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Source file src/image/decode_test.go

Documentation: image

     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  	"fmt"
    10  	"image"
    11  	"image/color"
    12  	"os"
    13  	"testing"
    14  
    15  	_ "image/gif"
    16  	_ "image/jpeg"
    17  	_ "image/png"
    18  )
    19  
    20  type imageTest struct {
    21  	goldenFilename string
    22  	filename       string
    23  	tolerance      int
    24  }
    25  
    26  var imageTests = []imageTest{
    27  	{"testdata/video-001.png", "testdata/video-001.png", 0},
    28  	// GIF images are restricted to a 256-color palette and the conversion
    29  	// to GIF loses significant image quality.
    30  	{"testdata/video-001.png", "testdata/video-001.gif", 64 << 8},
    31  	{"testdata/video-001.png", "testdata/video-001.interlaced.gif", 64 << 8},
    32  	{"testdata/video-001.png", "testdata/video-001.5bpp.gif", 128 << 8},
    33  	// JPEG is a lossy format and hence needs a non-zero tolerance.
    34  	{"testdata/video-001.png", "testdata/video-001.jpeg", 8 << 8},
    35  	{"testdata/video-001.png", "testdata/video-001.progressive.jpeg", 8 << 8},
    36  	{"testdata/video-001.221212.png", "testdata/video-001.221212.jpeg", 8 << 8},
    37  	{"testdata/video-001.cmyk.png", "testdata/video-001.cmyk.jpeg", 8 << 8},
    38  	{"testdata/video-001.rgb.png", "testdata/video-001.rgb.jpeg", 8 << 8},
    39  	{"testdata/video-001.progressive.truncated.png", "testdata/video-001.progressive.truncated.jpeg", 8 << 8},
    40  	// Grayscale images.
    41  	{"testdata/video-005.gray.png", "testdata/video-005.gray.jpeg", 8 << 8},
    42  	{"testdata/video-005.gray.png", "testdata/video-005.gray.png", 0},
    43  }
    44  
    45  func decode(filename string) (image.Image, string, error) {
    46  	f, err := os.Open(filename)
    47  	if err != nil {
    48  		return nil, "", err
    49  	}
    50  	defer f.Close()
    51  	return image.Decode(bufio.NewReader(f))
    52  }
    53  
    54  func decodeConfig(filename string) (image.Config, string, error) {
    55  	f, err := os.Open(filename)
    56  	if err != nil {
    57  		return image.Config{}, "", err
    58  	}
    59  	defer f.Close()
    60  	return image.DecodeConfig(bufio.NewReader(f))
    61  }
    62  
    63  func delta(u0, u1 uint32) int {
    64  	d := int(u0) - int(u1)
    65  	if d < 0 {
    66  		return -d
    67  	}
    68  	return d
    69  }
    70  
    71  func withinTolerance(c0, c1 color.Color, tolerance int) bool {
    72  	r0, g0, b0, a0 := c0.RGBA()
    73  	r1, g1, b1, a1 := c1.RGBA()
    74  	r := delta(r0, r1)
    75  	g := delta(g0, g1)
    76  	b := delta(b0, b1)
    77  	a := delta(a0, a1)
    78  	return r <= tolerance && g <= tolerance && b <= tolerance && a <= tolerance
    79  }
    80  
    81  func TestDecode(t *testing.T) {
    82  	rgba := func(c color.Color) string {
    83  		r, g, b, a := c.RGBA()
    84  		return fmt.Sprintf("rgba = 0x%04x, 0x%04x, 0x%04x, 0x%04x for %T%v", r, g, b, a, c, c)
    85  	}
    86  
    87  	golden := make(map[string]image.Image)
    88  loop:
    89  	for _, it := range imageTests {
    90  		g := golden[it.goldenFilename]
    91  		if g == nil {
    92  			var err error
    93  			g, _, err = decode(it.goldenFilename)
    94  			if err != nil {
    95  				t.Errorf("%s: %v", it.goldenFilename, err)
    96  				continue loop
    97  			}
    98  			golden[it.goldenFilename] = g
    99  		}
   100  		m, imageFormat, err := decode(it.filename)
   101  		if err != nil {
   102  			t.Errorf("%s: %v", it.filename, err)
   103  			continue loop
   104  		}
   105  		b := g.Bounds()
   106  		if !b.Eq(m.Bounds()) {
   107  			t.Errorf("%s: got bounds %v want %v", it.filename, m.Bounds(), b)
   108  			continue loop
   109  		}
   110  		for y := b.Min.Y; y < b.Max.Y; y++ {
   111  			for x := b.Min.X; x < b.Max.X; x++ {
   112  				if !withinTolerance(g.At(x, y), m.At(x, y), it.tolerance) {
   113  					t.Errorf("%s: at (%d, %d):\ngot  %v\nwant %v",
   114  						it.filename, x, y, rgba(m.At(x, y)), rgba(g.At(x, y)))
   115  					continue loop
   116  				}
   117  			}
   118  		}
   119  		if imageFormat == "gif" {
   120  			// Each frame of a GIF can have a frame-local palette override the
   121  			// GIF-global palette. Thus, image.Decode can yield a different ColorModel
   122  			// than image.DecodeConfig.
   123  			continue
   124  		}
   125  		c, _, err := decodeConfig(it.filename)
   126  		if m.ColorModel() != c.ColorModel {
   127  			t.Errorf("%s: color models differ", it.filename)
   128  			continue loop
   129  		}
   130  	}
   131  }
   132  

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