Re: I2C communication - C# Discussion Boards

Mazdak4-Mar-04 22:25

Mazdak

4-Mar-04 22:25

ASGill wrote:
it looks like they haved scraped these properties off checklisbox

Eek! | :eek:

Although I donn't have VS.NET 2003 but how is this possible? I can understand it.

Anyway, can't you set it programiically? Like this:

checklistbox1.DataSource = mytable;
checklistbox1.DisplayMember = columnname;

Mazy

"A bank is a place that will lend you money if you can prove that you don't need it." - Bob Hope

ASGill5-Mar-04 0:53

ASGill

5-Mar-04 0:53

Hi Mazy...( Eek! | :eek:

yeah i know its kinda shocking.. Smile | :)

)

anyways... i got the adding part working, its working alrite, but with a flaw...and i have got no clue of what so ever abt why its happennin

<br />
private void frmPrescription_Load(object sender, System.EventArgs e)<br />
		{<br />
			try<br />
			{<br />
				oleDbConnection1.Open();<br />
<br />
				oleDbDataAdapter1.SelectCommand.CommandText = "SELECT [Med Name] FROM Pharmacy";<br />
<br />
				oleDbDataAdapter1.SelectCommand.ExecuteNonQuery();<br />
<br />
				oleDbDataAdapter1.Fill(dataSet1);<br />
<br />
                                // add items to checkboxlistname.<br />
				for(int i = 0; i < dataSet1.Tables[0].Rows.Count; i++)<br />
				{<br />
					//add items unchecked<br />
					this.checkedListBoxName.Items.Add(dataSet1.Tables[0].Rows[i][4], false);  <br />
				}<br />
			}<br />
			catch (Exception LoadError)<br />
			{<br />
				MessageBox.Show(LoadError.ToString());<br />
			}<br />
			finally<br />
			{<br />
				oleDbConnection1.Close();<br />
				oleDbConnection1.Dispose();<br />
			}<br />

well when it adds the item, it adds it twice...i.e i have the value "Aspirin" in the column in the table...its s'pose to display it only once but i get

1. Aspirin //numbers represent checkboxes
2. Aspirin
3. Piriton
4. Piriton

and so on.....all of the values are added twice..whats wrong...

D'Oh! | :doh:

MasudM5-Mar-04 1:50

MasudM

5-Mar-04 1:50

Hi I 'm wondering why you :

oleDbDataAdapter1.SelectCommand.ExecuteNonQuery();

oleDbDataAdapter1.Fill(dataSet1);

you olny need to oleDbDataAdapter1.Fill(dataSet1);

why did you write
oleDbDataAdapter1.SelectCommand.ExecuteNonQuery();
first .?

bye.

Mazdak5-Mar-04 4:51

Mazdak

5-Mar-04 4:51

As Masud said remove oleDbDataAdapter1.SelectCommand.ExecuteNonQuery();
line then you call fill method set the DataSource and DisplayMemerb ofCheckListBox as I told you.

Mazy

"A bank is a place that will lend you money if you can prove that you don't need it." - Bob Hope

Question about Casting and Inheritance

ASGill5-Mar-04 7:04

ASGill

5-Mar-04 7:04

aight....got it fixed...

the oleDbDataAdapter.SelectCommand.ExecuteNonQuery(); was a mistake...the code i posted was an earlier version of it...sorry...

thx for the help guys

Big Grin | :-D

YCbCr image construction

yyyychan4-Mar-04 21:12

yyyychan

4-Mar-04 21:12

I'm reading a YCbCr image byte by byte from the parallel port and all I want
to do is to display the image on the screen using C#. I wonder how I can do
it. Ways that I can think of include:

1. Convert to RGB and construct a Bitmap object (Is there any simple way to
do the conversion?)

2. Construct an Image object with YCbCr pixel format (I should that Image
has a Flags property which includes YCbCr color space. But how can I make
use of this?)

A thousand thanks.

