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