756 lines
24 KiB
C#
756 lines
24 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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using SkiaSharp;
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using System.Collections;
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using System.Collections.Specialized;
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using Microsoft.Maui.Graphics;
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namespace Microsoft.Maui.Platform;
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/// <summary>
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/// Base class for Skia-rendered items views (CollectionView, ListView).
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/// Provides item rendering, scrolling, and virtualization.
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/// </summary>
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public class SkiaItemsView : SkiaView
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{
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private IEnumerable? _itemsSource;
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private List<object> _items = new();
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protected float _scrollOffset;
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private float _itemHeight = 44; // Default item height
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private float _itemSpacing = 0;
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private int _firstVisibleIndex;
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private int _lastVisibleIndex;
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private bool _isDragging;
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private bool _isDraggingScrollbar;
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private float _dragStartY;
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private float _dragStartOffset;
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private float _scrollbarDragStartY;
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private float _scrollbarDragStartScrollOffset;
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private float _scrollbarDragAvailableTrack;
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private float _scrollbarDragMaxScroll;
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private float _velocity;
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private DateTime _lastDragTime;
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// Scroll bar
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private bool _showVerticalScrollBar = true;
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private float _scrollBarWidth = 8;
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private SKColor _scrollBarColor = new SKColor(128, 128, 128, 128);
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private SKColor _scrollBarTrackColor = new SKColor(200, 200, 200, 64);
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public IEnumerable? ItemsSource
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{
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get => _itemsSource;
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set
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{
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if (_itemsSource is INotifyCollectionChanged oldCollection)
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{
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oldCollection.CollectionChanged -= OnCollectionChanged;
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}
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_itemsSource = value;
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RefreshItems();
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if (_itemsSource is INotifyCollectionChanged newCollection)
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{
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newCollection.CollectionChanged += OnCollectionChanged;
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}
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Invalidate();
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}
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}
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public float ItemHeight
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{
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get => _itemHeight;
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set
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{
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_itemHeight = value;
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Invalidate();
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}
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}
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public float ItemSpacing
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{
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get => _itemSpacing;
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set
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{
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_itemSpacing = value;
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Invalidate();
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}
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}
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public ScrollBarVisibility VerticalScrollBarVisibility { get; set; } = ScrollBarVisibility.Default;
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public ScrollBarVisibility HorizontalScrollBarVisibility { get; set; } = ScrollBarVisibility.Never;
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public object? EmptyView { get; set; }
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public string? EmptyViewText { get; set; } = "No items";
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// Item rendering delegate (legacy)
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public Func<object, int, SKRect, SKCanvas, SKPaint, bool>? ItemRenderer { get; set; }
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// Item view creator - creates SkiaView from data item using DataTemplate
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public Func<object, SkiaView?>? ItemViewCreator { get; set; }
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// Cache of created item views for virtualization
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protected readonly Dictionary<int, SkiaView> _itemViewCache = new();
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// Cache of individual item heights for variable height items
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protected readonly Dictionary<int, float> _itemHeights = new();
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// Track last measured width to clear cache when width changes
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private float _lastMeasuredWidth = 0;
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// Selection support (overridden in SkiaCollectionView)
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public virtual int SelectedIndex { get; set; } = -1;
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public event EventHandler<ItemsScrolledEventArgs>? Scrolled;
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public event EventHandler<ItemsViewItemTappedEventArgs>? ItemTapped;
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public SkiaItemsView()
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{
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IsFocusable = true;
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}
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protected virtual void RefreshItems()
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{
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Console.WriteLine($"[SkiaItemsView] RefreshItems called, clearing {_items.Count} items and {_itemViewCache.Count} cached views");
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_items.Clear();
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_itemViewCache.Clear(); // Clear cached views when items change
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_itemHeights.Clear(); // Clear cached heights
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if (_itemsSource != null)
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{
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foreach (var item in _itemsSource)
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{
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_items.Add(item);
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}
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}
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Console.WriteLine($"[SkiaItemsView] RefreshItems done, now have {_items.Count} items");
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_scrollOffset = 0;
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}
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private void OnCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
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{
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RefreshItems();
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Invalidate();
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}
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/// <summary>
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/// Gets the height for a specific item, using cached height or default.
