How to change main window color when textbox input changes in WPF application?

Question

I want to change main window color when textbox input changes in WPF application. Currently, when mouse hover or enters the textbox color changes but I will remove this as I do not want this effect. But I want the same effect when mouse cursor enters into textboxes, it should change main back ground colors.

MainWindow background color is:

LightBlue, when mouse cursor enters A inputbox
LightGreen, when mouse cursor enters B inputbox
LightGray,all other cases.

Model.cs

public abstract class ObservableBase : INotifyPropertyChanged
{
    public void Set(ref TValue field, TValue newValue, [CallerMemberName] string propertyName = "")
    {
        if (!EqualityComparer.Default.Equals(field, default(TValue)) && field.Equals(newValue)) return;
        field = newValue;
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public void NotifyPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}


public abstract class ViewModelBase : ObservableBase
{
    public bool IsInDesignMode
        => (bool)DesignerProperties.IsInDesignModeProperty
            .GetMetadata(typeof(DependencyObject))
            .DefaultValue;
}

MainViewModel.cs

 public class MainViewModel : ViewModelBase
    {
        public MainViewModel()
        {
            valueAisValid = true;
            valueBisValid = true;
            if (IsInDesignMode)
            {
                Calc();
            }
        }

        #region Properties

        private string valueA;
        public string ValueA
        {
            get => valueA;
            set
            {
                if (!string.IsNullOrEmpty(value))
                {
                    Set(ref valueA, value);
                    Set(ref valueAisValid, double.TryParse(ValueA, out double d));
                    NotifyPropertyChanged(nameof(ValueAIsValid));
                    Calc();
                }
            }
        }

        private bool valueAisValid;
        public bool ValueAIsValid => valueAisValid;

        private string valueB;
        public string ValueB
        {
            get => valueB;
            set
            {
                if (!string.IsNullOrEmpty(value))
                {
                    Set(ref valueB, value);
                    Set(ref valueBisValid, double.TryParse(ValueB, out double d));
                    NotifyPropertyChanged(nameof(ValueBIsValid));
                    Calc();
                }
            }
        }

        private bool valueBisValid;
        public bool ValueBIsValid => valueBisValid;

        private string valueC;
        public string ValueC
        {
            get => valueC;
            set => Set(ref valueC, value);
        }

        private string valueD;
        public string ValueD
        {
            get => valueD;
            set => Set(ref valueD, value);
        }

        public bool InputsValid => ValueAIsValid && ValueBIsValid;

        #endregion

        #region Methods

        private void Calc()
        {
            if (InputsValid)
            {
                double sum = Convert.ToDouble(valueA) + Convert.ToDouble(valueB);
                double product = Convert.ToDouble(valueA) * Convert.ToDouble(valueB);
                ValueC = sum.ToString(CultureInfo.InvariantCulture);
                ValueD = product.ToString(CultureInfo.InvariantCulture);
            }
            else
            {
                ValueC = "NAN";
                ValueD = "NAN";
            }
        }

        #endregion
    }

BoolToBackgroundColorConverter

   public class BoolToBackgroundColorConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value != null && !(bool)value)
            {
                return new SolidColorBrush(Colors.Red);
            }
            else if (value != null && (bool)value && parameter != null)
            {
                return (SolidColorBrush)parameter;
            }
            else
            {
                return new SolidColorBrush(Colors.White);
            }
        }
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

Xaml

Mac · Accepted Answer

Here's the MainWindow.xaml.cs

using System.Windows;
using System.Windows.Input;
using System.Windows.Media;

namespace WpfApp1
{
    public partial class MainWindow
    {
        public MainWindow()
        {
            InitializeComponent();
            AttachCustomBehaviors();
        }

        // There's a better way of doing this, read attached behavior in wpf
        private void AttachCustomBehaviors()
        {
            TextBoxA.GotFocus += (s, args) => ChangeMainWindowBackground(this, Brushes.LightBlue);
            TextBoxB.GotFocus += (s, args) => ChangeMainWindowBackground(this, Brushes.LightGreen);
            TextBoxA.LostFocus += (s, args) => ChangeMainWindowBackground(this, Brushes.Gray);
            TextBoxB.LostFocus += (s, args) => ChangeMainWindowBackground(this, Brushes.Gray);
        }

        private void InputFieldsHovered(object sender, MouseEventArgs e)
        {
            if (!TextBoxA.IsFocused && !TextBoxB.IsFocused)
            {
                ChangeMainWindowBackground(this, Brushes.Gray);
            }
            else if(TextBoxA.IsFocused)
            {
                ChangeMainWindowBackground(this, Brushes.LightBlue);
            }
            else if (TextBoxB.IsFocused)
            {
                ChangeMainWindowBackground(this, Brushes.LightGreen);
            }
        }

        private static void ChangeMainWindowBackground(Window window, SolidColorBrush color)
        {
            window.Background = color;
        }
    }
}

Here's the updated xaml:

How to change main window color when textbox input changes in WPF application?

Answers (2)

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