--- /dev/null
+// 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 tiff
+
+import (
+ "bufio"
+ "io"
+ "os"
+)
+
+type byteReader interface {
+ io.Reader
+ io.ByteReader
+}
+
+// unpackBits decodes the PackBits-compressed data in src and returns the
+// uncompressed data.
+//
+// The PackBits compression format is described in section 9 (p. 42)
+// of the TIFF spec.
+func unpackBits(r io.Reader) ([]byte, os.Error) {
+ buf := make([]byte, 128)
+ dst := make([]byte, 0, 1024)
+ br, ok := r.(byteReader)
+ if !ok {
+ br = bufio.NewReader(r)
+ }
+
+ for {
+ b, err := br.ReadByte()
+ if err != nil {
+ if err == os.EOF {
+ return dst, nil
+ }
+ return nil, err
+ }
+ code := int(int8(b))
+ switch {
+ case code >= 0:
+ n, err := io.ReadFull(br, buf[:code+1])
+ if err != nil {
+ return nil, err
+ }
+ dst = append(dst, buf[:n]...)
+ case code == -128:
+ // No-op.
+ default:
+ if b, err = br.ReadByte(); err != nil {
+ return nil, err
+ }
+ for j := 0; j < 1-code; j++ {
+ buf[j] = b
+ }
+ dst = append(dst, buf[:1-code]...)
+ }
+ }
+ panic("unreachable")
+}
package tiff
import (
+ "image"
"io/ioutil"
"os"
+ "strings"
"testing"
)
}
}
+// TestUnpackBits tests the decoding of PackBits-encoded data.
+func TestUnpackBits(t *testing.T) {
+ var unpackBitsTests = []struct {
+ compressed string
+ uncompressed string
+ }{{
+ // Example data from Wikipedia.
+ "\xfe\xaa\x02\x80\x00\x2a\xfd\xaa\x03\x80\x00\x2a\x22\xf7\xaa",
+ "\xaa\xaa\xaa\x80\x00\x2a\xaa\xaa\xaa\xaa\x80\x00\x2a\x22\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa",
+ }}
+ for _, u := range unpackBitsTests {
+ buf, err := unpackBits(strings.NewReader(u.compressed))
+ if err != nil {
+ t.Fatal(err)
+ }
+ if string(buf) != u.uncompressed {
+ t.Fatalf("unpackBits: want %x, got %x", u.uncompressed, buf)
+ }
+ }
+}
+
+// TestDecompress tests that decoding some TIFF images that use different
+// compression formats result in the same pixel data.
+func TestDecompress(t *testing.T) {
+ var decompressTests = []string{
+ "bw-uncompressed.tiff",
+ "bw-deflate.tiff",
+ "bw-packbits.tiff",
+ }
+ var img0 image.Image
+ for _, name := range decompressTests {
+ f, err := os.Open("testdata/" + name)
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer f.Close()
+ if img0 == nil {
+ img0, err = Decode(f)
+ if err != nil {
+ t.Fatalf("decoding %s: %v", name, err)
+ }
+ continue
+ }
+
+ img1, err := Decode(f)
+ if err != nil {
+ t.Fatalf("decoding %s: %v", name, err)
+ }
+ b := img1.Bounds()
+ // Compare images.
+ if !b.Eq(img0.Bounds()) {
+ t.Fatalf("wrong image size: want %s, got %s", img0.Bounds(), b)
+ }
+ for y := b.Min.Y; y < b.Max.Y; y++ {
+ for x := b.Min.X; x < b.Max.X; x++ {
+ c0 := img0.At(x, y)
+ c1 := img1.At(x, y)
+ r0, g0, b0, a0 := c0.RGBA()
+ r1, g1, b1, a1 := c1.RGBA()
+ if r0 != r1 || g0 != g1 || b0 != b1 || a0 != a1 {
+ t.Fatalf("pixel at (%d, %d) has wrong color: want %v, got %v", x, y, c0, c1)
+ }
+ }
+ }
+ }
+}
+
const filename = "testdata/video-001-uncompressed.tiff"
// BenchmarkDecode benchmarks the decoding of an image.