Jpeg 8x8px block compression demo with both Avalonia and WPF using WriteableBitmap. The Encoder/Decoder works for Baseline/Progressive Jpeg with chroma subsampling (to Bitmap) but only common formats are supported yet.
This purpose of this project:
- Show graphically how fundamentals of the jpeg compression works: Discrete Cosine Transform (DCT), Quantization, Zigzag, Progressive
- Write Jpeg decoder (basline/progressive/chrome subsampling) and encoder (baseline only)
The graphical part is implemented in both Avalonia and WPF (.Net) using WriteableBitmap
This project reveals some issues with Avalonia
- Performance problems with multiple TextBlocks
- Grid columns that should be equally sized are not, due to overflowing TextBlocks. This can cause Grid columns to resize infinitely as demonstrated in the project JpegAvaloniaAsync (to reproduce: run the project and reduce the window to cause Textblock overflow).
WriteableBitmap in Avalonia has the advantage over WPF that it can be created in worker thread for better performance (that does not apply to the Textblocks in Canvas though).
Project JpegAvaloniaAsync shows worker thread (async) processing of WriteableBitmap.
If you want to learn more about the Jpeg format I recommend Daniel Harding's series https://www.youtube.com/watch?v=CPT4FSkFUgs&ab_channel=DanielHarding Some of the code was ported from his repo (C++) https://github.com/dannye/jed