public void DrawString(string s, Font font, Brush brush, RectangleF layoutRectangle, StringFormat format = null)
        {
            if (font == null)
                throw new ArgumentNullException ("font");
            if (brush == null)
                throw new ArgumentNullException ("brush");
            if (s == null || s.Length == 0)
                return;

            if (format == null)
            {
                format = StringFormat.GenericDefault;
            }

            // TODO: Take into consideration units

            // Not sure we need the Save and Restore around this yet.
            context.SaveState();

            // TextMatrix is not part of the Graphics State and Restore
            var saveMatrix = context.TextMatrix;
            bool layoutAvailable = true;

            //			context.SelectFont ( font.nativeFont.PostScriptName,
            //			                    font.SizeInPoints,
            //			                    CGTextEncoding.MacRoman);
            //
            //			context.SetCharacterSpacing(1);
            //			context.SetTextDrawingMode(CGTextDrawingMode.Fill); // 5
            //
            //			// Setup both the stroke and the fill ?
            //			brush.Setup(this, true);
            //			brush.Setup(this, false);
            //
            //			var textMatrix = font.nativeFont.Matrix;
            //
            //			textMatrix.Scale(1,-1);
            //			context.TextMatrix = textMatrix;
            //
            //			context.ShowTextAtPoint(layoutRectangle.X,
            //			                        layoutRectangle.Y + font.nativeFont.CapHeightMetric, s);
            //
            //
            // First we call the brush with a fill of false so the brush can setup the stroke color
            // that the text will be using.
            // For LinearGradientBrush this will setup a TransparentLayer so the gradient can
            // be filled at the end.  See comments.
            brush.Setup(this, false); // Stroke

            // I think we only Fill the text with no Stroke surrounding
            context.SetTextDrawingMode(CGTextDrawingMode.Fill);

            var attributedString = buildAttributedString(s, font, format, lastBrushColor);

            // Work out the geometry
            RectangleF insetBounds = layoutRectangle;
            if (insetBounds.Size == SizeF.Empty)
            {
                insetBounds.Width = boundingBox.Width;
                insetBounds.Height = boundingBox.Height;
                layoutAvailable = false;
            }

            PointF textPosition = new PointF(insetBounds.X,
                                             insetBounds.Y);

            float boundsWidth = insetBounds.Width;

            // Calculate the lines
            int start = 0;
            int length = attributedString.Length;
            float baselineOffset = 0;

            var typesetter = new CTTypesetter(attributedString);

            // First we need to calculate the offset for Vertical Alignment if we
            // are using anything but Top
            if (layoutAvailable && format.LineAlignment != StringAlignment.Near) {
                while (start < length) {
                    int count = typesetter.SuggestLineBreak (start, boundsWidth);
                    var line = typesetter.GetLine (new NSRange(start, count));

                    // Create and initialize some values from the bounds.
                    float ascent;
                    float descent;
                    float leading;
                    line.GetTypographicBounds (out ascent, out descent, out leading);
                    baselineOffset += (float)Math.Ceiling (ascent + descent + leading + 1); // +1 matches best to CTFramesetter's behavior
                    line.Dispose ();
                    start += count;
                }

                //textPosition.Y += baselineOffset;
            }

            // If we are drawing vertial direction then we need to rotate our context transform by 90 degrees
            if ((format.FormatFlags & StringFormatFlags.DirectionVertical) == StringFormatFlags.DirectionVertical)
            {
                //textMatrix.Rotate (ConversionHelpers.DegreesToRadians (90));
                var verticalOffset = 0.0f;
                while (start < length) {
                    int count = typesetter.SuggestLineBreak (start, boundsWidth);
                    var line = typesetter.GetLine (new NSRange(start, count));

                    // Create and initialize some values from the bounds.
                    float ascent;
                    float descent;
                    float leading;
                    line.GetTypographicBounds (out ascent, out descent, out leading);
                    verticalOffset += (float)Math.Ceiling (ascent + descent + leading + 1); // +1 matches best to CTFramesetter's behavior
                    line.Dispose ();
                    start += count;
                }
                context.TranslateCTM (layoutRectangle.X, layoutRectangle.Y);
                context.RotateCTM (ConversionHelpers.DegreesToRadians (90));
                context.TranslateCTM (-layoutRectangle.X, -layoutRectangle.Y);
                context.TranslateCTM (0, -verticalOffset);
                start = 0;
            }

            start = 0;
            while (start < length && textPosition.Y < insetBounds.Bottom)
            {

