BeWoPlaner/BeWo/OutlinedTextBlock.cs

using System;
using System.ComponentModel;
using System.Globalization;
using System.Windows;
using System.Windows.Documents;
using System.Windows.Markup;
using System.Windows.Media;

namespace BeWo
{
	[ContentProperty("Text")]
	public class OutlinedTextBlock : FrameworkElement
	{
		public static readonly DependencyProperty FillProperty = DependencyProperty.Register(
			"Fill",
			typeof(Brush),
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(Brushes.Black, FrameworkPropertyMetadataOptions.AffectsRender));

		public static readonly DependencyProperty StrokeProperty = DependencyProperty.Register(
			"Stroke",
			typeof(Brush),
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(Brushes.Black, FrameworkPropertyMetadataOptions.AffectsRender));

		public static readonly DependencyProperty StrokeThicknessProperty = DependencyProperty.Register(
			"StrokeThickness",
			typeof(double),
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(1d, FrameworkPropertyMetadataOptions.AffectsRender));

		public static readonly DependencyProperty FontFamilyProperty = TextElement.FontFamilyProperty.AddOwner(
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(OnFormattedTextUpdated));

		public static readonly DependencyProperty FontSizeProperty = TextElement.FontSizeProperty.AddOwner(
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(OnFormattedTextUpdated));

		public static readonly DependencyProperty FontStretchProperty = TextElement.FontStretchProperty.AddOwner(
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(OnFormattedTextUpdated));

		public static readonly DependencyProperty FontStyleProperty = TextElement.FontStyleProperty.AddOwner(
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(OnFormattedTextUpdated));

		public static readonly DependencyProperty FontWeightProperty = TextElement.FontWeightProperty.AddOwner(
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(OnFormattedTextUpdated));

		public static readonly DependencyProperty TextProperty = DependencyProperty.Register(
			"Text",
			typeof(string),
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(OnFormattedTextInvalidated));

		public static readonly DependencyProperty TextAlignmentProperty = DependencyProperty.Register(
			"TextAlignment",
			typeof(TextAlignment),
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(OnFormattedTextUpdated));

		public static readonly DependencyProperty TextDecorationsProperty = DependencyProperty.Register(
			"TextDecorations",
			typeof(TextDecorationCollection),
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(OnFormattedTextUpdated));

		public static readonly DependencyProperty TextTrimmingProperty = DependencyProperty.Register(
			"TextTrimming",
			typeof(TextTrimming),
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(OnFormattedTextUpdated));

		public static readonly DependencyProperty TextWrappingProperty = DependencyProperty.Register(
			"TextWrapping",
			typeof(TextWrapping),
			typeof(OutlinedTextBlock),
			new FrameworkPropertyMetadata(TextWrapping.NoWrap, OnFormattedTextUpdated));

		private FormattedText formattedText;
		private Geometry textGeometry;

		public OutlinedTextBlock()
		{
			TextDecorations = new TextDecorationCollection();
		}

		public Brush Fill
		{
			get { return (Brush)GetValue(FillProperty); }
			set { SetValue(FillProperty, value); }
		}

		public FontFamily FontFamily
		{
			get { return (FontFamily)GetValue(FontFamilyProperty); }
			set { SetValue(FontFamilyProperty, value); }
		}

		[TypeConverter(typeof(FontSizeConverter))]
		public double FontSize
		{
			get { return (double)GetValue(FontSizeProperty); }
			set { SetValue(FontSizeProperty, value); }
		}

		public FontStretch FontStretch
		{
			get { return (FontStretch)GetValue(FontStretchProperty); }
			set { SetValue(FontStretchProperty, value); }
		}

		public FontStyle FontStyle
		{
			get { return (FontStyle)GetValue(FontStyleProperty); }
			set { SetValue(FontStyleProperty, value); }
		}

		public FontWeight FontWeight
		{
			get { return (FontWeight)GetValue(FontWeightProperty); }
			set { SetValue(FontWeightProperty, value); }
		}

		public Brush Stroke
		{
			get { return (Brush)GetValue(StrokeProperty); }
			set { SetValue(StrokeProperty, value); }
		}

