WPF 虚拟化面板
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public class VirtualizingWrapPanel : VirtualizingPanel, IScrollInfo { #region Fields UIElementCollection _children; ItemsControl _itemsControl; IItemContainerGenerator _generator; private Point _offset = new Point(0, 0); private Size _extent = new Size(0, 0); private Size _viewport = new Size(0, 0); private int firstIndex = 0; private Size childSize; private Size _pixelMeasuredViewport = new Size(0, 0); Dictionary<UIElement, Rect> _realizedChildLayout = new Dictionary<UIElement, Rect>(); WrapPanelAbstraction _abstractPanel; #endregion #region Properties private Size ChildSlotSize { get { return new Size(ItemWidth, ItemHeight); } } #endregion #region Dependency Properties [TypeConverter(typeof(LengthConverter))] public double ItemHeight { get { return (double)base.GetValue(ItemHeightProperty); } set { base.SetValue(ItemHeightProperty, value); } } [TypeConverter(typeof(LengthConverter))] public double ItemWidth { get { return (double)base.GetValue(ItemWidthProperty); } set { base.SetValue(ItemWidthProperty, value); } } public Orientation Orientation { get { return (Orientation)GetValue(OrientationProperty); } set { SetValue(OrientationProperty, value); } } public static readonly DependencyProperty ItemHeightProperty = DependencyProperty.Register("ItemHeight", typeof(double), typeof(VirtualizingWrapPanel), new FrameworkPropertyMetadata(double.PositiveInfinity)); public static readonly DependencyProperty ItemWidthProperty = DependencyProperty.Register("ItemWidth", typeof(double), typeof(VirtualizingWrapPanel), new FrameworkPropertyMetadata(double.PositiveInfinity)); public static readonly DependencyProperty OrientationProperty = StackPanel.OrientationProperty.AddOwner(typeof(VirtualizingWrapPanel), new FrameworkPropertyMetadata(Orientation.Horizontal)); #endregion #region Methods private void SetFirstRowViewItemIndex(int index) { SetVerticalOffset((index) / Math.Floor((_viewport.Width) / childSize.Width)); SetHorizontalOffset((index) / Math.Floor((_viewport.Height) / childSize.Height)); } public void Resizing(object sender, EventArgs e) { if (_viewport.Width != 0) { int firstIndexCache = firstIndex; _abstractPanel = null; MeasureOverride(_viewport); SetFirstRowViewItemIndex(firstIndex); firstIndex = firstIndexCache; } } public int GetFirstVisibleSection() { int section; var maxSection = 0; if (_abstractPanel != null) { maxSection = _abstractPanel.Max(x => x.Section); } if (Orientation == Orientation.Horizontal) { section = (int)_offset.Y; } else { section = (int)_offset.X; } if (section > maxSection) section = maxSection; return section; } public int GetFirstVisibleIndex() { int section = GetFirstVisibleSection(); if (_abstractPanel != null) { var item = _abstractPanel.Where(x => x.Section == section).FirstOrDefault(); if (item != null) return item._index; } return 0; } public void CleanUpItems(int minDesiredGenerated, int maxDesiredGenerated) { for (int i = _children.Count - 1; i >= 0; i--) { GeneratorPosition childGeneratorPos = new GeneratorPosition(i, 0); int itemIndex = _generator.IndexFromGeneratorPosition(childGeneratorPos); if (itemIndex < minDesiredGenerated || itemIndex > maxDesiredGenerated) { _generator.Remove(childGeneratorPos, 1); RemoveInternalChildRange(i, 1); } } } private void ComputeExtentAndViewport(Size pixelMeasuredViewportSize, int visibleSections) { if (Orientation == Orientation.Horizontal) { _viewport.Height = visibleSections; _viewport.Width = pixelMeasuredViewportSize.Width; } else { _viewport.Width = visibleSections; _viewport.Height = pixelMeasuredViewportSize.Height; } if (Orientation == Orientation.Horizontal) { _extent.Height = _abstractPanel.SectionCount + ViewportHeight - 1; } else { _extent.Width = _abstractPanel.SectionCount + ViewportWidth - 1; } _owner.InvalidateScrollInfo(); } private void ResetScrollInfo() { _offset.X = 0; _offset.Y = 0; } private int GetNextSectionClosestIndex(int itemIndex) { var abstractItem = _abstractPanel[itemIndex]; if (abstractItem.Section < _abstractPanel.SectionCount - 1) { var ret = _abstractPanel. Where(x => x.Section == abstractItem.Section + 1). OrderBy(x => Math.Abs(x.SectionIndex - abstractItem.SectionIndex)). First(); return ret._index; } else return itemIndex; } private int GetLastSectionClosestIndex(int itemIndex) { var abstractItem = _abstractPanel[itemIndex]; if (abstractItem.Section > 0) { var ret = _abstractPanel. Where(x => x.Section == abstractItem.Section - 1). OrderBy(x => Math.Abs(x.SectionIndex - abstractItem.SectionIndex)). First(); return ret._index; } else return itemIndex; } private void NavigateDown() { var gen = _generator.GetItemContainerGeneratorForPanel(this); UIElement selected = (UIElement)Keyboard.FocusedElement; int itemIndex = gen.IndexFromContainer(selected); int depth = 0; while (itemIndex == -1) { selected = (UIElement)VisualTreeHelper.GetParent(selected); itemIndex = gen.IndexFromContainer(selected); depth++; } DependencyObject next = null; if (Orientation == Orientation.Horizontal) { int nextIndex = GetNextSectionClosestIndex(itemIndex); next = gen.ContainerFromIndex(nextIndex); while (next == null) { SetVerticalOffset(VerticalOffset + 1); UpdateLayout(); next = gen.ContainerFromIndex(nextIndex); } } else { if (itemIndex == _abstractPanel._itemCount - 1) return; next = gen.ContainerFromIndex(itemIndex + 1); while (next == null) { SetHorizontalOffset(HorizontalOffset + 1); UpdateLayout(); next = gen.ContainerFromIndex(itemIndex + 1); } } while (depth != 0) { next = VisualTreeHelper.GetChild(next, 0); depth--; } (next as UIElement).Focus(); } private void NavigateLeft() { var gen = _generator.GetItemContainerGeneratorForPanel(this); UIElement selected = (UIElement)Keyboard.FocusedElement; int itemIndex = gen.IndexFromContainer(selected); int depth = 0; while (itemIndex == -1) { selected = (UIElement)VisualTreeHelper.GetParent(selected); itemIndex = gen.IndexFromContainer(selected); depth++; } DependencyObject next = null; if (Orientation == Orientation.Vertical) { int nextIndex = GetLastSectionClosestIndex(itemIndex); next = gen.ContainerFromIndex(nextIndex); while (next == null) { SetHorizontalOffset(HorizontalOffset - 1); UpdateLayout(); next = gen.ContainerFromIndex(nextIndex); } } else { if (itemIndex == 0) return; next = gen.ContainerFromIndex(itemIndex - 1); while (next == null) { SetVerticalOffset(VerticalOffset - 1); UpdateLayout(); next = gen.ContainerFromIndex(itemIndex - 1); } } while (depth != 0) { next = VisualTreeHelper.GetChild(next, 0); depth--; } (next as UIElement).Focus(); } private void NavigateRight() { var gen = _generator.GetItemContainerGeneratorForPanel(this); UIElement selected = (UIElement)Keyboard.FocusedElement; int itemIndex = gen.IndexFromContainer(selected); int depth = 0; while (itemIndex == -1) { selected = (UIElement)VisualTreeHelper.GetParent(selected); itemIndex = gen.IndexFromContainer(selected); depth++; } DependencyObject next = null; if (Orientation == Orientation.Vertical) { int nextIndex = GetNextSectionClosestIndex(itemIndex); next = gen.ContainerFromIndex(nextIndex); while (next == null) { SetHorizontalOffset(HorizontalOffset + 1); UpdateLayout(); next = gen.ContainerFromIndex(nextIndex); } } else { if (itemIndex == _abstractPanel._itemCount - 1) return; next = gen.ContainerFromIndex(itemIndex + 1); while (next == null) { SetVerticalOffset(VerticalOffset + 1); UpdateLayout(); next = gen.ContainerFromIndex(itemIndex + 1); } } while (depth != 0) { next = VisualTreeHelper.GetChild(next, 0); depth--; } (next as UIElement).Focus(); } private void NavigateUp() { var gen = _generator.GetItemContainerGeneratorForPanel(this); UIElement selected = (UIElement)Keyboard.FocusedElement; int itemIndex = gen.IndexFromContainer(selected); int depth = 0; while (itemIndex == -1) { selected = (UIElement)VisualTreeHelper.GetParent(selected); itemIndex = gen.IndexFromContainer(selected); depth++; } DependencyObject next = null; if (Orientation == Orientation.Horizontal) { int nextIndex = GetLastSectionClosestIndex(itemIndex); next = gen.ContainerFromIndex(nextIndex); while (next == null) { SetVerticalOffset(VerticalOffset - 1); UpdateLayout(); next = gen.ContainerFromIndex(nextIndex); } } else { if (itemIndex == 0) return; next = gen.ContainerFromIndex(itemIndex - 1); while (next == null) { SetHorizontalOffset(HorizontalOffset - 1); UpdateLayout(); next = gen.ContainerFromIndex(itemIndex - 1); } } while (depth != 0) { next = VisualTreeHelper.GetChild(next, 0); depth--; } (next as UIElement).Focus(); } #endregion #region Override protected override void OnKeyDown(KeyEventArgs e) { switch (e.Key) { case Key.Down: NavigateDown(); e.Handled = true; break; case Key.Left: NavigateLeft(); e.Handled = true; break; case Key.Right: NavigateRight(); e.Handled = true; break; case Key.Up: NavigateUp(); e.Handled = true; break; default: base.OnKeyDown(e); break; } } protected override void OnItemsChanged(object sender, ItemsChangedEventArgs args) { base.OnItemsChanged(sender, args); _abstractPanel = null; ResetScrollInfo(); } protected override void OnInitialized(EventArgs e) { base.OnInitialized(e); _itemsControl = ItemsControl.GetItemsOwner(this); _children = InternalChildren; _generator = ItemContainerGenerator; this.SizeChanged += new SizeChangedEventHandler(this.Resizing); } protected override Size MeasureOverride(Size availableSize) { if (_itemsControl == null || _itemsControl.Items.Count == 0) return availableSize; if (_abstractPanel == null) _abstractPanel = new WrapPanelAbstraction(_itemsControl.Items.Count); _pixelMeasuredViewport = availableSize; _realizedChildLayout.Clear(); Size realizedFrameSize = availableSize; int itemCount = _itemsControl.Items.Count; int firstVisibleIndex = GetFirstVisibleIndex(); GeneratorPosition startPos = _generator.GeneratorPositionFromIndex(firstVisibleIndex); int childIndex = (startPos.Offset == 0) ? startPos.Index : startPos.Index + 1; int current = firstVisibleIndex; int visibleSections = 1; using (_generator.StartAt(startPos, GeneratorDirection.Forward, true)) { bool stop = false; bool isHorizontal = Orientation == Orientation.Horizontal; double currentX = 0; double currentY = 0; double maxItemSize = 0; int currentSection = GetFirstVisibleSection(); while (current < itemCount) { bool newlyRealized; // Get or create the child UIElement child = _generator.GenerateNext(out newlyRealized) as UIElement; if (newlyRealized) { // Figure out if we need to insert the child at the end or somewhere in the middle if (childIndex >= _children.Count) { base.AddInternalChild(child); } else { base.InsertInternalChild(childIndex, child); } _generator.PrepareItemContainer(child); child.Measure(ChildSlotSize); } else { // The child has already been created, let's be sure it's in the right spot Debug.Assert(child == _children[childIndex], "Wrong child was generated"); } childSize = child.DesiredSize; Rect childRect = new