TextBlockService.cs

//-----------------------------------------------------------------------
// <copyright file="TextBlockService.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
// <summary>
// Provides attached properties for TextBlock control.
// </summary>
//-----------------------------------------------------------------------

namespace Microsoft.Management.UI.Internal
{
    using System;
    using System.Windows;
    using System.Windows.Controls;
    using System.Windows.Media;
    using System.Diagnostics.CodeAnalysis;
    using System.ComponentModel;
    using System.Diagnostics;

    /// <summary>
    /// Attached property provider to <see cref="TextBlock"/> control.
    /// </summary>
    [SuppressMessage("Microsoft.MSInternal", "CA903:InternalNamespaceShouldNotContainPublicTypes")]
    public static partial class TextBlockService
    {
        static partial void IsTextTrimmedMonitoringEnabledProperty_PropertyChangedImplementation(DependencyObject o, DependencyPropertyChangedEventArgs e)
        {
            TextBlock tb = o as TextBlock;
            if (tb == null)
            {
                return;
            }
          
            if ((bool)e.OldValue == true)
            {
                tb.SizeChanged -= OnTextBlockSizeChanged;
            }
            else
            {
                tb.SizeChanged += OnTextBlockSizeChanged;
            }
        }

        private static void OnTextBlockSizeChanged(object sender, SizeChangedEventArgs e)
        {
            var textBlock = (TextBlock)sender;
            UpdateIsTextTrimmed(textBlock);
        }

        static void OnTextBlockPropertyChanged(object sender, EventArgs e)
        {
            var textBlock = (TextBlock)sender;
            UpdateIsTextTrimmed(textBlock);
        }

        static void UpdateIsTextTrimmed(TextBlock textBlock)
        {
            Debug.Assert(textBlock != null);

            if (textBlock.TextWrapping != TextWrapping.NoWrap || textBlock.TextTrimming == TextTrimming.None)
            {
                SetIsTextTrimmed(textBlock, false);
            }
            else
            {
                SetIsTextTrimmed(textBlock, CalculateIsTextTrimmed(textBlock));
            }
        }

        private static bool CalculateIsTextTrimmed(TextBlock textBlock)
        {
            if (!textBlock.IsArrangeValid)
            {
                return GetIsTextTrimmed(textBlock);
            }

            Typeface typeface = new Typeface(
                textBlock.FontFamily,
                textBlock.FontStyle,
                textBlock.FontWeight,
                textBlock.FontStretch);

            // FormattedText is used to measure the whole width of the text held up by TextBlock container
            FormattedText formattedText = new FormattedText(
                textBlock.Text,
                System.Threading.Thread.CurrentThread.CurrentCulture,
                textBlock.FlowDirection,
                typeface,
                textBlock.FontSize,
                textBlock.Foreground);

            return (formattedText.Width > textBlock.ActualWidth);
        }
    }
}