Steven He
5 months ago
8 changed files with 372 additions and 30 deletions
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using System; |
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using System.Collections.Generic; |
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using Avalonia.Collections.Pooled; |
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using Avalonia.Platform; |
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using Avalonia.Rendering; |
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namespace Avalonia.Rendering.Composition; |
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internal readonly struct CompositionHitTestCandidate(CompositionVisual visual, int order) |
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{ |
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public CompositionVisual Visual { get; } = visual; |
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public int Order { get; } = order; |
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} |
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internal sealed class CompositionHitTestRTree |
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{ |
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private const int MaxChildren = 8; |
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private readonly List<Entry> _entries = new(); |
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private readonly List<CompositionHitTestCandidate> _unbounded = new(); |
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private Node? _root; |
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private CompositionVisual? _indexedRoot; |
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public ulong Revision { get; private set; } |
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public bool IsCurrent(CompositionVisual root, ulong revision) => |
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ReferenceEquals(_indexedRoot, root) && Revision == revision; |
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public void Rebuild(CompositionVisual? root, ulong revision) |
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{ |
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_indexedRoot = root; |
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Revision = revision; |
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_root = null; |
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_entries.Clear(); |
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_unbounded.Clear(); |
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if (root == null) |
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return; |
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var order = 0; |
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AddVisual(root, ref order); |
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_root = BuildTree(_entries); |
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_entries.Clear(); |
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} |
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public void Query(Point point, PooledList<CompositionHitTestCandidate> results) |
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{ |
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if (_root != null) |
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Query(_root, point, results); |
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foreach (var candidate in _unbounded) |
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results.Add(candidate); |
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} |
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private void AddVisual(CompositionVisual visual, ref int order) |
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{ |
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if (visual is CompositionContainerVisual container) |
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{ |
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for (var c = container.Children.Count - 1; c >= 0; c--) |
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AddVisual(container.Children[c], ref order); |
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} |
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if (visual is not CompositionDrawListVisual drawListVisual) |
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return; |
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var visualOrder = order++; |
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if (drawListVisual.Visual is ICustomHitTest) |
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{ |
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if (drawListVisual.TryGetServerGlobalTransform() != null) |
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_unbounded.Add(new CompositionHitTestCandidate(drawListVisual, visualOrder)); |
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return; |
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} |
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if (TryGetTransformedBounds(drawListVisual, out var bounds)) |
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_entries.Add(new Entry(bounds, drawListVisual, visualOrder)); |
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} |
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private static bool TryGetTransformedBounds(CompositionDrawListVisual visual, out LtrbRect bounds) |
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{ |
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bounds = default; |
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if (visual.DrawList?.Bounds is not { } localBounds) |
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return false; |
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if (visual.TryGetServerGlobalTransform() is not { } transform) |
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return false; |
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bounds = localBounds.TransformToAABB(transform); |
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return !bounds.IsZeroSize; |
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} |
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private static Node? BuildTree(List<Entry> entries) |
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{ |
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if (entries.Count == 0) |
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return null; |
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entries.Sort(CompareEntries); |
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var nodes = new List<Node>((entries.Count + MaxChildren - 1) / MaxChildren); |
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for (var i = 0; i < entries.Count; i += MaxChildren) |
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{ |
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var count = Math.Min(MaxChildren, entries.Count - i); |
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var leafEntries = new Entry[count]; |
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entries.CopyTo(i, leafEntries, 0, count); |
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nodes.Add(new Node(GetBounds(leafEntries), leafEntries, null)); |
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} |
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while (nodes.Count > 1) |
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{ |
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nodes.Sort(CompareNodes); |
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var parents = new List<Node>((nodes.Count + MaxChildren - 1) / MaxChildren); |
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for (var i = 0; i < nodes.Count; i += MaxChildren) |
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{ |
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var count = Math.Min(MaxChildren, nodes.Count - i); |
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var children = new Node[count]; |
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nodes.CopyTo(i, children, 0, count); |
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parents.Add(new Node(GetBounds(children), null, children)); |
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} |
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nodes = parents; |
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} |
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return nodes[0]; |
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} |
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private static void Query(Node node, Point point, PooledList<CompositionHitTestCandidate> results) |
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{ |
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if (!Contains(node.Bounds, point)) |
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return; |
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if (node.Entries != null) |
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{ |
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foreach (var entry in node.Entries) |
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{ |
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if (Contains(entry.Bounds, point)) |
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results.Add(new CompositionHitTestCandidate(entry.Visual, entry.Order)); |
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} |
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} |
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else if (node.Children != null) |
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{ |
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foreach (var child in node.Children) |
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Query(child, point, results); |
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} |
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} |
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private static bool Contains(LtrbRect bounds, Point point) => |
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point.X >= bounds.Left && point.X <= bounds.Right && |
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point.Y >= bounds.Top && point.Y <= bounds.Bottom; |
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private static int CompareEntries(Entry left, Entry right) |
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{ |
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var result = (left.Bounds.Left + left.Bounds.Right).CompareTo(right.Bounds.Left + right.Bounds.Right); |
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return result != 0 |
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? result |
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: (left.Bounds.Top + left.Bounds.Bottom).CompareTo(right.Bounds.Top + right.Bounds.Bottom); |
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} |
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private static int CompareNodes(Node left, Node right) |
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{ |
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var result = (left.Bounds.Left + left.Bounds.Right).CompareTo(right.Bounds.Left + right.Bounds.Right); |
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return result != 0 |
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? result |
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: (left.Bounds.Top + left.Bounds.Bottom).CompareTo(right.Bounds.Top + right.Bounds.Bottom); |
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} |
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private static LtrbRect GetBounds(Entry[] entries) |
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{ |
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var bounds = entries[0].Bounds; |
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for (var i = 1; i < entries.Length; i++) |
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bounds = Union(bounds, entries[i].Bounds); |
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return bounds; |
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} |
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private static LtrbRect GetBounds(Node[] nodes) |
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{ |
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var bounds = nodes[0].Bounds; |
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for (var i = 1; i < nodes.Length; i++) |
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bounds = Union(bounds, nodes[i].Bounds); |
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return bounds; |
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} |
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private static LtrbRect Union(LtrbRect left, LtrbRect right) => |
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new( |
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Math.Min(left.Left, right.Left), |
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Math.Min(left.Top, right.Top), |
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Math.Max(left.Right, right.Right), |
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Math.Max(left.Bottom, right.Bottom)); |
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private readonly struct Entry(LtrbRect bounds, CompositionVisual visual, int order) |
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{ |
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public LtrbRect Bounds { get; } = bounds; |
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public CompositionVisual Visual { get; } = visual; |
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public int Order { get; } = order; |
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} |
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private sealed class Node(LtrbRect bounds, Entry[]? entries, Node[]? children) |
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{ |
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public LtrbRect Bounds { get; } = bounds; |
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public Entry[]? Entries { get; } = entries; |
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public Node[]? Children { get; } = children; |
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} |
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} |
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