summaryrefslogtreecommitdiff
path: root/Xamarin.Forms.Platform.iOS/RendererPool.cs
blob: babfa7bcd89d5caa5b6d2f2b14f7003f60622d26 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
using System;
using System.Collections.Generic;

namespace Xamarin.Forms.Platform.iOS
{
	public sealed class RendererPool
	{
		readonly Dictionary<Type, Stack<IVisualElementRenderer>> _freeRenderers = new Dictionary<Type, Stack<IVisualElementRenderer>>();

		readonly VisualElement _oldElement;

		readonly IVisualElementRenderer _parent;

		public RendererPool(IVisualElementRenderer renderer, VisualElement oldElement)
		{
			if (renderer == null)
				throw new ArgumentNullException("renderer");

			if (oldElement == null)
				throw new ArgumentNullException("oldElement");

			_oldElement = oldElement;
			_parent = renderer;
		}

		public IVisualElementRenderer GetFreeRenderer(VisualElement view)
		{
			if (view == null)
				throw new ArgumentNullException("view");

			var rendererType = Registrar.Registered.GetHandlerType(view.GetType()) ?? typeof(ViewRenderer);

			Stack<IVisualElementRenderer> renderers;
			if (!_freeRenderers.TryGetValue(rendererType, out renderers) || renderers.Count == 0)
				return null;

			var renderer = renderers.Pop();
			renderer.SetElement(view);
			return renderer;
		}

		public void UpdateNewElement(VisualElement newElement)
		{
			if (newElement == null)
				throw new ArgumentNullException("newElement");

			var sameChildrenTypes = true;

			var oldChildren = ((IElementController)_oldElement).LogicalChildren;
			var newChildren = ((IElementController)newElement).LogicalChildren;

			if (oldChildren.Count == newChildren.Count)
			{
				for (var i = 0; i < oldChildren.Count; i++)
				{
					if (oldChildren[i].GetType() != newChildren[i].GetType())
					{
						sameChildrenTypes = false;
						break;
					}
				}
			}
			else
				sameChildrenTypes = false;

			if (!sameChildrenTypes)
			{
				ClearRenderers(_parent);
				FillChildrenWithRenderers(newElement);
			}
			else
				UpdateRenderers(newElement);
		}

		void ClearRenderers(IVisualElementRenderer renderer)
		{
			if (renderer == null)
				return;

			var subviews = renderer.NativeView.Subviews;
			for (var i = 0; i < subviews.Length; i++)
			{
				var childRenderer = subviews[i] as IVisualElementRenderer;
				if (childRenderer != null)
				{
					PushRenderer(childRenderer);

					if (ReferenceEquals(childRenderer, Platform.GetRenderer(childRenderer.Element)))
						childRenderer.Element.ClearValue(Platform.RendererProperty);
				}

				subviews[i].RemoveFromSuperview();
			}
		}

		void FillChildrenWithRenderers(VisualElement element)
		{
			foreach (var logicalChild in ((IElementController)element).LogicalChildren)
			{
				var child = logicalChild as VisualElement;
				if (child != null)
				{
					var renderer = GetFreeRenderer(child) ?? Platform.CreateRenderer(child);
					Platform.SetRenderer(child, renderer);

					_parent.NativeView.AddSubview(renderer.NativeView);
				}
			}
		}

		void PushRenderer(IVisualElementRenderer renderer)
		{
			var rendererType = renderer.GetType();

			Stack<IVisualElementRenderer> renderers;
			if (!_freeRenderers.TryGetValue(rendererType, out renderers))
				_freeRenderers[rendererType] = renderers = new Stack<IVisualElementRenderer>();

			renderers.Push(renderer);
		}

		void UpdateRenderers(Element newElement)
		{
			var newElementController = (IElementController)newElement;

			if (newElementController.LogicalChildren.Count == 0)
				return;

			var subviews = _parent.NativeView.Subviews;
			for (var i = 0; i < subviews.Length; i++)
			{
				var childRenderer = subviews[i] as IVisualElementRenderer;
				if (childRenderer == null)
					continue;

				var x = (int)childRenderer.NativeView.Layer.ZPosition / 1000;
				var element = newElementController.LogicalChildren[x] as VisualElement;
				if (element == null)
					continue;

				if (childRenderer.Element != null && ReferenceEquals(childRenderer, Platform.GetRenderer(childRenderer.Element)))
					childRenderer.Element.ClearValue(Platform.RendererProperty);

				childRenderer.SetElement(element);
				Platform.SetRenderer(element, childRenderer);
			}
		}
	}
}