Re: Updating Winforms and multi-threading - C# Discussion Boards

#realJSOP6-Mar-08 9:48

#realJSOP

6-Mar-08 9:48

Try

dtt.Rows[i][1] = addrID;

You can also use the ["TheNameOfTheColumn"] instead of [1], like so:

dtt.Rows[i]["AddressID"] = addrID;

"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
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baranils6-Mar-08 10:00

baranils

6-Mar-08 10:00

Thank You John

Yes I got it and you are right : using the field name avoid confusion or even mismatch when the user reorder column in a datagridview for example

However indexing using an ordinal can be faster and usefull sometime

#realJSOP6-Mar-08 10:30

#realJSOP

6-Mar-08 10:30

baranils wrote:
However indexing using an ordinal can be faster and usefull sometime

It may be a little faster, but not nearly as maintainable for the guy that follows you into the code.

Updating Winforms and multi-threading

baranils6-Mar-08 10:52

baranils

6-Mar-08 10:52

Right !!

Jergosh6-Mar-08 8:29

Jergosh

6-Mar-08 8:29

Is there any other way of updating forms in a thread safe way apart from the delegate/InvokeRequired trick?

I'm working on an app (RSS Reader) which has a separate thread for checking if new items appeared and updating context menus accordingly, can I acquire some sort of lock to a control or do I have to create UpdateContextMenuItem(ToolStripMenuItem menuitem, ToolStripItem subitem)-esque methods for each and every action that I may need to perform? I'm new to C#/.NET, and despite initial bias I was quite impressed how clean and well-designed it is, until now.

TIA,
Greg

Re: Updating Winforms and multi-threading [modified]

led mike6-Mar-08 8:42

led mike

6-Mar-08 8:42

Jergosh wrote:
I'm new to C#/.NET

What about Object Oriented Programming and/or Design Patterns, are you new to those as well? What is your background?

Jergosh wrote:
apart from the delegate/InvokeRequired trick?

Why is that a trick? It's an implementation of inter-thread communications, do you know of some way to communicate between threads that doesn't involve communicating between threads?

led mike

Jergosh6-Mar-08 9:09

Jergosh

6-Mar-08 9:09

led mike wrote:

What about Object Oriented Programming and/or Design Patterns, are you new to those as well? What is your background?

I have experience with C, C++ and Python as well as have completed misc university courses (algorithms and data structures etc) but I don't see how that's relevant.

led mike wrote:
Why is that a trick? It's an implementation of inter-thread communications, do you know of some way to communicate between threads that doesn't involve communicating between threads?

I'd say it's less standard than just acquiring lock, doing whatever we like with the object and then releasing it. Less convenient as well if I want, say, clear a menu and populate it with dynamic content as I have to write several helper methods. Apart from that, replacing
menuItem.DropDownItems.Clear();
with self-made
ClearDropDownMenu(menuItem) isn't particularly object-oriented (or at least doesn't look as if it was). Could we please get back to my initial question?

modified on Thursday, March 6, 2008 3:15 PM

led mike6-Mar-08 9:26

led mike

6-Mar-08 9:26

Jergosh wrote:
I'd say it's less standard than just acquiring lock

How does acquiring a lock switch your codes execution context to another thread?

Jergosh wrote:
Could we please get back to my initial question?

Your initial question appears to be based upon a misunderstanding of some of the things that are involved in the answer to your question. The direction of my posts was based on the idea that you might consider it of value to gain an improved understanding of these rather than just be given a "do this" solution. If that's not the case then so be it.

led mike

Luc Pattyn6-Mar-08 9:16

Luc Pattyn

6-Mar-08 9:16

Hi,

accessing a Control must be done by the thread that created the Control, normally the main
thread a.k.a. GUI thread. So other threads must SOMEHOW pass the GUI access actions to the
main thread. There are basically two ways to do that:

1. the Control.InvokeRequired/Invoke pattern

2. otherwise passing sufficient data to the GUI thread and have it access the Controls
(e.g. prepare a collection with new data, and have it processed by a Windows.Forms.Timer,
which always ticks on GUI thread!

Smile | :)

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Jergosh6-Mar-08 9:24

Jergosh

6-Mar-08 9:24

Luc Pattyn wrote:
There are basically two ways to do that:

1. the Control.InvokeRequired/Invoke pattern

2. otherwise passing sufficient data to the GUI thread and have it access the Controls
(e.g. prepare a collection with new data, and have it processed by a Windows.Forms.Timer,
which always ticks on GUI thread!

Most helpful, many thanks Smile | :)

How do I determine the end-of-file in a spreadsheet/excel application

Luc Pattyn6-Mar-08 9:33

Luc Pattyn

6-Mar-08 9:33

You're welcome.

Smile | :)

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gzip library

damianrda6-Mar-08 7:39

damianrda

6-Mar-08 7:39

hey guys, im writing my own auto update component for my apps, it downloads a compressed archive (.gz) and i was wondering if anyone could recommend a good gzip library i can use to deflate the file and then copy the files.

