C# CALayer类代码示例

		public override void ViewDidLoad ()
		{
			base.ViewDidLoad ();

			TKChart chart = new TKChart (this.View.Bounds);
			chart.AutoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight;
			this.View.AddSubview (chart);

			string[] months = new string[]{ "Jan", "Feb", "Mar", "Apr", "May", "Jun" };
			int[] values = new int[]{ 95, 40, 55, 30, 76, 34 };
			List<TKChartDataPoint> list = new List<TKChartDataPoint> ();

			for (int i = 0; i < months.Length; i++) {
				list.Add (new TKChartDataPoint(new NSString(months[i]), new NSNumber(values[i])));
			}
			chart.AddSeries (new TKChartAreaSeries (list.ToArray()));

			CALayer layer = new CALayer ();
			layer.Bounds = new RectangleF (0, 0, 100, 100);
			layer.BackgroundColor = new UIColor(1, 0, 0, 0.6f).CGColor;
			layer.ShadowRadius = 10;
			layer.ShadowColor = UIColor.Yellow.CGColor;
			layer.ShadowOpacity = 1;
			layer.CornerRadius = 10;

			TKChartLayerAnnotation a = new TKChartLayerAnnotation(layer, new NSString("Mar"), new NSNumber(80), chart.Series[0]);
			a.ZPosition = TKChartAnnotationZPosition.AboveSeries;
			chart.AddAnnotation(a);
		}

 public OuterShadow(CALayer targetLayer, SizeF frameSize, float shadowDepth)
 {
     this.targetLayer = targetLayer;
     FrameSize = frameSize;
     ShadowDepth = shadowDepth;
     shadows[Edge.Top] = shadows[Edge.Right] = shadows[Edge.Bottom] = shadows[Edge.Left] = null;
 }

		public static void Draw(CALayer target, IViewport viewport, IStyle style, IFeature feature)
		{
			const string styleKey = "laag";

			if(feature[styleKey] == null) feature[styleKey] = ToiOSBitmap(feature.Geometry);

			var bitmap = (UIImage)feature [styleKey];

			var dest = WorldToScreen(viewport, feature.Geometry.GetBoundingBox());
			dest = new BoundingBox(
				dest.MinX,
				dest.MinY,
				dest.MaxX,
				dest.MaxY);

			var destination = RoundToPixel(dest);

			var tile = new CALayer
			{
				Frame = destination,
				Contents = bitmap.CGImage,
			};
			
			target.AddSublayer(tile);
		}

		public override void ViewDidLoad ()
		{
			base.ViewDidLoad ();

			sessionManager = new SessionManager ();
			sessionManager.StartRunning ();

			previewLayer = new AVCaptureVideoPreviewLayer (sessionManager.CaptureSession) {
				Frame = previewView.Bounds,
				VideoGravity = AVLayerVideoGravity.ResizeAspectFill
			};

			if (previewLayer.Connection != null && previewLayer.Connection.SupportsVideoOrientation)
				previewLayer.Connection.VideoOrientation = AVCaptureVideoOrientation.LandscapeLeft;
			previewView.Layer.AddSublayer (previewLayer);
			previewView.Layer.MasksToBounds = true;

			barcodeTargetLayer = new CALayer () {
				Frame = View.Layer.Bounds
			};
			View.Layer.AddSublayer (barcodeTargetLayer);

			synth = new Synth ();
			synth.LoadPreset (this);

			// the loop that continuously looks for barcodes to detect
			stepTimer = NSTimer.CreateScheduledTimer (0.15, this, new Selector ("step:"), null, true);
		}

		public override void ViewDidLoad ()
		{
			base.ViewDidLoad ();

			sessionManager = new SessionManager ();
			sessionManager.StartRunning ();

			previewLayer = new AVCaptureVideoPreviewLayer (sessionManager.CaptureSession) {
				Frame = previewView.Bounds,
				VideoGravity = AVLayerVideoGravity.ResizeAspectFill
			};

			if (previewLayer.Connection != null && previewLayer.Connection.SupportsVideoOrientation)
				previewLayer.Connection.VideoOrientation = AVCaptureVideoOrientation.LandscapeLeft;
			previewView.Layer.AddSublayer (previewLayer);
			previewView.Layer.MasksToBounds = true;

			barcodeTargetLayer = new CALayer () {
				Frame = View.Layer.Bounds
			};
			View.Layer.AddSublayer (barcodeTargetLayer);

			synth = new Synth ();
			synth.LoadPreset (this);
		}

        public static void PositionMultiPolygon(CALayer shape, MultiPolygon multiPolygon, IStyle style, IViewport viewport)
        {
            var shapeLayer = shape as CAShapeLayer;
            var path = multiPolygon.ToUIKit(viewport);
            //var frame = ConvertBoundingBox (multiPolygon.GetBoundingBox(), viewport);
            shapeLayer.Path = path.CGPath;
            //shape.Frame = frame;
            /*
            if (viewport.Resolution > MinResolution || viewport.Resolution < MaxResolution) {
                //recalculate
                var newImage = RenderMultiPolygonOnLayer (multiPolygon, style, viewport);

                shape.Contents = newImage.Contents;
                shape.Frame = newImage.Frame;

                var resolution = ZoomHelper.ClipResolutionToExtremes (Resolutions, viewport.Resolution);

