Re: can any body tell the syntex of reading and writing an object into file? - C# Discussion Boards

can any body tell the syntex of reading and writing an object into file?

27-Sep-02 22:52

When the control calles this method on itself, and its scrollbars are showing, does this only paint the visible bit, or the non-visible bit as well?

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

Re: Control.Invalidate()

James T. Johnson28-Sep-02 5:02

James T. Johnson

28-Sep-02 5:02

You're going to hate this answer, but it paints whatever the control wants to paint.

Part of the Paint event tells it what part needs to be redrawn, but if the control ignores that it will attempt to redraw everything. The paint event is smart enough to set the clipping area so only the part that was supposed to be redrawn actually gets refreshed in the control.

James
Sig code stolen from David Wulff

imran_rafique27-Sep-02 16:09

imran_rafique

27-Sep-02 16:09

if i have a class like
class{
String *str;
int a ;
}
i want to right its object into file.after that i want to send it to different computer through network and again want to read it again if i have the same class there may i read it into that class object.
is it possible ?
can any body tell the syntex of reading and writing an object into file?

r00d0034@yahoo.com

Re: can any body tell the syntex of reading and writing an object into file?

Nnamdi Onyeyiri27-Sep-02 22:49

Re: can any body tell the syntex of reading and writing an object into file?

27-Sep-02 22:49

if you want to serialize the object to file, you can use the BinaryFormatter class, in the System.Runtime.Formatters.Binary namespace. Which has two very handy functions to serialize and deserialize objects. Smile | :)

using System.Runtime.Formatters.Binary;
 
.....
 
// Write data to stream.
BinaryFormatter bf = new BinaryFormatter();
bf.Serialize(theStream, theObject);
theStream.Close();
 
// read data
BinaryFormatter bf = new BinaryFormatter();
theObject = bf.Deserialize(theStream);
theStream.Close();

Of course, theStream could be a NetworkStream to send datathrough networks, or a FileStream to read/write data to file, etc.

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

imran_rafique28-Sep-02 15:22

imran_rafique

28-Sep-02 15:22

A bundle of thanks.

i need a little more help how to write data using FileStream into a file or read theobject from a file to the FileStream object only then it is possible to serialize or Deserialize it?

HOW to creat FileStream object that coud write into a file ?
can you explain any of its constructor?

i want to write a hastable object into a file that contain class objects,and class objects further contain hashtable and other class objects.
may i write that hashtable into a file and retrive again?

i study the api but could not understand what methods to use.

r00d0034@yahoo.com

Re: can any body tell the syntex of reading and writing an object into file?

Nnamdi Onyeyiri28-Sep-02 22:46

Re: can any body tell the syntex of reading and writing an object into file?

28-Sep-02 22:46

im not quite sure what a hash table is, but im sure its held within one object. If you require to store more than one object in the file, simple create a structure that holds all the various types of information, and serialize that.

this is how you use FileStream

using System.IO;
using System.Runtime.Formatters.Binary;
...
public object LoadFile(string filename)
{
   Stream stream = new FileStream(filename, FileMode.Open);
   BinaryFormatter bf = new BinaryFormatter();
   object obj = bf.Deserialize(stream);
   stream.Close();
   return obj;
}

public void SaveFile(string filename, object data)
{
   Stream stream = new FileStream(filename, FileMode.Create);
   BinaryFormatter bf = new BinaryFormatter();
   bf.Serialize(stream, data);
   stream.Close();
}

Simple.

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

imran_rafique29-Sep-02 15:49

imran_rafique

29-Sep-02 15:49

thanks again.
one more question.this line of code
bf.Serialize(stream, data);
alwas write data at the end of file or not ?
i mean where it write in the file.

this line of code
object obj = bf.Deserialize(stream);
alwas read data from the begining of file or not ?
i mean where it read from the file.

r00d0034@yahoo.com

Re: can any body tell the syntex of reading and writing an object into file?

Nnamdi Onyeyiri29-Sep-02 20:59

29-Sep-02 20:59

im not sure, i presume it reads from where ever the current position, set in stream.Seek to the end of the file, but i cant swear to it.

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

VFW in C#

Jarrett Vance27-Sep-02 10:43

Jarrett Vance

27-Sep-02 10:43

Is it possible to call upon video for windows VFW in C#? Is there any existing code for compressing an AVI in C#? Thanks for any help or links you can provide.

Re: VFW in C#

Stephane Rodriguez.27-Sep-02 22:29

Stephane Rodriguez.

