`quiver` support

[paolobrasolin]

• [ ] injector
  • [ ] curve
  • [ ] offset
  • [ ] label_position
  • [ ] shorten
  • [ ] special arrow names (adjunction, corners)
• [ ] projector
  • [ ] curve
  • [ ] offset
  • [ ] label_position
  • [ ] shorten
  • [ ] special arrow names (adjunction, corners)

[paolobrasolin]

label_position and shorten are expressed in terms of the arrow lenght. We can map them to the unit interval.

curve and offset are tricky, as quiver reasons in term of absolute lengths. What do?

A unique Bézier quadratic with given endpoints is completely determined by either a third point or the head and tail angles.

However TikZ uses cubics, so two extra parameters of looseness are needed.

XY-pic does a similar thing, even though it has no notion of looseness, I believe.