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/// </summary>
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protected float GetItemHeight(int index)
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{
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return _itemHeights.TryGetValue(index, out var height) ? height : _itemHeight;
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}
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/// <summary>
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/// Gets the Y offset for a specific item (cumulative height of all previous items).
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/// </summary>
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protected float GetItemOffset(int index)
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{
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float offset = 0;
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for (int i = 0; i < index && i < _items.Count; i++)
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{
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offset += GetItemHeight(i) + _itemSpacing;
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}
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return offset;
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}
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/// <summary>
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/// Calculates total content height based on individual item heights.
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/// </summary>
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protected float TotalContentHeight
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{
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get
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{
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if (_items.Count == 0) return 0;
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float total = 0;
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for (int i = 0; i < _items.Count; i++)
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{
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total += GetItemHeight(i);
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if (i < _items.Count - 1) total += _itemSpacing;
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}
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return total;
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}
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}
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// Use ScreenBounds.Height for visible viewport
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protected float MaxScrollOffset => Math.Max(0, TotalContentHeight - ScreenBounds.Height);
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protected override void OnDraw(SKCanvas canvas, SKRect bounds)
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{
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Console.WriteLine($"[SkiaItemsView] OnDraw - bounds={bounds}, items={_items.Count}, ItemViewCreator={(ItemViewCreator != null ? "set" : "null")}");
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// Draw background
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if (BackgroundColor != SKColors.Transparent)
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{
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using var bgPaint = new SKPaint
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{
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Color = BackgroundColor,
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Style = SKPaintStyle.Fill
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};
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canvas.DrawRect(bounds, bgPaint);
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}
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// If no items, show empty view
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if (_items.Count == 0)
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{
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DrawEmptyView(canvas, bounds);
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return;
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}
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// Find first visible index by walking through items
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_firstVisibleIndex = 0;
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float cumulativeOffset = 0;
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for (int i = 0; i < _items.Count; i++)
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{
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var itemH = GetItemHeight(i);
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if (cumulativeOffset + itemH > _scrollOffset)
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{
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_firstVisibleIndex = i;
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break;
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}
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cumulativeOffset += itemH + _itemSpacing;
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}
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// Clip to bounds
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canvas.Save();
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canvas.ClipRect(bounds);
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// Draw visible items using variable heights
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using var paint = new SKPaint
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{
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IsAntialias = true
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};
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float currentY = bounds.Top + GetItemOffset(_firstVisibleIndex) - _scrollOffset;
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for (int i = _firstVisibleIndex; i < _items.Count; i++)
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{
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var itemH = GetItemHeight(i);
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var itemRect = new SKRect(bounds.Left, currentY, bounds.Right - (_showVerticalScrollBar ? _scrollBarWidth : 0), currentY + itemH);
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// Stop if we've passed the visible area
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if (itemRect.Top > bounds.Bottom)
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{
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_lastVisibleIndex = i - 1;
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break;
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}
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_lastVisibleIndex = i;
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if (itemRect.Bottom >= bounds.Top)
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{
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DrawItem(canvas, _items[i], i, itemRect, paint);
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}
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currentY += itemH + _itemSpacing;
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}
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canvas.Restore();
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// Draw scrollbar
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if (_showVerticalScrollBar && TotalContentHeight > bounds.Height)
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{
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DrawScrollBar(canvas, bounds);
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}
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}
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protected virtual void DrawItem(SKCanvas canvas, object item, int index, SKRect bounds, SKPaint paint)
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{
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// Draw selection highlight
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if (index == SelectedIndex)
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{
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paint.Color = new SKColor(0x21, 0x96, 0xF3, 0x59); // Light blue with 35% opacity
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paint.Style = SKPaintStyle.Fill;
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canvas.DrawRect(bounds, paint);
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}
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// Try to use ItemViewCreator for templated rendering
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if (ItemViewCreator != null)
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{
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Console.WriteLine($"[SkiaItemsView] DrawItem {index} - ItemViewCreator exists, item: {item}");
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// Get or create cached view for this index
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if (!_itemViewCache.TryGetValue(index, out var itemView) || itemView == null)
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{
