A Sample Silverlight 4 Application Using MEF, MVVM, and WCF RIA Services - Part 1

using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.ComponentModel.Composition;
using GalaSoft.MvvmLight;
using IssueVision.Common;

namespace IssueVision.Client
{
    public partial class LoginForm : UserControl
    {
        #region "Constructor"
        public LoginForm()
        {
            InitializeComponent();

            if (!ViewModelBase.IsInDesignModeStatic)
            {
                // Use MEF To load the View Model
                this.DataContext = App.Container.GetExportedValue<ViewModelBase>(
                    ViewModelTypes.LoginFormViewModel);
            }
        }
        #endregion "Constructor"

        #region "Event handlers"

        private void userNameTextBox_TextChanged(object sender, TextChangedEventArgs e)
        {
            // dynamically enable/disable error message
            if (!string.IsNullOrWhiteSpace(this.loginScreenErrorMessageTextBox.Text))
                this.loginScreenErrorMessageTextBox.Text = string.Empty;

            // dynamically enable/disable login button
            this.loginButton.IsEnabled = !(string.IsNullOrWhiteSpace(this.userNameTextBox.Text) ||
                string.IsNullOrWhiteSpace(this.passwordPasswordBox.Password));
        }

        private void passwordPasswordBox_PasswordChanged(object sender, RoutedEventArgs e)
        {
            // dynamically enable/disable error message
            if (!string.IsNullOrWhiteSpace(this.loginScreenErrorMessageTextBox.Text))
                this.loginScreenErrorMessageTextBox.Text = string.Empty;

            // dynamically enable/disable login button
            this.loginButton.IsEnabled = !(string.IsNullOrWhiteSpace(this.userNameTextBox.Text) ||
                string.IsNullOrWhiteSpace(this.passwordPasswordBox.Password));
        }

        private void securityAnswerPasswordBox_PasswordChanged(object sender, RoutedEventArgs e)
        {
            // dynamically enable/disable error message
            if (!string.IsNullOrWhiteSpace(this.resetPasswordScreenErrorMessageTextBox.Text))
                this.resetPasswordScreenErrorMessageTextBox.Text = string.Empty;

            // dynamically enable/disable reset password button
            this.resetPasswordButton.IsEnabled = !(string.IsNullOrWhiteSpace(this.newPasswordPasswordBox.Password) ||
                string.IsNullOrWhiteSpace(this.confirmPasswordPasswordBox.Password) ||
                string.IsNullOrEmpty(this.securityAnswerPasswordBox.Password));
        }

        private void newPasswordPasswordBox_PasswordChanged(object sender, RoutedEventArgs e)
        {
            // update the ActualPassword every time password changes
            this.ActualPasswordTextBlock.Text = this.newPasswordPasswordBox.Password;

            // dynamically enable/disable error message
            if (!string.IsNullOrWhiteSpace(this.resetPasswordScreenErrorMessageTextBox.Text))
                this.resetPasswordScreenErrorMessageTextBox.Text = string.Empty;

            // dynamically enable/disable reset password button
            this.resetPasswordButton.IsEnabled = !(string.IsNullOrWhiteSpace(this.newPasswordPasswordBox.Password) ||
                string.IsNullOrWhiteSpace(this.confirmPasswordPasswordBox.Password) ||
                string.IsNullOrEmpty(this.securityAnswerPasswordBox.Password));
        }

        private void newPasswordPasswordBox_LostFocus(object sender, RoutedEventArgs e)
        {
            // If confirm password is not empty, we need to re-validate confirm
            // password after leaving password field
            if (!string.IsNullOrEmpty(this.confirmPasswordPasswordBox.Password))
            {
                BindingExpression be = this.confirmPasswordPasswordBox.GetBindingExpression(PasswordBox.PasswordProperty);
                if (be != null)
                    be.UpdateSource();
            }
        }

        private void confirmPasswordPasswordBox_PasswordChanged(object sender, RoutedEventArgs e)
        {
            // dynamically enable/disable error message
            if (!string.IsNullOrWhiteSpace(this.resetPasswordScreenErrorMessageTextBox.Text))
                this.resetPasswordScreenErrorMessageTextBox.Text = string.Empty;

            // dynamically enable/disable reset password button
            this.resetPasswordButton.IsEnabled = !(string.IsNullOrWhiteSpace(this.newPasswordPasswordBox.Password) ||
                string.IsNullOrWhiteSpace(this.confirmPasswordPasswordBox.Password) ||
                string.IsNullOrEmpty(this.securityAnswerPasswordBox.Password));
        }

        #endregion "Event handlers"
    }
}