// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package png
import (
"bytes"
"compress/zlib"
"encoding/binary"
"fmt"
"image"
"image/color"
"io"
"io/ioutil"
"testing"
)
func diff(m0, m1 image.Image) error {
b0, b1 := m0.Bounds(), m1.Bounds()
if !b0.Size().Eq(b1.Size()) {
return fmt.Errorf("dimensions differ: %v vs %v", b0, b1)
}
dx := b1.Min.X - b0.Min.X
dy := b1.Min.Y - b0.Min.Y
for y := b0.Min.Y; y < b0.Max.Y; y++ {
for x := b0.Min.X; x < b0.Max.X; x++ {
c0 := m0.At(x, y)
c1 := m1.At(x+dx, y+dy)
r0, g0, b0, a0 := c0.RGBA()
r1, g1, b1, a1 := c1.RGBA()
if r0 != r1 || g0 != g1 || b0 != b1 || a0 != a1 {
return fmt.Errorf("colors differ at (%d, %d): %v vs %v", x, y, c0, c1)
}
}
}
return nil
}
func encodeDecode(m image.Image) (image.Image, error) {
var b bytes.Buffer
err := Encode(&b, m)
if err != nil {
return nil, err
}
return Decode(&b)
}
func TestWriter(t *testing.T) {
// The filenames variable is declared in reader_test.go.
names := filenames
if testing.Short() {
names = filenamesShort
}
for _, fn := range names {
qfn := "testdata/pngsuite/" + fn + ".png"
// Read the image.
m0, err := readPNG(qfn)
if err != nil {
t.Error(fn, err)
continue
}
// Read the image again, encode it, and decode it.
m1, err := readPNG(qfn)
if err != nil {
t.Error(fn, err)
continue
}
m2, err := encodeDecode(m1)
if err != nil {
t.Error(fn, err)
continue
}
// Compare the two.
err = diff(m0, m2)
if err != nil {
t.Error(fn, err)
continue
}
}
}
func TestWriterPaletted(t *testing.T) {
const width, height = 32, 16
testCases := []struct {
plen int
bitdepth uint8
datalen int
}{
{
plen: 256,
bitdepth: 8,
datalen: (1 + width) * height,
},
{
plen: 128,
bitdepth: 8,
datalen: (1 + width) * height,
},
{
plen: 16,
bitdepth: 4,
datalen: (1 + width/2) * height,
},
{
plen: 4,
bitdepth: 2,
datalen: (1 + width/4) * height,
},
{
plen: 2,
bitdepth: 1,
datalen: (1 + width/8) * height,
},
}
for _, tc := range testCases {
t.Run(fmt.Sprintf("plen-%d", tc.plen), func(t *testing.T) {
// Create a paletted image with the correct palette length
palette := make(color.Palette, tc.plen)
for i := range palette {
palette[i] = color.NRGBA{
R: uint8(i),
G: uint8(i),
B: uint8(i),
A: 255,
}
}
m0 := image.NewPaletted(image.Rect(0, 0, width, height), palette)
i := 0
for y := 0; y < height; y++ {
for x := 0; x < width; x++ {
m0.SetColorIndex(x, y, uint8(i%tc.plen))
i++
}
}
// Encode the image
var b bytes.Buffer
if err := Encode(&b, m0); err != nil {
t.Error(err)
return
}
const chunkFieldsLength = 12 // 4 bytes for length, name and crc
data := b.Bytes()
i = len(pngHeader)
for i < len(data)-chunkFieldsLength {
length := binary.BigEndian.Uint32(data[i : i+4])
name := string(data[i+4 : i+8])
switch name {
case "IHDR":
bitdepth := data[i+8+8]
if bitdepth != tc.bitdepth {
t.Errorf("got bitdepth %d, want %d", bitdepth, tc.bitdepth)
}
case "IDAT":
// Uncompress the image data
r, err := zlib.NewReader(bytes.NewReader(data[i+8 : i+8+int(length)]))
if err != nil {
t.Error(err)
return
}
n, err := io.Copy(ioutil.Discard, r)
if err != nil {
t.Errorf("got error while reading image data: %v", err)
}
if n != int64(tc.datalen) {
t.Errorf("got uncompressed data length %d, want %d", n, tc.datalen)
}
}
i += chunkFieldsLength + int(length)
}
})
}
}
func TestWriterLevels(t *testing.T) {
