freehand

Live version

Prototype of a web-/SVG-based sketching app. Supports:

• pressure sensitivity
• multi-touch (multiple people drawing simultaneously on a single touchscreen)

Could serve as a basis for research:

• building a multi-touch interface for large (multi-user) touchscreens
• shape recognition
• collaborative (a)synchronous sketching
• compressing freehand drawing data (by removing data points that don’t matter, or approximating curvy lines with splines), like this paper: https://www.researchgate.net/publication/220998377_Sketch_Parameterization_Using_Curve_Approximation

TODOs (if we ever want to actually use this):

• Text mode
• Image (PNG, SVG, JPEG, …) import
• Rotating, resizing selection
• Xournal++ import/export
• SVG export (easy)
• Editor state + history (de-)serialization
• Improving sketch quality:
  • Pointer events in Firefox and Chrome currently have integer coordinates, even when zoomed in! As a result, diagonal lines drawn slowly look like staircases. Xournal++ has access to float coordinates, which looks better. https://github.com/w3c/pointerevents/issues/107
  • Line thickness should respond smoothly to pointer pressure, instead of in 10% increments.