/// <summary>
        /// Init.
        /// </summary>
        protected RGraphics(RAdapter adapter, RRect initialClip)
        {
            ArgChecker.AssertArgNotNull(adapter, "global");

            _adapter = adapter;
            _clipStack.Push(initialClip);
        }

        /// <summary>
        /// Get top-left location to start drawing the image at depending on background-position value.
        /// </summary>
        /// <param name="backgroundPosition">the background-position value</param>
        /// <param name="rectangle">the rectangle to position image in</param>
        /// <param name="imgSize">the size of the image</param>
        /// <returns>the top-left location</returns>
        private static RPoint GetLocation(string backgroundPosition, RRect rectangle, RSize imgSize)
        {
            double left = rectangle.Left;
            if (backgroundPosition.IndexOf("left", StringComparison.OrdinalIgnoreCase) > -1)
            {
                left = (rectangle.Left + .5f);
            }
            else if (backgroundPosition.IndexOf("right", StringComparison.OrdinalIgnoreCase) > -1)
            {
                left = rectangle.Right - imgSize.Width;
            }
            else if (backgroundPosition.IndexOf("0", StringComparison.OrdinalIgnoreCase) < 0)
            {
                left = (rectangle.Left + (rectangle.Width - imgSize.Width) / 2 + .5f);
            }

            double top = rectangle.Top;
            if (backgroundPosition.IndexOf("top", StringComparison.OrdinalIgnoreCase) > -1)
            {
                top = rectangle.Top;
            }
            else if (backgroundPosition.IndexOf("bottom", StringComparison.OrdinalIgnoreCase) > -1)
            {
                top = rectangle.Bottom - imgSize.Height;
            }
            else if (backgroundPosition.IndexOf("0", StringComparison.OrdinalIgnoreCase) < 0)
            {
                top = (rectangle.Top + (rectangle.Height - imgSize.Height) / 2 + .5f);
            }

            return new RPoint(left, top);
        }

        /// <summary>
        /// Init.
        /// </summary>
        /// <param name="g">the Perspex graphics object to use</param>
        /// <param name="initialClip">the initial clip of the graphics</param>
        /// <param name="releaseGraphics">optional: if to release the graphics object on dispose (default - false)</param>
        public GraphicsAdapter(IDrawingContext g, RRect initialClip, bool releaseGraphics = false)
            : base(PerspexAdapter.Instance, initialClip)
        {
            ArgChecker.AssertArgNotNull(g, "g");

            _g = g;
            _releaseGraphics = releaseGraphics;
        }

 protected override RBrush CreateLinearGradientBrush(RRect rect, RColor color1, RColor color2, double angle)
 {
     var startColor = angle <= 180 ? Utils.Convert(color1) : Utils.Convert(color2);
     var endColor = angle <= 180 ? Utils.Convert(color2) : Utils.Convert(color1);
     angle = angle <= 180 ? angle : angle - 180;
     double x = angle < 135 ? Math.Max((angle - 45) / 90, 0) : 1;
     double y = angle <= 45 ? Math.Max(0.5 - angle / 90, 0) : angle > 135 ? Math.Abs(1.5 - angle / 90) : 0;
     return new BrushAdapter(new LinearGradientBrush(startColor, endColor, new Point(x, y), new Point(1 - x, 1 - y)));
 }

        public override void PushClipExclude(RRect rect)
        {
            var geometry = new CombinedGeometry();
            geometry.Geometry1 = new RectangleGeometry(Utils.Convert(_clipStack.Peek()));
            geometry.Geometry2 = new RectangleGeometry(Utils.Convert(rect));
            geometry.GeometryCombineMode = GeometryCombineMode.Exclude;

            _clipStack.Push(_clipStack.Peek());
            _g.PushClip(geometry);
        }

 protected override RBrush CreateLinearGradientBrush(RRect rect, RColor color1, RColor color2, double angle)
 {
     XLinearGradientMode mode;
     if (angle < 45)
         mode = XLinearGradientMode.ForwardDiagonal;
     else if (angle < 90)
         mode = XLinearGradientMode.Vertical;
     else if (angle < 135)
         mode = XLinearGradientMode.BackwardDiagonal;
     else
         mode = XLinearGradientMode.Horizontal;
     return new BrushAdapter(new XLinearGradientBrush(Utils.Convert(rect), Utils.Convert(color1), Utils.Convert(color2), mode));
 }

