Steven Kirk
11 years ago
5 changed files with 303 additions and 349 deletions
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// Copyright (c) The Perspex Project. All rights reserved.
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// Licensed under the MIT license. See licence.md file in the project root for full license information.
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using System; |
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using System.Collections; |
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using System.Collections.Specialized; |
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using Perspex.Controls.Generators; |
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using Perspex.Controls.Templates; |
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using Perspex.Styling; |
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namespace Perspex.Controls.Presenters |
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{ |
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/// <summary>
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/// Base class for controls that present items inside an <see cref="ItemsControl"/>.
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/// </summary>
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public abstract class ItemsPresenterBase : Control, IItemsPresenter, ITemplatedControl |
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{ |
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/// <summary>
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/// Defines the <see cref="Items"/> property.
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/// </summary>
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public static readonly DirectProperty<ItemsPresenterBase, IEnumerable> ItemsProperty = |
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ItemsControl.ItemsProperty.AddOwner<ItemsPresenterBase>(o => o.Items, (o, v) => o.Items = v); |
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/// <summary>
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/// Defines the <see cref="ItemsPanel"/> property.
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/// </summary>
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public static readonly StyledProperty<ITemplate<IPanel>> ItemsPanelProperty = |
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ItemsControl.ItemsPanelProperty.AddOwner<ItemsPresenterBase>(); |
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/// <summary>
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/// Defines the <see cref="MemberSelector"/> property.
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/// </summary>
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public static readonly StyledProperty<IMemberSelector> MemberSelectorProperty = |
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ItemsControl.MemberSelectorProperty.AddOwner<ItemsPresenterBase>(); |
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private IEnumerable _items; |
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private bool _createdPanel; |
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private IItemContainerGenerator _generator; |
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/// <summary>
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/// Initializes static members of the <see cref="ItemsPresenter"/> class.
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/// </summary>
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static ItemsPresenterBase() |
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{ |
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TemplatedParentProperty.Changed.AddClassHandler<ItemsPresenterBase>(x => x.TemplatedParentChanged); |
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} |
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/// <summary>
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/// Gets or sets the items to be displayed.
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/// </summary>
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public IEnumerable Items |
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{ |
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get |
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{ |
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return _items; |
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} |
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set |
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{ |
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if (_createdPanel) |
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{ |
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INotifyCollectionChanged incc = _items as INotifyCollectionChanged; |
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if (incc != null) |
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{ |
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incc.CollectionChanged -= ItemsCollectionChanged; |
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} |
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} |
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if (_createdPanel && value != null) |
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{ |
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INotifyCollectionChanged incc = value as INotifyCollectionChanged; |
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if (incc != null) |
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{ |
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incc.CollectionChanged += ItemsCollectionChanged; |
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} |
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} |
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SetAndRaise(ItemsProperty, ref _items, value); |
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if (_createdPanel) |
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{ |
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ItemsChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset)); |
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} |
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} |
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} |
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/// <summary>
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/// Gets the item container generator.
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/// </summary>
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public IItemContainerGenerator ItemContainerGenerator |
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{ |
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get |
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{ |
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if (_generator == null) |
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{ |
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var i = TemplatedParent as ItemsControl; |
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_generator = (i?.ItemContainerGenerator) ?? new ItemContainerGenerator(this); |
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} |
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return _generator; |
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} |
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internal set |
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{ |
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if (_generator != null) |
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{ |
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throw new InvalidOperationException("ItemContainerGenerator already created."); |
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} |
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_generator = value; |
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} |
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} |
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/// <summary>
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/// Gets or sets a template which creates the <see cref="Panel"/> used to display the items.
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/// </summary>
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public ITemplate<IPanel> ItemsPanel |
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{ |
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get { return GetValue(ItemsPanelProperty); } |
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set { SetValue(ItemsPanelProperty, value); } |
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} |
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/// <summary>
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/// Selects a member from <see cref="Items"/> to use as the list item.
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/// </summary>
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public IMemberSelector MemberSelector |
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{ |
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get { return GetValue(MemberSelectorProperty); } |
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set { SetValue(MemberSelectorProperty, value); } |
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} |
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/// <summary>
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/// Gets the panel used to display the items.
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/// </summary>
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public IPanel Panel |
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{ |
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get; |
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private set; |
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} |
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/// <inheritdoc/>
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public override sealed void ApplyTemplate() |
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{ |
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if (!_createdPanel) |
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{ |
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CreatePanel(); |
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} |
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} |
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/// <inheritdoc/>
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protected override Size MeasureOverride(Size availableSize) |
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{ |
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Panel.Measure(availableSize); |
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return Panel.DesiredSize; |
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} |
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/// <inheritdoc/>
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protected override Size ArrangeOverride(Size finalSize) |
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{ |
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Panel.Arrange(new Rect(finalSize)); |
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return finalSize; |
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} |
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/// <summary>
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/// Creates the <see cref="Panel"/> when <see cref="ApplyTemplate"/> is called for the first
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/// time.
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/// </summary>
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protected virtual void CreatePanel() |
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{ |
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Panel = ItemsPanel.Build(); |
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Panel.SetValue(TemplatedParentProperty, TemplatedParent); |
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LogicalChildren.Clear(); |
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VisualChildren.Clear(); |
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LogicalChildren.Add(Panel); |
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VisualChildren.Add(Panel); |
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_createdPanel = true; |
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INotifyCollectionChanged incc = Items as INotifyCollectionChanged; |
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if (incc != null) |
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{ |
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incc.CollectionChanged += ItemsCollectionChanged; |
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} |
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ItemsChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset)); |
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} |
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/// <summary>
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/// Called when the items for the presenter change, either because <see cref="Items"/>
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/// has been set, or the items collection has been modified.
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/// </summary>
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/// <param name="e">A description of the change.</param>
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protected abstract void ItemsChanged(NotifyCollectionChangedEventArgs e); |
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/// <summary>
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/// Called when the <see cref="Items"/> collection changes.
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/// </summary>
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/// <param name="sender">The sender.</param>
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/// <param name="e">The event args.</param>
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private void ItemsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e) |
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{ |
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if (_createdPanel) |
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{ |
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ItemsChanged(e); |
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} |
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} |
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private void TemplatedParentChanged(PerspexPropertyChangedEventArgs e) |
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{ |
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(e.NewValue as IItemsPresenterHost)?.RegisterItemsPresenter(this); |
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} |
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} |
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} |
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