tree 3002d8ac34b2989acc12fa1d67f0230ae955d340
parent c53fa16781cb10dd75d2e62c6a4db691cbde3e55
author Nigel Tao <nigeltao@golang.org> 1428369745 +1000
committer Nigel Tao <nigeltao@golang.org> 1428387374 +0000

draw: switch on the Op compositing operator.

This change only *prepares* the codegen to handle multiple Ops. The
actual generated code still only supports one Op (Src) and not the other
(Over). A follow-up change will add Over.

This Op switch (an eventual x2 multiplier in the amount of code
generated) should be the last of the codegen LoC multipliers. The dst
and src mask options will be implemented in the slow path fallback.

Change-Id: Iecbcc6fad063e2aac36d78d5380c0a0947c709df
Reviewed-on: https://go-review.googlesource.com/8488
Reviewed-by: Rob Pike <r@golang.org>