How to customise imagepath resolving - whistyun/Markdown.Avalonia GitHub Wiki

Abstract

Relative paths can be used to indicate a hyperlink and a image resource in Markdown. In Markdown.Avalonia, you can use IPathResolver to change the way to resolve relative path of image resource.

Sample

The following is an example of

allow only absolute paths to be acquired
restrict the acquisition of images from the Internet

Implements PathResolver

class MyPathResolver: IPathResolver
{
    public string? AssetPathRoot { set; private get; }
    public IEnumerable<string>? CallerAssemblyNames { set; private get; }

    public async Task<Stream?>? ResolveImageResource(string relativeOrAbsolutePath)
    {
        if (Uri.TryCreate(relativeOrAbsolutePath, UriKind.Absolute, out var aburl))
        {
            return await OpenStream(aburl);
        }

        throw new NotImplementedException();
    }

    private async Task<Stream?> OpenStream(Uri url)
    {
        switch (url.Scheme)
        {
            case "file":
                if (!File.Exists(url.LocalPath)) return null;
                return File.OpenRead(url.LocalPath);

            case "avares":
                if (!AssetLoader.Exists(url))
                    return null;

                return AssetLoader.Open(url);

            default:
                throw new InvalidDataException($"unsupport scheme '{url.Scheme}'");
        }
    }
}

Registers PathResolver

Set it to the PathResolver property of the MdAvPlugins class to register a PathResolver

<Window
    xmlns:md="https://github.com/whistyun/Markdown.Avalonia"
    ...
    >

  <Window.Resources>
    <local:MyPathResolver x:Key="MyResolver"/>
  </Window.Resources>

  <md:MarkdownScrollViewer>
    <md:MarkdownScrollViewer.Plugins>
      <md:MdAvPlugins PathResolver="{StaticResource MyResolver}" />
    </md:MarkdownScrollViewer.Plugins>
  </md:MarkdownScrollViewer>
</Window>