107 lines
2.1 KiB
Go
107 lines
2.1 KiB
Go
package pngstructure
|
|
|
|
import (
|
|
"bufio"
|
|
"bytes"
|
|
"io"
|
|
"os"
|
|
|
|
log "github.com/dsoprea/go-logging"
|
|
riimage "github.com/dsoprea/go-utility/image"
|
|
)
|
|
|
|
// PngMediaParser knows how to parse a PNG stream.
|
|
type PngMediaParser struct {
|
|
}
|
|
|
|
// NewPngMediaParser returns a new `PngMediaParser` struct.
|
|
func NewPngMediaParser() *PngMediaParser {
|
|
|
|
// TODO(dustin): Add test
|
|
|
|
return new(PngMediaParser)
|
|
}
|
|
|
|
// Parse parses a PNG stream given a `io.ReadSeeker`.
|
|
func (pmp *PngMediaParser) Parse(rs io.ReadSeeker, size int) (mc riimage.MediaContext, err error) {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err = log.Wrap(state.(error))
|
|
}
|
|
}()
|
|
|
|
// TODO(dustin): Add test
|
|
|
|
ps := NewPngSplitter()
|
|
|
|
err = ps.readHeader(rs)
|
|
log.PanicIf(err)
|
|
|
|
s := bufio.NewScanner(rs)
|
|
|
|
// Since each segment can be any size, our buffer must be allowed to grow
|
|
// as large as the file.
|
|
buffer := []byte{}
|
|
s.Buffer(buffer, size)
|
|
s.Split(ps.Split)
|
|
|
|
for s.Scan() != false {
|
|
}
|
|
log.PanicIf(s.Err())
|
|
|
|
return ps.Chunks(), nil
|
|
}
|
|
|
|
// ParseFile parses a PNG stream given a file-path.
|
|
func (pmp *PngMediaParser) ParseFile(filepath string) (mc riimage.MediaContext, err error) {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err = log.Wrap(state.(error))
|
|
}
|
|
}()
|
|
|
|
f, err := os.Open(filepath)
|
|
log.PanicIf(err)
|
|
|
|
defer f.Close()
|
|
|
|
stat, err := f.Stat()
|
|
log.PanicIf(err)
|
|
|
|
size := stat.Size()
|
|
|
|
chunks, err := pmp.Parse(f, int(size))
|
|
log.PanicIf(err)
|
|
|
|
return chunks, nil
|
|
}
|
|
|
|
// ParseBytes parses a PNG stream given a byte-slice.
|
|
func (pmp *PngMediaParser) ParseBytes(data []byte) (mc riimage.MediaContext, err error) {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err = log.Wrap(state.(error))
|
|
}
|
|
}()
|
|
|
|
// TODO(dustin): Add test
|
|
|
|
br := bytes.NewReader(data)
|
|
|
|
chunks, err := pmp.Parse(br, len(data))
|
|
log.PanicIf(err)
|
|
|
|
return chunks, nil
|
|
}
|
|
|
|
// LooksLikeFormat returns a boolean indicating whether the stream looks like a
|
|
// PNG image.
|
|
func (pmp *PngMediaParser) LooksLikeFormat(data []byte) bool {
|
|
return bytes.Compare(data[:len(PngSignature)], PngSignature[:]) == 0
|
|
}
|
|
|
|
var (
|
|
// Enforce interface conformance.
|
|
_ riimage.MediaParser = new(PngMediaParser)
|
|
)
|