public unsafe override void Draw (RectangleF rect)
{
var start = new PointF (rect.Left, rect.Bottom);
var end = new PointF (rect.Left, rect.Top);
var domain = new nfloat[] {0f, 1f};
var range = new nfloat[] {0f, 1f, 0f, 1f};
using (var context = UIGraphics.GetCurrentContext ())
using (var rgb = CGColorSpace.CreateDeviceGray())
using (var shadingFunction = new CGFunction(domain, range, Shading))
using (var shading = CGShading.CreateAxial (rgb, start, end, shadingFunction, true, false))
{
context.DrawShading (shading);
}
base.Draw (rect);
}
// http://developer.apple.com/library/mac/#documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_shadings/dq_shadings.html#//apple_ref/doc/uid/TP30001066-CH207-BBCECJBF
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();
}
CGSize gradientRegionCg = context.GetClipBoundingBox().Size;
SizeF gradientRegion = new SizeF((float)gradientRegionCg.Width, (float)gradientRegionCg.Height);
// 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();
CGPoint cgsp = new CGPoint(sp.X, sp.Y), cgep = new CGPoint(ep.X, ep.Y);
var shading = CGShading.CreateAxial(colorSpace, cgsp, cgep, 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];
}