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I have a class that uses generics to have a typesafe DataSource property. I want to pass an instance of this class to a form and have it display the datasource. The code looks something like this:
public class DataSource<ItemType> where ItemType : StatefulObjectBase
{
public ItemType DataSource
{
....
}
public void Show()
{
DisplayForm f = new DisplayForm(this);
}
}
The question is, how do I code the parameter on the forms constructor. Using DataSource<StatefulObjectBase> doesnt work, even though the compiler should know that whatever is in the object is convertible to that type. Even using object didnt work.
All I want to do from the form is access some methods from my generic object. I dont care what type they are.
Any help would be much appreciated.
EDIT: oops, fixing generics.. damn less than and great thans
--
Dave
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There are couple problems with this.
1. You cannot have public ItemType DataSource property as DataSource is name of the class
2. C# does supports generic methods, but not generic constructors.
You can write your code like:
<code>
public interface StatefulObjectBase
{
}
public class DataSource<ItemType> where ItemType : StatefulObjectBase
{
public ItemType TheDataSource
{
get { return default(ItemType); }
}
public void Show()
{
DisplayForm f = new DisplayForm();
f.Show<ItemType>(this);
}
}
public class DisplayForm
{
public DisplayForm()
{
}
public void Show<ItemType>(DataSource<ItemType> source) where ItemType : StatefulObjectBase
{
}
}
</code>
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i am very new to c# and ASP.NET but i want to load audio files during application startup and play when button clicked. i got worked out how to do in windows forms with FileOpenDialog but i do not want openFileDialog in ASP.NET!
Any one with tips, hints please help!
Thank you
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Where do you want to load audio files from ? If from the server, then an open file dialog will not help anyhow. If from the client, I'm not sure that you can. You can replace an openfiledialgo with a hardcoded path, but the real issue is where are the sound files, on the client or the server ? If on the server, then they can be played, but I'm at a loss as to why you're worried about a file browser ( which can't see the server anyhow ).
Christian Graus - Microsoft MVP - C++
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right now, i have all files in local computer. Some under http://localhost: and audio files in c:\My Documents folder. I have created all web forms with button to play Audio file but in windows forms it is ok by using OpenFileDialog and playback. Let say, in web forms using c# how could i load audio files and play back using button with out using FileOpenDialog?
Thank you Christian
I appreciated any help!
Thank you
abudicha
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OK - so you want a webpage to load files off the users local computer, not off the server, and play them ? Why ? How can you browse to the users files without using a file browse dialog ? What are you hoping to have happen here ?
Christian Graus - Microsoft MVP - C++
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right now, i want to know how can i load files when i just
run files from localhost as "http://localhost/webApp/default.aspx" to load audio files with out interaction with fileDialog?
I do not mind which folder will be? i can put under wwwroot or under IIS if necessary. But i need direction how to do it?
Thank Christian
I appreciated any helps
Adam Budicha
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OK - so you're going to run them off the server. The but that I'm lost with is why you're talking about a file dialog. Do you want to allow the user to browse the music files ? A file dialog won't help here, the files are on the server.
Here[^] is an article on getting music files to play in a web page. ASP.NET has nothing to do with it, the browser needs to pass the file down in a format that the browser knows what to do with. I don't believe ASP.NET encapsulates that sort of behaviour in any classes, so you need to do it yourself.
Christian Graus - Microsoft MVP - C++
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I've added to my form a status bar and 2 panels.
The status bar is on the bottom, while the first panel is on the left the second panel is on the right.
I want the first panel is of 50 pixel always.
The second panel became bigger if the user resize the window.
It should attached to the first panel but the right follow the right of the window...
I would the status bar do that to... but i've not success neighter with the second panel nor the status bar...
why?
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You'll probably have to size and position it yourself by responding to the forms resize event. Plan on spending a few hours Trial and erroring out magic numbers relating to border widths and the like. The form's size includes the border/menu/title bar space, pixel 0,0 is the upperleft most pixel inside/below all of that.
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Need some help accesing methods of a parent form, from a child form.
How is this done?
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if those methods are public, child form can siply keep reference to it's parent.. oh wait.. that should we be in Owner property of child form, if you display it with ShowDialog( IWin32Window ) overload of that method. If they are not public, can you make them public? ( or internal)
David
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A parent form is a form which is a MdiContainer. A child form can call its parent using childfrom.MdiParent.
==== Lei Ming 2004 =====
====================
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Yes but the methods of the parent form are not shown using childform.MdiParent
What if i'm not using an MDI container?
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You need to cast it the concrete class. i.e.
MyMainForm frm = Parent as MyMainForm;
60% of statistics are made up on the spot
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Still not getting it.
This is my code:
In the MainForm (GameForm)...
BuyingForm f = new BuyingForm(new_item); //new instance of a "child" form
GameForm gameForm = Parent as GameForm;
f.Parent = gameForm;
f.Show();
In the ChildForm (BuyingForm)...
this.ParentForm.SomeMethod(); //the method is not listed
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Setup a field on your BuyingForm that holds a Form:
public class BuyingForm : Form
Form myParent;
.
.
.
myParent.PublicMethodCall( parameters );
When you create an instance of this form, just set this field before you show the form:
BuyingForm f = new BuyingForm(new_item);
f.myParent = this;
f.Show();
If you use the Parent property of the form to do this, you could have some very strange and unintended side effects.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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What would be the safest way to do this? To avoid the strange unintended side effect.
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If you look at my previous post, you don't have to worry about it.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Changed the code but i still cant access any user made methods in my parent form, and yes they are declared as public. All i can see is the usual methods, events and properties of a form. Sorry to be a drag but whats going on?
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ok finally got it working, thanks for your help!
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hi, I'm making a simple download application. How do I get information about the file before I download it such as its size and name (without all the http information and such)? Also, in many download managers there is the option to download the rest of the file later, how is this done, I'm not asking for the rediculous amount of code it would take, but could you point me in the right direction? Thanks,
Stephen
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Well, it is all done using the HTTP headers. One tells you the Content-Length,
other tells you the Content-Type, etc. And wneh you make an HTTP request, using
another HTTP header (don't remember the exact name) you can tell the offset
from which you want to receive tha data. That's it. Just find e good HTTP reference
and you'll be OK.
Cheers 
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Using C#, there's FileInfo class that can be instanciated. It gives all the informaion of a file, including size and date created, ect. For the download resume, there is a code at http://www.csharphelp.com/archives/archive9.html[^] that would give some insight of how to do it.
==== Lei Ming 2004 =====
====================
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