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// Copyright 2022 Google LLC. All rights reserved.
// SPDX-License-Identifier: BSD-2-Clause
#include "avif/internal.h"
#include <stdint.h>
#include <string.h>
avifResult avifGetExifTiffHeaderOffset(const avifRWData * exif, uint32_t * offset)
{
const uint8_t tiffHeaderBE[4] = { 'M', 'M', 0, 42 };
const uint8_t tiffHeaderLE[4] = { 'I', 'I', 42, 0 };
for (*offset = 0; *offset + 4 < exif->size; ++*offset) {
if (!memcmp(&exif->data[*offset], tiffHeaderBE, 4) || !memcmp(&exif->data[*offset], tiffHeaderLE, 4)) {
return AVIF_RESULT_OK;
}
}
// Couldn't find the TIFF header
return AVIF_RESULT_INVALID_EXIF_PAYLOAD;
}
avifResult avifImageExtractExifOrientationToIrotImir(avifImage * image)
{
const avifTransformFlags otherFlags = image->transformFlags & ~(AVIF_TRANSFORM_IROT | AVIF_TRANSFORM_IMIR);
uint32_t offset;
const avifResult result = avifGetExifTiffHeaderOffset(&image->exif, &offset);
if (result != AVIF_RESULT_OK) {
// Couldn't find the TIFF header
return result;
}
avifROData raw = { image->exif.data + offset, image->exif.size - offset };
const avifBool littleEndian = (raw.data[0] == 'I');
avifROStream stream;
avifROStreamStart(&stream, &raw, NULL, NULL);
// TIFF Header
uint32_t offsetTo0thIfd;
if (!avifROStreamSkip(&stream, 4) || // Skip tiffHeaderBE or tiffHeaderLE.
!avifROStreamReadU32Endianness(&stream, &offsetTo0thIfd, littleEndian)) {
return AVIF_RESULT_INVALID_EXIF_PAYLOAD;
}
avifROStreamSetOffset(&stream, offsetTo0thIfd);
uint16_t fieldCount;
if (!avifROStreamReadU16Endianness(&stream, &fieldCount, littleEndian)) {
return AVIF_RESULT_INVALID_EXIF_PAYLOAD;
}
for (uint16_t field = 0; field < fieldCount; ++field) { // for each field interoperability array
uint16_t tag;
uint16_t type;
uint32_t count;
uint16_t firstHalfOfValueOffset;
if (!avifROStreamReadU16Endianness(&stream, &tag, littleEndian) || !avifROStreamReadU16Endianness(&stream, &type, littleEndian) ||
!avifROStreamReadU32Endianness(&stream, &count, littleEndian) ||
!avifROStreamReadU16Endianness(&stream, &firstHalfOfValueOffset, littleEndian) || !avifROStreamSkip(&stream, 2)) {
return AVIF_RESULT_INVALID_EXIF_PAYLOAD;
}
// Orientation attribute according to JEITA CP-3451C section 4.6.4 (TIFF Rev. 6.0 Attribute Information):
const uint16_t shortType = 0x03;
if (tag == 0x0112 && type == shortType && count == 0x01) {
// Mapping from Exif orientation as defined in JEITA CP-3451C section 4.6.4.A Orientation
// to irot and imir boxes as defined in HEIF ISO/IEC 28002-12:2021 sections 6.5.10 and 6.5.12.
switch (firstHalfOfValueOffset) {
case 1: // The 0th row is at the visual top of the image, and the 0th column is the visual left-hand side.
image->transformFlags = otherFlags;
image->irot.angle = 0; // ignored
image->imir.mode = 0; // ignored
return AVIF_RESULT_OK;
case 2: // The 0th row is at the visual top of the image, and the 0th column is the visual right-hand side.
image->transformFlags = otherFlags | AVIF_TRANSFORM_IMIR;
image->irot.angle = 0; // ignored
image->imir.mode = 1;
return AVIF_RESULT_OK;
case 3: // The 0th row is at the visual bottom of the image, and the 0th column is the visual right-hand side.
image->transformFlags = otherFlags | AVIF_TRANSFORM_IROT;
image->irot.angle = 2;
image->imir.mode = 0; // ignored
return AVIF_RESULT_OK;
case 4: // The 0th row is at the visual bottom of the image, and the 0th column is the visual left-hand side.
image->transformFlags = otherFlags | AVIF_TRANSFORM_IMIR;
image->irot.angle = 0; // ignored
image->imir.mode = 0;
return AVIF_RESULT_OK;
case 5: // The 0th row is the visual left-hand side of the image, and the 0th column is the visual top.
image->transformFlags = otherFlags | AVIF_TRANSFORM_IROT | AVIF_TRANSFORM_IMIR;
image->irot.angle = 1; // applied before imir according to MIAF spec ISO/IEC 28002-12:2021 - section 7.3.6.7
image->imir.mode = 0;
return AVIF_RESULT_OK;
case 6: // The 0th row is the visual right-hand side of the image, and the 0th column is the visual top.
image->transformFlags = otherFlags | AVIF_TRANSFORM_IROT;
image->irot.angle = 3;
image->imir.mode = 0; // ignored
return AVIF_RESULT_OK;
case 7: // The 0th row is the visual right-hand side of the image, and the 0th column is the visual bottom.
image->transformFlags = otherFlags | AVIF_TRANSFORM_IROT | AVIF_TRANSFORM_IMIR;
image->irot.angle = 3; // applied before imir according to MIAF spec ISO/IEC 28002-12:2021 - section 7.3.6.7
image->imir.mode = 0;
return AVIF_RESULT_OK;
case 8: // The 0th row is the visual left-hand side of the image, and the 0th column is the visual bottom.
image->transformFlags = otherFlags | AVIF_TRANSFORM_IROT;
image->irot.angle = 1;
image->imir.mode = 0; // ignored
return AVIF_RESULT_OK;
default: // reserved
break;
}
}
}
// Orientation is in the 0th IFD, so no need to parse the following ones.
// The orientation tag is not mandatory (only recommended) according to JEITA CP-3451C section 4.6.8.A.
// The default value is 1 if the orientation tag is missing, meaning:
// The 0th row is at the visual top of the image, and the 0th column is the visual left-hand side.
image->transformFlags = otherFlags;
image->irot.angle = 0; // ignored
image->imir.mode = 0; // ignored
return AVIF_RESULT_OK;
}
void avifImageSetMetadataExif(avifImage * image, const uint8_t * exif, size_t exifSize)
{
avifRWDataSet(&image->exif, exif, exifSize);
// Ignore any Exif parsing failure.
(void)avifImageExtractExifOrientationToIrotImir(image);
}