icns

commit cff759cb543a1f59edfad29eba0d57274c35e59b
parent cb4307b7502e9bfa91daae633b6d9212bf1385eb
Author: Jack Mordaunt <jackmordaunt.dev@gmail.com>
Date:   Fri, 18 Sep 2026 16:09:29 -0400

icns: build element headers with encoding/binary

The package carried its own big-endian writer and copied the type field a
byte at a time, which the standard library and copy already do. Sharing
elementHeaderSize with the decoder keeps the encoder's idea of a header from
drifting from the parser's.

Diffstat:
M
icns.go
 | 
9
---------
M
writer.go
 | 
17
+++++------------

2 files changed, 5 insertions(+), 21 deletions(-)
diff --git a/icns.go b/icns.go
@@ -107,15 +107,6 @@ func resizeSquare(img image.Image, size uint, interp InterpolationFunction) imag
 	return dst
 }
 
-// Big-endian.
-// https://golang.org/src/image/png/writer.go
-func writeUint32(b []uint8, u uint32) {
-	b[0] = uint8(u >> 24)
-	b[1] = uint8(u >> 16)
-	b[2] = uint8(u >> 8)
-	b[3] = uint8(u >> 0)
-}
-
 var sizes = []uint{
 	1024,
 	512,
diff --git a/writer.go b/writer.go
@@ -2,6 +2,7 @@ package icns
 
 import (
 	"bytes"
+	"encoding/binary"
 	"image"
 	"image/png"
 	"io"
@@ -59,12 +60,8 @@ func encodeImage(img image.Image) ([]byte, error) {
 func (i *Icon) writeHeader(wr io.Writer) (int64, error) {
 	if !i.headerSet {
 		defer func() { i.headerSet = true }()
-		i.header[0] = i.Type.ID[0]
-		i.header[1] = i.Type.ID[1]
-		i.header[2] = i.Type.ID[2]
-		i.header[3] = i.Type.ID[3]
-		length := uint32(len(i.data) + 8)
-		writeUint32(i.header[4:8], length)
+		copy(i.header[:4], i.Type.ID)
+		binary.BigEndian.PutUint32(i.header[4:8], uint32(len(i.data)+elementHeaderSize))
 	}
 	written, err := wr.Write(i.header[:8])
 	return int64(written), err
@@ -123,12 +120,8 @@ func (s *IconSet) encodeIcons() error {
 func (s *IconSet) writeHeader(wr io.Writer) (int64, error) {
 	if !s.headerSet {
 		defer func() { s.headerSet = true }()
-		s.header[0] = 'i'
-		s.header[1] = 'c'
-		s.header[2] = 'n'
-		s.header[3] = 's'
-		length := uint32(len(s.data) + 8)
-		writeUint32(s.header[4:8], length)
+		copy(s.header[:4], "icns")
+		binary.BigEndian.PutUint32(s.header[4:8], uint32(len(s.data)+elementHeaderSize))
 	}
 	written, err := wr.Write(s.header[:8])
 	return int64(written), err