Function ImFontAtlasBuildRenderBitmapFromString 

pub unsafe extern "C" fn ImFontAtlasBuildRenderBitmapFromString(
    atlas: *mut ImFontAtlas,
    x: c_int,
    y: c_int,
    w: c_int,
    h: c_int,
    in_str: *const c_char,
    in_marker_char: c_char,
)