Graphite - Contributions to the Brush Tool

I recently worked with Orlp and TrueDoctor to add a brush tool to Graphite, an open source web based graphics editor being built in Rust. Some of my contributions include:

• Brush tool live preview - this built on the existing brush tool to allow users to preview as they were drawing, rather than having to wait until they had released the mouse button. This involved a lot of work getting the transforms to properly align. I also added left and right square bracket to change the size of the brush, and some linear interpolation when the mouse moved a long way in a single update.
  
• Make Brush tool use per-stroke options and improve its performance - I helped by fixing issues with the position of the stroke relative to the mouse pointer
  
• Allow drawing on top of an image when a layer containing a bitmap image is selected.
• Fix brush layers growing hugely when resizing transforms with Select tool - this fixed an issue where the brush layers would become extremely large because a transform node would square the size of the brush strokes. Fixing this involved some careful sketching of the order in which the affine matrices were applied.