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itemView = ItemViewCreator(item);
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if (itemView != null)
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{
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itemView.Parent = this;
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_itemViewCache[index] = itemView;
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}
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}
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if (itemView != null)
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{
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// Measure with large height to get natural size
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var availableSize = new SKSize(bounds.Width, float.MaxValue);
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var measuredSize = itemView.Measure(availableSize);
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// Store individual item height (with minimum of default height)
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var measuredHeight = Math.Max(measuredSize.Height, _itemHeight);
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if (!_itemHeights.TryGetValue(index, out var cachedHeight) || Math.Abs(cachedHeight - measuredHeight) > 1)
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{
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_itemHeights[index] = measuredHeight;
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// Request redraw if height changed significantly
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if (Math.Abs(cachedHeight - measuredHeight) > 5)
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{
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Invalidate();
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}
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}
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// Arrange with the actual measured height
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var actualBounds = new SKRect(bounds.Left, bounds.Top, bounds.Right, bounds.Top + measuredHeight);
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itemView.Arrange(actualBounds);
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itemView.Draw(canvas);
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return;
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}
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}
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else
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{
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Console.WriteLine($"[SkiaItemsView] DrawItem {index} - ItemViewCreator is NULL, falling back to ToString");
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}
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// Draw separator
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paint.Color = new SKColor(0xE0, 0xE0, 0xE0);
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paint.Style = SKPaintStyle.Stroke;
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paint.StrokeWidth = 1;
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canvas.DrawLine(bounds.Left, bounds.Bottom, bounds.Right, bounds.Bottom, paint);
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// Use custom renderer if provided
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if (ItemRenderer != null)
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{
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if (ItemRenderer(item, index, bounds, canvas, paint))
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return;
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}
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// Default rendering - just show ToString
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paint.Color = SKColors.Black;
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paint.Style = SKPaintStyle.Fill;
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using var font = new SKFont(SKTypeface.Default, 14);
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using var textPaint = new SKPaint(font)
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{
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Color = SKColors.Black,
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IsAntialias = true
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};
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var text = item?.ToString() ?? "";
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var textBounds = new SKRect();
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textPaint.MeasureText(text, ref textBounds);
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var x = bounds.Left + 16;
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var y = bounds.MidY - textBounds.MidY;
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canvas.DrawText(text, x, y, textPaint);
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}
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protected virtual void DrawEmptyView(SKCanvas canvas, SKRect bounds)
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{
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using var paint = new SKPaint
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{
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Color = new SKColor(0x80, 0x80, 0x80),
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IsAntialias = true
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};
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using var font = new SKFont(SKTypeface.Default, 16);
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using var textPaint = new SKPaint(font)
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{
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Color = new SKColor(0x80, 0x80, 0x80),
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IsAntialias = true
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};
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var text = EmptyViewText ?? "No items";
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var textBounds = new SKRect();
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textPaint.MeasureText(text, ref textBounds);
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var x = bounds.MidX - textBounds.MidX;
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var y = bounds.MidY - textBounds.MidY;
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canvas.DrawText(text, x, y, textPaint);
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}
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private void DrawScrollBar(SKCanvas canvas, SKRect bounds)
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{
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var trackRect = new SKRect(
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bounds.Right - _scrollBarWidth,
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bounds.Top,
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bounds.Right,
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bounds.Bottom);
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// Draw track
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using var trackPaint = new SKPaint
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{
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Color = _scrollBarTrackColor,
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Style = SKPaintStyle.Fill
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};
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canvas.DrawRect(trackRect, trackPaint);
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// Calculate thumb size and position
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var viewportRatio = bounds.Height / TotalContentHeight;
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var thumbHeight = Math.Max(20, bounds.Height * viewportRatio);
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var scrollRatio = _scrollOffset / MaxScrollOffset;
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var thumbY = bounds.Top + (bounds.Height - thumbHeight) * scrollRatio;
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var thumbRect = new SKRect(
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bounds.Right - _scrollBarWidth + 1,
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thumbY,
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bounds.Right - 1,
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thumbY + thumbHeight);
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// Draw thumb
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using var thumbPaint = new SKPaint
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{
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Color = _scrollBarColor,
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Style = SKPaintStyle.Fill,
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IsAntialias = true
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};
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var cornerRadius = (_scrollBarWidth - 2) / 2;
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canvas.DrawRoundRect(new SKRoundRect(thumbRect, cornerRadius), thumbPaint);
