IMarkdownImageSavingCallback

IMarkdownImageSavingCallback interface

Handles custom processing of images while saving to Markdown. Invoked once per image; mutate MarkdownImageSavingArgs to control the URI embedded in the Markdown output and/or redirect where the image bytes are written.

public interface IMarkdownImageSavingCallback

Methods

Name Description
ImageSaving(MarkdownImageSavingArgs) Called for each image being written to the Markdown document.

Examples

Scenario 1 — capture image bytes in memory and embed placeholder ids (useful when the caller wants to store images elsewhere or post-process them):

class CaptureImagesCallback : IMarkdownImageSavingCallback
{
    private int _index;
    private readonly Dictionary<string, MemoryStream> _images;

    public CaptureImagesCallback(Dictionary<string, MemoryStream> images) => _images = images;

    public void ImageSaving(MarkdownImageSavingArgs args)
    {
        var id = $"image{_index++}";
        var buffer = new MemoryStream();
        _images[id] = buffer;
        args.ImageStream = buffer;            // redirect image bytes into our buffer
        args.ImageFileName = id;              // placeholder URI written into the .md
        args.KeepImageStreamOpen = true;      // keep buffer readable after Convert() returns
    }
}

var captured = new Dictionary<string, MemoryStream>();
try
{
    var options = new WordProcessingConvertOptions { Format = WordProcessingFileType.Md };
    options.MarkdownOptions.ImageSavingCallback = new CaptureImagesCallback(captured);

    using var converter = new Converter("source.pdf");
    converter.Convert("output.md", options);
    // captured["image0"], captured["image1"], ... now hold the image bytes
}
finally
{
    foreach (var s in captured.Values) s.Dispose();  // caller owns the streams
}

Scenario 2 — persist images to disk alongside the .md and reference them by file name:

class FileImagesCallback : IMarkdownImageSavingCallback
{
    private readonly string _outputFolder;
    private int _index;

    public FileImagesCallback(string outputFolder) => _outputFolder = outputFolder;

    public void ImageSaving(MarkdownImageSavingArgs args)
    {
        var fileName = $"image{_index++}.png";
        args.ImageStream = new FileStream(Path.Combine(_outputFolder, fileName), FileMode.Create);
        args.ImageFileName = fileName;        // written into the .md as ![](image0.png)
        // KeepImageStreamOpen left at default (false) → the converter flushes and closes the file.
    }
}

var options = new WordProcessingConvertOptions { Format = WordProcessingFileType.Md };
options.MarkdownOptions.ImageSavingCallback = new FileImagesCallback("./out");

using var converter = new Converter("source.pdf");
converter.Convert("./out/output.md", options);
// ./out/image0.png, ./out/image1.png, ... are written and closed by the converter.

See Also

IDpiConvertOptions IPageRangedConvertOptions