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optimize

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dwelle
2025-09-25 14:21:13 +02:00
parent 70006555b8
commit 6957ac2b49
1 changed files with 16 additions and 16 deletions
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32
packages/excalidraw/data/blob.ts
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@@ -416,37 +416,37 @@ export const getFileHandle = async (
/**
* attempts to detect if a buffer is a valid image by checking its leading bytes
*/
const getActualMimeTypeFromImage = (buffer: ArrayBuffer) => {
const getActualMimeTypeFromImage = async (file: Blob | File) => {
let mimeType: ValueOf<
Pick<typeof MIME_TYPES, "png" | "jpg" | "gif" | "webp">
> | null = null;
const leadingBytes = `${[...new Uint8Array(buffer).slice(0, 15)].join(" ")} `;
const leadingBytes = [
...new Uint8Array(await blobToArrayBuffer(file.slice(0, 15))),
].join(" ");
// uint8 leading bytes
const bytes = {
// https://en.wikipedia.org/wiki/Portable_Network_Graphics#File_header
png: "137 80 78 71 13 10 26 10 ",
png: /^137 80 78 71 13 10 26 10\b/,
// https://en.wikipedia.org/wiki/JPEG#Syntax_and_structure
// jpg is a bit wonky. Checking the first three bytes should be enough,
// but may yield false positives. (https://stackoverflow.com/a/23360709/927631)
jpg: "255 216 255 ",
jpg: /^255 216 255\b/,
// https://en.wikipedia.org/wiki/GIF#Example_GIF_file
gif: "71 73 70 56 57 97 ",
gif: /^71 73 70 56 57 97\b/,
// 4 bytes for RIFF + 4 bytes for chunk size + WEBP identifier
webp: /^82 73 70 70 \d+ \d+ \d+ \d+ 87 69 66 80 86 80 56/,
webp: /^82 73 70 70 \d+ \d+ \d+ \d+ 87 69 66 80 86 80 56\b/,
};
if (leadingBytes.startsWith(bytes.png)) {
mimeType = MIME_TYPES.png;
} else if (leadingBytes.startsWith(bytes.jpg)) {
mimeType = MIME_TYPES.jpg;
} else if (leadingBytes.startsWith(bytes.gif)) {
mimeType = MIME_TYPES.gif;
} else if (bytes.webp.test(leadingBytes)) {
mimeType = MIME_TYPES.webp;
for (const type of Object.keys(bytes) as (keyof typeof bytes)[]) {
if (leadingBytes.match(bytes[type])) {
mimeType = MIME_TYPES[type];
break;
}
return mimeType;
}
return mimeType || file.type || null;
};
export const createFile = (
@@ -478,7 +478,7 @@ export const normalizeFile = async (file: File) => {
// when the file is an image, make sure the extension corresponds to the
// actual mimeType (this is an edge case, but happens - especially
// with AI generated images)
const mimeType = getActualMimeTypeFromImage(await blobToArrayBuffer(file));
const mimeType = await getActualMimeTypeFromImage(file);
if (mimeType && mimeType !== file.type) {
file = createFile(file, mimeType, file.name);
}