Eventhandler in C# - How to send parameter
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Hi, My question is "How to send a user defined variable value while calling eventhandler. Pls go thru the below example: 1. I have an array of Pictureboxes arranged on a Panel 2. I have handled the Click event on PictureBoxes as below but dont know: how to pass "string FilePath" as part of "Object sender"
/* I have a string value (FilePath) parameter which I want to send to the function ClickHandler which gets invoked whenerever someone clicks on a PictureBox */ string FilePath; //Has file path info picBoxes[index].Click += new System.EventHandler(ClickHandler); ... ... // Signature of ClickHandler method is as follows public void ClickHandler(Object sender, System.EventArgs e) { // I can get the handle to the PictureBox which was clicked by the user // as follows PictureBox pbx = new PictureBox(); pbx = (PictureBox) ((System.Windows.Forms.PictureBox)sender); // How do I access FilePath ? }Thanks -
Hi, My question is "How to send a user defined variable value while calling eventhandler. Pls go thru the below example: 1. I have an array of Pictureboxes arranged on a Panel 2. I have handled the Click event on PictureBoxes as below but dont know: how to pass "string FilePath" as part of "Object sender"
/* I have a string value (FilePath) parameter which I want to send to the function ClickHandler which gets invoked whenerever someone clicks on a PictureBox */ string FilePath; //Has file path info picBoxes[index].Click += new System.EventHandler(ClickHandler); ... ... // Signature of ClickHandler method is as follows public void ClickHandler(Object sender, System.EventArgs e) { // I can get the handle to the PictureBox which was clicked by the user // as follows PictureBox pbx = new PictureBox(); pbx = (PictureBox) ((System.Windows.Forms.PictureBox)sender); // How do I access FilePath ? }ThanksHello, I think what you want to do is only possible with an Inherited class and the usage of Custom Eventargs. 1) Inherit a class from PictureBox
public class SpecialPictureBox : System.Windows.Forms.PictureBox
- Add a string property FilePath
private string _filepath = "";
[System.ComponentModel.DefaultValue("")]
public string FilePath
{
get
{
return _filepath;
}
set
{
_filepath = value;
}
}3)Inherit a class from System.EventArgs with a string member
public class SpecialEventArgs : System.EventArgs
{
public string filepath;public SpecialEventArgs(string \_filepath) { filepath= \_filepath; }}
4)Create a delegate for your special event in your SpecialPictureBox class, which uses the SpecialEventArgs.
public delegate void SpecialEvent(object sender, SpecialEventArgs specialEA);
5)Create an event which uses the delegate
public event SpecialEvent SpecialChanged;
6)override the OnClick event of your PictureBox and fire the event, with the Filepath property.
if(SpecialChanged!=null)
{
SpecialChanged(this, new SpecialEventArgs(this.FilePath));
}7)In your Form Handle the SpecialChanged event and set the FilePath property
yourSpecialPictureBox.FilePath = "yourpath";
yourSpecialPictureBox.SpecialChanged+= new YourNamespace.SpecialEvent(yourSpecialPictureBox_SpecialChanged);private void yourSpecialPictureBox_SpecialChanged(object sender, SpecialEventArgs specialEA)
{
//specialEA.filepath
}Hope it helps! -- modified at 5:35 Friday 27th July, 2007
All the best, Martin
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Hello, I think what you want to do is only possible with an Inherited class and the usage of Custom Eventargs. 1) Inherit a class from PictureBox
public class SpecialPictureBox : System.Windows.Forms.PictureBox
- Add a string property FilePath
private string _filepath = "";
[System.ComponentModel.DefaultValue("")]
public string FilePath
{
get
{
return _filepath;
}
set
{
_filepath = value;
}
}3)Inherit a class from System.EventArgs with a string member
public class SpecialEventArgs : System.EventArgs
{
public string filepath;public SpecialEventArgs(string \_filepath) { filepath= \_filepath; }}
4)Create a delegate for your special event in your SpecialPictureBox class, which uses the SpecialEventArgs.
public delegate void SpecialEvent(object sender, SpecialEventArgs specialEA);
5)Create an event which uses the delegate
public event SpecialEvent SpecialChanged;
6)override the OnClick event of your PictureBox and fire the event, with the Filepath property.
