mirror of
https://github.com/dsoprea/go-exif.git
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08ac8466dd
This allows us to pass around individual tokens that we can use to generate IDs, names, and qualified and non-qualified IFD paths, rather than [necessarily] having to pass or store them individually. The previous global variables were strings. Now they are IfdIdentity structs and have been renamed to be more accurate (in general, as well as for this). The previous variables have been kept but are now just assigned to the newer variables. This is backwards-compatibility that will be removed in the future.
149 lines
3.1 KiB
Go
149 lines
3.1 KiB
Go
package exifundefined
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import (
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"bytes"
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"fmt"
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"encoding/binary"
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"github.com/dsoprea/go-logging"
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"github.com/dsoprea/go-exif/v2/common"
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)
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type Tag8828Oecf struct {
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Columns uint16
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Rows uint16
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ColumnNames []string
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Values []exifcommon.SignedRational
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}
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func (oecf Tag8828Oecf) String() string {
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return fmt.Sprintf("Tag8828Oecf<COLUMNS=(%d) ROWS=(%d)>", oecf.Columns, oecf.Rows)
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}
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func (oecf Tag8828Oecf) EncoderName() string {
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return "Codec8828Oecf"
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}
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type Codec8828Oecf struct {
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}
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func (Codec8828Oecf) Encode(value interface{}, byteOrder binary.ByteOrder) (encoded []byte, unitCount uint32, err error) {
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defer func() {
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if state := recover(); state != nil {
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err = log.Wrap(state.(error))
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}
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}()
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// TODO(dustin): Add test
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oecf, ok := value.(Tag8828Oecf)
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if ok == false {
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log.Panicf("can only encode a Tag8828Oecf")
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}
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b := new(bytes.Buffer)
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err = binary.Write(b, byteOrder, oecf.Columns)
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log.PanicIf(err)
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err = binary.Write(b, byteOrder, oecf.Rows)
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log.PanicIf(err)
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for _, name := range oecf.ColumnNames {
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_, err := b.Write([]byte(name))
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log.PanicIf(err)
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_, err = b.Write([]byte{0})
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log.PanicIf(err)
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}
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ve := exifcommon.NewValueEncoder(byteOrder)
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ed, err := ve.Encode(oecf.Values)
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log.PanicIf(err)
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_, err = b.Write(ed.Encoded)
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log.PanicIf(err)
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return b.Bytes(), uint32(b.Len()), nil
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}
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func (Codec8828Oecf) Decode(valueContext *exifcommon.ValueContext) (value EncodeableValue, err error) {
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defer func() {
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if state := recover(); state != nil {
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err = log.Wrap(state.(error))
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}
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}()
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// TODO(dustin): Add test using known good data.
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valueContext.SetUndefinedValueType(exifcommon.TypeByte)
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valueBytes, err := valueContext.ReadBytes()
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log.PanicIf(err)
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oecf := Tag8828Oecf{}
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oecf.Columns = valueContext.ByteOrder().Uint16(valueBytes[0:2])
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oecf.Rows = valueContext.ByteOrder().Uint16(valueBytes[2:4])
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columnNames := make([]string, oecf.Columns)
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// startAt is where the current column name starts.
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startAt := 4
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// offset is our current position.
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offset := startAt
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currentColumnNumber := uint16(0)
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for currentColumnNumber < oecf.Columns {
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if valueBytes[offset] == 0 {
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columnName := string(valueBytes[startAt:offset])
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if len(columnName) == 0 {
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log.Panicf("SFR column (%d) has zero length", currentColumnNumber)
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}
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columnNames[currentColumnNumber] = columnName
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currentColumnNumber++
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offset++
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startAt = offset
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continue
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}
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offset++
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}
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oecf.ColumnNames = columnNames
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rawRationalBytes := valueBytes[offset:]
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rationalSize := exifcommon.TypeSignedRational.Size()
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if len(rawRationalBytes)%rationalSize > 0 {
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log.Panicf("OECF signed-rationals not aligned: (%d) %% (%d) > 0", len(rawRationalBytes), rationalSize)
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}
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rationalCount := len(rawRationalBytes) / rationalSize
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parser := new(exifcommon.Parser)
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byteOrder := valueContext.ByteOrder()
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items, err := parser.ParseSignedRationals(rawRationalBytes, uint32(rationalCount), byteOrder)
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log.PanicIf(err)
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oecf.Values = items
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return oecf, nil
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}
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func init() {
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registerDecoder(
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exifcommon.IfdExifStandardIfdIdentity.UnindexedString(),
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0x8828,
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Codec8828Oecf{})
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}
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