From: Nigel Tao <nigeltao@golang.org>
Date: Mon, 1 Sep 2014 00:02:52 +0000 (+1000)
Subject: image/png: make the CompressionLevel constants negative, reserving
X-Git-Tag: go1.4beta1~600
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=686ecd83c04c9904de9457c7b14380cc2c04cff2;p=gostls13.git

image/png: make the CompressionLevel constants negative, reserving
positive numbers to mean a numeric zlib compression level.

LGTM=bradfitz, ruiu
R=bradfitz, ruiu
CC=golang-codereviews, jeff.allen
https://golang.org/cl/138860043
---

diff --git a/src/pkg/image/png/writer.go b/src/pkg/image/png/writer.go
index b1a70c79d3..df23270ee9 100644
--- a/src/pkg/image/png/writer.go
+++ b/src/pkg/image/png/writer.go
@@ -33,10 +33,13 @@ type encoder struct {
 type CompressionLevel int
 
 const (
-	DefaultCompression CompressionLevel = iota
-	NoCompression
-	BestSpeed
-	BestCompression
+	DefaultCompression CompressionLevel = 0
+	NoCompression      CompressionLevel = -1
+	BestSpeed          CompressionLevel = -2
+	BestCompression    CompressionLevel = -3
+
+	// Positive CompressionLevel values are reserved to mean a numeric zlib
+	// compression level, although that is not implemented yet.
 )
 
 // Big-endian.