                // Now we ask the typesetter to break off a line for us.
                // This also will take into account line feeds embedded in the text.
                //  Example: "This is text \n with a line feed embedded inside it"
                int count = typesetter.SuggestLineBreak(start, boundsWidth);
                var line = typesetter.GetLine(new NSRange(start, count));

                // Create and initialize some values from the bounds.
                float ascent;
                float descent;
                float leading;
                double lineWidth = line.GetTypographicBounds(out ascent, out descent, out leading);

                // Calculate the string format if need be
                var penFlushness = 0.0f;
                if (format != null)
                {
                    if (layoutAvailable)
                    {
                        if (format.Alignment == StringAlignment.Far)
                            penFlushness = (float)line.GetPenOffsetForFlush(1.0f, boundsWidth);
                        else if (format.Alignment == StringAlignment.Center)
                            penFlushness = (float)line.GetPenOffsetForFlush(0.5f, boundsWidth);
                    }
                    else
                    {
                        // We were only passed in a point so we need to format based
                        // on the point.
                        if (format.Alignment == StringAlignment.Far)
                            penFlushness -= (float)lineWidth;
                        else if (format.Alignment == StringAlignment.Center)
                            penFlushness -= (float)lineWidth / 2.0f;

                    }

                }

                // initialize our Text Matrix or we could get trash in here
                var textMatrix = new CGAffineTransform (
                    1, 0, 0, -1, 0, ascent);

                if (format.LineAlignment == StringAlignment.Near)
                    textMatrix.Translate (penFlushness + textPosition.X, textPosition.Y);
                if (format.LineAlignment == StringAlignment.Center)
                    textMatrix.Translate (penFlushness + textPosition.X, textPosition.Y + ((insetBounds.Height / 2) - (baselineOffset / 2)) );
                if (format.LineAlignment == StringAlignment.Far)
                    textMatrix.Translate(penFlushness + textPosition.X,  textPosition.Y + ((insetBounds.Height) - (baselineOffset)));

                context.TextMatrix = textMatrix;

                // and draw the line
                line.Draw(context);

                // Move the index beyond the line break.
                start += count;
                textPosition.Y += (float)Math.Ceiling(ascent + descent + leading + 1); // +1 matches best to CTFramesetter's behavior
                line.Dispose();

            }

            // Now we call the brush with a fill of true so the brush can do the fill if need be
            // For LinearGradientBrush this will draw the Gradient and end the TransparentLayer.
            // See comments.
            brush.Setup(this, true); // Fill

            context.TextMatrix = saveMatrix;
            context.RestoreState();
        }
        internal void NativeDrawString(string s, Font font, Color brush, RectangleF layoutRectangle, StringFormat stringFormat)
        {
            if (font == null)
                throw new ArgumentNullException ("font");

            if (s == null || s.Length == 0)
                return;

            var attributedString = buildAttributedString(s, font, brush);

            // Work out the geometry
            RectangleF insetBounds = layoutRectangle;
            bool layoutAvailable = true;

            if (insetBounds.Size == SizeF.Empty)
            {
                insetBounds.Size = new SizeF (8388608, 8388608);
                layoutAvailable = false;
            }

            PointF textPosition = new PointF(insetBounds.X,
                                             insetBounds.Y);

            float boundsWidth = insetBounds.Width;

            // Calculate the lines
            int start = 0;
            int length = attributedString.Length;

            var typesetter = new CTTypesetter(attributedString);

            float baselineOffset = 0;

            // First we need to calculate the offset for Vertical Alignment if we
            // are using anything but Top
            if (layoutAvailable && stringFormat.LineAlignment != StringAlignment.Near) {
                while (start < length) {
                    int count = typesetter.SuggestLineBreak (start, boundsWidth);
                    var line = typesetter.GetLine (new NSRange(start, count));

                    // Create and initialize some values from the bounds.
                    float ascent;
                    float descent;
                    float leading;
                    line.GetTypographicBounds (out ascent, out descent, out leading);
                    baselineOffset += (float)Math.Ceiling (ascent + descent + leading + 1); // +1 matches best to CTFramesetter's behavior
                    line.Dispose ();
                    start += count;
                }
            }

            start = 0;

            while (start < length && textPosition.Y < insetBounds.Bottom)
            {

                // Now we ask the typesetter to break off a line for us.
                // This also will take into account line feeds embedded in the text.
                //  Example: "This is text \n with a line feed embedded inside it"
                int count = typesetter.SuggestLineBreak(start, boundsWidth);
                var line = typesetter.GetLine(new NSRange(start, count));

