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feat(NavigationView): Include Always unlink parent
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microsoft/microsoft-ui-xaml#7087
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@MartinZikmund
MartinZikmund committed Sep 18, 2023
1 parent 7d9979e commit 5cfbc62
Showing 1 changed file with 117 additions and 122 deletions.
239 changes: 117 additions & 122 deletions src/Uno.UI/Microsoft/UI/Xaml/Controls/NavigationView/NavigationViewItemsFactory.cs
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Original file line number Diff line number Diff line change
@@ -1,173 +1,168 @@
// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License. See LICENSE in the project root for license information.
// MUX Reference NavigationViewItemsFactory.cpp, commit 5e503fa
// MUX Reference NavigationViewItemsFactory.cpp, commit f6b2101

using System;
using System.Collections.Generic;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

namespace Microsoft.UI.Xaml.Controls
namespace Microsoft.UI.Xaml.Controls;

internal class NavigationViewItemsFactory : ElementFactory
{
internal class NavigationViewItemsFactory : ElementFactory
{
private IElementFactoryShim m_itemTemplateWrapper = null;
private NavigationViewItemBase m_settingsItem = null;
private List<NavigationViewItem> navigationViewItemPool;
private IElementFactoryShim m_itemTemplateWrapper = null;
private NavigationViewItemBase m_settingsItem = null;
private List<NavigationViewItem> navigationViewItemPool;

internal void UserElementFactory(object newValue)
internal void UserElementFactory(object newValue)
{
m_itemTemplateWrapper = newValue as IElementFactoryShim;
if (m_itemTemplateWrapper == null)
{
m_itemTemplateWrapper = newValue as IElementFactoryShim;
if (m_itemTemplateWrapper == null)
// ItemTemplate set does not implement IElementFactoryShim. We also
// want to support DataTemplate and DataTemplateSelectors automagically.
if (newValue is DataTemplate dataTemplate)
{
// ItemTemplate set does not implement IElementFactoryShim. We also
// want to support DataTemplate and DataTemplateSelectors automagically.
if (newValue is DataTemplate dataTemplate)
{
m_itemTemplateWrapper = new ItemTemplateWrapper(dataTemplate);
}
else if (newValue is DataTemplateSelector selector)
{
m_itemTemplateWrapper = new ItemTemplateWrapper(selector);
}
m_itemTemplateWrapper = new ItemTemplateWrapper(dataTemplate);
}
else if (newValue is DataTemplateSelector selector)
{
m_itemTemplateWrapper = new ItemTemplateWrapper(selector);
}

navigationViewItemPool = new List<NavigationViewItem>();
}

internal void SettingsItem(NavigationViewItemBase settingsItem)
{
m_settingsItem = settingsItem;
}
navigationViewItemPool = new List<NavigationViewItem>();
}

// Retrieve the element that will be displayed for a specific data item.
// If the resolved element is not derived from NavigationViewItemBase, wrap in a NavigationViewItem before returning.
protected override UIElement GetElementCore(ElementFactoryGetArgs args)
internal void SettingsItem(NavigationViewItemBase settingsItem)
{
m_settingsItem = settingsItem;
}

// Retrieve the element that will be displayed for a specific data item.
// If the resolved element is not derived from NavigationViewItemBase, wrap in a NavigationViewItem before returning.
protected override UIElement GetElementCore(ElementFactoryGetArgs args)
{
object GetNewContent(IElementFactoryShim itemTemplateWrapper, NavigationViewItemBase settingsItem)
{
object GetNewContent(IElementFactoryShim itemTemplateWrapper, NavigationViewItemBase settingsItem)
// Do not template SettingsItem
if (settingsItem != null && settingsItem == args.Data)
{
// Do not template SettingsItem
if (settingsItem != null && settingsItem == args.Data)
{
return args.Data;
}

if (itemTemplateWrapper != null)
{
return itemTemplateWrapper.GetElement(args);
}
return args.Data;
}

var newContent = GetNewContent(m_itemTemplateWrapper, m_settingsItem);

// Element is already of expected type, just return it
if (newContent is NavigationViewItemBase newItem)
if (itemTemplateWrapper != null)
{
return newItem;
return itemTemplateWrapper.GetElement(args);
}
return args.Data;
}

var newContent = GetNewContent(m_itemTemplateWrapper, m_settingsItem);

// Element is already of expected type, just return it
if (newContent is NavigationViewItemBase newItem)
{
return newItem;
}

