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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "lib/extras/exif.h"
#include "lib/jxl/base/byte_order.h"
namespace jxl {
constexpr uint16_t kExifOrientationTag = 274;
void ResetExifOrientation(std::vector<uint8_t>& exif) {
if (exif.size() < 12) return; // not enough bytes for a valid exif blob
bool bigendian;
uint8_t* t = exif.data();
if (LoadLE32(t) == 0x2A004D4D) {
bigendian = true;
} else if (LoadLE32(t) == 0x002A4949) {
bigendian = false;
} else {
return; // not a valid tiff header
}
t += 4;
uint32_t offset = (bigendian ? LoadBE32(t) : LoadLE32(t));
if (exif.size() < 12 + offset + 2 || offset < 8) return;
t += offset - 4;
uint16_t nb_tags = (bigendian ? LoadBE16(t) : LoadLE16(t));
t += 2;
while (nb_tags > 0) {
if (t + 12 >= exif.data() + exif.size()) return;
uint16_t tag = (bigendian ? LoadBE16(t) : LoadLE16(t));
t += 2;
if (tag == kExifOrientationTag) {
uint16_t type = (bigendian ? LoadBE16(t) : LoadLE16(t));
t += 2;
uint32_t count = (bigendian ? LoadBE32(t) : LoadLE32(t));
t += 4;
if (type == 3 && count == 1) {
if (bigendian) {
StoreBE16(1, t);
} else {
StoreLE16(1, t);
}
}
return;
} else {
t += 10;
nb_tags--;
}
}
}
} // namespace jxl
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