92 lines
2.3 KiB
TypeScript
92 lines
2.3 KiB
TypeScript
export interface DecodedLocalImage {
|
|
readonly source: CanvasImageSource;
|
|
readonly width: number;
|
|
readonly height: number;
|
|
dispose: () => void;
|
|
}
|
|
|
|
const abortError = (): DOMException =>
|
|
new DOMException("Image decoding was cancelled.", "AbortError");
|
|
|
|
const decodeWithImageElement = (
|
|
file: File,
|
|
signal?: AbortSignal,
|
|
): Promise<DecodedLocalImage> =>
|
|
new Promise((resolve, reject) => {
|
|
if (signal?.aborted) {
|
|
reject(abortError());
|
|
return;
|
|
}
|
|
|
|
const objectUrl = URL.createObjectURL(file);
|
|
const image = new Image();
|
|
image.decoding = "async";
|
|
let settled = false;
|
|
const cleanup = (): void => {
|
|
image.onload = null;
|
|
image.onerror = null;
|
|
signal?.removeEventListener("abort", onAbort);
|
|
URL.revokeObjectURL(objectUrl);
|
|
};
|
|
const onAbort = (): void => {
|
|
if (settled) return;
|
|
settled = true;
|
|
image.src = "";
|
|
cleanup();
|
|
reject(abortError());
|
|
};
|
|
image.onload = () => {
|
|
if (settled) return;
|
|
settled = true;
|
|
cleanup();
|
|
resolve({
|
|
source: image,
|
|
width: image.naturalWidth,
|
|
height: image.naturalHeight,
|
|
dispose: () => {
|
|
image.src = "";
|
|
},
|
|
});
|
|
};
|
|
image.onerror = () => {
|
|
if (settled) return;
|
|
settled = true;
|
|
cleanup();
|
|
reject(new Error("The browser could not decode this image."));
|
|
};
|
|
signal?.addEventListener("abort", onAbort, { once: true });
|
|
image.src = objectUrl;
|
|
});
|
|
|
|
export const decodeLocalImage = async (
|
|
file: File,
|
|
signal?: AbortSignal,
|
|
): Promise<DecodedLocalImage> => {
|
|
if (signal?.aborted) throw abortError();
|
|
if (typeof createImageBitmap === "function") {
|
|
try {
|
|
const bitmap = await createImageBitmap(file, {
|
|
imageOrientation: "from-image",
|
|
});
|
|
if (signal?.aborted) {
|
|
bitmap.close();
|
|
throw abortError();
|
|
}
|
|
return {
|
|
source: bitmap,
|
|
width: bitmap.width,
|
|
height: bitmap.height,
|
|
dispose: () => bitmap.close(),
|
|
};
|
|
} catch (error) {
|
|
if (
|
|
signal?.aborted ||
|
|
(error instanceof DOMException && error.name === "AbortError")
|
|
)
|
|
throw error;
|
|
// Older browsers sometimes expose createImageBitmap without supporting every format.
|
|
}
|
|
}
|
|
return decodeWithImageElement(file, signal);
|
|
};
|