27-Sep-02 22:29

Anything you do with WIN32 and C/C++ is possible in C# thanks to interop.

When you know the method signature, you just need to declare it in your code with a [DllImport("dllname")] attribute like in ::SendMessage :

[DllImport("user32.dll", CharSet=CharSet.Auto)]
public static extern IntPtr SendMessage(IntPtr hWnd, int msg, int wParam, IntPtr lParam);

Even more interesting is that in your case there are COM components. And the VS.NET IDE automatically imports their type-library, wrap interfaces and makes them look like any namespace to you. That's what you get for instance when you need integration with Internet Explorer, MS Office, ...

Now about DirectShow itself, this SDK has both COM Components and simple low-level APIs. Just help yourself. Below is 2 CP articles about it :
DirectShow media player[^]
DirectShow.NET[^]

You've got an introductory article about DirectShow in MSDN Mag - july 2002[^].

if you start putting in too manay features, it no longer remains useful for beginners
quote in a CP article comment, shiraz baig

Re: VFW in C#

Daniel Strigl29-Sep-02 20:15

Daniel Strigl

29-Sep-02 20:15

Take a look on DirectShow.NET.

--
Nice greets, Daniel.

Windows Form Designer

Nnamdi Onyeyiri27-Sep-02 8:38

27-Sep-02 8:38

Does anyone know how to make my control such that when it is displayed in the windows form designer, the grid does not appear over it???

[edit]
oh, and im not gonna ask if there is something specific i have to do to my collectionbase derived class, to make the windows forms designer use the collection properly Mad | :mad:

[/edit]

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"All programmers are playwrights and all computers are lousy actors."

leppie27-Sep-02 9:15

27-Sep-02 9:15

Nnamdi Onyeyiri wrote:
oh, and im not gonna ask if there is something specific i have to do to my collectionbase derived class, to make the windows forms designer use the collection properly

You just need to implemenet an indexer Smile | :)

We had plenty disscussions about that during the last week. Have a look at the CollectionEditor class for more details, I'm still trying to figure out how to add multiple types, it sure did look easy Smile | :)

Cheers

PS: Where have u been?

Give them a chance! Do it for the kittens, dear God, the kittens!
As seen on MS File Transfer: Please enter an integer between 1 and 2.

Nnamdi Onyeyiri27-Sep-02 9:26

27-Sep-02 9:26

public class EBGroupCollection : CollectionBase
public EBGroup this[int index]
   {
    get
    {
     return (EBGroup)this.List[index];
    }

    set
    {
     this.List[index] = value;
    }
   }

   public EBGroupCollection()
   {
   }

   public void Add(EBGroup value)
   {
    this.List.Add(value);
   }

 }

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

Maciej Pirog27-Sep-02 9:48

Maciej Pirog

27-Sep-02 9:48

I just don't get those strange indexers.

Nnamdi Onyeyiri wrote:
EBGroup this[int index]

It looks like the good old C++'s operator[]

Ñ There is only one MP Ð

leppie27-Sep-02 9:55

27-Sep-02 9:55

Yes , the quote button is gone, they are the same Smile | :)

Give them a chance! Do it for the kittens, dear God, the kittens!
As seen on MS File Transfer: Please enter an integer between 1 and 2.

Nnamdi Onyeyiri27-Sep-02 10:13

27-Sep-02 10:13

that code is what i am using, and that code, is the code that isnt working Poke tongue | ;-P

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

leppie27-Sep-02 10:38

27-Sep-02 10:38

Oops,

make sure the type you are adding has a default constructor, as allways Smile | :)

Give them a chance! Do it for the kittens, dear God, the kittens!
As seen on MS File Transfer: Please enter an integer between 1 and 2.

Nnamdi Onyeyiri27-Sep-02 11:17

27-Sep-02 11:17

yer, it/they does/do.

EBGroup is a class, with another collection, i dentical to the other one, except for EBItem [also a class]. can i not use classes?

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

leppie28-Sep-02 1:53

28-Sep-02 1:53

Nnamdi Onyeyiri wrote:
EBGroup is a class, with another collection, i dentical to the other one, except for EBItem [also a class]. can i not use classes?

Yes you can! I would sugest you make a few small skeleton classes to see where the problem lies...start at the other container iow that 1st collection you mentioned.

Good luck Smile | :)

Give them a chance! Do it for the kittens, dear God, the kittens!
As seen on MS File Transfer: Please enter an integer between 1 and 2.