m := image.NewNRGBA(image.Rect(0, 0, 100, 100))
var b1, b2 bytes.Buffer
if err := (&Encoder{}).Encode(&b1, m); err != nil {
t.Fatal(err)
}
noenc := &Encoder{CompressionLevel: NoCompression}
if err := noenc.Encode(&b2, m); err != nil {
t.Fatal(err)
}
if b2.Len() <= b1.Len() {
t.Error("DefaultCompression encoding was larger than NoCompression encoding")
}
if _, err := Decode(&b1); err != nil {
t.Error("cannot decode DefaultCompression")
}
if _, err := Decode(&b2); err != nil {
t.Error("cannot decode NoCompression")
}
}
func TestSubImage(t *testing.T) {
m0 := image.NewRGBA(image.Rect(0, 0, 256, 256))
for y := 0; y < 256; y++ {
for x := 0; x < 256; x++ {
m0.Set(x, y, color.RGBA{uint8(x), uint8(y), 0, 255})
}
}
m0 = m0.SubImage(image.Rect(50, 30, 250, 130)).(*image.RGBA)
m1, err := encodeDecode(m0)
if err != nil {
t.Error(err)
return
}
err = diff(m0, m1)
if err != nil {
t.Error(err)
return
}
}
func BenchmarkEncodeGray(b *testing.B) {
img := image.NewGray(image.Rect(0, 0, 640, 480))
b.SetBytes(640 * 480 * 1)
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
Encode(ioutil.Discard, img)
}
}
type pool struct {
b *EncoderBuffer
}
func (p *pool) Get() *EncoderBuffer {
return p.b
}
func (p *pool) Put(b *EncoderBuffer) {
p.b = b
}
func BenchmarkEncodeGrayWithBufferPool(b *testing.B) {
img := image.NewGray(image.Rect(0, 0, 640, 480))
e := Encoder{
BufferPool: &pool{},
}
b.SetBytes(640 * 480 * 1)
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
e.Encode(ioutil.Discard, img)
}
}
func BenchmarkEncodeNRGBOpaque(b *testing.B) {
img := image.NewNRGBA(image.Rect(0, 0, 640, 480))
// Set all pixels to 0xFF alpha to force opaque mode.
bo := img.Bounds()
for y := bo.Min.Y; y < bo.Max.Y; y++ {
for x := bo.Min.X; x < bo.Max.X; x++ {
img.Set(x, y, color.NRGBA{0, 0, 0, 255})
}
}
if !img.Opaque() {
b.Fatal("expected image to be opaque")
}
b.SetBytes(640 * 480 * 4)
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
Encode(ioutil.Discard, img)
}
}
func BenchmarkEncodeNRGBA(b *testing.B) {
img := image.NewNRGBA(image.Rect(0, 0, 640, 480))
if img.Opaque() {
b.Fatal("expected image not to be opaque")
}
b.SetBytes(640 * 480 * 4)
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
Encode(ioutil.Discard, img)
}
}
func BenchmarkEncodePaletted(b *testing.B) {
img := image.NewPaletted(image.Rect(0, 0, 640, 480), color.Palette{
color.RGBA{0, 0, 0, 255},
color.RGBA{255, 255, 255, 255},
})
b.SetBytes(640 * 480 * 1)
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
Encode(ioutil.Discard, img)
}
}
func BenchmarkEncodeRGBOpaque(b *testing.B) {
img := image.NewRGBA(image.Rect(0, 0, 640, 480))
// Set all pixels to 0xFF alpha to force opaque mode.
bo := img.Bounds()
for y := bo.Min.Y; y < bo.Max.Y; y++ {
for x := bo.Min.X; x < bo.Max.X; x++ {
img.Set(x, y, color.RGBA{0, 0, 0, 255})
}
}
if !img.Opaque() {
b.Fatal("expected image to be opaque")
}
b.SetBytes(640 * 480 * 4)
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
Encode(ioutil.Discard, img)
}
}
func BenchmarkEncodeRGBA(b *testing.B) {
img := image.NewRGBA(image.Rect(0, 0, 640, 480))
if img.Opaque() {
b.Fatal("expected image not to be opaque")
}
b.SetBytes(640 * 480 * 4)
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
Encode(ioutil.Discard, img)
}
}
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