        protected override RBrush CreateLinearGradientBrush(RRect rect, RColor color1, RColor color2, double angle)
        {
            var startColor = angle <= 180 ? Util.Convert(color1) : Util.Convert(color2);
            var endColor = angle <= 180 ? Util.Convert(color2) : Util.Convert(color1);
            angle = angle <= 180 ? angle : angle - 180;
            double x = angle < 135 ? Math.Max((angle - 45) / 90, 0) : 1;
            double y = angle <= 45 ? Math.Max(0.5 - angle / 90, 0) : angle > 135 ? Math.Abs(1.5 - angle / 90) : 0;
            return new BrushAdapter(new LinearGradientBrush
            {
                StartPoint = new RelativePoint(x, y, RelativeUnit.Relative), 
                EndPoint = new RelativePoint(1 - x, 1 - y, RelativeUnit.Relative),
                GradientStops =
                {
                    new GradientStop(startColor, 0),
                    new GradientStop(endColor, 1)
                }
            });

        }

        /// <summary>
        /// Draw the background image of the given box in the given rectangle.<br/>
        /// Handle background-repeat and background-position values.
        /// </summary>
        /// <param name="g">the device to draw into</param>
        /// <param name="box">the box to draw its background image</param>
        /// <param name="imageLoadHandler">the handler that loads image to draw</param>
        /// <param name="rectangle">the rectangle to draw image in</param>
        public static void DrawBackgroundImage(RGraphics g, CssBox box, ImageLoadHandler imageLoadHandler, RRect rectangle)
        {
            // image size depends if specific rectangle given in image loader
            var imgSize = new RSize(imageLoadHandler.Rectangle == RRect.Empty ? imageLoadHandler.Image.Width : imageLoadHandler.Rectangle.Width,
                imageLoadHandler.Rectangle == RRect.Empty ? imageLoadHandler.Image.Height : imageLoadHandler.Rectangle.Height);

            // get the location by BackgroundPosition value
            var location = GetLocation(box.BackgroundPosition, rectangle, imgSize);

            var srcRect = imageLoadHandler.Rectangle == RRect.Empty
                ? new RRect(0, 0, imgSize.Width, imgSize.Height)
                : new RRect(imageLoadHandler.Rectangle.Left, imageLoadHandler.Rectangle.Top, imgSize.Width, imgSize.Height);

            // initial image destination rectangle
            var destRect = new RRect(location, imgSize);

            // need to clip so repeated image will be cut on rectangle
            var lRectangle = rectangle;
            lRectangle.Intersect(g.GetClip());
            g.PushClip(lRectangle);

            switch (box.BackgroundRepeat)
            {
                case "no-repeat":
                    g.DrawImage(imageLoadHandler.Image, destRect, srcRect);
                    break;
                case "repeat-x":
                    DrawRepeatX(g, imageLoadHandler, rectangle, srcRect, destRect, imgSize);
                    break;
                case "repeat-y":
                    DrawRepeatY(g, imageLoadHandler, rectangle, srcRect, destRect, imgSize);
                    break;
                default:
                    DrawRepeat(g, imageLoadHandler, rectangle, srcRect, destRect, imgSize);
                    break;
            }

            g.PopClip();
        }

 /// <summary>
 /// Draws all the border of the box with respect to style, width, etc.
 /// </summary>
 /// <param name="g">the device to draw into</param>
 /// <param name="box">the box to draw borders for</param>
 /// <param name="rect">the bounding rectangle to draw in</param>
 /// <param name="isFirst">is it the first rectangle of the element</param>
 /// <param name="isLast">is it the last rectangle of the element</param>
 public static void DrawBoxBorders(RGraphics g, CssBox box, RRect rect, bool isFirst, bool isLast)
 {
     if (rect.Width > 0 && rect.Height > 0)
     {
         if (!(string.IsNullOrEmpty(box.BorderTopStyle) || box.BorderTopStyle == CssConstants.None || box.BorderTopStyle == CssConstants.Hidden) && box.ActualBorderTopWidth > 0)
         {
             DrawBorder(Border.Top, box, g, rect, isFirst, isLast);
         }
         if (isFirst && !(string.IsNullOrEmpty(box.BorderLeftStyle) || box.BorderLeftStyle == CssConstants.None || box.BorderLeftStyle == CssConstants.Hidden) && box.ActualBorderLeftWidth > 0)
         {
             DrawBorder(Border.Left, box, g, rect, true, isLast);
         }
         if (!(string.IsNullOrEmpty(box.BorderBottomStyle) || box.BorderBottomStyle == CssConstants.None || box.BorderBottomStyle == CssConstants.Hidden) && box.ActualBorderBottomWidth > 0)
         {
             DrawBorder(Border.Bottom, box, g, rect, isFirst, isLast);
         }
         if (isLast && !(string.IsNullOrEmpty(box.BorderRightStyle) || box.BorderRightStyle == CssConstants.None || box.BorderRightStyle == CssConstants.Hidden) && box.ActualBorderRightWidth > 0)
         {
             DrawBorder(Border.Right, box, g, rect, isFirst, true);
         }
     }
 }