                // Create and initialize some values from the bounds.
                float ascent;
                float descent;
                float leading;
                double lineWidth = line.GetTypographicBounds(out ascent, out descent, out leading);

                if (!layoutAvailable)
                {
                    insetBounds.Width = (float)lineWidth;
                    insetBounds.Height = ascent + descent + leading;
                }

                // Calculate the string format if need be
                var penFlushness = 0.0f;

                if (stringFormat.Alignment == StringAlignment.Far)
                    penFlushness = (float)line.GetPenOffsetForFlush(1.0f, insetBounds.Width);
                else if (stringFormat.Alignment == StringAlignment.Center)
                    penFlushness = (float)line.GetPenOffsetForFlush(0.5f, insetBounds.Width);

                // initialize our Text Matrix or we could get trash in here
                var textMatrix = new CGAffineTransform (
                                     1, 0, 0, -1, 0, ascent);

                if (stringFormat.LineAlignment == StringAlignment.Near)
                    textMatrix.Translate (penFlushness + textPosition.X, textPosition.Y); //insetBounds.Height - textPosition.Y -(float)Math.Floor(ascent - 1));
                if (stringFormat.LineAlignment == StringAlignment.Center)
                    textMatrix.Translate (penFlushness + textPosition.X, textPosition.Y + ((insetBounds.Height / 2) - (baselineOffset / 2)) );  // -(float)Math.Floor(ascent)
                if (stringFormat.LineAlignment == StringAlignment.Far)
                    textMatrix.Translate(penFlushness + textPosition.X,  textPosition.Y + ((insetBounds.Height) - (baselineOffset)));

                var glyphRuns = line.GetGlyphRuns ();

                for (int glyphRunIndex = 0; glyphRunIndex < glyphRuns.Length; glyphRunIndex++)
                {

                    var glyphRun = glyphRuns [glyphRunIndex];
                    var glyphs = glyphRun.GetGlyphs ();
                    var glyphPositions = glyphRun.GetPositions ();
                    //var textMatrix = glyphRun.TextMatrix;

                    // Create and initialize some values from the bounds.
                    float glyphAscent;
                    float glyphDescent;
                    float glyphLeading;

                    var elementPoints = new PointF[3];

                    for (int glyphIndex = 0; glyphIndex < glyphs.Length; glyphIndex++)
                    {
                        if (glyphIndex > 0)
                        {
                            textMatrix.x0 += glyphPositions [glyphIndex].X - glyphPositions[glyphIndex - 1].X;
                            textMatrix.y0 += glyphPositions [glyphIndex].Y - glyphPositions[glyphIndex - 1].Y;
                        }

                        var glyphPath = font.nativeFont.GetPathForGlyph (glyphs [glyphIndex]);

                        // glyphPath = null if it is a white space character
                        if (glyphPath != null) {

                            glyphPath.Apply (
                                delegate (CGPathElement pathElement) {

                                        elementPoints[0] = textMatrix.TransformPoint(pathElement.Point1);
                                        elementPoints[1] = textMatrix.TransformPoint(pathElement.Point2);
                                        elementPoints[2] = textMatrix.TransformPoint(pathElement.Point3);
                                //Console.WriteLine ("Applying {0} - {1}, {2}, {3}", pathElement.Type, elementPoints[0], elementPoints[1], elementPoints[2]);

                                        // now add position offsets
                                        switch(pathElement.Type)
                                        {
                                        case CGPathElementType.MoveToPoint:
                                            start_new_fig = true;
                                            Append(elementPoints[0].X, elementPoints[0].Y,PathPointType.Line,true);
                                            break;
                                        case CGPathElementType.AddLineToPoint:
                                            var lastPoint = points[points.Count - 1];
                                            AppendPoint(lastPoint, PathPointType.Line, false);
                                            AppendPoint(elementPoints[0], PathPointType.Line, false);
                                            break;
                                        case CGPathElementType.AddCurveToPoint:
                                        case CGPathElementType.AddQuadCurveToPoint:
                                            //  This is the only thing I can think of right now for the fonts that
                                            //  I have tested.  See the description of the quadraticToCubic method for
                                            //  more information

                                            // Get the last point
                                            var pt1 = points[points.Count - 1];
                                            var pt2 = PointF.Empty;
                                            var pt3 = PointF.Empty;
                                            var pt4 = elementPoints[1];
                                            GeomUtilities.QuadraticToCubic(pt1, elementPoints[0], elementPoints[1], out pt2, out pt3);
                                            Append (pt1.X, pt1.Y, PathPointType.Line, true);
                                            AppendBezier (pt2.X, pt2.Y, pt3.X, pt3.Y, pt4.X, pt4.Y);
                                            break;
                                        case CGPathElementType.CloseSubpath:
                                            CloseFigure();
                                            break;
                                        }