		public double StrokeThickness
		{
			get { return (double)GetValue(StrokeThicknessProperty); }
			set { SetValue(StrokeThicknessProperty, value); }
		}

		public string Text
		{
			get { return (string)GetValue(TextProperty); }
			set { SetValue(TextProperty, value); }
		}

		public TextAlignment TextAlignment
		{
			get { return (TextAlignment)GetValue(TextAlignmentProperty); }
			set { SetValue(TextAlignmentProperty, value); }
		}

		public TextDecorationCollection TextDecorations
		{
			get { return (TextDecorationCollection)GetValue(TextDecorationsProperty); }
			set { SetValue(TextDecorationsProperty, value); }
		}

		public TextTrimming TextTrimming
		{
			get { return (TextTrimming)GetValue(TextTrimmingProperty); }
			set { SetValue(TextTrimmingProperty, value); }
		}

		public TextWrapping TextWrapping
		{
			get { return (TextWrapping)GetValue(TextWrappingProperty); }
			set { SetValue(TextWrappingProperty, value); }
		}

		protected override void OnRender(DrawingContext drawingContext)
		{
			EnsureGeometry();

			drawingContext.DrawGeometry(Fill, new Pen(Stroke, StrokeThickness), textGeometry);
		}

		protected override Size MeasureOverride(Size availableSize)
		{
			EnsureFormattedText();

			// constrain the formatted text according to the available size
			// the Math.Min call is important - without this constraint (which seems arbitrary, but is the maximum allowable text width), things blow up when availableSize is infinite in both directions
			// the Math.Max call is to ensure we don't hit zero, which will cause MaxTextHeight to throw
			formattedText.MaxTextWidth = Math.Min(3579139, availableSize.Width);
			formattedText.MaxTextHeight = Math.Max(0.0001d, availableSize.Height);

			// return the desired size
			return new Size(formattedText.Width, formattedText.Height);
		}

		protected override Size ArrangeOverride(Size finalSize)
		{
			EnsureFormattedText();

			// update the formatted text with the final size
			formattedText.MaxTextWidth = finalSize.Width;
			formattedText.MaxTextHeight = finalSize.Height;

			// need to re-generate the geometry now that the dimensions have changed
			textGeometry = null;

			return finalSize;
		}

		private static void OnFormattedTextInvalidated(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
		{
			var outlinedTextBlock = (OutlinedTextBlock)dependencyObject;
			outlinedTextBlock.formattedText = null;
			outlinedTextBlock.textGeometry = null;

			outlinedTextBlock.InvalidateMeasure();
			outlinedTextBlock.InvalidateVisual();
		}

		private static void OnFormattedTextUpdated(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
		{
			var outlinedTextBlock = (OutlinedTextBlock)dependencyObject;
			outlinedTextBlock.UpdateFormattedText();
			outlinedTextBlock.textGeometry = null;

			outlinedTextBlock.InvalidateMeasure();
			outlinedTextBlock.InvalidateVisual();
		}

		private void EnsureFormattedText()
		{
			if (formattedText != null || Text == null)
			{
				return;
			}

			formattedText = new FormattedText(
				Text,
				CultureInfo.CurrentUICulture,
				FlowDirection,
				new Typeface(FontFamily, FontStyle, FontWeight, FontStretches.Normal),
				FontSize,
				Brushes.Black);

			UpdateFormattedText();
		}

		private void UpdateFormattedText()
		{
			if (formattedText == null)
			{
				return;
			}

			formattedText.MaxLineCount = TextWrapping == TextWrapping.NoWrap ? 1 : int.MaxValue;
			formattedText.TextAlignment = TextAlignment;
			formattedText.Trimming = TextTrimming;

			formattedText.SetFontSize(FontSize);
			formattedText.SetFontStyle(FontStyle);
			formattedText.SetFontWeight(FontWeight);
			formattedText.SetFontFamily(FontFamily);
			formattedText.SetFontStretch(FontStretch);
			formattedText.SetTextDecorations(TextDecorations);
		}

		private void EnsureGeometry()
		{
			if (textGeometry != null)
			{
				return;
			}

			EnsureFormattedText();
			textGeometry = formattedText.BuildGeometry(new Point(0, 0));
		}
	}
}