PowerShell-master/src/Microsoft.Management.UI.Internal/ManagementList/Common/MessageTextBox.cs

// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.

using System;
using System.Diagnostics.CodeAnalysis;
using System.Windows;
using System.Windows.Controls;

namespace Microsoft.Management.UI.Internal
{
    /// <content>
    /// Partial class implementation for MessageTextBox control.
    /// </content>
    [SuppressMessage("Microsoft.MSInternal", "CA903:InternalNamespaceShouldNotContainPublicTypes")]
    public partial class MessageTextBox : TextBox
    {
        static partial void StaticConstructorImplementation()
        {
            TextProperty.OverrideMetadata(
                                          typeof(MessageTextBox),
                                          new FrameworkPropertyMetadata(
                                                                        string.Empty,
                                                                        null,
                                                                        new CoerceValueCallback(OnTextBoxTextCoerce)));
        }

        #region Non-Public Methods

        private void UpdateIsBackgroundTextShown(string text)
        {
            if (string.IsNullOrEmpty(text) == false && this.IsBackgroundTextShown)
            {
                this.IsBackgroundTextShown = false;
            }
            else if (string.IsNullOrEmpty(text) && this.IsBackgroundTextShown == false)
            {
                this.IsBackgroundTextShown = true;
            }
        }

        private static object OnTextBoxTextCoerce(DependencyObject o, object baseValue)
        {
            MessageTextBox mtb = (MessageTextBox)o;

            mtb.UpdateIsBackgroundTextShown((string)baseValue);

            if (baseValue == null)
            {
                return string.Empty;
            }

            return baseValue;
        }

        #endregion Non-Public Methods
    }
}