Rect(new Point(currentX, currentY), childSize); if (isHorizontal) { maxItemSize = Math.Max(maxItemSize, childRect.Height); if (childRect.Right > realizedFrameSize.Width) //wrap to a new line { currentY = currentY + maxItemSize; currentX = 0; maxItemSize = childRect.Height; childRect.X = currentX; childRect.Y = currentY; currentSection++; visibleSections++; } if (currentY > realizedFrameSize.Height) stop = true; currentX = childRect.Right; } else { maxItemSize = Math.Max(maxItemSize, childRect.Width); if (childRect.Bottom > realizedFrameSize.Height) //wrap to a new column { currentX = currentX + maxItemSize; currentY = 0; maxItemSize = childRect.Width; childRect.X = currentX; childRect.Y = currentY; currentSection++; visibleSections++; } if (currentX > realizedFrameSize.Width) stop = true; currentY = childRect.Bottom; } _realizedChildLayout.Add(child, childRect); _abstractPanel.SetItemSection(current, currentSection); if (stop) break; current++; childIndex++; } } CleanUpItems(firstVisibleIndex, current - 1); ComputeExtentAndViewport(availableSize, visibleSections); return availableSize; } protected override Size ArrangeOverride(Size finalSize) { if (_children != null) { foreach (UIElement child in _children) { var layoutInfo = _realizedChildLayout[child]; child.Arrange(layoutInfo); } } return finalSize; } #endregion #region IScrollInfo Members private bool _canHScroll = false; public bool CanHorizontallyScroll { get { return _canHScroll; } set { _canHScroll = value; } } private bool _canVScroll = false; public bool CanVerticallyScroll { get { return _canVScroll; } set { _canVScroll = value; } } public double ExtentHeight { get { return _extent.Height; } } public double ExtentWidth { get { return _extent.Width; } } public double HorizontalOffset { get { return _offset.X; } } public double VerticalOffset { get { return _offset.Y; } } public void LineDown() { if (Orientation == Orientation.Vertical) SetVerticalOffset(VerticalOffset + 20); else SetVerticalOffset(VerticalOffset + 1); } public void LineLeft() { if (Orientation == Orientation.Horizontal) SetHorizontalOffset(HorizontalOffset - 20); else SetHorizontalOffset(HorizontalOffset - 1); } public void LineRight() { if (Orientation == Orientation.Horizontal) SetHorizontalOffset(HorizontalOffset + 20); else SetHorizontalOffset(HorizontalOffset + 1); } public void LineUp() { if (Orientation == Orientation.Vertical) SetVerticalOffset(VerticalOffset - 20); else SetVerticalOffset(VerticalOffset - 1); } public Rect MakeVisible(Visual visual, Rect rectangle) { var gen = (ItemContainerGenerator)_generator.GetItemContainerGeneratorForPanel(this); var element = (UIElement)visual; int itemIndex = gen.IndexFromContainer(element); while (itemIndex == -1) { element = (UIElement)VisualTreeHelper.GetParent(element); itemIndex = gen.IndexFromContainer(element); } int section = _abstractPanel[itemIndex].Section; Rect elementRect = _realizedChildLayout[element]; if (Orientation == Orientation.Horizontal) { double viewportHeight = _pixelMeasuredViewport.Height; if (elementRect.Bottom > viewportHeight) _offset.Y += 1; else if (elementRect.Top < 0) _offset.Y -= 1; } else { double viewportWidth = _pixelMeasuredViewport.Width; if (elementRect.Right > viewportWidth) _offset.X += 1; else if (elementRect.Left < 0) _offset.X -= 1; } InvalidateMeasure(); return elementRect; } public void MouseWheelDown() { PageDown(); } public void MouseWheelLeft() { PageLeft(); } public void MouseWheelRight() { PageRight(); } public void MouseWheelUp() { PageUp(); } public void PageDown() { SetVerticalOffset(VerticalOffset + _viewport.Height * 0.8); } public void