if(SpecialChanged!=null)
{
SpecialChanged(this, new SpecialEventArgs(this.FilePath));
}7)In your Form Handle the SpecialChanged event and set the FilePath property
yourSpecialPictureBox.FilePath = "yourpath";
yourSpecialPictureBox.SpecialChanged+= new YourNamespace.SpecialEvent(yourSpecialPictureBox_SpecialChanged);private void yourSpecialPictureBox_SpecialChanged(object sender, SpecialEventArgs specialEA)
{
//specialEA.filepath
}Hope it helps! -- modified at 5:35 Friday 27th July, 2007
All the best, Martin
-
Hello, I think what you want to do is only possible with an Inherited class and the usage of Custom Eventargs. 1) Inherit a class from PictureBox
public class SpecialPictureBox : System.Windows.Forms.PictureBox
- Add a string property FilePath
private string _filepath = "";
[System.ComponentModel.DefaultValue("")]
public string FilePath
{
get
{
return _filepath;
}
set
{
_filepath = value;
}
}3)Inherit a class from System.EventArgs with a string member
public class SpecialEventArgs : System.EventArgs
{
public string filepath;public SpecialEventArgs(string \_filepath) { filepath= \_filepath; }}
4)Create a delegate for your special event in your SpecialPictureBox class, which uses the SpecialEventArgs.
public delegate void SpecialEvent(object sender, SpecialEventArgs specialEA);
5)Create an event which uses the delegate
public event SpecialEvent SpecialChanged;
6)override the OnClick event of your PictureBox and fire the event, with the Filepath property.
if(SpecialChanged!=null)
{
SpecialChanged(this, new SpecialEventArgs(this.FilePath));
}7)In your Form Handle the SpecialChanged event and set the FilePath property
yourSpecialPictureBox.FilePath = "yourpath";
yourSpecialPictureBox.SpecialChanged+= new YourNamespace.SpecialEvent(yourSpecialPictureBox_SpecialChanged);private void yourSpecialPictureBox_SpecialChanged(object sender, SpecialEventArgs specialEA)
{
//specialEA.filepath
}Hope it helps! -- modified at 5:35 Friday 27th July, 2007
All the best, Martin
In .NET Framework 2.0, if you're following the
EventArgspattern, you don't need to declare your own delegate, you can use the genericEventHandler<T>delegate. Saves time and metadata space. So you'd havepublic event EventHandler<SpecialEventArgs> SpecialChanged;
yourSpecialPictureBox.SpecialChanged +=
new EventHandler<SpecialEventArgs>(yourSpecialPictureBox_SpecialChanged);I'm finding this pretty handy.
Stability. What an interesting concept. -- Chris Maunder
-
In .NET Framework 2.0, if you're following the
EventArgspattern, you don't need to declare your own delegate, you can use the genericEventHandler<T>delegate. Saves time and metadata space. So you'd havepublic event EventHandler<SpecialEventArgs> SpecialChanged;
yourSpecialPictureBox.SpecialChanged +=
new EventHandler<SpecialEventArgs>(yourSpecialPictureBox_SpecialChanged);I'm finding this pretty handy.
Stability. What an interesting concept. -- Chris Maunder
-
Hello, I think what you want to do is only possible with an Inherited class and the usage of Custom Eventargs. 1) Inherit a class from PictureBox
public class SpecialPictureBox : System.Windows.Forms.PictureBox
- Add a string property FilePath
private string _filepath = "";
[System.ComponentModel.DefaultValue("")]
public string FilePath
{
get
{
return _filepath;
}
set
{
_filepath = value;
}
}3)Inherit a class from System.EventArgs with a string member
public class SpecialEventArgs : System.EventArgs
{
public string filepath;public SpecialEventArgs(string \_filepath) { filepath= \_filepath; }}
4)Create a delegate for your special event in your SpecialPictureBox class, which uses the SpecialEventArgs.
public delegate void SpecialEvent(object sender, SpecialEventArgs specialEA);
5)Create an event which uses the delegate
public event SpecialEvent SpecialChanged;
6)override the OnClick event of your PictureBox and fire the event, with the Filepath property.
if(SpecialChanged!=null)
{
SpecialChanged(this, new SpecialEventArgs(this.FilePath));
}7)In your Form Handle the SpecialChanged event and set the FilePath property
yourSpecialPictureBox.FilePath = "yourpath";
yourSpecialPictureBox.SpecialChanged+= new YourNamespace.SpecialEvent(yourSpecialPictureBox_SpecialChanged);private void yourSpecialPictureBox_SpecialChanged(object sender, SpecialEventArgs specialEA)
{
//specialEA.filepath
}Hope it helps! -- modified at 5:35 Friday 27th July, 2007
All the best, Martin