chromium/third_party/libavif/src/src/exif.c

// 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)
{ … }

// 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)
{ … }

avifResult avifImageExtractExifOrientationToIrotImir(avifImage * image)
{ … }

#if defined(AVIF_ENABLE_EXPERIMENTAL_MINI)
uint8_t avifImageIrotImirToExifOrientation(const avifImage * image)
{
    if (!(image->transformFlags & AVIF_TRANSFORM_IROT) || image->irot.angle == 0) {
        if (!(image->transformFlags & AVIF_TRANSFORM_IMIR)) {
            return 1; // The 0th row is at the visual top of the image, and the 0th column is the visual left-hand side.
        }
        if (image->imir.axis == 0) {
            return 4; // The 0th row is at the visual bottom of the image, and the 0th column is the visual left-hand side.
        }
        // image->imir.axis == 1
        return 2; // The 0th row is at the visual top of the image, and the 0th column is the visual right-hand side.
    }

    if (image->irot.angle == 1) {
        if (!(image->transformFlags & AVIF_TRANSFORM_IMIR)) {
            return 8; // The 0th row is the visual left-hand side of the image, and the 0th column is the visual bottom.
        }
        if (image->imir.axis == 0) {
            return 5; // The 0th row is the visual left-hand side of the image, and the 0th column is the visual top.
        }
        // image->imir.axis == 1
        return 7; // The 0th row is the visual right-hand side of the image, and the 0th column is the visual bottom.
    }

    if (image->irot.angle == 2) {
        if (!(image->transformFlags & AVIF_TRANSFORM_IMIR)) {
            return 3; // The 0th row is at the visual bottom of the image, and the 0th column is the visual right-hand side.
        }
        if (image->imir.axis == 0) {
            return 2; // The 0th row is at the visual top of the image, and the 0th column is the visual right-hand side.
        }
        // image->imir.axis == 1
        return 4; // The 0th row is at the visual bottom of the image, and the 0th column is the visual left-hand side.
    }

    // image->irot.angle == 3
    if (!(image->transformFlags & AVIF_TRANSFORM_IMIR)) {
        return 6; // The 0th row is the visual right-hand side of the image, and the 0th column is the visual top.
    }
    if (image->imir.axis == 0) {
        return 7; // The 0th row is the visual right-hand side of the image, and the 0th column is the visual bottom.
    }
    // image->imir.axis == 1
    return 5; // The 0th row is the visual left-hand side of the image, and the 0th column is the visual top.
}
#endif // AVIF_ENABLE_EXPERIMENTAL_MINI

avifResult avifImageSetMetadataExif(avifImage * image, const uint8_t * exif, size_t exifSize)
{ … }