private static void onHtmlChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var owner = (RichTextBlock)d;
var status = owner.GetStatus();
if (status == null)
{
status = new RichTextBlockStatus();
owner.SetStatus(status);
owner.Loaded += Owner_Loaded;
owner.Unloaded += Owner_Unloaded;
status.RequestedThemePropertyToken = owner.RegisterPropertyChangedCallback(FrameworkElement.RequestedThemeProperty, onRequestedThemeChanged);
status.ForegroundToken = owner.RegisterPropertyChangedCallback(RichTextBlock.ForegroundProperty, onForegroundChanged);
owner.SizeChanged += onSizeChanged;
}
var newValue = e.NewValue as string;
if (string.IsNullOrWhiteSpace(newValue))
return;
var html = (HtmlDocument)HtmlParser.Parse(newValue, true);
owner.Blocks.Clear();
status.BaseUri = owner.GetBaseUri();
status.Foreground = owner.Foreground;
status.ActualWidth = owner.ActualWidth;
status.RequestedTheme = owner.RequestedTheme;
status.Images.Clear();
status.Hyperlinks.Clear();
status.Lines.Clear();
status.HyperlinkButtons.Clear();
var paragraph = new Paragraph();
CreateChildren(paragraph.Inlines, html.Body, status);
owner.Blocks.Add(paragraph);
}
private static void SetStatus(this FrameworkElement @this, RichTextBlockStatus value) => @this.SetValue(StatusPorperty, value);
private static void CreateElement(InlineCollection parent, Node node, RichTextBlockStatus status)
{
switch (node)
{
case Element element:
switch (element.TagName.ToLower())
{
case "a":
{
// We want to change BaseUri easily, so we use `GetAttribute("href")` instead of `HtmlAnchorElement.Href`
var href = element.GetAttribute("href");
if (!status.TryCreateUri(href, out var uri))
break;
parent.Add(new Run() { Text = " " });
var hyperlink = new Hyperlink()
{
NavigateUri = uri,
Foreground = status.Foreground
};
foreach (var child in element.ChildNodes)
{
switch (child)
{
case HtmlImageElement childElement:
if (CreateImage(element, status) is Image image)
{
if (hyperlink.Inlines.Count != 0)
{
hyperlink.SetUri(href);
status.Hyperlinks.Add(hyperlink);
parent.Add(hyperlink);
}
var button = new HyperlinkButton()
{
NavigateUri = uri,
Content = image,
RequestedTheme = status.RequestedTheme
};
button.SetUri(href);
status.HyperlinkButtons.Add(button);
parent.Add(new InlineUIContainer() { Child = button });
hyperlink = new Hyperlink()
{
NavigateUri = uri,
Foreground = status.Foreground
};
}
break;
default:
CreateElement(hyperlink.Inlines, child, status);
break;
}
break;
}
if (hyperlink.Inlines.Count != 0)
{
hyperlink.SetUri(href);
status.Hyperlinks.Add(hyperlink);
parent.Add(hyperlink);
}
parent.Add(new Run() { Text = " " });
}
break;
case "img":
{
if (CreateImage(element, status) is Image image)
parent.Add(new InlineUIContainer() { Child = image });
}
break;
case "strong":
case "b":
{
var span = new Span() { FontWeight = FontWeights.Bold };
CreateChildren(span.Inlines, element, status);
parent.Add(span);
}
break;
case "div":
case "font":
case "p":
case "span":
{
var span = new Span();
foreach (var s in ParseStyle(element.GetAttribute("style")))
switch (s.Key)
{
case "font-size":
{
var value = s.Value;
double fontSize;
if (value.EndsWith("px"))
fontSize = double.Parse(value.Remove(value.Length - 2));
else if (value.EndsWith("%"))
fontSize = 14 * double.Parse(value.Remove(value.Length - 1)) / 100;
else
fontSize = 14 * double.Parse(value);
span.FontSize = fontSize;
}
break;
case "font-weight":
switch (s.Value)
{
case "bold":
span.FontWeight = FontWeights.Bold;
break;
}
break;
}
CreateChildren(span.Inlines, element, status);
parent.Add(span);
}
break;
case "br":
if (element.NextSibling is Text nextText &&
nextText.Data.StartsWith("\n"))
break;
parent.Add(new LineBreak());
break;
case "hr":
parent.Add(new LineBreak());
var line = new Border()
{
BorderThickness = new Thickness(0, 1, 0, 0),
BorderBrush = status.Foreground,
Margin = new Thickness(8, 0, 8, 0),
Height = 1,
};
if (status.ActualWidth > 16)
line.Width = status.ActualWidth - 16;
status.Lines.Add(line);
parent.Add(new InlineUIContainer() { Child = line });
parent.Add(new LineBreak());
break;
case "iframe": // Ignore
case "script":
case "noscript":
break;
#if DEBUG
default:
Debug.WriteLine($"Ignore unknown tag {element.TagName}");
break;
#endif
}
break;
case Text text:
parent.Add(new Run() { Text = text.Data });
break;
}
}
private static void CreateChildren(InlineCollection parent, Element node, RichTextBlockStatus status)
{
foreach (var child in node.ChildNodes)
CreateElement(parent, child, status);
}
private static Image CreateImage(Element image, RichTextBlockStatus status)
{
var src = image.GetAttribute("src");
if (!status.TryCreateUri(src, out var uri))
return null;
if (!uri.Scheme.StartsWith("http"))
return null;
var result = new Image()
{
Source = UriToBitmapImageConverter.Instance.Convert(uri),
MaxWidth = status.ActualWidth
};
result.SetUri(src);
result.ImageOpened += Result_ImageOpened;
if (image.HasAttribute("width"))
result.Width = double.Parse(image.GetAttribute("width"));
else
result.Width = 0;
if (image.HasAttribute("height"))
result.Height = double.Parse(image.GetAttribute("height"));
else
result.Height = 0;
status.Images.Add(result);
return result;
}
