writer_test.go

Documentation: golang.org/x/image/bmp

     1  // Copyright 2013 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 bmp
     6  
     7  import (
     8  	"bytes"
     9  	"fmt"
    10  	"image"
    11  	"image/draw"
    12  	"io/ioutil"
    13  	"os"
    14  	"testing"
    15  	"time"
    16  )
    17  
    18  func openImage(filename string) (image.Image, error) {
    19  	f, err := os.Open(testdataDir + filename)
    20  	if err != nil {
    21  		return nil, err
    22  	}
    23  	defer f.Close()
    24  	return Decode(f)
    25  }
    26  
    27  func convertToRGBA(in image.Image) image.Image {
    28  	b := in.Bounds()
    29  	out := image.NewRGBA(b)
    30  	draw.Draw(out, b, in, b.Min, draw.Src)
    31  	return out
    32  }
    33  
    34  func convertToNRGBA(in image.Image) image.Image {
    35  	b := in.Bounds()
    36  	out := image.NewNRGBA(b)
    37  	draw.Draw(out, b, in, b.Min, draw.Src)
    38  	return out
    39  }
    40  
    41  func TestEncode(t *testing.T) {
    42  	testCases := []string{
    43  		"video-001.bmp",
    44  		"yellow_rose-small.bmp",
    45  	}
    46  
    47  	for _, tc := range testCases {
    48  		img0, err := openImage(tc)
    49  		if err != nil {
    50  			t.Errorf("%s: Open BMP: %v", tc, err)
    51  			continue
    52  		}
    53  
    54  		buf := new(bytes.Buffer)
    55  		err = Encode(buf, img0)
    56  		if err != nil {
    57  			t.Errorf("%s: Encode BMP: %v", tc, err)
    58  			continue
    59  		}
    60  
    61  		img1, err := Decode(buf)
    62  		if err != nil {
    63  			t.Errorf("%s: Decode BMP: %v", tc, err)
    64  			continue
    65  		}
    66  
    67  		err = compare(img0, img1)
    68  		if err != nil {
    69  			t.Errorf("%s: Compare BMP: %v", tc, err)
    70  			continue
    71  		}
    72  
    73  		buf2 := new(bytes.Buffer)
    74  		rgba := convertToRGBA(img0)
    75  		err = Encode(buf2, rgba)
    76  		if err != nil {
    77  			t.Errorf("%s: Encode pre-multiplied BMP: %v", tc, err)
    78  			continue
    79  		}
    80  
    81  		img2, err := Decode(buf2)
    82  		if err != nil {
    83  			t.Errorf("%s: Decode pre-multiplied BMP: %v", tc, err)
    84  			continue
    85  		}
    86  
    87  		// We need to do another round trip to NRGBA to compare to, since
    88  		// the conversion process is lossy.
    89  		img3 := convertToNRGBA(rgba)
    90  
    91  		err = compare(img3, img2)
    92  		if err != nil {
    93  			t.Errorf("%s: Compare pre-multiplied BMP: %v", tc, err)
    94  		}
    95  	}
    96  }
    97  
    98  // TestZeroWidthVeryLargeHeight tests that encoding and decoding a degenerate
    99  // image with zero width but over one billion pixels in height is faster than
   100  // naively calling an io.Reader or io.Writer method once per row.
   101  func TestZeroWidthVeryLargeHeight(t *testing.T) {
   102  	c := make(chan error, 1)
   103  	go func() {
   104  		b := image.Rect(0, 0, 0, 0x3fffffff)
   105  		var buf bytes.Buffer
   106  		if err := Encode(&buf, image.NewRGBA(b)); err != nil {
   107  			c <- err
   108  			return
   109  		}
   110  		m, err := Decode(&buf)
   111  		if err != nil {
   112  			c <- err
   113  			return
   114  		}
   115  		if got := m.Bounds(); got != b {
   116  			c <- fmt.Errorf("bounds: got %v, want %v", got, b)
   117  			return
   118  		}
   119  		c <- nil
   120  	}()
   121  	select {
   122  	case err := <-c:
   123  		if err != nil {
   124  			t.Fatal(err)
   125  		}
   126  	case <-time.After(3 * time.Second):
   127  		t.Fatalf("timed out")
   128  	}
   129  }
   130  
   131  // BenchmarkEncode benchmarks the encoding of an image.
   132  func BenchmarkEncode(b *testing.B) {
   133  	img, err := openImage("video-001.bmp")
   134  	if err != nil {
   135  		b.Fatal(err)
   136  	}
   137  	s := img.Bounds().Size()
   138  	b.SetBytes(int64(s.X * s.Y * 4))
   139  	b.ResetTimer()
   140  	for i := 0; i < b.N; i++ {
   141  		Encode(ioutil.Discard, img)
   142  	}
   143  }
   144
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