ios-samples/QuartzSample/QuartzBlendingViewController.xib.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Foundation;
using UIKit;
using QuartzSample;
using CoreGraphics;

namespace QuartzSample
{
	public partial class QuartzBlendingViewController : QuartzViewController
	{
		#region Constructors

		// The IntPtr and initWithCoder constructors are required for items that need
		// to be able to be created from a xib rather than from managed code

		public QuartzBlendingViewController (IntPtr handle) : base (handle)
		{
			Initialize ();
		}

		[Export ("initWithCoder:")]
		public QuartzBlendingViewController (NSCoder coder) : base (coder)
		{
			Initialize ();
		}

		public QuartzBlendingViewController () : base ("QuartzBlendingViewController", null)
		{
			Initialize ();
		}

		public QuartzBlendingViewController (CreateView creator, string title, string info) : base (creator, "QuartzBlendingViewController", title, info)
		{
			Array.Sort (Colors, ColorSortByLuminance);
		}

		void Initialize ()
		{
		}

		#endregion

		static UIColor [] Colors = new UIColor [] {
			UIColor.Red,
			UIColor.Green,
			UIColor.Blue,
			UIColor.Yellow,
			UIColor.Magenta,
			UIColor.Cyan,
			UIColor.Orange,
			UIColor.Purple,
			UIColor.Brown,
			UIColor.White,
			UIColor.LightGray,
			UIColor.DarkGray,
			UIColor.Black
		};

		static string [] BlendModes = new string [] {
			"Normal",
			"Multiply",
			"Screen",
			"Overlay",
			"Darken",
			"Lighten",
			"ColorDodge",
			"ColorBurn",
			"SoftLight",
			"HardLight",
			"Difference",
			"Exclusion",
			"Hue",
			"Saturation",
			"Color",
			"Luminosity",
			// Porter-Duff Blend Modes
			"Clear",
			"Copy",
			"SourceIn",
			"SourceOut",
			"SourceAtop",
			"DestinationOver",
			"DestinationIn",
			"DestinationOut",
			"DestinationAtop",
			"XOR",
			"PlusDarker",
			"PlusLighter",
		};

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

			picker.Model = new BlendSelector (this);

			var qbv = (QuartzBlendingView) quartzView;
			picker.Select (Array.IndexOf (Colors, qbv.DestinationColor), 0, false);
			picker.Select (Array.IndexOf (Colors, qbv.SourceColor), 1, false);
			picker.Select ((int) qbv.BlendMode, 2, false);
		}

		static nfloat LuminanceForColor (UIColor color)
		{
			CGColor cgcolor = color.CGColor;
			var components = cgcolor.Components;
			nfloat luminance = 0;

			switch (cgcolor.ColorSpace.Model){
			case CGColorSpaceModel.Monochrome:
				// For grayscale colors, the luminance is the color value
				luminance = components[0];
				break;

			case CGColorSpaceModel.RGB:
				// For RGB colors, we calculate luminance assuming sRGB Primaries as per
				// http://en.wikipedia.org/wiki/Luminance_(relative)
				luminance = 0.2126f * components[0] + 0.7152f * components[1] + 0.0722f * components[2];
				break;

			default:
				// We don't implement support for non-gray, non-rgb colors at this time.
				// Since our only consumer is colorSortByLuminance, we return a larger than normal
				// value to ensure that these types of colors are sorted to the end of the list.
				luminance = 2.0f;
				break;
			}
			return luminance;
		}

		// Simple comparison function that sorts the two (presumed) UIColors according to their luminance value.
		static int ColorSortByLuminance (UIColor color1,  UIColor color2)
		{
			nfloat luminance1 = LuminanceForColor(color1);
			nfloat luminance2 = LuminanceForColor(color2);

			if (luminance1 == luminance2)
				return 0;
			else if (luminance1 < luminance2)
				return -1;
			else
				return 1;
		}

		public class BlendSelector : UIPickerViewModel
		{
			QuartzBlendingViewController parent;

			public BlendSelector (QuartzBlendingViewController parent)
			{
				this.parent = parent;
			}

			public override nint GetComponentCount (UIPickerView picker){
				return 3;
			}

			public override nint GetRowsInComponent (UIPickerView picker, nint component)
			{
				if (component == 0 || component == 1)
					return Colors.Length;
				return BlendModes.Length;
			}

			public override nfloat GetComponentWidth (UIPickerView picker, nint component)
			{
				if (component == 0 || component == 1)
					return 48f;
				return 192f;
			}

			const int kColorTag = 1;
			const int kLabelTag = 1;

			public override UIView GetView (UIPickerView picker, nint row, nint component, UIView view)
			{
				var size = picker.RowSizeForComponent (component);

				if (component == 0 || component == 1){
					if (view == null || view.Tag != kColorTag){
						view = new UIView (new CGRect (0, 0, size.Width-4, size.Height-4)){
							Tag = kColorTag
						};
					}
					view.BackgroundColor = Colors [row];
				} else {
					if (view == null || view.Tag != kLabelTag){
						view = new UILabel (new CGRect (0, 0, size.Width-4, size.Height-4)){
							Tag = kLabelTag,
							Opaque = false,
							BackgroundColor = UIColor.Clear
						};
					}
					var label = (UILabel) view;
					label.TextColor = UIColor.Black;
					label.Text = BlendModes [row];
					label.Font = UIFont.BoldSystemFontOfSize (18f);
				}
				return view;
			}

			public override void Selected (UIPickerView picker, nint row, nint component)
			{
				var qbv = (QuartzBlendingView) parent.quartzView;
				qbv.DestinationColor = Colors [picker.SelectedRowInComponent (0)];
				qbv.SourceColor = Colors [picker.SelectedRowInComponent (1)];
				qbv.BlendMode = (CGBlendMode) (int)picker.SelectedRowInComponent (2);
				qbv.SetNeedsDisplay ();
			}
		}
	}

	public class QuartzBlendingView : QuartzView {
		public UIColor SourceColor { get; set; }
		public UIColor DestinationColor { get; set; }
		public CGBlendMode BlendMode { get; set; }

		public QuartzBlendingView () : base () {
			SourceColor = UIColor.White;
			DestinationColor = UIColor.Black;
			BlendMode = CGBlendMode.Normal;
		}

		public override void DrawInContext (CGContext context)
		{
			// Start with a background whose color we don't use in the demo
			context.SetFillColor (0.2f, 1);
			context.FillRect (Bounds);

			// We want to just lay down the background without any blending so we use the Copy mode rather than Normal
			context.SetBlendMode(CGBlendMode.Copy);

			// Draw a rect with the "background" color - this is the "Destination" for the blending formulas
			context.SetFillColor (DestinationColor.CGColor);
			context.FillRect(new CGRect (110, 20, 100, 100));

			// Set up our blend mode
			context.SetBlendMode (BlendMode);

			// And draw a rect with the "foreground" color - this is the "Source" for the blending formulas
			context.SetFillColor (SourceColor.CGColor);
			context.FillRect (new CGRect (60, 45, 200, 50));
		}
	}
}