-Dec-05 4:04

Search for an ActionList component on codeproject, this should help you.

'A programmer is just a tool which converts caffeine into code'

BackgroundWorker and ProgressBar

SunsOfFun4-Dec-05 3:57

SunsOfFun

4-Dec-05 3:57

I want to display the status in a ProgressBar when copying large files across the network. I am using FileInfo.CopyTo method within the DoWork Method of the BackgroundWorker class (please see the code below). How am I able to fire events while the copying is taking place to update the ProgressBar. The problem is that the execution enters FileInfo.CopyTo method and does not leave until the process is complete.

Hope this makes sense.

private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e) {<br />
         <br />
            BackgroundWorker worker = sender as BackgroundWorker;<br />
            reached = 0;<br />
                fileInfoFrom = new FileInfo(@"C:\Temp\Path1\Test.zip");<br />
                fileInfoTo = new FileInfo(@"C:\Temp\Path2\Test.zip");<br />
<br />
               <br />
                fs = (fileInfoTo.Exists) ? fileInfoTo.Length : 0f;<br />
                fileInfoFrom.CopyTo(@"C:\Temp\Path2\Test.zip", true);<br />
                /* thought about using the file size to <br />
                 * calculate the percentage for the progressbar*/<br />
                int completed =<br />
                    (int)((float)fs / (float)fileInfoFrom.Length * 100);<br />
                if (completed > reached) {<br />
                        reached = completed;<br />
                    worker.ReportProgress(completed);<br />
                }<br />
        }

-- modified at 12:47 Sunday 4th December, 2005

Re: BackgroundWorker and ProjessBar

Rob Philpott4-Dec-05 4:40

Rob Philpott

4-Dec-05 4:40

Well, the way I'd tackle it would be to implement the File Copy function myself. I could raise events with controlled frequency as I shovel the data from the source file to the new destination file.

Regards,
Rob Philpott.

Re: BackgroundWorker and ProjessBar

SunsOfFun4-Dec-05 6:49

SunsOfFun

4-Dec-05 6:49

Do you know of any examples that I can take a look at?

Re: BackgroundWorker and ProjessBar

Rob Philpott4-Dec-05 8:09

Rob Philpott

4-Dec-05 8:09

Hi,

I've cobbled together an implementation you can use to get you started. Please note this is rough and ready and has no Exception handling in it etc. Ideally, to do the job properly I'd implement a new class and provide BeginCopy, CancelCopy and EndCopy static methods as we are encouraged to do for asynchronous methods.

BTW - because you will launch the copy on a worker thread, make sure you switch thread before attempting to update your progress bar (use Control.BeginInvoke).

<br />
using System;<br />
using System.Collections.Generic;<br />
using System.Text;<br />
using System.IO;<br />
<br />
namespace ConsoleApplication1<br />
{<br />
    class Program<br />
    {<br />
        static void Main(string[] args)<br />
        {<br />
            FileCopy(@"f:\BTSDev Hard Disk.vhd", @"c:\test.vhd", new UpdateProgressDelegate(RelayProgress));<br />
        }<br />
<br />
        public static void RelayProgress(int percentile)<br />
        {<br />
            Console.WriteLine("{0}% complete", percentile);<br />
        }<br />
<br />
        delegate void UpdateProgressDelegate(int percentile);<br />
<br />
        static void FileCopy(string sourceFileName, string destinationFileName, UpdateProgressDelegate handler)<br />
        {<br />
            byte[] buffer = new byte[1024];<br />
<br />
            FileStream fsInput = new FileStream(sourceFileName, FileMode.Open, FileAccess.Read);<br />
            FileStream fsOutput = new FileStream(destinationFileName, FileMode.Create, FileAccess.Write);<br />
            <br />
            long totalLength = fsInput.Length;<br />
            long readSoFar = 0;<br />
            int percentile = 0;<br />
<br />
            // send the 0% complete messsage<br />
            handler(0);<br />
                       <br />
            int readThisBuffer = fsInput.Read(buffer, 0, 1024);<br />
<br />
            while (readThisBuffer > 0)<br />
            {<br />
                readSoFar += readThisBuffer;<br />
                int newPercentile = (int)((double)readSoFar / (double)totalLength * 100.0);<br />
                if (newPercentile > percentile)<br />
                {<br />
                    percentile = newPercentile;<br />
                    <br />
                    if (handler != null)<br />
                    {<br />
                        handler(percentile);<br />
                    }<br />
                }<br />
                <br />
                fsOutput.Write(buffer, 0, readThisBuffer);<br />
                readThisBuffer = fsInput.Read(buffer, 0, 1024);<br />
            }<br />
<br />
            // send the 100% complete messsage<br />
            handler(100);<br />
<br />
            fsInput.Close();<br />
            fsOutput.Close();<br />
        }   <br />
    }<br />
}<br />

Regards,
Rob Philpott.

Re: BackgroundWorker and ProjessBar

SunsOfFun4-Dec-05 19:04

SunsOfFun

4-Dec-05 19:04

Thank you, that makes sense. Do you think this method would be slower than the FileInfo or File classes? I am sure thaey use a very similar method within those classes.

Thank you once again. Will be implementing the method.

Re: BackgroundWorker and ProjessBar

Rob Philpott4-Dec-05 22:02

Rob Philpott

4-Dec-05 22:02

Hi,

No problem, glad to be of help Smile | :)

Performace wise I'd expect the Framework methods to have the edge as they use unmanaged Win32 calls behind the scenes (probably the reason asynchronous methods aren't provided for us). One thing you could do if the files you are copying are very big is to increase the size of the buffer from 1KB to say 8KB or more.

