116 lines
3.9 KiB
Go
116 lines
3.9 KiB
Go
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package web
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import (
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"bytes"
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"encoding/binary"
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"image"
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"image/color"
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"image/jpeg"
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"testing"
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"github.com/disintegration/imaging"
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)
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// jpegBytes encodes a w×h test image as JPEG (no EXIF).
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func jpegBytes(t *testing.T, w, h int) []byte {
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t.Helper()
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img := image.NewRGBA(image.Rect(0, 0, w, h))
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for y := 0; y < h; y++ {
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for x := 0; x < w; x++ {
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img.Set(x, y, color.RGBA{uint8(x * 30), uint8(y * 30), 100, 255})
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}
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}
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var buf bytes.Buffer
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if err := jpeg.Encode(&buf, img, &jpeg.Options{Quality: 90}); err != nil {
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t.Fatalf("encode jpeg: %v", err)
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}
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return buf.Bytes()
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}
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// withOrientation splices a minimal big-endian EXIF APP1 segment carrying the
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// given Orientation value into a JPEG (right after the SOI marker).
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func withOrientation(t *testing.T, jpg []byte, orientation uint16) []byte {
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t.Helper()
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tiff := new(bytes.Buffer)
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tiff.WriteString("MM") // big-endian
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binary.Write(tiff, binary.BigEndian, uint16(0x002A)) // magic
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binary.Write(tiff, binary.BigEndian, uint32(8)) // IFD0 at offset 8
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binary.Write(tiff, binary.BigEndian, uint16(1)) // one entry
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binary.Write(tiff, binary.BigEndian, uint16(0x0112)) // tag: Orientation
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binary.Write(tiff, binary.BigEndian, uint16(3)) // type: SHORT
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binary.Write(tiff, binary.BigEndian, uint32(1)) // count
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binary.Write(tiff, binary.BigEndian, orientation) // value (in high 2 bytes)
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binary.Write(tiff, binary.BigEndian, uint16(0)) // value padding
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binary.Write(tiff, binary.BigEndian, uint32(0)) // next IFD: none
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payload := append([]byte("Exif\x00\x00"), tiff.Bytes()...)
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app1 := new(bytes.Buffer)
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app1.Write([]byte{0xFF, 0xE1})
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binary.Write(app1, binary.BigEndian, uint16(len(payload)+2)) // segment length
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app1.Write(payload)
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out := make([]byte, 0, len(jpg)+app1.Len())
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out = append(out, jpg[:2]...) // SOI
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out = append(out, app1.Bytes()...)
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out = append(out, jpg[2:]...)
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return out
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}
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func TestExifOrientation(t *testing.T) {
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plain := jpegBytes(t, 4, 2)
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if got := exifOrientation(plain); got != 0 {
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t.Errorf("plain JPEG: orientation = %d, want 0 (no tag)", got)
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}
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for _, o := range []uint16{1, 3, 6, 8} {
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tagged := withOrientation(t, plain, o)
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if got := exifOrientation(tagged); got != int(o) {
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t.Errorf("tagged orientation %d: got %d", o, got)
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}
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}
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if got := exifOrientation([]byte("not a jpeg")); got != 0 {
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t.Errorf("non-JPEG: orientation = %d, want 0", got)
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}
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}
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func TestNormalizeOrientationPassThrough(t *testing.T) {
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plain := jpegBytes(t, 4, 2)
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// Non-JPEG mime → untouched.
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png := []byte("fake png bytes")
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if got := normalizeOrientation(png, "image/png"); !bytes.Equal(got, png) {
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t.Error("png should pass through unchanged")
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}
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// JPEG without EXIF → untouched (can't know, don't guess or recompress).
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if got := normalizeOrientation(plain, "image/jpeg"); !bytes.Equal(got, plain) {
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t.Error("EXIF-less JPEG should pass through byte-for-byte")
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}
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// JPEG already upright (orientation 1) → untouched.
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up := withOrientation(t, plain, 1)
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if got := normalizeOrientation(up, "image/jpeg"); !bytes.Equal(got, up) {
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t.Error("orientation-1 JPEG should pass through byte-for-byte")
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}
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}
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func TestNormalizeOrientationRotates(t *testing.T) {
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// Stored 4×2 (wide) image tagged orientation 6 ("rotate 90° CW to view") must
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// come out upright — i.e. tall (2×4) — with the EXIF tag stripped.
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wide := jpegBytes(t, 4, 2)
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tagged := withOrientation(t, wide, 6)
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out := normalizeOrientation(tagged, "image/jpeg")
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if bytes.Equal(out, tagged) {
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t.Fatal("orientation-6 JPEG should have been re-encoded upright")
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}
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if got := exifOrientation(out); got != 0 {
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t.Errorf("output still carries orientation tag %d; want stripped (0)", got)
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}
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img, err := imaging.Decode(bytes.NewReader(out))
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if err != nil {
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t.Fatalf("decode output: %v", err)
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}
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b := img.Bounds()
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if b.Dx() != 2 || b.Dy() != 4 {
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t.Errorf("output dims = %dx%d, want 2x4 (rotated upright)", b.Dx(), b.Dy())
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}
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}
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