Re: Variable scope errors - C# Discussion Boards

Rickard Andersson²⁰22-May-02 6:51

22-May-02 6:51

Do I have to import SendMessage from user32.dll or is there any similar method in C#?
It shouldn't because the WM_ messages aren't defined... but I ask anyway! Smile | :)

And if I import the function.. is WPARAM and LPARAM the same (maybe not the same) UINTs in C#??

Rickard Andersson@Suza Computing
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Re: SendMessage()

James T. Johnson22-May-02 8:56

James T. Johnson

22-May-02 8:56

Yes, you'll have to P/Invoke it. If you look at the Message struct you'll see that WParam and LParam are defined as IntPtr, considering the way that it is used you may want to follow suit.

James

Simplicity Rules!

Re: SendMessage()

Rickard Andersson²⁰22-May-02 9:58

Rickard Andersson²⁰

22-May-02 9:58

Okay!
So then I would import the SendMessage API like this:

int SendMessage(IntPtr window, UINT message, IntPtr wParam, IntPtr lParam);

Rickard Andersson@Suza Computing
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Re: SendMessage()

Rickard Andersson²⁰22-May-02 10:29

Rickard Andersson²⁰

22-May-02 10:29

What is wrong here:

[DllImport("user32.dll")] public static int SendMessage(IntPtr window, UINT message, IntPtr wParam, IntPtr lParam);

I get "Expected class, delegate, enum, interface or struct" error on the return type of SendMessage API...

Rickard Andersson@Suza Computing
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E-mail: nikado@pc.nu
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Re: SendMessage()

James T. Johnson22-May-02 14:32

James T. Johnson

22-May-02 14:32

public static extern ... Smile | :)

James

Simplicity Rules!

Re: SendMessage()

Rickard Andersson²⁰22-May-02 21:17

Rickard Andersson²⁰

22-May-02 21:17

What does that extern mean?
I have know that before but have formated my brain after installed Windows in it and lost my knowledge...

Rickard Andersson@Suza Computing
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E-mail: nikado@pc.nu
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Variable scope errors

Steve Severance22-May-02 4:57

Steve Severance

22-May-02 4:57

I am working on an ASP.NET app. In my global.asax I have a publicly exposed SqlConnection. Everything was working fine until I changed the connection string. Now all the places I used it say "An object reference is required for the nonstatic field, method, or property 'Pharmacy.Global.sqlConnection'". All I did was change the connection string. It is still public. Thanks.

Steve

Not all who wander are lost...

Re: Variable scope errors

James T. Johnson22-May-02 8:58

James T. Johnson

22-May-02 8:58

Steve Severance wrote:
"An object reference is required for the nonstatic field, method, or property 'Pharmacy.Global.sqlConnection'

This error leads me to believe that sqlConnection is not a static field of the global.asax, the quick fix is to make it a static field (public static SqlConnection sqlConnection)

HTH,

James

Simplicity Rules!

OnGotFocus

Nish Nishant21-May-02 22:33

Nish Nishant

21-May-02 22:33

In MFC we have OnSetFocus(CWnd *pOldWnd)

Thus we know which window had previous focus.

In .NET we only have this :-

protected virtual void OnGotFocus(EventArgs e)

So, how do we find out which window just lost focus???

Regards
Nish

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Nish
Native CPian.
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Re: OnGotFocus

James T. Johnson22-May-02 9:03

James T. Johnson

22-May-02 9:03

You use the LostFocus event? Smile | :)

Actually according to the docs you should use Enter/Leave for Controls and Activate/Deactivate for Forms; GotFocus/LostFocus should only be used for updating UICues.

Whew, that was a lot of <code> and </code>'s Big Grin | :-D

James

Simplicity Rules!

Re: OnGotFocus

Nish Nishant22-May-02 14:42

Nish Nishant

22-May-02 14:42

James T. Johnson wrote:
You use the LostFocus event?

BLAST!!!

That's not what I asked at all!!!!
If my control gets focus, I need to figure out which control was previously focussed. I seriously don't see how I can use LostFocus of my control to figure out which other control previously had focus!!!!!

James T. Johnson wrote:
Whew, that was a lot of <code> and </code>'s

Oh yeah????

Blast again!!!

Nish

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Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.

Re: OnGotFocus

James T. Johnson22-May-02 15:05

James T. Johnson

22-May-02 15:05

Control lastFocused = null;

private void ControlLeave(object sender, EventArgs e)
{
  lastFocused = sender as Control;
}

private override OnLoad(EventArgs e)
{
  EventHandler eh = new EventHandler(lastFocused);

  foreach(Control c in Controls)
  {
    c.Leave += eh;
  }
}

Then in the handler for the GotFocus event you can use lastFocused to see what control last had focus.

You could also use the WndProc and look for the WM_SETFOCUS message and use Control.FromHandle to get the corresponding Control object (returns null if one doesn't exist).

James

Simplicity Rules!