Re: gzip library

Not Active6-Mar-08 8:03

Not Active

6-Mar-08 8:03

How about the GZIPStream[^] class in System.IO.Compression namespace

only two letters away from being an asset

Interop Access Violation

Member 45984256-Mar-08 7:27

Member 4598425

6-Mar-08 7:27

I'm having a problem using an unmanaged library from C#. The C++ sample app uses the following

<br />
typedef struct {<br />
  char *filename; //pointer to file name <br />
  char **paddr;   //double pointer to memory address of data<br />
  long *pbytes;   //pointer to the number of bytes of data in memory.  The length of paddr<br />
  long *pbuflen;  //pointer to the number of bytes allocated. Can be allocated to zero<br />
} MEMIOSTRUCT;<br />
<br />
extern "C" { __declspec (dllimport) int WINAPI OUTRun(LPSTR, MEMIOSTRUCT **); }<br />

Okay now my C# app uses the following

<br />
<br />
/// <summary>Memory File Structure</summary><br />
        [StructLayout(LayoutKind.Sequential)]<br />
        public struct MEMIOSTRUCT<br />
        {<br />
            /// <summary>Directory\File name</summary><br />
            public string filename;<br />
<br />
            /// <summary>Data replacement</summary><br />
            public string data;<br />
<br />
            /// <summary>Size of the data replacement</summary><br />
            public int dataSize;<br />
<br />
            /// <summary>Number of bytes allocated in memory</summary><br />
            public int bufferSize;<br />
        }<br />
<br />
[DllImport(@"owrm32c.dll", CallingConvention = CallingConvention.Winapi)]<br />
[return: MarshalAs(UnmanagedType.I4)]<br />
private static extern int OUTRun ( [MarshalAs(UnmanagedType.LPStr)] string s , [Out] MEMIOSTRUCT [ ] m );<br />
...<br />
MEMIOSTRUCT [ ] memioAlias = MemoryAliases.ToArray( ); // MemoryAliases is a List<memiostruct><br />
int exitCode = OUTRun(command , memioAlias);<br />
</memiostruct>

When I run this I get a AccessViolationException. How am I implementing this wrong? BTW, I'm not a C++ guy so don't flame me if this is simple.

Thanks,
Dan

Walaza6-Mar-08 6:15

Walaza

6-Mar-08 6:15

Hi,

I developed an application that opens an excel doc, and reads/displays its contents to a datagrid. How do I determine its start and end rows? I have tried some code but it does not give me the result I need. e.g. I tried:
//get start and end rows
Object[] startRow = {worksheet.get_Range("A4", "O4")};
Object[] endRow = {worksheet.Rows.get_End(XlDirection.xlDown)};

which did not work for me.

See below:

// loop through all rows of the spreadsheet and place each row in the datagrid.
for (int i = 4; i <= 50; i++)
{
Microsoft.Office.Interop.Excel.Range range = worksheet.get_Range("A" + i.ToString(), "Z" + i.ToString());
System.Array myvalues = (System.Array)range.Cells.Value2;

string[] strArray = ConvertToStringArray(myvalues);

DataGridViewRow row = new DataGridViewRow();
Object[] vals = strArray;
row.CreateCells(dgOutput, vals);
dgOutput.Rows.Add(row);
}

This displays the 1st 50 rows. I do not want to display 50 rows, I want to display all the rows in the spreadsheet. I need a variable that will replace the 50 (in the for loop) and represent the end-of-file.
Please help. D'Oh! | :doh:

Mvelo Walaza
Developer
Telkom SA

Re: How do I determine the end-of-file in a spreadsheet/excel application

Jimmanuel6-Mar-08 7:30

Jimmanuel

6-Mar-08 7:30

int lastUsedRow = worksheet.Cells.SpecialCells(XlCellType.xlCellTypeLastCell, Type.Missing).Row;

Re: How do I determine the end-of-file in a spreadsheet/excel application

Walaza6-Mar-08 19:47

Walaza

6-Mar-08 19:47

Thanks man, it worked!!

Can you please recommend any sites I can get more info/code about Excel applications. I still have lots to do in this application like manipulating the data in the cells and inserting the data from the spreadsheet to an Oracle database table. Thanks again!

Mvelo Walaza
Developer
Telkom SA

Re: How do I determine the end-of-file in a spreadsheet/excel application

Jimmanuel7-Mar-08 2:52

Jimmanuel

7-Mar-08 2:52

Glad to help.

The best I can do is give you some MSDN links, other than that good documentation isn't easy to find for the Excel stuff. After MSDN and Google I'd recommend using Intellisense to explore the Excel namespace and just try anything that looks useful (and of course posting here)!

http://msdn2.microsoft.com/en-us/library/microsoft.office.tools.excel(VS.80).aspx[^]
http://support.microsoft.com/kb/302084[^]

Associate File Extension with Internet Explorer

Brad Wick6-Mar-08 6:12

Brad Wick

6-Mar-08 6:12

I have associated a file extension with my application using the Setup Application in VS 2005 which allows me to click on a file and it automatically opens my application. The problem is when I click a link on a webpage that points to this file extension I am prompted to Save or Open the file. With MS Word/Adobe Acrobat it automatically opens the application when a document is clicked on.

How can I do this same thing for my application?

Re: Associate File Extension with Internet Explorer

Not Active6-Mar-08 8:00

Not Active

6-Mar-08 8:00

You would need to write an IE Add-on for your application. If you look at the Add-on manager for IE you should see one for Adobe, Adobe PDF Reader Link Helper.

only two letters away from being an asset

Opening a form inside other form

NewToAspDotNet6-Mar-08 6:07

NewToAspDotNet

6-Mar-08 6:07

Hi guys,
Is it possible to open/load a form as child from inside of a TabPage of a parent form??? How can i do that?

Thanx.

#realJSOP6-Mar-08 6:09

#realJSOP

6-Mar-08 6:09

Just do this:

MyOtherForm myOtherForm = new MyOtherForm();
myOtherForm.Show(); // I think this is the right method to call to make it show up

NewToAspDotNet6-Mar-08 6:53

NewToAspDotNet

6-Mar-08 6:53

It's the right methode to show up the myotherform bud not inside the tabpage of the other form

Dan Neely6-Mar-08 7:02

Dan Neely

6-Mar-08 7:02

Move all of the controls of the child form into a panel class in a separate CS file. Put the panel in both the stand alone child form and as a tab page in the parent form.

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