                MinResolution = ZoomHelper.ZoomOut (Resolutions, resolution);
                MaxResolution = ZoomHelper.ZoomIn (Resolutions, resolution);

            } else {
                //reposition Geometry
                var frame = ConvertBoundingBox (multiPolygon.GetBoundingBox(), viewport);
                var newFrame = new RectangleF (frame.X, (frame.Y), frame.Width, frame.Height);

                shape.Frame = newFrame;
                //shape.Frame = frame;
            }
            */
        }

		protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
		{
			base.OnElementChanged(e);

			if (e.NewElement != null && !isInitialized)
			{
				var formsEntry = e.NewElement as LoginEntry;
				formsEntry.FontFamily = "SegoeUI-Light";
				formsEntry.TextColor = Color.FromHex("#778687");
				formsEntry.FontSize = 18;

				nativeTextField = Control as UITextField;
				nativeTextField.BorderStyle = UITextBorderStyle.None;

				//Figure out how to reference font from Resources as Embedded Resource
				if (!String.IsNullOrEmpty(formsEntry.Placeholder))
					nativeTextField.AttributedPlaceholder = new NSAttributedString(formsEntry.Placeholder, UIFont.FromName("SegoeUI-Light", 18), Color.FromHex("#778687").ToUIColor());

				bottomBorder = new CALayer();
				bottomBorder.BackgroundColor = Color.FromHex("#778687").ToCGColor();
				Control.Layer.AddSublayer(bottomBorder);

				isInitialized = true;
			}
		}

		public override void ViewDidLoad ()
		{
			base.ViewDidLoad ();
			View.BackgroundColor = UIColor.White;
			View.UserInteractionEnabled = true;

			layer = new CALayer {
				Bounds = new CGRect (0, 0, 50, 50),
				Position = new CGPoint (50, 50),
				Contents = UIImage.FromFile ("monkey2.png").CGImage,
				ContentsGravity = CALayer.GravityResize,
				BorderWidth = 1.5f,
				BorderColor = UIColor.Green.CGColor
			};

			View.Layer.AddSublayer (layer);

			View.AddGestureRecognizer (new UITapGestureRecognizer (() => {
				ViewController initalViewController = (ViewController)MainStoryboard.InstantiateViewController("InitalViewController");

				initalViewController.ModalTransitionStyle = UIModalTransitionStyle.FlipHorizontal;

				PresentViewController(initalViewController, true, null);
			}));
		}

		public static void AddBorder(this UIView view, UIRectEdge edge, UIColor color, nfloat thickness) {

			var border = new CALayer ();
			var f = view.Frame;
			switch(edge)
			{
			case UIRectEdge.Top:
				border.Frame = new CGRect(0, 0, f.Width, thickness);
				break;
			case UIRectEdge.Bottom:
				border.Frame = new CGRect (0, f.Height - thickness, f.Width, thickness);
				break;
			case UIRectEdge.Left:
				border.Frame = new CGRect(0, 0, thickness, f.Height);
				break;
			case UIRectEdge.Right:
				border.Frame = new CGRect(f.Width - thickness, 0, thickness, f.Height);
				break;
			default:
				break;
			}

			border.BackgroundColor = color.CGColor;
			view.Layer.AddSublayer (border);
		}

        public ShimmeringMaskLayer()
        {
            FadeLayer = new CALayer();
            FadeLayer.BackgroundColor = UIColor.White.CGColor;
            AddSublayer(FadeLayer);

            RemoveAllAnimations();
        }

		public override void Clone (CALayer other)
		{
			CircleLayer o = (CircleLayer) other;
			Radius = o.Radius;
			Color = o.Color;
			Thickness = o.Thickness;
			base.Clone (other);
		}

        public override void AwakeFromNib()
        {
            base.AwakeFromNib();

