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