(function exportCardPreviewMath(root)
{
    /** Find inclusive nontransparent bounds in bottom-origin RGBA pixels. */
    function findAlphaBounds(pixels, width, height)
    {
        let min_x = width;
        let min_y = height;
        let max_x = -1;
        let max_y = -1;
        for(let y = 0; y < height; ++y)
        {
            for(let x = 0; x < width; ++x)
            {
                if(pixels[(y * width + x) * 4 + 3] != 0)
                {
                    min_x = Math.min(min_x, x);
                    min_y = Math.min(min_y, y);
                    max_x = Math.max(max_x, x);
                    max_y = Math.max(max_y, y);
                }
            }
        }
        return max_x < 0 ? null : {min_x, min_y, max_x, max_y};
    }

    /** Crop and flip bottom-origin WebGL pixels into top-origin RGBA data. */
    function cropWebGLPixels(pixels, source_width, bounds)
    {
        const width = bounds.max_x - bounds.min_x + 1;
        const height = bounds.max_y - bounds.min_y + 1;
        const data = new Uint8ClampedArray(width * height * 4);
        for(let output_y = 0; output_y < height; ++output_y)
        {
            const source_y = bounds.max_y - output_y;
            for(let output_x = 0; output_x < width; ++output_x)
            {
                const source_x = bounds.min_x + output_x;
                const source_offset =
                    (source_y * source_width + source_x) * 4;
                const output_offset = (output_y * width + output_x) * 4;
                data.set(
                    pixels.subarray(source_offset, source_offset + 4),
                    output_offset);
            }
        }
        return {width, height, data};
    }

    /** Scale dimensions proportionally so their long side is exact. */
    function scaleDimensions(width, height, long_side)
    {
        if(!Number.isInteger(long_side) || long_side < 1)
        {
            throw(new Error("The thumbnail size is invalid."));
        }
        const scale = long_side / Math.max(width, height);
        return {
            width: Math.max(1, Math.round(width * scale)),
            height: Math.max(1, Math.round(height * scale)),
        };
    }

    const api = {findAlphaBounds, cropWebGLPixels, scaleDimensions};
    if(typeof module != "undefined" && module.exports != null)
    {
        module.exports = api;
    }
    else
    {
        root.cardPreviewMath = api;
    }
})(globalThis);