dansiegel/MarkdownView.cs

## MarkdownView.cs
using System;
using System.Collections.Generic;
using System.Text;
using Xamarin.Forms;
using HeyRed.MarkdownSharp;
using System.Runtime.CompilerServices;

// https://www.nuget.org/packages/Markdown/
namespace AwesomeApp.Controls
{
    public class MarkdownView : WebView
    {
        public static readonly BindableProperty MarkdownProperty =
            BindableProperty.Create(nameof(Markdown), typeof(string), typeof(MarkdownView), null, propertyChanged: OnMarkdownPropertyChanged);

        public static readonly BindableProperty OptionsProperty =
            BindableProperty.Create(nameof(Options), typeof(MarkdownOptions), typeof(MarkdownView), null, propertyChanged: OnMarkdownPropertyChanged);

        private static void OnMarkdownPropertyChanged(BindableObject bindable, object oldValue, object newValue)
        {
            if(bindable is MarkdownView mdv)
            {
                mdv.GenerateMarkdownSource();
            }
        }

        public string Markdown
        {
            get => (string)GetValue(MarkdownProperty);
            set => SetValue(MarkdownProperty, value);
        }

        public MarkdownOptions Options
        {
            get => (MarkdownOptions)GetValue(OptionsProperty);
            set => SetValue(OptionsProperty, value);
        }

        protected override void OnPropertyChanging([CallerMemberName] string propertyName = null)
        {
            if (propertyName == nameof(Source))
            {
                if (Source != null)
                {
                    Navigating -= MarkdownView_Navigating;
                }
                else
                {
                    Navigating += MarkdownView_Navigating;
                }
            }
        }

        private void GenerateMarkdownSource()
        {
            if(string.IsNullOrEmpty(Markdown))
            {
                Source = null;
            }

            var options = Options;
            if(options == null)
            {
                options = new MarkdownOptions
                {
                    AutoHyperlink = true,
                    AutoNewLines = true,
                    LinkEmails = true,
                    QuoteSingleLine = true,
                    StrictBoldItalic = true
                };
            }
            Markdown mark = new Markdown(options);
            var html = $@"<!DOCTYPE html>
<html>
<body>
{mark.Transform(Markdown)}
</body>
</html>";

            Source = new HtmlWebViewSource
            {
                Html = html
            };
        }

        private void MarkdownView_Navigating(object sender, WebNavigatingEventArgs e)
        {
            if (Uri.TryCreate(e.Url, UriKind.Absolute, out var uri) && uri.Scheme == "https" || uri.Scheme == "http")
            {
                e.Cancel = true;
                Xamarin.Essentials.Browser.OpenAsync(uri);
            }
        }
    }
}
	using System;
	using System.Collections.Generic;
	using System.Text;
	using Xamarin.Forms;
	using HeyRed.MarkdownSharp;
	using System.Runtime.CompilerServices;

	// https://www.nuget.org/packages/Markdown/
	namespace AwesomeApp.Controls
	{
	public class MarkdownView : WebView
	{
	public static readonly BindableProperty MarkdownProperty =
	BindableProperty.Create(nameof(Markdown), typeof(string), typeof(MarkdownView), null, propertyChanged: OnMarkdownPropertyChanged);

	public static readonly BindableProperty OptionsProperty =
	BindableProperty.Create(nameof(Options), typeof(MarkdownOptions), typeof(MarkdownView), null, propertyChanged: OnMarkdownPropertyChanged);

	private static void OnMarkdownPropertyChanged(BindableObject bindable, object oldValue, object newValue)
	{
	if(bindable is MarkdownView mdv)
	{
	mdv.GenerateMarkdownSource();
	}
	}

	public string Markdown
	{
	get => (string)GetValue(MarkdownProperty);
	set => SetValue(MarkdownProperty, value);
	}

	public MarkdownOptions Options
	{
	get => (MarkdownOptions)GetValue(OptionsProperty);
	set => SetValue(OptionsProperty, value);
	}

	protected override void OnPropertyChanging([CallerMemberName] string propertyName = null)
	{
	if (propertyName == nameof(Source))
	{
	if (Source != null)
	{
	Navigating -= MarkdownView_Navigating;
	}
	else
	{
	Navigating += MarkdownView_Navigating;
	}
	}
	}

	private void GenerateMarkdownSource()
	{
	if(string.IsNullOrEmpty(Markdown))
	{
	Source = null;
	}

	var options = Options;
	if(options == null)
	{
	options = new MarkdownOptions
	{
	AutoHyperlink = true,
	AutoNewLines = true,
	LinkEmails = true,
	QuoteSingleLine = true,
	StrictBoldItalic = true
	};
	}
	Markdown mark = new Markdown(options);
	var html = $@"<!DOCTYPE html>
	<html>
	<body>
	{mark.Transform(Markdown)}
	</body>
	</html>";

	Source = new HtmlWebViewSource
	{
	Html = html
	};
	}

	private void MarkdownView_Navigating(object sender, WebNavigatingEventArgs e)
	{
	if (Uri.TryCreate(e.Url, UriKind.Absolute, out var uri) && uri.Scheme == "https" \|\| uri.Scheme == "http")
	{
	e.Cancel = true;
	Xamarin.Essentials.Browser.OpenAsync(uri);
	}
	}
	}
	}