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to-image-element.ts
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/
to-image-element.ts
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/*
* Copyright (C) 2019 Toshiba Corporation
* SPDX-License-Identifier: Apache-2.0
*/
import { EShapeImageLike } from "../e-shape-image-like";
type ImageElement = Promise<EShapeImageLike> | EShapeImageLike;
const imageElementCache: Record<string, ImageElement | undefined> = {};
export const toImageElement = (dataUrl: string): Promise<EShapeImageLike> => {
const cachedImageElement = imageElementCache[dataUrl];
if (cachedImageElement != null) {
if ("url" in cachedImageElement) {
return Promise.resolve(cachedImageElement);
} else {
return cachedImageElement;
}
} else {
const result = new Promise<EShapeImageLike>((resolve, reject): void => {
const imageElement = document.createElement("img");
imageElement.onload = () => {
const resolved = {
url: dataUrl,
width: imageElement.width,
height: imageElement.height,
source: imageElement
};
imageElementCache[dataUrl] = resolved;
resolve(resolved);
};
imageElement.onabort = imageElement.onerror = () => {
reject();
};
imageElement.src = dataUrl;
});
imageElementCache[dataUrl] = result;
return result;
}
};