Re: [PATCH] gdiplus: Implement transform matrix for line gradient brushes

[Vincent Povirk]

I wrote a test program (attached), and it doesn't work when the start
point isn't 0,0.
> +    if (line->startpoint.X == line->endpoint.X)
> +        t = line->startpoint.Y > line->endpoint.Y ? 3.f * M_PI / 2.f : M_PI / 2.f;
> +    else
> +        t = atanf((line->endpoint.Y - line->startpoint.Y) / (line->endpoint.X - line->startpoint.X));
> +
> +    t_cos = cosf(t);
> +    t_sin = sinf(t);

This seems like an oddly complicated and fragile way to normalize a vector.