Visual Basic

8-Jan-07 9:17

You can't use the File Stream objects to do this. They can only be used on actual files.

You're looking for something more like this[^] example.

Dave Kreskowiak
Microsoft MVP - Visual Basic

Image Comparision

ParticleBoy8-Jan-07 8:11

ParticleBoy

8-Jan-07 8:11

I need a way to tell if 2 images are the same. more specifically, i need to know if 2 screen shots taken less than one second apart are the same or are different. I have tryed using the Image1.Equals(Image2) but this apparently just compares objects and not the data contained with in them. I found some obscure code on sourceforge, but im not sure i will be able to convert it to do what i want it to do. Also I am assuming that if i take 2 screen shots and nothing on the screen has changed, that the 2 resulting images should be identical pixel for pixel. I could be wrong on this part, but i have no way to test this as of yet. suggestions please.

Re: Image Comparision

Christian Graus8-Jan-07 9:13

Christian Graus

8-Jan-07 9:13

My image processing articles show how to access the bits of a bitmap. Then it's a snap to iterate over them and see if any have changed.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

Database Error

Karma312518-Jan-07 8:06

Karma31251

8-Jan-07 8:06

ok so i am making a program with VB 2005 Express Edition and an Access database connected to it. when i run the program in the IDE it works fine but when i install it and run it, it talks about not being able to find the database. Now my question is... when you make a program with a database in the resource file, isn't the program supposed to copy to database to where ever it is supposed to read from and if it isnt then where\how to i get the program to copy and read the database upon installation. Also, i am keeping on the back burner the fact that when i install the program i want to be able to go into the database and change information and/or be able to print reports on the data.
the error:
upon startup the program cannot find the database and is looking in a folder that the program creates on its own(i didnt programmably make it)
the folder:
c:\Documemts and Settings\myUser\Local Settings\Apps\2.0\Data\993YD61J.131\C9JHJHC1.JGY \star..tion_8549497152147e43_0001.0000_603d66f8611c4d37\Data\Resources\

now why would it be looking there of all places and how can i correct this problem, this tis the knowledge i seek! lol
thanks
Joshua

Re: Database Error

Dave Kreskowiak8-Jan-07 9:13

8-Jan-07 9:13

You have to include the .MDB file in the installation project and make sure that it get's placed in the folder that your app is expecting. There is nothing that does this automatically. It's just another file, like you app's .EXE, that you're responsible for in the install.

Dave Kreskowiak
Microsoft MVP - Visual Basic

Re: Database Error

Karma312519-Jan-07 4:02

Karma31251

9-Jan-07 4:02

Ok so how would i add it i mean im using VB 2005 Express and i dont know if thats even an option, if it is i cant find it. Id ont think they give you a lot of options in the free version. anyone know a good How To on attach a data to an installation file?

Re: Database Error

Dave Kreskowiak9-Jan-07 12:32

9-Jan-07 12:32

Well, I played with ClickOnce for a little bit. It doesn't look like you can add the extra file. I actually have no idea if you can or can't. I don't use ClickOnce for any of my deployments.

Dave Kreskowiak
Microsoft MVP - Visual Basic

MDI Forms

Jason Holland8-Jan-07 7:44

Jason Holland

8-Jan-07 7:44

Is there a way to make all children forms see the MDI left as anything other than 0. For instance if I wanted to make all child forms left=150, is there a way to set a property of the MDI form to 150.

Re: MDI Forms

nlarson118-Jan-07 8:02

nlarson11

8-Jan-07 8:02

'routine in the mdi
Sub ChangeLocation(iLeft as int16)

For Each ChildForm As Form In Me.MdiChildren
ChildForm.left = iLeft
Next

end sub

MDI Forms

Jason Holland8-Jan-07 7:44

Jason Holland

8-Jan-07 7:44

Re: MDI Forms

Dave Kreskowiak8-Jan-07 9:10

Implementing Implements System.IDisposable

8-Jan-07 9:10

Nope. You can change the left edge of the MdiClient control that your child forms are rendered in though. Search the MDI Parent forms Control container for the only control that is an MdiClient. You can then make anyn changes you want to it, just like any other control you drag and drop on the form. By default, the MdiClient is Docked to Fill the form it's on, so in order to change it's location, you'll have to set it's Dock property to None. Then you'll be able to change Location and Size properties.

Dave Kreskowiak
Microsoft MVP - Visual Basic

Marcus J. Smith8-Jan-07 7:24

8-Jan-07 7:24

I have been looking around the net and the examples are so generic I am having trouble following them. I have taken over code that contains a class that calls .NET Interop code, so this is present.