Re: OnGotFocus

Nish Nishant22-May-02 18:23

Nish Nishant

22-May-02 18:23

James T. Johnson wrote:
Control lastFocused = null;private void ControlLeave(object sender, EventArgs e){ lastFocused = sender as Control;}private override OnLoad(EventArgs e){ EventHandler eh = new EventHandler(lastFocused); foreach(Control c in Controls) { c.Leave += eh; }}

Jambo Frown | :-(

That's not what I want at all!!!!

I don't have control over the other controls, okay?
I am writing my own control.
My control wont know what other controls are there in the form.

Nish

Regards,
Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.

Re: OnGotFocus

James T. Johnson22-May-02 19:14

James T. Johnson

22-May-02 19:14

Nish - Native CPian wrote:
I am writing my own control.

Well you didn't say that! Smile | :)

That changes it completely, leaving you with the WndProc solution.

James

Simplicity Rules!

Re: OnGotFocus

Nish Nishant22-May-02 19:41

Nish Nishant

22-May-02 19:41

James T. Johnson wrote:
Well you didn't say that! That changes it completely, leaving you with the WndProc solution.

Blush | :O

Regards,
Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.

Re: OnGotFocus

Chris Maunder22-May-02 15:30

Chris Maunder

22-May-02 15:30

I cannot believe the guys called it 'OnGotFocus'...

Why didn't they simply go all the way and call it 'OnGottenFocus'.

cheers,
Chris Maunder

Re: OnGotFocus

Nish Nishant22-May-02 18:27

Nish Nishant

22-May-02 18:27

Chris Maunder wrote:
Why didn't they simply go all the way and call it 'OnGottenFocus'.

I am glad someone actually finds some humor in all this Frown | :-(

Nish

p.s. Am stuck at this real bad, Chris Frown | :-(

Regards,
Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.

Re: OnGotFocus

Rama Krishna Vavilala22-May-02 18:41

Rama Krishna Vavilala

22-May-02 18:41

In that case use WndProc as the last resort.

I have to see in ILDasm or Anakrino what the framework does with the handle.

protected override void WndProc(ref Message m)
{
switch(m.Msg)
{
case WM_SETFOCUS: //replace with appropriate ID
//m.LParam probably would give you the Hwnd lost focus
break;
}
}

Re: OnGotFocus

Nish Nishant22-May-02 18:46

Nish Nishant

22-May-02 18:46

Yeah Rama. That's what I finally did.
But I wanted a more elegant solution.
Anyhow, WndProc it is, for now! Frown | :-(

Nish

Regards,
Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.

Re: OnGotFocus

Rama Krishna Vavilala23-May-02 3:53

Rama Krishna Vavilala

23-May-02 3:53

Unfortunately there is no elegant soln. the framework just throws away the hwnd parameter so you have to use WndProc.

Graphics/Socket/Books

BLaZiNiX21-May-02 19:21

BLaZiNiX

21-May-02 19:21

I want to know if someone can tell me where I can Fin a very good reference on Socket and/or Graphics programming (like step-by-step,like a book).

Or anyone have the name of the best books on Sockets programming and Graphics programming in C# (I don't want book that talk about 16 bits all the entire book, I want 32 bits application reference, of course it's sure i will got the famous Hello World in 16 bit but it's a detail)

Thanks

Re: Graphics/Socket/Books

Neil Van Note21-May-02 19:37

Neil Van Note

21-May-02 19:37

I don't know of any hard-core Socket programming books specifically for C# off the top of my head, but if you don’t mind C, I have found the TCP/IP Illustrated references I, II, & III, and especially the UNIX Network Programming Volume 1 by W. Richard Stevens pretty good.

Regards

Re: Graphics/Socket/Books

Christian Graus21-May-02 19:40

Christian Graus

21-May-02 19:40

BLaZiNiX wrote:
Or anyone have the name of the best books on Sockets programming and Graphics programming in C#

I dunno about sockets, but THE C# GDI+ book is from Charles Petzold.

BLaZiNiX wrote:
(I don't want book that talk about 16 bits all the entire book, I want 32 bits application reference, of course it's sure i will got the famous Hello World in 16 bit but it's a detail)

What the hell are you talking about ?

Christian

The tragedy of cyberspace - that so much can travel so far, and yet mean so little.

And you don't spend much time with the opposite sex working day and night, unless the pizza delivery person happens to be young, cute, single and female. I can assure you, I've consumed more than a programmer's allotment of pizza, and these conditions have never aligned. - Christopher Duncan - 18/04/2002

New C# Section

Nick Parker21-May-02 17:10

Nick Parker

21-May-02 17:10

This is to all the powers that be:
We need to add a new sub category in the C# Programming section. I think "Security" would be the best title for it. I know my latest article could go there Get The User Name In C# For NT Authentication. I'm sure there will be other security related articles dealing with encryption coming soon (hint, hint) Smile | :)

Nick Parker

Actually, real programmers don't need the enter key- they just type in 00001101."

Re: New C# Section

Nish Nishant21-May-02 17:12

Nish Nishant

21-May-02 17:12

Nick Parker wrote:
I'm sure there will be other security related articles dealing with encryption coming soon (hint, hint)

You are hinting that you are planning on a few of those??

Nish

Regards,
Nish
Native CPian.
Born and brought up on CP.
With the CP blood in him.

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