The stroking algorithm is a placeholder. A proper one will land in a future change once the API is agreed upon. R=r, rsc CC=golang-dev, rog http://codereview.appspot.com/1708045
Introduce MonochromePainter and GammaCorrectionPainter. R=r, rsc CC=golang-dev http://codereview.appspot.com/904041
R=r, rsc CC=golang-dev http://codereview.appspot.com/841042