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}
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public override void OnPointerPressed(PointerEventArgs e)
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{
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Console.WriteLine($"[SkiaItemsView] OnPointerPressed - x={e.X}, y={e.Y}, Bounds={Bounds}, ScreenBounds={ScreenBounds}, ItemCount={_items.Count}");
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if (!IsEnabled) return;
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// Check if clicking on scrollbar thumb
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if (_showVerticalScrollBar && TotalContentHeight > Bounds.Height)
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{
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var thumbBounds = GetScrollbarThumbBounds();
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if (thumbBounds.Contains(e.X, e.Y))
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{
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_isDraggingScrollbar = true;
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_scrollbarDragStartY = e.Y;
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_scrollbarDragStartScrollOffset = _scrollOffset;
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// Cache values to prevent stutter
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var thumbHeight = Math.Max(20, Bounds.Height * (Bounds.Height / TotalContentHeight));
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_scrollbarDragAvailableTrack = Bounds.Height - thumbHeight;
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_scrollbarDragMaxScroll = MaxScrollOffset;
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return;
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}
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}
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// Regular content drag
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_isDragging = true;
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_dragStartY = e.Y;
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_dragStartOffset = _scrollOffset;
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_lastDragTime = DateTime.Now;
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_velocity = 0;
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}
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/// <summary>
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/// Gets the bounds of the scrollbar thumb in screen coordinates.
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/// </summary>
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private SKRect GetScrollbarThumbBounds()
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{
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// Use ScreenBounds for hit testing (input events use screen coordinates)
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var screenBounds = ScreenBounds;
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var viewportRatio = screenBounds.Height / TotalContentHeight;
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var thumbHeight = Math.Max(20, screenBounds.Height * viewportRatio);
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var scrollRatio = MaxScrollOffset > 0 ? _scrollOffset / MaxScrollOffset : 0;
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var thumbY = screenBounds.Top + (screenBounds.Height - thumbHeight) * scrollRatio;
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return new SKRect(
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screenBounds.Right - _scrollBarWidth,
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thumbY,
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screenBounds.Right,
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thumbY + thumbHeight);
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}
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public override void OnPointerMoved(PointerEventArgs e)
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{
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// Handle scrollbar dragging - use cached values to prevent stutter
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if (_isDraggingScrollbar)
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{
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if (_scrollbarDragAvailableTrack > 0)
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{
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var deltaY = e.Y - _scrollbarDragStartY;
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var scrollDelta = (deltaY / _scrollbarDragAvailableTrack) * _scrollbarDragMaxScroll;
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SetScrollOffset(_scrollbarDragStartScrollOffset + scrollDelta);
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}
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return;
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}
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if (!_isDragging) return;
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var delta = _dragStartY - e.Y;
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var newOffset = _dragStartOffset + delta;
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// Calculate velocity for momentum scrolling
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var now = DateTime.Now;
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var timeDelta = (now - _lastDragTime).TotalSeconds;
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if (timeDelta > 0)
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{
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_velocity = (float)((_scrollOffset - newOffset) / timeDelta);
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}
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_lastDragTime = now;
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SetScrollOffset(newOffset);
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}
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public override void OnPointerReleased(PointerEventArgs e)
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{
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// Handle scrollbar drag release
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if (_isDraggingScrollbar)
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{
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_isDraggingScrollbar = false;
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return;
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}
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if (_isDragging)
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{
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_isDragging = false;
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// Check for tap (minimal movement)
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var totalDrag = Math.Abs(e.Y - _dragStartY);
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if (totalDrag < 5)
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{
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// This was a tap - find which item was tapped using variable heights
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var screenBounds = ScreenBounds;
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var localY = e.Y - screenBounds.Top + _scrollOffset;
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// Find tapped index by walking through item heights
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int tappedIndex = -1;
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float cumulativeY = 0;
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for (int i = 0; i < _items.Count; i++)
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{
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var itemH = GetItemHeight(i);
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if (localY >= cumulativeY && localY < cumulativeY + itemH)
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{
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tappedIndex = i;
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break;
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}
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cumulativeY += itemH + _itemSpacing;
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}
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Console.WriteLine($"[SkiaItemsView] Tap at Y={e.Y}, screenBounds.Top={screenBounds.Top}, scrollOffset={_scrollOffset}, localY={localY}, index={tappedIndex}");
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if (tappedIndex >= 0 && tappedIndex < _items.Count)
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{
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OnItemTapped(tappedIndex, _items[tappedIndex]);
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}
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}
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}
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}
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/// <summary>
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/// Gets the total Y scroll offset from all parent ScrollViews.
