Silverlight 3/Wpf : Adding Controls Dynamicallys

Lets see how to dynamically add controls and attaching event handler to the added control.

Here I am creating an object of button class and adding it into the Grid using the Add method of Grid's Children property.

private void btnAddControl_Click(object sender, RoutedEventArgs e)
{
Button btn = new Button();
btn.Click += new RoutedEventHandler(btn_Click);
btn.Content = "Shalvin";
btn.Width = 75;
btn.Height = 25;
Grid1.Children.Add(btn);
}

private void btn_Click(object sender, RoutedEventArgs e)
{
//MessageBox works only with WPF , Silverlight 3 and not with Silverlight 2
MessageBox.Show("ShalvinPD.blogspot.com");
}

Result

WPF Routed Event

A routed event is a type of event that can invoke handlers on multiple listeners in an element tree, rather than just on the object that raised the event.

For example if you want a single event handler for the buttons inside a Grid you can define a Routed event as Button.Click = "Grid_Click" inside the Grid as shown in the diagram.









private void Grid_Click(object sender, RoutedEventArgs e)
{
//MessageBox works only with WPF and not Silverlight 2
MessageBox.Show("ShalvinPD.blogspot.com");
}

WPF and Silverlight Creating Class with Constructors

(I have updated this blog on Mar 23, 2010 to showcase Silverlight 4 and Visual Studio 2010.
The same will work with WPF)















Create a new Silverlight 4 Application in Visual Studio 2010.

Creating a Silverlight Application Project creates two projects one a Silverlight Project and another a Web Project used for Hosting Silverlight.

Select Silverlight Project, Add a class by selecting Project, Add class menu option. Give the class a good name say Bank.

So we are going to create a Bank Class with two properties and one method.







In this article we are going to take up the issue of creating a class in C#.

C# has the notion of read write, read only and write only properties. Here we are going to have one read write properties, Bank.
For creating a class there property procedures. For read write property we should have both getter and setter and a private memory variable which actually holds the value. Getter is used for returning the value of the private memory variable and Setter is used for setting a value to the private memory variable which in effect reflects the value of the property.

The methods are Deposit and Withdraw.

I am also implementing a default and a parameterized constructor.



Here is the code of Bank class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace WpFCSClass
{
class Bank
{
public Bank()
{
miBalance = 5000;
}

public Bank(int mAmount)
{
Balance = mAmount;
}
private int miBalance;
public int Balance
{
get {
return miBalance;
}
set {
miBalance = value;
}
}

public void Deposit(int Amount)
{
Balance = Balance + Amount;
}

public void Withdraw(int Amount)
{
Balance = Balance - Amount;
}
}
}

Having created the class we can shift out attention to the presentation layer. The presentation layer can be anything ranging from Windows Forms Application, Web Forms Application, WPF etc. I decided to choose WPF.




















Bank ShalvinBank = new Bank(2000);
private void Window_Loaded(object sender, RoutedEventArgs e)
{
ShowBal();
}
private void ShowBal()
{
lblCurBal.Content = ShalvinBank.Balance.ToString();
txtAmount.Text = "";
txtAmount.Focus();
}

private void btnDeposit_Click(object sender, RoutedEventArgs e)
{
ShalvinBank.Deposit(Int32.Parse(txtAmount.Text));
ShowBal();
}

private void btnWithdraw_Click(object sender, RoutedEventArgs e)
{
ShalvinBank.Withdraw(Int32.Parse(txtAmount.Text));
ShowBal();
}

Happy Programming

shalvin@gmail.com