Yawen

I2C communication

yyyychan4-Mar-04 21:05

yyyychan

4-Mar-04 21:05

I'd like to use my PC's serial port to communicate with my IC which uses the I2C standard. Is there any class or functions that I can use to do that?

Thanks very much.

Yawen

Re: I2C communication

Heath Stewart5-Mar-04 6:19

Heath Stewart

5-Mar-04 6:19

You should search CodeProject for a number of articles describing serial communications in .NET. Since the .NET base class library does not provide this functionality, there are many libraries available to help you.

If you download the VB.NET Resource Kit from http://msdn.microsoft.com/vbasic/vbrkit[^], you can use Sax.NET. Don't worry that it's in the VB.NET RK. In the .NET Framework, all source compiles to IL that's placed in modules and into assemblies. Any .NET language can use an assembly written in any other .NET language because they all compile to IL.

Microsoft MVP, Visual C#
My Articles

tsunsau7174-Mar-04 19:37

tsunsau717

4-Mar-04 19:37

Suppose I have Class:

1) class Shape{}
2) class Square : Shape {}
3) class Circle : Shape {}

and Method:

1) void f(Shape s){}
2) void f(Square s){}
3) void f(Circle c){}

Now, I declare 3 variables:
1) Shape a1 = new Shape();
2) Square a2 = new Square();
3) Circle a3 = new Circle();

If I call f(a1), it will go to method 1.
If I call f(a2), it will go to method 2.
If I call f(a3), it will go to method 3.
Right?

But If I call f((Shape)a2), it will go to method 1.

Is there anyway to make if I call f((Shape)a2), and it will go to method 2 directly?

partyganger4-Mar-04 20:50

4-Mar-04 20:50

I'm not sure what you want to do, but here's my two cents:
If your parameter is cast to Shape, and Square is derived from Shape, first the runtime / compiler will look in the class Square if it can find a method with the f(Shape s) signature.
Since it can only find the f(Square s) method, it'll go up on class (which is Shape) and there it WILL find the wanted menthod.
If you want class Square to have it's own f(Shape s) method, you'll have to overload the original one, i.e. recreate the f(Shape s) method in the Square class...

tsunsau7174-Mar-04 21:44

tsunsau717

4-Mar-04 21:44

Actually the method f is not a member method of Shape, Square, Circle.

It is static method of another class, which can takes "Shape" or "Square" or "Circle" as parameter.

Actually, what I am doing now is:

public static f(Shape s){
if (s is Square){
f((Square)s);
}
else if (s is Circle){
f((Circle)s);
}
}

public static f(Square s){
MessageBox.Show("It is a Square"):
}

public static f(Circle s){
MessageBox.Show("It is a Circle"):
}

It works, but the problem is when there is a lot of derived class, the f(Shape c) method will be very bulky.

partyganger5-Mar-04 10:10

5-Mar-04 10:10

I Really don't understand what you're trying to do here. WHy define a static class where you process objects that have nothing to do with that class (it is static, so the class that holds the static method can't do anything with the passed object???? The whole idea behind OO is that you put things that belong together in a class, so if you want to edit a Square, use the f in Square.
Then, there's the "virtual" keyword as well, if you define f as virtual in Shape and pass it a Square it will try to locate the f method in Shapes subclasses.....

Roman Rodov4-Mar-04 23:55

Roman Rodov

4-Mar-04 23:55

Why write 3 different overloads of the method if you are casting all the parameters to Shape anyway.

The whole point of method overloads is that you can theoretically pass it any kind of Shape derived object(or whatever for that matter) and the runtime will work out the right overload to call. Maybe I am not clearly understanding what you are trying to do, but this seems a little bit silly.