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/// </summary>
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private float GetTotalParentScrollY()
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{
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float total = 0;
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var parent = Parent;
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while (parent != null)
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{
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if (parent is SkiaScrollView scrollView)
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{
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total += scrollView.ScrollY;
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}
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parent = parent.Parent;
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}
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return total;
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}
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protected virtual void OnItemTapped(int index, object item)
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{
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SelectedIndex = index;
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ItemTapped?.Invoke(this, new ItemsViewItemTappedEventArgs(index, item));
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Invalidate();
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}
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public override void OnScroll(ScrollEventArgs e)
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{
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var delta = e.DeltaY * 20;
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SetScrollOffset(_scrollOffset + delta);
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e.Handled = true;
|
|
}
|
|
|
|
private void SetScrollOffset(float offset)
|
|
{
|
|
var oldOffset = _scrollOffset;
|
|
_scrollOffset = Math.Clamp(offset, 0, MaxScrollOffset);
|
|
|
|
if (Math.Abs(_scrollOffset - oldOffset) > 0.1f)
|
|
{
|
|
Scrolled?.Invoke(this, new ItemsScrolledEventArgs(_scrollOffset, TotalContentHeight));
|
|
Invalidate();
|
|
}
|
|
}
|
|
|
|
public void ScrollToIndex(int index, bool animate = true)
|
|
{
|
|
if (index < 0 || index >= _items.Count) return;
|
|
|
|
var targetOffset = GetItemOffset(index);
|
|
SetScrollOffset(targetOffset);
|
|
}
|
|
|
|
public void ScrollToItem(object item, bool animate = true)
|
|
{
|
|
var index = _items.IndexOf(item);
|
|
if (index >= 0)
|
|
{
|
|
ScrollToIndex(index, animate);
|
|
}
|
|
}
|
|
|
|
public override void OnKeyDown(KeyEventArgs e)
|
|
{
|
|
if (!IsEnabled) return;
|
|
|
|
switch (e.Key)
|
|
{
|
|
case Key.Up:
|
|
if (SelectedIndex > 0)
|
|
{
|
|
SelectedIndex--;
|
|
EnsureIndexVisible(SelectedIndex);
|
|
Invalidate();
|
|
}
|
|
e.Handled = true;
|
|
break;
|
|
|
|
case Key.Down:
|
|
if (SelectedIndex < _items.Count - 1)
|
|
{
|
|
SelectedIndex++;
|
|
EnsureIndexVisible(SelectedIndex);
|
|
Invalidate();
|
|
}
|
|
e.Handled = true;
|
|
break;
|
|
|
|
case Key.PageUp:
|
|
SetScrollOffset(_scrollOffset - Bounds.Height);
|
|
e.Handled = true;
|
|
break;
|
|
|
|
case Key.PageDown:
|
|
SetScrollOffset(_scrollOffset + Bounds.Height);
|
|
e.Handled = true;
|
|
break;
|
|
|
|
case Key.Home:
