| // Copyright 2022 Google LLC |
| // SPDX-License-Identifier: BSD-2-Clause |
| |
| #include "avif/internal.h" |
| |
| #include <stdint.h> |
| #include <string.h> |
| |
| avifResult avifGetExifTiffHeaderOffset(const uint8_t * exif, size_t exifSize, size_t * offset) |
| { |
| const uint8_t tiffHeaderBE[4] = { 'M', 'M', 0, 42 }; |
| const uint8_t tiffHeaderLE[4] = { 'I', 'I', 42, 0 }; |
| exifSize = AVIF_MIN(exifSize, UINT32_MAX); |
| for (*offset = 0; *offset + 4 < exifSize; ++*offset) { |
| if (!memcmp(&exif[*offset], tiffHeaderBE, 4) || !memcmp(&exif[*offset], tiffHeaderLE, 4)) { |
| return AVIF_RESULT_OK; |
| } |
| } |
| // Couldn't find the TIFF header |
| return AVIF_RESULT_INVALID_EXIF_PAYLOAD; |
| } |
| |
| // Returns the offset to the Exif 8-bit orientation value and AVIF_RESULT_OK, or an error. |
| // If the offset is set to exifSize, there was no parsing error but no orientation tag was found. |
| avifResult avifGetExifOrientationOffset(const uint8_t * exif, size_t exifSize, size_t * offset) |
| { |
| const avifResult result = avifGetExifTiffHeaderOffset(exif, exifSize, offset); |
| if (result != AVIF_RESULT_OK) { |
| // Couldn't find the TIFF header |
| return result; |
| } |
| |
| avifROData raw = { exif + *offset, exifSize - *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) { |
| // Only consider non-reserved orientation values, so that it is known that |
| // the most meaningful byte of firstHalfOfValueOffset is 0. |
| if (firstHalfOfValueOffset >= 1 && firstHalfOfValueOffset <= 8) { |
| // Offset to the least meaningful byte of firstHalfOfValueOffset. |
| *offset += avifROStreamOffset(&stream) - (littleEndian ? 4 : 3); |
| return AVIF_RESULT_OK; |
| } |
| } |
| } |
| // Orientation is in the 0th IFD, so no need to parse the following ones. |
| |
| *offset = exifSize; // Signal missing orientation tag in valid Exif payload. |
| return AVIF_RESULT_OK; |
| } |
| |
| avifResult avifImageExtractExifOrientationToIrotImir(avifImage * image) |
| { |
| const avifTransformFlags otherFlags = image->transformFlags & ~(AVIF_TRANSFORM_IROT | AVIF_TRANSFORM_IMIR); |
| size_t offset; |
| const avifResult result = avifGetExifOrientationOffset(image->exif.data, image->exif.size, &offset); |
| if (result != AVIF_RESULT_OK) { |
| return result; |
| } |
| if (offset < image->exif.size) { |
| const uint8_t orientation = image->exif.data[offset]; |
| // 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 (orientation) { |
| 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; |
| } |
| } |
| |
| // 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); |
| } |