Converting WMF Images to PNG in RTF Documents with RadWordsProcessing

Environment

Version	Product	Author
2024.3.806	RadWordsProcessing	Desislava Yordanova

Description

This article demonstrates a sample approach how to convert the images in WMF format to PNG within an RTF document.

Solution

To convert WMF images to PNG format within an RTF document using RadWordsProcessing, follow these steps:

1. Import the RTF file as a RadFlowDocument.

2. Iterate through the floating images in the document.

3. Convert each WMF image to PNG format.

4. Export the modified document.

Here is a sample code snippet demonstrating this process:

using System.Diagnostics;
using Telerik.Windows.Documents.Flow.Model;
using Telerik.Windows.Documents.Flow.Model.Shapes;
using Telerik.Windows.Documents.Media;

static void Main(string[] args)
{
    string inputFilePath = "yourfile.rtf";
    Telerik.Windows.Documents.Flow.Model.RadFlowDocument document;

    Telerik.Windows.Documents.Flow.FormatProviders.Rtf.RtfFormatProvider provider = new Telerik.Windows.Documents.Flow.FormatProviders.Rtf.RtfFormatProvider();

    using (Stream input = File.OpenRead(inputFilePath))
    {
        document = provider.Import(input);
    }

    ConvertInlineWmfImagesToPng(document);

    string outputFilePath = "converted.rtf";
    File.Delete(outputFilePath);
    using (Stream output = File.Create(outputFilePath))
    {
        provider.Export(document, output);
    }
    Process.Start(new ProcessStartInfo() { FileName = outputFilePath, UseShellExecute = true });
}

private static void ConvertInlineWmfImagesToPng(RadFlowDocument document)
{
    foreach (FloatingImage image in document.EnumerateChildrenOfType<FloatingImage>())
    {
        if (image.Image.ImageSource.Extension.Equals("wmf", StringComparison.InvariantCultureIgnoreCase))
        {
            using (MemoryStream wmfImageStream = new MemoryStream(image.Image.ImageSource.Data))
            {
                using (MemoryStream pngImageStream = new MemoryStream())
                {
                    var imageDrawing = System.Drawing.Image.FromStream(wmfImageStream);
                    imageDrawing.Save(pngImageStream, System.Drawing.Imaging.ImageFormat.Png);
                    byte[] pngBytes = pngImageStream.ToArray();

                    image.Image.ImageSource = new ImageSource(pngBytes, "png");
                }
            }
        }
    }
}

Notes

• Ensure you have referenced all necessary assemblies and namespaces, particularly those related to Telerik Document Processing and System.Drawing for image conversion.
• The code snippet assumes the presence of a WMF image in the document. If your document contains images in formats other than WMF, they won't be affected.
• This solution applies to floating images. For inline images, a similar approach can be taken with slight adjustments to target InlineImage instances if necessary.

See Also

• RadWordsProcessing Documentation
• RadFlowDocument Overview
• RtfFormatProvider Documentation