export const charWidth = 6, charHeight = 9;

export async function loadFont(src: RequestInfo | URL): Promise<ImageBitmap[]> {
    const fontImg = await fetch(src);
    const fontBlob = await fontImg.blob();

    async function getCharBitmap(x: number, y: number) {
        const fontOffsetX = 1, fontOffsetY = 1, fontPaddingX = 2, fontPaddingY = 2;

        const offsetX = (charWidth + fontPaddingX) * x + fontOffsetX;
        const offsetY = (charHeight + fontPaddingY) * y + fontOffsetY;

        return await createImageBitmap(fontBlob, offsetX, offsetY, charWidth, charHeight);
    }

    const font = Array(256);

    for (let y = 0; y < 16; ++y) {
        for (let x = 0; x < 16; ++x) {
            const i = 16 * y + x;
            font[i] = getCharBitmap(x, y);
        }
    }
    return await Promise.all(font);
}