                                }

                            );
                        }

                    }
                }

                // Move the index beyond the line break.
                start += count;
                textPosition.Y += (float)Math.Ceiling(ascent + descent + leading + 1); // +1 matches best to CTFramesetter's behavior
                line.Dispose();

            }
        }
		internal static void NativeDrawString (CGBitmapContext bitmapContext, string s, CTFont font, CCColor4B brush, CGRect layoutRectangle)
		{
			if (font == null)
				throw new ArgumentNullException ("font");

			if (s == null || s.Length == 0)
				return;

			bitmapContext.ConcatCTM (bitmapContext.GetCTM().Invert());

            // This is not needed here since the color is set in the attributed string.
			//bitmapContext.SetFillColor(brush.R/255f, brush.G/255f, brush.B/255f, brush.A/255f);

            // I think we only Fill the text with no Stroke surrounding
			//bitmapContext.SetTextDrawingMode(CGTextDrawingMode.Fill);

			var attributedString = buildAttributedString(s, font, brush);

			// Work out the geometry
			CGRect insetBounds = layoutRectangle;

			CGPoint textPosition = new CGPoint(insetBounds.X,
			                                 insetBounds.Y);

            float boundsWidth = (float)insetBounds.Width;

			// Calculate the lines
			nint start = 0;
            nint length = attributedString.Length;

			var typesetter = new CTTypesetter(attributedString);

			float baselineOffset = 0;

			// First we need to calculate the offset for Vertical Alignment if we 
			// are using anything but Top
			if (vertical != CCVerticalTextAlignment.Top) {
				while (start < length) {

                    nint count = typesetter.SuggestLineBreak((int)start, (double)boundsWidth);

                    var line = typesetter.GetLine (new NSRange(start, count));

					// Create and initialize some values from the bounds.
					nfloat ascent;
					nfloat descent;
					nfloat leading;
                    line.GetTypographicBounds(out ascent, out descent, out leading);
                    baselineOffset += (float)Math.Ceiling ((float)(ascent + descent + leading + 1)); // +1 matches best to CTFramesetter's behavior  
					line.Dispose ();
					start += count;
				}
			}

			start = 0;

			while (start < length && textPosition.Y < insetBounds.Bottom)
			{

				// Now we ask the typesetter to break off a line for us.
				// This also will take into account line feeds embedded in the text.
				//  Example: "This is text \n with a line feed embedded inside it"
                nint count = typesetter.SuggestLineBreak((int)start, (double)boundsWidth);
				var line = typesetter.GetLine(new NSRange(start, count));

				// Create and initialize some values from the bounds.
				nfloat ascent;
				nfloat descent;
				nfloat leading;
				line.GetTypographicBounds(out ascent, out descent, out leading);

				// Calculate the string format if need be
				var penFlushness = 0.0f;

				if (horizontal == CCTextAlignment.Right)
					penFlushness = (float)line.GetPenOffsetForFlush(1.0f, boundsWidth);
				else if (horizontal == CCTextAlignment.Center)
					penFlushness = (float)line.GetPenOffsetForFlush(0.5f, boundsWidth);

				// initialize our Text Matrix or we could get trash in here
				var textMatrix = CGAffineTransform.MakeIdentity();

				if (vertical == CCVerticalTextAlignment.Top)
					textMatrix.Translate(penFlushness, insetBounds.Height - textPosition.Y -(float)Math.Floor(ascent - 1));
				if (vertical == CCVerticalTextAlignment.Center)
					textMatrix.Translate(penFlushness, ((insetBounds.Height / 2) + (baselineOffset / 2)) - textPosition.Y -(float)Math.Floor(ascent - 1));
				if (vertical == CCVerticalTextAlignment.Bottom)
					textMatrix.Translate(penFlushness, baselineOffset - textPosition.Y -(float)Math.Floor(ascent - 1));

				// Set our matrix
				bitmapContext.TextMatrix = textMatrix;

				// and draw the line
				line.Draw(bitmapContext);

				// Move the index beyond the line break.
				start += count;
				textPosition.Y += (float)Math.Ceiling(ascent + descent + leading + 1); // +1 matches best to CTFramesetter's behavior  
				line.Dispose();

			}

		}