Add codec for tag 0xC4A5 PrintImageMatching #81
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,81 @@ | ||
| package exifundefined | ||
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| import ( | ||
| "bytes" | ||
| "encoding/binary" | ||
| "fmt" | ||
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| log "github.com/dsoprea/go-logging" | ||
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| exifcommon "github.com/dsoprea/go-exif/v3/common" | ||
| ) | ||
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| var PrintImageMatchingHeader = []byte{0x50, 0x72, 0x69, 0x6e, 0x74, 0x49, 0x4d, 0x00} | ||
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| type TagC4A5PrintImageMatching struct { | ||
| Version string | ||
| Value []byte | ||
| } | ||
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| func (TagC4A5PrintImageMatching) EncoderName() string { | ||
| return "CodecC4A5PrintImageMatching" | ||
| } | ||
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| func (ev TagC4A5PrintImageMatching) String() string { | ||
| return fmt.Sprintf("TagC4A5PrintImageMatching<VERSION=(%s) BYTES=(%v)>", ev.Version, ev.Value) | ||
| } | ||
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| type CodecC4A5PrintImageMatching struct{} | ||
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| func (CodecC4A5PrintImageMatching) Encode(value interface{}, byteOrder binary.ByteOrder) (encoded []byte, unitCount uint32, err error) { | ||
| defer func() { | ||
| if state := recover(); state != nil { | ||
| err = log.Wrap(state.(error)) | ||
| } | ||
| }() | ||
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| pim, ok := value.(TagC4A5PrintImageMatching) | ||
| if !ok { | ||
| log.Panicf("can only encode a TagC4A5PrintImageMatching") | ||
| } | ||
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| return pim.Value, uint32(len(pim.Value)), nil | ||
| } | ||
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| func (CodecC4A5PrintImageMatching) Decode(valueContext *exifcommon.ValueContext) (value EncodeableValue, err error) { | ||
| // PIM structure explanation: https://www.ozhiker.com/electronics/pjmt/jpeg_info/pim.html Looks like | ||
| // there is no sufficient open documentation about this tag: | ||
| // https://github.com/Exiv2/exiv2/issues/1419#issuecomment-739723214 | ||
| // For that reason we are just preserving its raw bytes | ||
| defer func() { | ||
| if state := recover(); state != nil { | ||
| err = log.Wrap(state.(error)) | ||
| } | ||
| }() | ||
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| ev := TagC4A5PrintImageMatching{} | ||
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| valueContext.SetUndefinedValueType(exifcommon.TypeByte) | ||
| rawBytes, err := valueContext.ReadBytes() | ||
| ev.Value = rawBytes | ||
|
There was a problem hiding this comment. The documentation describes how to find an entry count and the list of entries. We can parse things better than just yielding an opaque byte slice, yes? There was a problem hiding this comment. I could not find any decent documentation on PrintIM. It is not specified in the exif 2.2 spec. The only thing I found was the link I posted above and it does not agree with my images. My images have a 106 byte PrintIM. According to the spec this would mean Header: 8 This works out if there are 15 entries. However here is the actual PrintIM bytes of one of my photos: Bytes 15-16 are Let's say we ignore the count and treat the remaining bytes as 6 byte entries. Here is what we get: and so on. If the first 2 bytes of each entry would designate its tag id we have 2 tag ids of That's why I gave up and decided I would rather keep the tag opaque rather than parse it incorrectly. |
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| if !bytes.Equal(rawBytes[0:8], PrintImageMatchingHeader[:]) { | ||
| log.Panicf("invalid header for tag 0xC4A5 PrintImageMatching") | ||
| } | ||
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| versionLen := bytes.IndexByte(rawBytes[8:], 0) | ||
|
There was a problem hiding this comment. Validate that |
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| ev.Version = string(rawBytes[8 : 8+versionLen]) | ||
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| return ev, nil | ||
| } | ||
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| func init() { | ||
| registerEncoder( | ||
| TagC4A5PrintImageMatching{}, | ||
| CodecC4A5PrintImageMatching{}) | ||
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| registerDecoder( | ||
| exifcommon.IfdStandardIfdIdentity.UnindexedString(), | ||
| 0xc4a5, | ||
| CodecC4A5PrintImageMatching{}) | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| package exifundefined | ||
|
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| import ( | ||
| "bytes" | ||
| "reflect" | ||
| "testing" | ||
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| log "github.com/dsoprea/go-logging" | ||
| rifs "github.com/dsoprea/go-utility/v2/filesystem" | ||
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| exifcommon "github.com/dsoprea/go-exif/v3/common" | ||
| ) | ||
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| func TestTagC4A5PrintImageMatching_String(t *testing.T) { | ||
| ut := TagC4A5PrintImageMatching{ | ||
| Version: "0300", | ||
| Value: []byte{0x01, 0x02, 0x03, 0x04}, | ||
| } | ||
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| s := ut.String() | ||
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| if s != "TagC4A5PrintImageMatching<VERSION=(0300) BYTES=([1 2 3 4])>" { | ||
| t.Fatalf("String not correct: [%s]", s) | ||
| } | ||
| } | ||
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| func TestCodecC4A5PrintImageMatching_Encode(t *testing.T) { | ||
| rawBytes := []byte{ | ||
| 0x50, 0x72, 0x69, 0x6e, 0x74, 0x49, 0x4d, 0x00, | ||
| 0x30, 0x33, 0x30, 0x30, 0x00, | ||
| 0x01, 0x02, 0x03, 0x04, | ||
| } | ||
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| ut := TagC4A5PrintImageMatching{ | ||
| Version: "0300", | ||
| Value: rawBytes, | ||
| } | ||
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| codec := CodecC4A5PrintImageMatching{} | ||
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| encoded, unitCount, err := codec.Encode(ut, exifcommon.TestDefaultByteOrder) | ||
| log.PanicIf(err) | ||
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| if bytes.Equal(encoded, rawBytes) != true { | ||
| exifcommon.DumpBytesClause(encoded) | ||
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| t.Fatalf("Encoded bytes not correct.") | ||
| } else if unitCount != 17 { | ||
| t.Fatalf("Unit-count not correct: (%d)", unitCount) | ||
| } | ||
| } | ||
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| func TestCodecC4A5PrintImageMatching_Decode(t *testing.T) { | ||
| rawBytes := []byte{ | ||
| 0x50, 0x72, 0x69, 0x6e, 0x74, 0x49, 0x4d, 0x00, | ||
| 0x30, 0x33, 0x30, 0x30, 0x00, | ||
| 0x01, 0x02, 0x03, 0x04, | ||
| } | ||
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| valueContext := exifcommon.NewValueContext( | ||
| "", | ||
| 0, | ||
| uint32(len(rawBytes)), | ||
| 0, | ||
| nil, | ||
| rifs.NewSeekableBufferWithBytes(rawBytes), | ||
| exifcommon.TypeUndefined, | ||
| exifcommon.TestDefaultByteOrder) | ||
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| codec := CodecC4A5PrintImageMatching{} | ||
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| value, err := codec.Decode(valueContext) | ||
| log.PanicIf(err) | ||
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| expectedValue := TagC4A5PrintImageMatching{ | ||
| Version: "0300", | ||
| Value: rawBytes, | ||
| } | ||
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| if reflect.DeepEqual(value, expectedValue) != true { | ||
| t.Fatalf("Decoded value not correct: %s", value) | ||
| } | ||
| } |
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Do not include module changes.