			View.Layer = new CALayer();
			View.WantsLayer = true;

			textContainer = new CALayer();
			textContainer.AnchorPoint = CGPoint.Empty;
			textContainer.Position = new CGPoint(10, 10);
			textContainer.ZPosition = 100;
			textContainer.BackgroundColor = NSColor.Black.CGColor;
			textContainer.BorderColor = NSColor.White.CGColor;
			textContainer.BorderWidth = 2;
			textContainer.CornerRadius = 15;
			textContainer.ShadowOpacity = 0.5f;
			View.Layer.AddSublayer(textContainer);

			textLayer = new CATextLayer();
			textLayer.AnchorPoint = CGPoint.Empty;
			textLayer.Position = new CGPoint(10, 6);
			textLayer.ZPosition = 100;
			textLayer.FontSize = 24;
			textLayer.ForegroundColor = NSColor.White.CGColor;
			textContainer.AddSublayer(textLayer);

			// Rely on setText: to set the above layers' bounds: [self setText:@"Loading..."];
			SetText("Loading...", textLayer);


			var dirs = NSSearchPath.GetDirectories(NSSearchPathDirectory.LibraryDirectory, NSSearchPathDomain.Local);
			foreach (string dir in dirs) {
				Console.WriteLine("Dir: {0}", dir);
			}
			string libDir = dirs[0];
			string desktopPicturesDir = Path.Combine(libDir, "Desktop Pictures");
			Console.WriteLine("DP Dir: {0}", desktopPicturesDir);

			// Launch loading of images on background thread
			Task.Run(async () => {
				await AddImagesFromFolderUrlAsync(desktopPicturesDir);
			});

			repositionButton.Layer.ZPosition = 100;
			durationTextField.Layer.ZPosition = 100;
			lastWindowSize = Window.Frame.Size;

			Window.DidResize += (sender, e) => {
				if (Math.Abs(lastWindowSize.Width - Window.Frame.Width) > 25 || Math.Abs(lastWindowSize.Height - Window.Frame.Height) > 25) {
					windowIsResizing = true;
					repositionImages(repositionButton);
					lastWindowSize = Window.Frame.Size;
					windowIsResizing = false;
				}
			};

        }

 public override void Clone(CALayer other)
 {
     RoundProgressLayer o = (RoundProgressLayer) other;
     Progress = o.Progress;
     StartAngle = o.StartAngle;
     TintColor = o.TintColor;
     TrackColor = o.TrackColor;
     base.Clone (other);
 }

        private void MaskImageWithImage(UIImageView imgView, UIImage maskImage)
        {
            var aMaskLayer = new CALayer();

            aMaskLayer.Frame = new CGRect(0, 0, imgView.Image.Size.Width, imgView.Image.Size.Height);
            aMaskLayer.Contents = maskImage.CGImage;

            imgView.Layer.Mask = aMaskLayer;
        }

		public static List<IFeature> RenderStackedLabelLayer(IViewport viewport, BasicLayer layer)
		{
			lock(_syncRoot)
			{
				var renderedFeatures = new List<IFeature> ();
				var canvas = new CALayer ();
				canvas.Opacity = (float)layer.Opacity;

				//todo: take into account the priority 
				var features = layer.GetFeaturesInView (viewport.Extent, viewport.Resolution);
				var margin = viewport.Resolution * 15;

				var clusters = new List<Cluster> ();
				//todo: repeat until there are no more merges
				ClusterFeatures (clusters, features, margin, null, viewport, viewport.Resolution);
				//CenterClusters (clusters);

				//CATransaction.Begin();
				//CATransaction.SetValueForKey (MonoTouch.Foundation.NSNumber.FromBoolean(true), CATransaction.DisableActionsKey);

				foreach(var cluster in clusters){

					var feature = cluster.Features.OrderBy(f => f.Geometry.GetBoundingBox().GetCentroid().Y).FirstOrDefault();
					//SetFeatureOutline (feature, layer.LayerName, cluster.Features.Count);
					//var bb = RenderBox(cluster.Box, viewport);

					//Zorg dat dit ALTIJD decimal zelfde ISet als ViewChanged is
					//var feature = cluster.Features.FirstOrDefault ();

					var styles = feature.Styles ?? Enumerable.Empty<IStyle>();
					foreach (var style in styles)
					{
						if (feature.Styles != null && style.Enabled)
						{
							var styleKey = layer.LayerName; //feature.GetHashCode ().ToString ();
							var renderedGeometry = (feature[styleKey] != null) ? (CALayer)feature[styleKey] : null;

							if (renderedGeometry == null) {
								renderedGeometry = GeometryRenderer.RenderPoint (feature.Geometry as Mapsui.Geometries.Point, style, viewport);

								feature [styleKey] = renderedGeometry;
								feature ["first"] = true;

							} else {
								feature ["first"] = false;
							}
						}
					}
					renderedFeatures.Add (feature);

					//renderedFeatures.Add (bb);
				}

				return renderedFeatures;
			}
		}