Create Custom JpegImageConverter in .Net Standard
| Product Version | Product | Author |
|---|---|---|
| up to 2023.1.410 | RadPdfProcessing | Martin Velikov |
| 2.1.6 | ImageSharp |
Description
.NET Standard specification does not define APIs for converting images or scaling their quality. That is why, when inserting images in a PDF document different than Jpeg and Jpeg2000 or ImageQuality different than High, you will need to implement the JpegImageConverterBase abstract class. This implementation should be passed to the JpegImageConverter property of the FixedExtensibilityManager.
With the R2 2023 changes SkiaSharp replaced ImageSharp as the required dependency.
Solution
The following code snippets demonstrate how to create a custom implementation of the JpegImageConverterBase abstract class using the SixLabors.ImageSharp library and set it to the JpegImageConverter property of the FixedExtensibilityManager. We are using the ImageSharp library to convert the images from one of the library's supported formats to Jpeg and to change their quality if it is set. Note that this approach is valid up to version 2023.1.410 of RadPdfProcessing.
Create a custom implementation inheriting the JpegImageConverterBase abstract class
public class CustomJpegImageConverter : JpegImageConverterBase
{
public override bool TryConvertToJpegImageData(byte[] imageData, ImageQuality imageQuality, out byte[] jpegImageData)
{
try
{
IImageFormat imageFormat;
using (SixLabors.ImageSharp.Image image = SixLabors.ImageSharp.Image.Load(imageData, out imageFormat))
{
if (imageFormat.GetType() == typeof(PngFormat))
{
image.Mutate(x => x.BackgroundColor(Color.White));
}
JpegEncoder options = new JpegEncoder
{
Quality = (int)imageQuality,
};
using (MemoryStream ms = new MemoryStream())
{
image.SaveAsJpeg(ms, options);
jpegImageData = ms.ToArray();
}
}
return true;
}
catch (Exception ex)
{
if (ex is UnknownImageFormatException || ex is ImageProcessingException)
{
jpegImageData = null;
return false;
}
else
{
throw ex;
}
}
}
}
Set the custom implementation to the JpegImageConverter property of the FixedExtensibilityManager
JpegImageConverterBase customJpegImageConverter = new CustomJpegImageConverter();
FixedExtensibilityManager.JpegImageConverter = customJpegImageConverter;
// RadPdfProcessing version up to 2023.1.410
PdfFormatProvider provider = new PdfFormatProvider();
string imageFolderPath = @"......\images";
string[] imageFiles = Directory.GetFiles(imageFolderPath);
RadFixedDocument fixedDocument = new RadFixedDocument();
RadFixedDocumentEditor documentEditor = new RadFixedDocumentEditor(fixedDocument);
foreach (string imageFilePath in imageFiles)
{
FileStream fileStream = new FileStream(imageFilePath, FileMode.Open);
Telerik.Windows.Documents.Fixed.Model.Resources.ImageSource _imageSource = new Telerik.Windows.Documents.Fixed.Model.Resources.ImageSource(fileStream);
documentEditor.InsertImageInline(_imageSource);
documentEditor.InsertLineBreak();
}
documentEditor.Dispose();
string outputFilePath = @"output.pdf";
File.Delete(outputFilePath);
using (Stream output = File.OpenWrite(outputFilePath))
{
provider.Export(fixedDocument, output);
}
Process.Start(new ProcessStartInfo() { FileName = outputFilePath, UseShellExecute = true });