PageLeft() { SetHorizontalOffset(HorizontalOffset - _viewport.Width * 0.8); } public void PageRight() { SetHorizontalOffset(HorizontalOffset + _viewport.Width * 0.8); } public void PageUp() { SetVerticalOffset(VerticalOffset - _viewport.Height * 0.8); } private ScrollViewer _owner; public ScrollViewer ScrollOwner { get { return _owner; } set { _owner = value; } } public void SetHorizontalOffset(double offset) { if (offset < 0 || _viewport.Width >= _extent.Width) { offset = 0; } else { if (offset + _viewport.Width >= _extent.Width) { offset = _extent.Width - _viewport.Width; } } _offset.X = offset; if (_owner != null) _owner.InvalidateScrollInfo(); InvalidateMeasure(); firstIndex = GetFirstVisibleIndex(); } public void SetVerticalOffset(double offset) { if (offset < 0 || _viewport.Height >= _extent.Height) { offset = 0; } else { if (offset + _viewport.Height >= _extent.Height) { offset = _extent.Height - _viewport.Height; } } _offset.Y = offset; if (_owner != null) _owner.InvalidateScrollInfo(); //_trans.Y = -offset; InvalidateMeasure(); firstIndex = GetFirstVisibleIndex(); } public double ViewportHeight { get { return _viewport.Height; } } public double ViewportWidth { get { return _viewport.Width; } } #endregion #region helper data structures class ItemAbstraction { public ItemAbstraction(WrapPanelAbstraction panel, int index) { _panel = panel; _index = index; } WrapPanelAbstraction _panel; public readonly int _index; int _sectionIndex = -1; public int SectionIndex { get { if (_sectionIndex == -1) { return _index % _panel._averageItemsPerSection - 1; } return _sectionIndex; } set { if (_sectionIndex == -1) _sectionIndex = value; } } int _section = -1; public int Section { get { if (_section == -1) { return _index / _panel._averageItemsPerSection; } return _section; } set { if (_section == -1) _section = value; } } } class WrapPanelAbstraction : IEnumerable<ItemAbstraction> { public WrapPanelAbstraction(int itemCount) { List<ItemAbstraction> items = new List<ItemAbstraction>(itemCount); for (int i = 0; i < itemCount; i++) { ItemAbstraction item = new ItemAbstraction(this, i); items.Add(item); } Items = new ReadOnlyCollection<ItemAbstraction>(items); _averageItemsPerSection = itemCount; _itemCount = itemCount; } public readonly int _itemCount; public int _averageItemsPerSection; private int _currentSetSection = -1; private int _currentSetItemIndex = -1; private int _itemsInCurrentSecction = 0; private object _syncRoot = new object(); public int SectionCount { get { int ret = _currentSetSection + 1; if (_currentSetItemIndex + 1 < Items.Count) { int itemsLeft = Items.Count - _currentSetItemIndex; ret += itemsLeft / _averageItemsPerSection + 1; } return ret; } } private ReadOnlyCollection<ItemAbstraction> Items { get; set; } public void SetItemSection(int index, int section) { lock (_syncRoot) { if (section <= _currentSetSection + 1 && index == _currentSetItemIndex + 1) { _currentSetItemIndex++; Items[index].Section = section; if (section == _currentSetSection + 1) { _currentSetSection = section; if (section > 0) { _averageItemsPerSection = (index) / (section); } _itemsInCurrentSecction = 1; } else _itemsInCurrentSecction++; Items[index].SectionIndex = _itemsInCurrentSecction - 1; } } } public ItemAbstraction this[int index] { get { return Items[index]; } } #region IEnumerable<ItemAbstraction> Members public IEnumerator<ItemAbstraction> GetEnumerator() { return Items.GetEnumerator(); } #endregion #region IEnumerable Members System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return GetEnumerator(); } #endregion } #endregion } 0 0
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