C# TextFontGraphics Class

TextFontGraphics.cs

public static class TextFontGraphics
    {
        public static int GetNumberOfLines(this string text)
        {
            return text.Split('\n').Length;
        }
        public static int GetTextCharacterCount(this string text)
        {
            return text.Count(c => c != '\r' && c != '\n');
        }
        public static Size MeasureText(this string text, Font font, int addwidth = 0, int addheight = 0)
        {
            if (string.IsNullOrEmpty(text)) return Size.Empty;
            var mh = text.GetMinimumTextBoxHeight(font);
            var mw = text.GetMinimumTextBoxWidth(font);
            var fs = font.GetFontSize();
            var Height = mh + (int) fs.Height * addheight;
            var Width = mw + (int) fs.Width * addwidth;
            return new Size((int) Width, (int) Height);
        }
        public static SizeF GetFontSize(this Font f)
        {
            if (f == null) return SizeF.Empty;
            Image fakeImage = new Bitmap(1, 1);
            var graphics = Graphics.FromImage(fakeImage);
            var size = graphics.MeasureString("Ag", f);
            var ns = new SizeF();
            ns.Height = size.Height;
            ns.Width = size.Width / 2;
            return ns;
        }
        public static SizeF GetFontSize(this Font f, string l)
        {
            if (f == null) return SizeF.Empty;
            if (string.IsNullOrEmpty(l)) return Size.Empty;
            Image fakeImage = new Bitmap(1, 1);
            var graphics = Graphics.FromImage(fakeImage);
            var size = graphics.MeasureString(l, f);
            var ns = new SizeF();
            ns.Height = size.Height;
            ns.Width = size.Width;
            return ns;
        }
        public static float GetMinimumTextBoxHeight(this string text, Font font)
        {
            if (font == null) return 0;
            if (string.IsNullOrEmpty(text)) return 0;
            var lineCount = text.Split('\n').Length;
            var fs = font.GetFontSize();
            var MinimumSize = lineCount * 1.15f * fs.Height;
            return MinimumSize;
        }
        public static float GetMinimumTextBoxWidth(this string text, Font font)
        {
            if (font == null) return 0;
            if (string.IsNullOrEmpty(text)) return 0;
            var lines = text.Split('\n');
            var MaxFontLength = 0;
            foreach (var l in lines)
            {
                var fs = (int) Math.Ceiling(font.GetFontSize(l).Width);
                if (fs > MaxFontLength) MaxFontLength = fs;
            }

            return MaxFontLength;
        }
        [STAThread]
        public static SizeF GetCurrentScreenSize()
        {
            var f = new Window();
            var helper = new WindowInteropHelper(f);
            var currentScreen = Screen.FromHandle(helper.Handle);
            var s = currentScreen.Bounds.Size;
            return s;
        }
    }