1 files changed, 22 insertions, 5 deletions
diff --git a/src/pkg/image/png/writer_test.go b/src/pkg/image/png/writer_test.go
index a61e1c95a..f218a5564 100644
--- a/src/pkg/image/png/writer_test.go
+++ b/src/pkg/image/png/writer_test.go
@@ -5,6 +5,7 @@
 package png
 
 import (
+	"bytes"
 	"fmt"
 	"image"
 	"io"
@@ -13,15 +14,16 @@ import (
 )
 
 func diff(m0, m1 image.Image) os.Error {
-	if m0.Width() != m1.Width() || m0.Height() != m1.Height() {
-		return os.NewError(fmt.Sprintf("dimensions differ: %dx%d vs %dx%d", m0.Width(), m0.Height(), m1.Width(), m1.Height()))
+	b0, b1 := m0.Bounds(), m1.Bounds()
+	if !b0.Eq(b1) {
+		return fmt.Errorf("dimensions differ: %v vs %v", b0, b1)
 	}
-	for y := 0; y < m0.Height(); y++ {
-		for x := 0; x < m0.Width(); x++ {
+	for y := b0.Min.Y; y < b0.Max.Y; y++ {
+		for x := b0.Min.X; x < b0.Max.X; x++ {
 			r0, g0, b0, a0 := m0.At(x, y).RGBA()
 			r1, g1, b1, a1 := m1.At(x, y).RGBA()
 			if r0 != r1 || g0 != g1 || b0 != b1 || a0 != a1 {
-				return os.NewError(fmt.Sprintf("colors differ at (%d, %d): %v vs %v", x, y, m0.At(x, y), m1.At(x, y)))
+				return fmt.Errorf("colors differ at (%d, %d): %v vs %v", x, y, m0.At(x, y), m1.At(x, y))
 			}
 		}
 	}
@@ -67,3 +69,18 @@ func TestWriter(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkEncodePaletted(b *testing.B) {
+	b.StopTimer()
+	img := image.NewPaletted(640, 480,
+		[]image.Color{
+			image.RGBAColor{0, 0, 0, 255},
+			image.RGBAColor{255, 255, 255, 255},
+		})
+	b.StartTimer()
+	buffer := new(bytes.Buffer)
+	for i := 0; i < b.N; i++ {
+		buffer.Reset()
+		Encode(buffer, img)
+	}
+}