|
|
SelectedIndex = 0;
|
|
SetScrollOffset(0);
|
|
Invalidate();
|
|
e.Handled = true;
|
|
break;
|
|
|
|
case Key.End:
|
|
SelectedIndex = _items.Count - 1;
|
|
SetScrollOffset(MaxScrollOffset);
|
|
Invalidate();
|
|
e.Handled = true;
|
|
break;
|
|
|
|
case Key.Enter:
|
|
if (SelectedIndex >= 0 && SelectedIndex < _items.Count)
|
|
{
|
|
OnItemTapped(SelectedIndex, _items[SelectedIndex]);
|
|
}
|
|
e.Handled = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
private void EnsureIndexVisible(int index)
|
|
{
|
|
var itemTop = GetItemOffset(index);
|
|
var itemBottom = itemTop + GetItemHeight(index);
|
|
|
|
if (itemTop < _scrollOffset)
|
|
{
|
|
SetScrollOffset(itemTop);
|
|
}
|
|
else if (itemBottom > _scrollOffset + Bounds.Height)
|
|
{
|
|
SetScrollOffset(itemBottom - Bounds.Height);
|
|
}
|
|
}
|
|
|
|
protected int ItemCount => _items.Count;
|
|
protected object? GetItemAt(int index) => index >= 0 && index < _items.Count ? _items[index] : null;
|
|
|
|
/// <summary>
|
|
/// Override HitTest to handle scrollbar clicks properly.
|
|
/// HitTest receives content-space coordinates (already transformed by parent ScrollView).
|
|
/// </summary>
|
|
public override SkiaView? HitTest(float x, float y)
|
|
{
|
|
// HitTest uses Bounds (content space) - coordinates are transformed by parent
|
|
if (!IsVisible || !Bounds.Contains(new SKPoint(x, y)))
|
|
return null;
|
|
|
|
// Check scrollbar area FIRST before content
|
|
// This ensures scrollbar clicks are handled by this view
|
|
if (_showVerticalScrollBar && TotalContentHeight > Bounds.Height)
|
|
{
|
|
var trackArea = new SKRect(Bounds.Right - _scrollBarWidth, Bounds.Top, Bounds.Right, Bounds.Bottom);
|
|
if (trackArea.Contains(x, y))
|
|
return this;
|
|
}
|
|
|
|
return this;
|
|
}
|
|
|
|
protected override SKSize MeasureOverride(SKSize availableSize)
|
|
{
|
|
var width = availableSize.Width < float.MaxValue ? availableSize.Width : 200;
|
|
var height = availableSize.Height < float.MaxValue ? availableSize.Height : 300;
|
|
|
|
// Clear item caches when width changes significantly (items need re-measurement for text wrapping)
|
|
if (Math.Abs(width - _lastMeasuredWidth) > 5)
|
|
{
|
|
_itemHeights.Clear();
|
|
_itemViewCache.Clear();
|
|
_lastMeasuredWidth = width;
|
|
}
|
|
|
|
// Items view takes all available space
|
|
return new SKSize(width, height);
|
|
}
|
|
|
|
protected override void Dispose(bool disposing)
|
|
{
|
|
if (disposing)
|
|
{
|
|
if (_itemsSource is INotifyCollectionChanged collection)
|
|
{
|
|
collection.CollectionChanged -= OnCollectionChanged;
|
|
}
|
|
}
|
|
base.Dispose(disposing);
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Event args for items view scroll events.
|
|
/// </summary>
|
|
public class ItemsScrolledEventArgs : EventArgs
|
|
{
|
|
public float ScrollOffset { get; }
|
|
public float TotalHeight { get; }
|
|
|
|
public ItemsScrolledEventArgs(float scrollOffset, float totalHeight)
|
|
{
|
|
ScrollOffset = scrollOffset;
|
|
TotalHeight = totalHeight;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Event args for items view item tap events.
|
|
/// </summary>
|
|
public class ItemsViewItemTappedEventArgs : EventArgs
|
|
{
|
|
public int Index { get; }
|
|
public object Item { get; }
|
|
|
|
public ItemsViewItemTappedEventArgs(int index, object item)
|
|
{
|
|
Index = index;
|
|
Item = item;
|
|
}
|
|
}
|