Function tryConvertDataURLToBlobSync

src/inject/dynamic-theme/image.ts:357–380

(dataURL: string)

const dataURLBlobURLs = new Map<number, string>();

function tryConvertDataURLToBlobSync(dataURL: string): Blob | null {
    const colonIndex = dataURL.indexOf(':');
    const semicolonIndex = dataURL.indexOf(';', colonIndex + 1);
    const commaIndex = dataURL.indexOf(',', semicolonIndex + 1);
    const encoding = dataURL.substring(semicolonIndex + 1, commaIndex).toLocaleLowerCase();
    const mediaType = dataURL.substring(colonIndex + 1, semicolonIndex);

    // It should be possible to easily convert UTF-8,
    // though it is unclear if decodeURIComponent will be necessary
    // and if it will be performant enough for big Data URLs
    if (encoding !== 'base64' || !mediaType) {
        return null;
    }
    let base64Content = dataURL.substring(commaIndex + 1);
    if (base64Content.includes('%')) {
        base64Content = decodeURIComponent(base64Content);
    }
    const characters = atob(base64Content);
    const bytes = new Uint8Array(characters.length);
    for (let i = 0; i < characters.length; i++) {
        bytes[i] = characters.charCodeAt(i);
    }
    return new Blob([bytes], {type: mediaType});
}

export async function tryConvertDataURLToBlobURL(dataURL: string): Promise<string | null> {
    if (!isBlobURLSupported) {