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// Copyright 2011 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 image_test
import (
"bufio"
"image"
"image/color"
"os"
"testing"
_ "image/gif"
_ "image/jpeg"
_ "image/png"
)
type imageTest struct {
goldenFilename string
filename string
tolerance int
}
var imageTests = []imageTest{
{"testdata/video-001.png", "testdata/video-001.png", 0},
// GIF images are restricted to a 256-color palette and the conversion
// to GIF loses significant image quality.
{"testdata/video-001.png", "testdata/video-001.gif", 64 << 8},
{"testdata/video-001.png", "testdata/video-001.interlaced.gif", 64 << 8},
{"testdata/video-001.png", "testdata/video-001.5bpp.gif", 128 << 8},
// JPEG is a lossy format and hence needs a non-zero tolerance.
{"testdata/video-001.png", "testdata/video-001.jpeg", 8 << 8},
{"testdata/video-001.png", "testdata/video-001.progressive.jpeg", 8 << 8},
// Grayscale images.
{"testdata/video-005.gray.png", "testdata/video-005.gray.jpeg", 8 << 8},
{"testdata/video-005.gray.png", "testdata/video-005.gray.png", 0},
}
func decode(filename string) (image.Image, string, error) {
f, err := os.Open(filename)
if err != nil {
return nil, "", err
}
defer f.Close()
return image.Decode(bufio.NewReader(f))
}
func decodeConfig(filename string) (image.Config, string, error) {
f, err := os.Open(filename)
if err != nil {
return image.Config{}, "", err
}
defer f.Close()
return image.DecodeConfig(bufio.NewReader(f))
}
func delta(u0, u1 uint32) int {
d := int(u0) - int(u1)
if d < 0 {
return -d
}
return d
}
func withinTolerance(c0, c1 color.Color, tolerance int) bool {
r0, g0, b0, a0 := c0.RGBA()
r1, g1, b1, a1 := c1.RGBA()
r := delta(r0, r1)
g := delta(g0, g1)
b := delta(b0, b1)
a := delta(a0, a1)
return r <= tolerance && g <= tolerance && b <= tolerance && a <= tolerance
}
func TestDecode(t *testing.T) {
golden := make(map[string]image.Image)
loop:
for _, it := range imageTests {
g := golden[it.goldenFilename]
if g == nil {
var err error
g, _, err = decode(it.goldenFilename)
if err != nil {
t.Errorf("%s: %v", it.goldenFilename, err)
continue loop
}
golden[it.goldenFilename] = g
}
m, imageFormat, err := decode(it.filename)
if err != nil {
t.Errorf("%s: %v", it.filename, err)
continue loop
}
b := g.Bounds()
if !b.Eq(m.Bounds()) {
t.Errorf("%s: want bounds %v got %v", it.filename, b, m.Bounds())
continue loop
}
for y := b.Min.Y; y < b.Max.Y; y++ {
for x := b.Min.X; x < b.Max.X; x++ {
if !withinTolerance(g.At(x, y), m.At(x, y), it.tolerance) {
t.Errorf("%s: at (%d, %d), want %v got %v", it.filename, x, y, g.At(x, y), m.At(x, y))
continue loop
}
}
}
if imageFormat == "gif" {
// Each frame of a GIF can have a frame-local palette override the
// GIF-global palette. Thus, image.Decode can yield a different ColorModel
// than image.DecodeConfig.
continue
}
c, _, err := decodeConfig(it.filename)
if m.ColorModel() != c.ColorModel {
t.Errorf("%s: color models differ", it.filename)
continue loop
}
}
}
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