From: Nigel Tao <nigeltao@golang.org>
Date: Sat, 13 Jun 2020 02:28:08 +0000 (+1000)
Subject: image/gif: speed up initializing test image
X-Git-Tag: go1.15rc1~107
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=97019105884ced2c4658f9763528e7f6983f8773;p=gostls13.git

image/gif: speed up initializing test image

The benchmark throughput numbers don't change, but the set-up time (the
time taken before the b.ResetTimer() call) drops from 460ms to 4ms.

Change-Id: I5a6756643dff6127f6d902455d83459c084834fc
Reviewed-on: https://go-review.googlesource.com/c/go/+/237757
Reviewed-by: Rob Pike <r@golang.org>
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---

diff --git a/src/image/gif/writer_test.go b/src/image/gif/writer_test.go
index b619961787..9b15c8d99d 100644
--- a/src/image/gif/writer_test.go
+++ b/src/image/gif/writer_test.go
@@ -657,7 +657,6 @@ func TestEncodeWrappedImage(t *testing.T) {
 }
 
 func BenchmarkEncode(b *testing.B) {
-	bo := image.Rect(0, 0, 640, 480)
 	rnd := rand.New(rand.NewSource(123))
 
 	// Restrict to a 256-color paletted image to avoid quantization path.
@@ -671,10 +670,8 @@ func BenchmarkEncode(b *testing.B) {
 		}
 	}
 	img := image.NewPaletted(image.Rect(0, 0, 640, 480), palette)
-	for y := bo.Min.Y; y < bo.Max.Y; y++ {
-		for x := bo.Min.X; x < bo.Max.X; x++ {
-			img.Set(x, y, palette[rnd.Intn(256)])
-		}
+	for i := range img.Pix {
+		img.Pix[i] = uint8(rnd.Intn(256))
 	}
 
 	b.SetBytes(640 * 480 * 4)