System.Drawing.Drawing2D.LinearGradientBrush.Setup C# (CSharp) 메소드

        internal override void Setup(Graphics graphics, bool fill)
        {
            CGContext context = graphics.context;

            // if fill is false then we are being called from a Pen stroke so
            // we need to setup a transparency layer
            // http://developer.apple.com/library/mac/#documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_shadings/dq_shadings.html#//apple_ref/doc/uid/TP30001066-CH207-BBCECJBF
            if (!fill)
            {
                context.BeginTransparencyLayer();
                hasTransparencyLayer = true;
                // Make sure we set a color here so that the gradient shows up
                graphics.lastBrushColor = Color.Black;
                return;
            }

            // if this is the same as the last that was set and no changes have been made
            // then return.
            if (graphics.LastBrush != this || changed)
            {
                setupShadingColors();
            }

            SizeF gradientRegion = context.GetClipBoundingBox().Size.ToSizeF ();
            //			SizeF gradientRegionPath = context.GetPathBoundingBox().Size;
            PointF sp = startPoint;
            PointF ep = endPoint;
            PointF[] points = {sp, ep};

            // Transform the start and end points using the brush's transformation matrix
            gradientTransform.TransformPoints(points);

            sp = points[0];
            ep = points[1];

            var cgf = CyclicGradientFunction(gradientRegion,
                                         ref sp, ref ep);

            var colorSpace = CGColorSpace.CreateDeviceRGB();
            var shading = CGShading.CreateAxial (colorSpace, sp.ToCGPoint (), ep.ToCGPoint (), cgf, false, false);

            colorSpace.Dispose();

            context.SaveState();

            // if path is empty here then we are being called from a Pen stroke so
            // we set the blend mode for strokes and clip the path for fills
            if (!context.IsPathEmpty())
            {
                context.Clip();
            }
            else
            {
                context.SetBlendMode(CGBlendMode.SourceIn);
            }

            context.DrawShading(shading);
            context.RestoreState();

            // If we are in a Transparency layer then we need to end the transparency
            if (hasTransparencyLayer) {
                context.EndTransparencyLayer();
            }

            cgf.Dispose();
            shading.Dispose();
            shading = null;

            changed = false;

            graphics.LastBrush = this;
            // We will reset the last pen so that it can be setup again
            // so that we do not loose the settings after stroking the gradient
            // not sure where the setting are being reset so this may be a hack
            // and things are just not being restored correctly.
            graphics.LastPen = null;
            // I am setting this to be used for Text coloring in DrawString
            graphics.lastBrushColor = colors[0];
        }