libgo/go/image/decode_test.go

   1 // Copyright 2011 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package image_test
   6
   7 import (
   8         "bufio"
   9         "image"
  10         "image/color"
  11         "os"
  12         "testing"
  13
  14         _ "image/gif"
  15         _ "image/jpeg"
  16         _ "image/png"
  17 )
  18
  19 type imageTest struct {
  20         goldenFilename string
  21         filename       string
  22         tolerance      int
  23 }
  24
  25 var imageTests = []imageTest{
  26         {"testdata/video-001.png", "testdata/video-001.png", 0},
  27         // GIF images are restricted to a 256-color palette and the conversion
  28         // to GIF loses significant image quality.
  29         {"testdata/video-001.png", "testdata/video-001.gif", 64 << 8},
  30         {"testdata/video-001.png", "testdata/video-001.interlaced.gif", 64 << 8},
  31         {"testdata/video-001.png", "testdata/video-001.5bpp.gif", 128 << 8},
  32         // JPEG is a lossy format and hence needs a non-zero tolerance.
  33         {"testdata/video-001.png", "testdata/video-001.jpeg", 8 << 8},
  34         {"testdata/video-001.png", "testdata/video-001.progressive.jpeg", 8 << 8},
  35         // Grayscale images.
  36         {"testdata/video-005.gray.png", "testdata/video-005.gray.jpeg", 8 << 8},
  37         {"testdata/video-005.gray.png", "testdata/video-005.gray.png", 0},
  38 }
  39
  40 func decode(filename string) (image.Image, string, error) {
  41         f, err := os.Open(filename)
  42         if err != nil {
  43                 return nil, "", err
  44         }
  45         defer f.Close()
  46         return image.Decode(bufio.NewReader(f))
  47 }
  48
  49 func decodeConfig(filename string) (image.Config, string, error) {
  50         f, err := os.Open(filename)
  51         if err != nil {
  52                 return image.Config{}, "", err
  53         }
  54         defer f.Close()
  55         return image.DecodeConfig(bufio.NewReader(f))
  56 }
  57
  58 func delta(u0, u1 uint32) int {
  59         d := int(u0) - int(u1)
  60         if d < 0 {
  61                 return -d
  62         }
  63         return d
  64 }
  65
  66 func withinTolerance(c0, c1 color.Color, tolerance int) bool {
  67         r0, g0, b0, a0 := c0.RGBA()
  68         r1, g1, b1, a1 := c1.RGBA()
  69         r := delta(r0, r1)
  70         g := delta(g0, g1)
  71         b := delta(b0, b1)
  72         a := delta(a0, a1)
  73         return r <= tolerance && g <= tolerance && b <= tolerance && a <= tolerance
  74 }
  75
  76 func TestDecode(t *testing.T) {
  77         golden := make(map[string]image.Image)
  78 loop:
  79         for _, it := range imageTests {
  80                 g := golden[it.goldenFilename]
  81                 if g == nil {
  82                         var err error
  83                         g, _, err = decode(it.goldenFilename)
  84                         if err != nil {
  85                                 t.Errorf("%s: %v", it.goldenFilename, err)
  86                                 continue loop
  87                         }
  88                         golden[it.goldenFilename] = g
  89                 }
  90                 m, imageFormat, err := decode(it.filename)
  91                 if err != nil {
  92                         t.Errorf("%s: %v", it.filename, err)
  93                         continue loop
  94                 }
  95                 b := g.Bounds()
  96                 if !b.Eq(m.Bounds()) {
  97                         t.Errorf("%s: want bounds %v got %v", it.filename, b, m.Bounds())
  98                         continue loop
  99                 }
 100                 for y := b.Min.Y; y < b.Max.Y; y++ {
 101                         for x := b.Min.X; x < b.Max.X; x++ {
 102                                 if !withinTolerance(g.At(x, y), m.At(x, y), it.tolerance) {
 103                                         t.Errorf("%s: at (%d, %d), want %v got %v", it.filename, x, y, g.At(x, y), m.At(x, y))
 104                                         continue loop
 105                                 }
 106                         }
 107                 }
 108                 if imageFormat == "gif" {
 109                         // Each frame of a GIF can have a frame-local palette override the
 110                         // GIF-global palette. Thus, image.Decode can yield a different ColorModel
 111                         // than image.DecodeConfig.
 112                         continue
 113                 }
 114                 c, _, err := decodeConfig(it.filename)
 115                 if m.ColorModel() != c.ColorModel {
 116                         t.Errorf("%s: color models differ", it.filename)
 117                         continue loop
 118                 }
 119         }
 120 }