        /// <summary>
        /// On image load process is complete with image or without update the image box.
        /// </summary>
        /// <param name="image">the image loaded or null if failed</param>
        /// <param name="rectangle">the source rectangle to draw in the image (empty - draw everything)</param>
        /// <param name="async">is the callback was called async to load image call</param>
        private void OnLoadImageComplete(RImage image, RRect rectangle, bool async)
        {
            _imageWord.Image = image;
            _imageWord.ImageRectangle = rectangle;
            _imageLoadingComplete = true;
            _wordsSizeMeasured = false;

            if (_imageLoadingComplete && image == null)
            {
                SetErrorBorder();
            }

            if (!HtmlContainer.AvoidImagesLateLoading || async)
            {
                var width = new CssLength(Width);
                var height = new CssLength(Height);
                var layout = (width.Number <= 0 || width.Unit != CssUnit.Pixels) || (height.Number <= 0 || height.Unit != CssUnit.Pixels);
                HtmlContainer.RequestRefresh(layout);
            }
        }

 public override void DrawImage(RImage image, RRect destRect)
 {
     _g.DrawImage(((ImageAdapter) image).Image, 1, new Rect(0, 0, image.Width, image.Height),
         Util.Convert(destRect));
 }

        public override RBrush GetTextureBrush(RImage image, RRect dstRect, RPoint translateTransformLocation)
        {
            //TODO: Implement texture brush
            return PerspexAdapter.Instance.GetSolidBrush(Util.Convert(Colors.Magenta));

            //var brush = new ImageBrush(((ImageAdapter)image).Image);
            //brush.Stretch = Stretch.None;
            //brush.TileMode = TileMode.Tile;
            //brush.Viewport = Utils.Convert(dstRect);
            //brush.ViewportUnits = BrushMappingMode.Absolute;
            //brush.Transform = new TranslateTransform(translateTransformLocation.X, translateTransformLocation.Y);
            //brush.Freeze();
            //return new BrushAdapter(brush);
        }

 /// <summary>
 /// Draw image failed to load icon.
 /// </summary>
 /// <param name="g">the device to draw into</param>
 /// <param name="htmlContainer"></param>
 /// <param name="r">the rectangle to draw icon in</param>
 public static void DrawImageErrorIcon(RGraphics g, HtmlContainerInt htmlContainer, RRect r)
 {
     g.DrawRectangle(g.GetPen(RColor.LightGray), r.Left + 2, r.Top + 2, 15, 15);
     var image = htmlContainer.Adapter.GetLoadingFailedImage();
     g.DrawImage(image, new RRect(r.Left + 3, r.Top + 3, image.Width, image.Height));
 }

        /// <summary>
        /// Creates a rounded rectangle using the specified corner radius<br/>
        /// NW-----NE
        ///  |       |
        ///  |       |
        /// SW-----SE
        /// </summary>
        /// <param name="g">the device to draw into</param>
        /// <param name="rect">Rectangle to round</param>
        /// <param name="nwRadius">Radius of the north east corner</param>
        /// <param name="neRadius">Radius of the north west corner</param>
        /// <param name="seRadius">Radius of the south east corner</param>
        /// <param name="swRadius">Radius of the south west corner</param>
        /// <returns>GraphicsPath with the lines of the rounded rectangle ready to be painted</returns>
        public static RGraphicsPath GetRoundRect(RGraphics g, RRect rect, double nwRadius, double neRadius, double seRadius, double swRadius)
        {
            var path = g.GetGraphicsPath();

            path.Start(rect.Left + nwRadius, rect.Top);

            path.LineTo(rect.Right - neRadius, rect.Y);

            if (neRadius > 0f)
                path.ArcTo(rect.Right, rect.Top + neRadius, neRadius, RGraphicsPath.Corner.TopRight);

            path.LineTo(rect.Right, rect.Bottom - seRadius);

            if (seRadius > 0f)
                path.ArcTo(rect.Right - seRadius, rect.Bottom, seRadius, RGraphicsPath.Corner.BottomRight);

            path.LineTo(rect.Left + swRadius, rect.Bottom);

            if (swRadius > 0f)
                path.ArcTo(rect.Left, rect.Bottom - swRadius, swRadius, RGraphicsPath.Corner.BottomLeft);

            path.LineTo(rect.Left, rect.Top + nwRadius);

