Previously, the entire image was encoded into a buffer,
then encoded to a base64 string, which was concatenated
with another string, and written to stdout in one swoop.
We can do this more efficiently by writing the PNG image
to a base64 encoder directly, and using buffered I/O to
batch writes to stdout into moderately-sized chunks.
As an added bonus, though really the main motivation for
doing this optimization now, this helps avoid triggering
the golang/go#38751 issue on the Go Playground.
Switch to the best compression level instead of the default,
reducing encoded image size at the cost of extra computation.
Playground snippets need to be transferred over the network
and kept in storage, so it should be a favorable trade-off.
This CL was based on CL 232177.
For golang/go#38751.
Change-Id: I565fe538aa15910caaff98be156ac64b0d35fff4
Co-authored-by: Alexander Rakoczy <alex@golang.org>
Reviewed-on: https://go-review.googlesource.com/c/tour/+/232867
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alexander Rakoczy <alex@golang.org>
It's hard to write a normal test because ShowImage writes
to os.Stdout unconditionally. Add an example test instead.
Change-Id: I52e02908e94aa212a05c058edb4f504851b5bb8d
Reviewed-on: https://go-review.googlesource.com/c/tour/+/232866
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alexander Rakoczy <alex@golang.org>
Effective Go¹ says every package should have a package comment,
and every exported name in a package should have a doc comment.
This package is mentioned in the Go tour. Let's set a good example.
¹ https://golang.org/doc/effective_go.html#commentary
Change-Id: Iac561c7530fc49d5ff17c51d925151ec8319ef24
Reviewed-on: https://go-review.googlesource.com/c/tour/+/232865
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alexander Rakoczy <alex@golang.org>
Dmitri Shuralyov
Andrew Gerrand
Rob Pike