<br />
Public Class ClassName<br />
Implements System.IDisposable<br />
<br />
        Public Sub Dispose() Implements System.IDisposable.Dispose<br />
<br />
        End Sub<br />

That is it in terms of the Dispose code in the class. What do I need to add to this to make it useful and do I need it at all?

Thanks,
Cleako

nlarson118-Jan-07 7:34

nlarson11

8-Jan-07 7:34

this is good information:

http://www.codeproject.com/useritems/idisposable.asp

Marcus J. Smith8-Jan-07 8:49

8-Jan-07 8:49

Man, I do alot of coding but when it comes to the Dispose calls I just dont get it. That page is like a math book giving an example of an equation such as y=2x+b then the 1st problem you get is 2-y=x^81 + b/4 or some other nonsense.

In other words that sounds great and I get when to put object.Dispose but I guess Im unsure what objects require a Dispose call and which ones dont and when do I actually call Dispose and when does the code do it for me?

Cleako

Dave Kreskowiak8-Jan-07 9:15

8-Jan-07 9:15

If the Dispose method is empty, you don't need it. Dispose is used when an object needs to clean up resources, like unmanaged file handles and such or managed objects that your object holds onto that don't clean themselves up, like a Graphics object. You put the code in the Dispose method that cleans these "loose ends" up before your object is destroyed.

Dave Kreskowiak
Microsoft MVP - Visual Basic

Christian Graus8-Jan-07 9:17

Christian Graus

8-Jan-07 9:17

cleako wrote:
I guess Im unsure what objects require a Dispose call

Any objects that hold resources of significant size, or resources that are unmanaged ( such as GDI handles )

cleako wrote:
when do I actually call Dispose

That bit is easy - when you are about to lose access to an object, either because it's a local variable, or you're about to change the value ( or, you may set a value to null after calling Dispose on the basis that you don't need it anymore )

cleako wrote:
when does the code do it for me?

Never. The code will call Finalise when it finally GCs the object. I don't think that Dispose is ever called by the framework. Really, your code should use finalise as well, and clean up anything there that was not Dispose'd of.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

Marcus J. Smith8-Jan-07 9:39

8-Jan-07 9:39

I used to call .Dispose on objects all the time then I asked a trainer about it and they made it sound like I was doing too much. So 2 more questions then.

What is a good resource other than that page I was pointed to read up on this stuff and when should I do something like .Dispose and when should I do something like Implements IDisposable etc...?

Cleako

Dave Kreskowiak8-Jan-07 9:58

8-Jan-07 9:58

As a general rule of thumb, you call .Dispose on object that implement it.

You implement IDisposable on your own object when they have resources that you need to specifically release when your done with them.

Dave Kreskowiak
Microsoft MVP - Visual Basic

nlarson118-Jan-07 9:35

nlarson11

8-Jan-07 9:35

rules to live by:

1) if an object has a dispose method, you should ALWAYS call it or bad things like memory leaks can occur

2) "try" to never rely on vb to clean up your objects for you.

3) add a dispose method to your classes and call it to safely release(close,dispose,nothing) all of your objects.

4) in routines, try to utilize they key word "using" which is supposed to guarantee (according to the help file) proper release of memory that your object was taking up.

Marcus J. Smith8-Jan-07 9:42

8-Jan-07 9:42

So if I have a class for DataAccess and I call it just to make the connection and return a dataset, should I also have a .Dispose in that class that disposes of the Connection Object everytime and any data adapters etc...?

Cleako

Dave Kreskowiak8-Jan-07 10:00

8-Jan-07 10:00

You should be closing your database connection when you're done with the SQL query. NEVER hold open an SQL connection longer than is absolutely necessary. SQL server licenses are expensive. Holding a connection open for the life of your application hogs that license so no other application can use it when you're not using it. Remember, Windows and Servers are SHARED resources, so you have to write your code to work and play nice with others.

Dave Kreskowiak
Microsoft MVP - Visual Basic

Marcus J. Smith8-Jan-07 12:29

8-Jan-07 12:29

Oh no, dont mark me as a bad coder! I wont be able to answer questions in good conscience again! I always close the connection in the Finally block after I use it. What I was asking as an example are what objects in that class are "Disposable"? Would I not only call a CN.Close but also a CN.Dispose? I think you can call a StreamReader.Close/Flush/Dispose.

So the path that got me to where I am right now is I havent used Implements IDisposable before. I also lost touch with my .Dispose self somewhere along the line and I guess I need to get back in touch with it.

The code I have "inherited" implements the IDisposable in a data access class. I dont know why but it does. The information I have read about Implements IDisposable makes it sound as if you only call that with COM objects, COM wrappers, unmanaged code calls, etc... Im trying to figure out the boundary of crazy "Disposing" and necessary "Disposing"

Thanks!!
Cleako