export async function compressBase64Image()

in src/lib/utils/file.ts [26:74]
42 lines of code
5 McCabe index (conditional complexity)

export async function compressBase64Image(options: CompressBase64Options): Promise<string> {
	const {
		base64,
		maxSizeKB,
		outputFormat = "image/jpeg",
		minQuality = 0.1,
		maxQuality = 1.0,
		maxIterations = 10,
	} = options;

	const img = await new Promise<HTMLImageElement>((resolve, reject) => {
		const image = new Image();
		image.crossOrigin = "Anonymous";
		image.onload = () => resolve(image);
		image.onerror = reject;
		image.src = base64;
	});

	const canvas = document.createElement("canvas");
	canvas.width = img.width;
	canvas.height = img.height;
	const ctx = canvas.getContext("2d");
	if (!ctx) throw new Error("Could not get canvas context");
	ctx.drawImage(img, 0, 0);

	let minQ = minQuality;
	let maxQ = maxQuality;
	let bestBase64 = "";

	for (let i = 0; i < maxIterations; i++) {
		const q = (minQ + maxQ) / 2;
		const b64 = canvas.toDataURL(outputFormat, q);
		const size = getBase64ImageSize(b64).kilobytes;

		if (size > maxSizeKB) {
			maxQ = q;
		} else {
			minQ = q;
			bestBase64 = b64;
		}
	}

	// If no quality produced a small enough image, return the lowest quality result
	if (!bestBase64) {
		bestBase64 = canvas.toDataURL(outputFormat, minQuality);
	}

	return bestBase64;
}