            if (nwRadius > 0f)
                path.ArcTo(rect.Left + nwRadius, rect.Top, nwRadius, RGraphicsPath.Corner.TopLeft);

            return path;
        }

        /// <summary>
        /// Paints the background of the box
        /// </summary>
        /// <param name="g">the device to draw into</param>
        /// <param name="rect">the bounding rectangle to draw in</param>
        /// <param name="isFirst">is it the first rectangle of the element</param>
        /// <param name="isLast">is it the last rectangle of the element</param>
        protected void PaintBackground(RGraphics g, RRect rect, bool isFirst, bool isLast)
        {
            if (rect.Width > 0 && rect.Height > 0)
            {
                RBrush brush = null;

                if (BackgroundGradient != CssConstants.None)
                {
                    brush = g.GetLinearGradientBrush(rect, ActualBackgroundColor, ActualBackgroundGradient, ActualBackgroundGradientAngle);
                }
                else if (RenderUtils.IsColorVisible(ActualBackgroundColor))
                {
                    brush = g.GetSolidBrush(ActualBackgroundColor);
                }

                if (brush != null)
                {
                    // TODO:a handle it correctly (tables background)
                    // if (isLast)
                    //  rectangle.Width -= ActualWordSpacing + CssUtils.GetWordEndWhitespace(ActualFont);

                    RGraphicsPath roundrect = null;
                    if (IsRounded)
                    {
                        roundrect = RenderUtils.GetRoundRect(g, rect, ActualCornerNw, ActualCornerNe, ActualCornerSe, ActualCornerSw);
                    }

                    Object prevMode = null;
                    if (HtmlContainer != null && !HtmlContainer.AvoidGeometryAntialias && IsRounded)
                    {
                        prevMode = g.SetAntiAliasSmoothingMode();
                    }

                    if (roundrect != null)
                    {
                        g.DrawPath(brush, roundrect);
                    }
                    else
                    {
                        g.DrawRectangle(brush, Math.Ceiling(rect.X), Math.Ceiling(rect.Y), rect.Width, rect.Height);
                    }

                    g.ReturnPreviousSmoothingMode(prevMode);

                    if (roundrect != null)
                        roundrect.Dispose();
                    brush.Dispose();
                }

                if (_imageLoadHandler != null && _imageLoadHandler.Image != null && isFirst)
                {
                    BackgroundImageDrawHandler.DrawBackgroundImage(g, this, _imageLoadHandler, rect);
                }
            }
        }

 /// <summary>
 /// Offsets the rectangle of the specified linebox by the specified gap,
 /// and goes deep for rectangles of children in that linebox.
 /// </summary>
 /// <param name="lineBox"></param>
 /// <param name="gap"></param>
 internal void OffsetRectangle(CssLineBox lineBox, double gap)
 {
     if (Rectangles.ContainsKey(lineBox))
     {
         var r = Rectangles[lineBox];
         Rectangles[lineBox] = new RRect(r.X, r.Y + gap, r.Width, r.Height);
     }
 }

 /// <summary>
 /// On image load process complete with image request refresh for it to be painted.
 /// </summary>
 /// <param name="image">the image loaded or null if failed</param>
 /// <param name="rectangle">the source rectangle to draw in the image (empty - draw everything)</param>
 /// <param name="async">is the callback was called async to load image call</param>
 private void OnImageLoadComplete(RImage image, RRect rectangle, bool async)
 {
     if (image != null && async)
         HtmlContainer.RequestRefresh(false);
 }

 public override void PushClip(RRect rect)
 {
     _clipStack.Push(_g.PushClip(Util.Convert(rect)));
     //_clipStack.Push(rect);
     //_g.PushClip(new RectangleGeometry(Utils.Convert(rect)));
 }

 /// <summary>
 /// Get linear gradient color brush from <paramref name="color1"/> to <paramref name="color2"/>.
 /// </summary>
 /// <param name="rect">the rectangle to get the brush for</param>
 /// <param name="color1">the start color of the gradient</param>
 /// <param name="color2">the end color of the gradient</param>
 /// <param name="angle">the angle to move the gradient from start color to end color in the rectangle</param>
 /// <returns>linear gradient color brush instance</returns>
 public RBrush GetLinearGradientBrush(RRect rect, RColor color1, RColor color2, double angle)
 {
     return _adapter.GetLinearGradientBrush(rect, color1, color2, angle);
 }

 /// <summary>
 /// Draws the specified Image at the specified location and with the specified size.
 /// </summary>
 /// <param name="image">Image to draw. </param>
 /// <param name="destRect">Rectangle structure that specifies the location and size of the drawn image. </param>
 public abstract void DrawImage(RImage image, RRect destRect);