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Generalize makernote number parsing

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This commit is contained in:
Sam Becker 2025-02-20 22:19:07 -06:00
parent 486c6dc1ae
commit 55afe9e09a
1 changed files with 42 additions and 31 deletions
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73
src/platforms/fujifilm/index.ts
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@ -6,64 +6,75 @@ import type { ExifData } from 'ts-exif-parser';
export const MAKE_FUJIFILM = 'FUJIFILM';
const BYTE_INDEX_TAG_COUNT = 12;
const BYTE_INDEX_FIRST_TAG = 14;
const BYTES_PER_TAG = 12;
// Makernote Offsets
const BYTE_OFFSET_TAG_COUNT = 12;
const BYTE_OFFSET_FIRST_TAG = 14;
// Tag Offsets
const BYTE_OFFSET_TAG_TYPE = 2;
const BYTE_OFFSET_TAG_SIZE = 4;
const BYTE_OFFSET_TAG_VALUE = 8;
// Tag Sizes
const BYTES_PER_TAG = 12;
const BYTES_PER_TAG_VALUE = 4;
export const isExifForFujifilm = (data: ExifData) =>
data.tags?.Make === MAKE_FUJIFILM;
export const parseFujifilmMakerNote = (
bytes: Buffer,
valueForTagNumbers: (tagId: number, numbers: number[]) => void,
sendTagNumbers: (tagId: number, numbers: number[]) => void,
) => {
const tagCount = bytes.readUint16LE(BYTE_INDEX_TAG_COUNT);
const tagCount = bytes.readUint16LE(BYTE_OFFSET_TAG_COUNT);
for (let i = 0; i < tagCount; i++) {
const index = BYTE_INDEX_FIRST_TAG + i * BYTES_PER_TAG;
const index = BYTE_OFFSET_FIRST_TAG + i * BYTES_PER_TAG;
if (index + BYTES_PER_TAG < bytes.length) {
const tagId = bytes.readUInt16LE(index);
const tagType = bytes.readUInt16LE(index + BYTE_OFFSET_TAG_TYPE);
const tagValueSize = bytes.readUInt16LE(index + BYTE_OFFSET_TAG_SIZE);
const sendNumbersForDataType = (
calculateNumberForOffset: (offset: number) => number,
sizeInBytes: number,
) => {
let values: number[] = [];
if (tagValueSize * sizeInBytes <= BYTES_PER_TAG_VALUE) {
// Retrieve values if they fit in tag block
values = Array.from({ length: tagValueSize }, (_, i) =>
calculateNumberForOffset(
index + BYTE_OFFSET_TAG_VALUE + i * sizeInBytes,
),
);
} else {
// Retrieve outside values if they don't fit in tag block
const offset = bytes.readUint16LE(index + BYTE_OFFSET_TAG_VALUE);
values = [];
for (let i = 0; i < tagValueSize; i++) {
values.push(calculateNumberForOffset(offset + i * sizeInBytes));
}
}
sendTagNumbers(tagId, values);
};
switch (tagType) {
// Int8 (UInt8 read as Int8)
case 1:
valueForTagNumbers(
tagId,
[bytes.readInt8(index + BYTE_OFFSET_TAG_VALUE)],
);
sendNumbersForDataType(offset => bytes.readInt8(offset), 1);
break;
// UInt16
case 3:
valueForTagNumbers(
tagId,
[bytes.readUInt16LE(index + BYTE_OFFSET_TAG_VALUE)],
);
sendNumbersForDataType(offset => bytes.readUInt16LE(offset), 2);
break;
// UInt32
case 4:
valueForTagNumbers(
tagId,
[bytes.readUInt32LE(index + BYTE_OFFSET_TAG_VALUE)],
);
sendNumbersForDataType(offset => bytes.readUInt32LE(offset), 4);
break;
// Int32
case 9:
if (tagValueSize === 1) {
valueForTagNumbers(
tagId,
[bytes.readInt32LE(index + BYTE_OFFSET_TAG_VALUE)],
);
} else {
const offset = bytes.readInt32LE(index + BYTE_OFFSET_TAG_VALUE);
const values: number[] = [];
for (let i = 0; i < tagValueSize; i++) {
values.push(bytes.readInt32LE(offset + i * 4));
}
valueForTagNumbers(tagId, values);
}
sendNumbersForDataType(offset => bytes.readInt32LE(offset), 4);
break;
}
}