How to associate icons with ContextMenu ?

killerslaytanic5-Mar-04 14:23

killerslaytanic

5-Mar-04 14:23

Seems to me you have some misunderstanding about the concepts:

First of all the methods "f" belong to which class(es)?
Second: The typecast (shape)a2 is redundant (don´t remember if it is syntactically ok but if so it has nonsense anyway)a2 is a Square so it IS a Shape anyway

how inheritance and polymorphism works...
I guess you wanted to do something like this:
You have the classes and their respective methods:

class Shape<br />
{<br />
   virtual void f{} to treat the Shape object (Whatever it be) who owns it<br />
}<br />
<br />
class Square : Shape <br />
{<br />
 override void f{}//supposedly to treat the Square object who owns it<br />
<br />
}<br />
<br />
class Circle : Shape <br />
{<br />
 override void f{}//supposedly to treat the Circle object who owns it<br />
}

if you do
Shape a1 = new Shape();
Square a2 = new Square();
Circle a3 = new Circle();

Logically,
a1.f() will call the Shape´s f method; a2.f() the Square´s, etc

BUT ALSO if you do this....( and that´s the nice part)

 Shape a1 ;<br />
 Square a2 = new Square();<br />
 Circle a3 = new Circle();<br />
a1= a2;<br />
a1.f(); //Will call the Square´s f method<br />
a1= a3;<br />
a1.f(); //Will call te Circle´s f method

which is something similar to what you said and is the usual way in which these kind of things are accomplished

This happens because the fmethod is declared virtual in Shape class an is overriden in the child classes otherwise, if they weren´t virtual then the calls of a1.f() always would call the Shape´s f method

Notice this approach is specially useful in this case

Class TestShapes{

void DoSomethingWithShapes(Shape s)
{
s.f();
//it will call the proper f method regarding if s is in fact a Square or a Circle or a general Shape (if this class is conceived to have instances ,thing that generally shouldn´t be taht way)

}
}

Maybe it helps

nigs_krec4-Mar-04 19:25

nigs_krec

4-Mar-04 19:25

Hello all,
My requirement is to add icons to the ContextMenu items. Any ideas how this can be achieved using C# ? There are lot many articles about how to associate icons with menus but none talk about context menus. Any help would be appreciated.
Thanks and regards,
Amit

Re: How to associate icons with ContextMenu ?

partyganger4-Mar-04 20:41

How to access parent form objects

4-Mar-04 20:41

In the standard Contextmenu you can't add an Image. You'll either have to write a derived class with it's own OnDraw method or build an Enxtender.
Or you download one of the existing open source menu / Context Menu systems, like Magic Library or Sandbar...

hongheo764-Mar-04 19:05

hongheo76

4-Mar-04 19:05

I am writing a form-based program with 2 forms: main & child.

The main form call the child form as:

frmChild child = new frmChild();
child.ShowDialog();

The problem is that in the child form, I want to change some properties of the main form (like button.Text, labels, etc). I also want to call some functions declared in the frmMain class.

I tried to use the Intelli Sense of VS in child, but when I type frmMain., it doesn't show up both the form main controls and the public functions declared in the frmMain class.

Can anyone intruct me how to do this ?

Thank you very much for your help.

Re: How to access parent form objects

Roman Rodov4-Mar-04 19:13

Roman Rodov

4-Mar-04 19:13

assume your parent forms class is "MyParentForm"
what you want to do in your child for is this:

<br />
MyParentForm frmParent = (MyParentForm)this.Parent<br />

this way you get to all the properties and public fields/methods of your parent form

It doesn't work

hongheo764-Mar-04 19:44

hongheo76

4-Mar-04 19:44

Sorry but it doesn't work at all.

VS didn't complain anything during compilation. However, during runtime, I got an exception saying:
Object reference not set to an instance of an object.

The watch window shows that frmParent (in your example) is an undefined value.

============
assume your parent forms class is "MyParentForm"
what you want to do in your child for is this:

MyParentForm frmParent = (MyParentForm)this.Parent

this way you get to all the properties and public fields/methods of your parent form

Re: It doesn't work

4-Mar-04 20:05

when you declare the child form in the parent form you must initialize the parent property of the child form before calling show() or showdialog()

EG. ChildForm frm = new ChildForm() ;
frm.parent = this ;
frm.ShowDialog() ;

Re: It doesn't work

partyganger4-Mar-04 20:52