import type { RasterImage } from './types';

export const MAX_SIDE = 2000;

export function fitSize(width: number, height: number, maxSide: number): { width: number; height: number } {
  const s = Math.min(1, maxSide / Math.max(width, height));
  return { width: Math.round(width * s), height: Math.round(height * s) };
}

export async function loadPhoto(file: Blob): Promise<RasterImage> {
  const bitmap = await createImageBitmap(file, { imageOrientation: 'from-image' });
  try {
    const { width, height } = fitSize(bitmap.width, bitmap.height, MAX_SIDE);
    const canvas = new OffscreenCanvas(width, height);
    const ctx = canvas.getContext('2d')!;
    ctx.drawImage(bitmap, 0, 0, width, height);
    return { width, height, data: ctx.getImageData(0, 0, width, height).data };
  } finally {
    bitmap.close();
  }
}