Regards,
Rob Philpott.

About encoding setting?

pmasknguyen4-Dec-05 3:34

pmasknguyen

4-Dec-05 3:34

I usually use special characters in many Form, in VS.NET i must use Advanced Save to change my Encoding. How i can change VS.NET 2003 to default encoding Unicode UTF 8 for all project? Thanks

Nothing

ComboBox question

1nsp1r3d4-Dec-05 1:11

1nsp1r3d

4-Dec-05 1:11

Hi all,

I wanted to ask if it is possible to make the combobox only accept values from its dropdown options, because you can just enter some rubbish in the combobox and then I would have to check if the chosen input actually is a valid input(ie one from the options). Is there another way to do this or I would have to validate the input against the options?

Regards,
gamehack

Re: ComboBox question

Curtis Schlak.4-Dec-05 2:38

Curtis Schlak.

4-Dec-05 2:38

Yes, you can. Check out the ComboBox.DropDownStyle property.

"we must lose precision to make significant statements about complex systems."
-deKorvin on uncertainty

Re: ComboBox question

1nsp1r3d4-Dec-05 3:36

1nsp1r3d

4-Dec-05 3:36

Thank you

Re: ComboBox question

Curtis Schlak.4-Dec-05 11:31

Curtis Schlak.

4-Dec-05 11:31

My pleasure. Happy coding!

"we must lose precision to make significant statements about complex systems."
-deKorvin on uncertainty

Using Dispose in Classes?

redfish343-Dec-05 23:24

redfish34

3-Dec-05 23:24

I was looking at some advanced code for learning experience. Can someone explain why a Dispose method would be used in classes? Is the destructor not good enough?

~RythmMachineApp()
{
Dispose();
}

public void Dispose()
{
if (Mixer != null)
Mixer.Dispose();
System.GC.SuppressFinalize(this);
}

Re: Using Dispose in Classes?

Guffa3-Dec-05 23:41

Guffa

3-Dec-05 23:41

A Dispose method is used to make the object release any unmanaged resources. If you would put that in the destructor instead, the resources would no be released until the object is garbage collected.

---
b { font-weight: normal; }

Re: Using Dispose in Classes?

Colin Angus Mackay3-Dec-05 23:42

Colin Angus Mackay

3-Dec-05 23:42

The reason is that you have zero control over when the "finalizer" (as the destructor is called in C#) is called.

If you have a class that has a Dispose method then you are supposed to call it when you are done with any object of that class. The Dispose method would normally close connections to external resources, free up unmanaged objects and so on.

You call Dispose from the finaliser in case the caller of the class did not clean it up properly. It also means that you only have one method where the clean up code resides.

You can have the language automatically called Dispose on objects with an IDisposable interface like this:

using (SomeDisposableObject obj = new SomeDisposableObject())
{
    // Do stuff with obj
}
// By the time the code gets here obj.Dispose() has been called by
// the framework.

Does this help?

My: Blog | Photos

"Man who stand on hill with mouth open will wait long time for roast duck to drop in." -- Confucious

Thanks for Help

redfish344-Dec-05 13:07

redfish34

4-Dec-05 13:07

I have an understanding now. I thought the redundancy with destructor and Dispose was odd, but now i see it is a way to have more control over the NET framework behavior.

What Does this Code Mean?

redfish343-Dec-05 23:21

redfish34

3-Dec-05 23:21

I was looking at some advanced code for learning experience. Can someone go over and explain the weird looking parts of the following code snippets?

SNIPPET #1
What is with the '?' and ':'?

public int GetBufferedSize()
{
return m_Player != null ? m_Player.GetBufferedSize() : 0;
}

lock(this)
{
return m_Playing ? this.Size : 0;
}

SNIPPET #2
What is with the 'this'?

public Track this[int ndx]
{
get
{
lock(m_Tracks)
return (Track)m_Tracks[ndx];
}
}

Re: What Does this Code Mean?

Colin Angus Mackay3-Dec-05 23:44

Colin Angus Mackay

3-Dec-05 23:44

?: is the ternary operator that is the equivalent of if/else
a?b:c ==> if(a){b}else{c}

Does this help?

My: Blog | Photos

"Man who stand on hill with mouth open will wait long time for roast duck to drop in." -- Confucious

Re: What Does this Code Mean?

leppie4-Dec-05 2:30

leppie

4-Dec-05 2:30

Colin Angus Mackay wrote:
?: is the ternary operator that is the equivalent of if/else

Not strictly correct Smile | :)

I wish if could return a value too!

^{xacc.ide-0.1 released! Download and screenshots}

Re: What Does this Code Mean?

Colin Angus Mackay3-Dec-05 23:46

Colin Angus Mackay

3-Dec-05 23:46

Forgot the second one.

In the context you have presented this[] creates an indexer method for the class.

My: Blog | Photos

"Man who stand on hill with mouth open will wait long time for roast duck to drop in." -- Confucious

Re: What Does this Code Mean?

Guffa3-Dec-05 23:52

Guffa

3-Dec-05 23:52

It's a conditional value. If the value in front of the question mark is true, the first value is used, otherwise the second. It has the same effect as:

public int GetBufferedSize()
{
	if (m_Player != null) {
		return m_Player.GetBufferedSize();
	} else {
		return 0;
	}
}

redfish34 wrote:
What is with the 'this'?

That is the way you declare an indexer for the class.

---
b { font-weight: normal; }

Thanks for Help

redfish344-Dec-05 13:21

redfish34

4-Dec-05 13:21

Got it.

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.