超链接未呈现Xamarin.forms

Question

我创建了一个试图从一组标签中解析超链接的类，它似乎可以识别超链接，但从未将标签中的正确跨度更改为超链接。我首先尝试：

public class HtmlLabelConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var formatted = new FormattedString();

            foreach (var item in ProcessString((string)value))
                formatted.Spans.Add(CreateSpan(item));

            return formatted;
        }

        private Span CreateSpan(StringSection section)
        {
            var span = new Span()
            {
                Text = section.Text
            };

            if (!string.IsNullOrEmpty(section.Link))
            {
                span.GestureRecognizers.Add(new TapGestureRecognizer()
                {
                    Command = _navigationCommand,
                    CommandParameter = section.Link
                });
                span.TextColor = Color.Blue;
                span.TextDecorations = TextDecorations.Underline;
            }

            return span;
        }

        public IList<StringSection> ProcessString(string rawText)
        {
            const string spanPattern = @"(<a.*?>.*?</a>)";

            MatchCollection collection = Regex.Matches(rawText, spanPattern, RegexOptions.Singleline);

            var sections = new List<StringSection>();

            var lastIndex = 0;

            foreach (Match item in collection)
            {
                var foundText = item.Value;
                sections.Add(new StringSection() { Text = rawText.Substring(lastIndex, item.Index) });
                lastIndex += item.Index + item.Length;

                // Get HTML href 
                var html = new StringSection()
                {
                    Link = Regex.Match(item.Value, "(?<=href=\\\")[\\S]+(?=\\\")").Value,
                    Text = Regex.Replace(item.Value, "<.*?>", string.Empty)
                };

                sections.Add(html);
            }

            sections.Add(new StringSection() { Text = rawText.Substring(lastIndex) });

            return sections;
        }

        public class StringSection
        {
            public string Text { get; set; }
            public string Link { get; set; }
        }

        private ICommand _navigationCommand = new Command<string>((url) =>
        {
            //Device.OpenUri(new Uri(url));
            Launcher.TryOpenAsync(new Uri(url));
        });

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

与xaml中的

<Label x:Name="labelParagraph"
               FormattedText="{Binding Paragraph, Converter={StaticResource HtmlLabelConverter}}"/>

和格式如下的文本<a href="www.google.com"> link </a>，它从文本中删除了<a href>部分，但没有将link变成超链接。这告诉我它正在查找超链接，但由于某种原因未执行该命令。其次，我尝试了以下自定义标签：

public class LinksLabel : Label
    {
        public static BindableProperty LinksTextProperty = BindableProperty.Create(nameof(LinksText), typeof(string), typeof(LinksLabel), propertyChanged: OnLinksTextPropertyChanged);

        private readonly ICommand _linkTapGesture = new Command<string>((url) => Device.OpenUri(new Uri(url)));

        public string LinksText
        {
            get => GetValue(LinksTextProperty) as string;
            set => SetValue(LinksTextProperty, value);
        }

        private void SetFormattedText()
        {
            var formattedString = new FormattedString();

            if (!string.IsNullOrEmpty(LinksText))
            {
                var splitText = LinksText.Split(' ');

                foreach (string textPart in splitText)
                {
                    var span = new Span { Text = $"{textPart} " };

                    if (IsUrl(textPart)) // a link
                    {
                        span.TextColor = Color.DeepSkyBlue;
                        span.GestureRecognizers.Add(new TapGestureRecognizer
                        {
                            Command = _linkTapGesture,
                            CommandParameter = textPart
                        });
                    }

                    formattedString.Spans.Add(span);
                }
            }

            this.FormattedText = formattedString;
        }

        private bool IsUrl(string input)
        {
            return Uri.TryCreate(input, UriKind.Absolute, out var uriResult) &&
              (uriResult.Scheme == Uri.UriSchemeHttp || uriResult.Scheme == Uri.UriSchemeHttps);
        }

        private static void OnLinksTextPropertyChanged(BindableObject bindable, object oldValue, object newValue)
        {
            var linksLabel = bindable as LinksLabel;
            linksLabel.SetFormattedText();
        }
    }

使用

<custom:LinksLabel
LinksText="blah blah blah www.google.com blah"/>

但是同样，这不会将任何内容呈现给超链接。

Answer 1

尝试此解决方案，它将为您提供外观超链接。

XAML：

<Label HorizontalOptions="Center"
       VerticalOptions="CenterAndExpand">
    <Label.FormattedText>
        <FormattedString>
            <Span Text="Hello " />
            <Span Text="Click Me!"
                  TextColor="Blue"
                  TextDecorations="Underline">
                <Span.GestureRecognizers>
                    <TapGestureRecognizer Command="{Binding ClickCommand}"
                                          CommandParameter="https://xamarin.com" />
                </Span.GestureRecognizers>
            </Span>
            <Span Text=" Some more text." />
        </FormattedString>
    </Label.FormattedText>
</Label>

如果使用ViewModel create命令或使用轻击手势

public ICommand ClickCommand => new Command<string>((url) =>
{
    Device.OpenUri(new System.Uri(url));
});