use exif-terminator

vendor/github.com/dsoprea/go-png-image-structure/v2/chunk_decoder.go

@@ -0,0 +1,87 @@
+package pngstructure
+
+import (
+	"bytes"
+	"fmt"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+type ChunkDecoder struct {
+}
+
+func NewChunkDecoder() *ChunkDecoder {
+	return new(ChunkDecoder)
+}
+
+func (cd *ChunkDecoder) Decode(c *Chunk) (decoded interface{}, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err := log.Wrap(state.(error))
+			log.Panic(err)
+		}
+	}()
+
+	switch c.Type {
+	case "IHDR":
+		ihdr, err := cd.decodeIHDR(c)
+		log.PanicIf(err)
+
+		return ihdr, nil
+	}
+
+	// We don't decode this particular type.
+	return nil, nil
+}
+
+type ChunkIHDR struct {
+	Width             uint32
+	Height            uint32
+	BitDepth          uint8
+	ColorType         uint8
+	CompressionMethod uint8
+	FilterMethod      uint8
+	InterlaceMethod   uint8
+}
+
+func (ihdr *ChunkIHDR) String() string {
+	return fmt.Sprintf("IHDR<WIDTH=(%d) HEIGHT=(%d) DEPTH=(%d) COLOR-TYPE=(%d) COMP-METHOD=(%d) FILTER-METHOD=(%d) INTRLC-METHOD=(%d)>", ihdr.Width, ihdr.Height, ihdr.BitDepth, ihdr.ColorType, ihdr.CompressionMethod, ihdr.FilterMethod, ihdr.InterlaceMethod)
+}
+
+func (cd *ChunkDecoder) decodeIHDR(c *Chunk) (ihdr *ChunkIHDR, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err := log.Wrap(state.(error))
+			log.Panic(err)
+		}
+	}()
+
+	b := bytes.NewBuffer(c.Data)
+
+	ihdr = new(ChunkIHDR)
+
+	err = binary.Read(b, binary.BigEndian, &ihdr.Width)
+	log.PanicIf(err)
+
+	err = binary.Read(b, binary.BigEndian, &ihdr.Height)
+	log.PanicIf(err)
+
+	err = binary.Read(b, binary.BigEndian, &ihdr.BitDepth)
+	log.PanicIf(err)
+
+	err = binary.Read(b, binary.BigEndian, &ihdr.ColorType)
+	log.PanicIf(err)
+
+	err = binary.Read(b, binary.BigEndian, &ihdr.CompressionMethod)
+	log.PanicIf(err)
+
+	err = binary.Read(b, binary.BigEndian, &ihdr.FilterMethod)
+	log.PanicIf(err)
+
+	err = binary.Read(b, binary.BigEndian, &ihdr.InterlaceMethod)
+	log.PanicIf(err)
+
+	return ihdr, nil
+}