#if !HAS_UNO_WINUI
// Accidentally adding a OS XAML NavigationViewItem to WinUI's NavigationView can cause unnecessary confusion for developers
// due to unexpected rendering, potentially without an easy way to understand what went wrong here. To help out developers,
// we are explicitly checking for this scenario here and throw a helpful error message so that they can quickly fix their app.
if (newContent is Windows.UI.Xaml.Controls.NavigationViewItemBase)
{
throw new InvalidOperationException("A NavigationView instance contains a Windows.UI.Xaml.Controls.NavigationViewItem. This control requires that its NavigationViewItems be of type Microsoft.UI.Xaml.Controls.NavigationViewItem.");
}
// Accidentally adding a OS XAML NavigationViewItem to WinUI's NavigationView can cause unnecessary confusion for developers
// due to unexpected rendering, potentially without an easy way to understand what went wrong here. To help out developers,
// we are explicitly checking for this scenario here and throw a helpful error message so that they can quickly fix their app.
if (newContent is Windows.UI.Xaml.Controls.NavigationViewItemBase)
{
throw new InvalidOperationException("A NavigationView instance contains a Windows.UI.Xaml.Controls.NavigationViewItem. This control requires that its NavigationViewItems be of type Microsoft.UI.Xaml.Controls.NavigationViewItem.");
}
#endif

// Get or create a wrapping container for the data
NavigationViewItem GetNavigationViewItem()
// Get or create a wrapping container for the data
NavigationViewItem GetNavigationViewItem()
{
if (navigationViewItemPool.Count > 0)
{
if (navigationViewItemPool.Count > 0)
{
var nvi = navigationViewItemPool[navigationViewItemPool.Count - 1];
navigationViewItemPool.RemoveAt(navigationViewItemPool.Count - 1);
return nvi;
}
return new NavigationViewItem();
var nvi = navigationViewItemPool[navigationViewItemPool.Count - 1];
navigationViewItemPool.RemoveAt(navigationViewItemPool.Count - 1);
return nvi;
}
var nvi = GetNavigationViewItem();
var nviImpl = nvi;
nviImpl.CreatedByNavigationViewItemsFactory = true;
return new NavigationViewItem();
}
var nvi = GetNavigationViewItem();
var nviImpl = nvi;
nviImpl.CreatedByNavigationViewItemsFactory = true;

// If a user provided item template exists, just pass the template and data down to the ContentPresenter of the NavigationViewItem
if (m_itemTemplateWrapper != null)
// If a user provided item template exists, just pass the template and data down to the ContentPresenter of the NavigationViewItem
if (m_itemTemplateWrapper != null)
{
if (m_itemTemplateWrapper is ItemTemplateWrapper itemTemplateWrapper)
{
if (m_itemTemplateWrapper is ItemTemplateWrapper itemTemplateWrapper)
{
// Recycle newContent
var tempArgs = new ElementFactoryRecycleArgs();
tempArgs.Element = newContent as UIElement;
m_itemTemplateWrapper.RecycleElement(tempArgs);
// Recycle newContent
var tempArgs = new ElementFactoryRecycleArgs();
tempArgs.Element = newContent as UIElement;
m_itemTemplateWrapper.RecycleElement(tempArgs);


nviImpl.Content = args.Data;
nviImpl.ContentTemplate = itemTemplateWrapper.Template;
nviImpl.ContentTemplateSelector = itemTemplateWrapper.TemplateSelector;
return nviImpl;
}
nviImpl.Content = args.Data;
nviImpl.ContentTemplate = itemTemplateWrapper.Template;
nviImpl.ContentTemplateSelector = itemTemplateWrapper.TemplateSelector;
return nviImpl;
}

nviImpl.Content = newContent;
return nviImpl;
}

protected override void RecycleElementCore(ElementFactoryRecycleArgs args)
nviImpl.Content = newContent;
return nviImpl;
}

protected override void RecycleElementCore(ElementFactoryRecycleArgs args)
{
var element = args.Element;
if (element != null)
{
var element = args.Element;
if (element != null)
if (element is NavigationViewItem nvi)
{
if (element is NavigationViewItem nvi)
var nviImpl = nvi;
// Check whether we wrapped the element in a NavigationViewItem ourselves.
// If yes, we are responsible for recycling it.
if (nviImpl.CreatedByNavigationViewItemsFactory)
{
var nviImpl = nvi;
// Check whether we wrapped the element in a NavigationViewItem ourselves.
// If yes, we are responsible for recycling it.
if (nviImpl.CreatedByNavigationViewItemsFactory)
nviImpl.CreatedByNavigationViewItemsFactory = false;
UnlinkElementFromParent(args);
args.Element = null;

// Retain the NVI that we created for future re-use
navigationViewItemPool.Add(nvi);

// Retrieve the proper element that requires recycling for a user defined item template
// and update the args correspondingly
if (m_itemTemplateWrapper != null)
{
nviImpl.CreatedByNavigationViewItemsFactory = false;
UnlinkElementFromParent(args);
args.Element = null;

// Retain the NVI that we created for future re-use
navigationViewItemPool.Add(nvi);

// Retrieve the proper element that requires recycling for a user defined item template
// and update the args correspondingly
if (m_itemTemplateWrapper != null)
{
// TODO: Retrieve the element and add to the args
}
// TODO: Retrieve the element and add to the args
}
}
}

// Do not recycle SettingsItem
bool isSettingsItem = m_settingsItem != null && m_settingsItem == args.Element;

if (m_itemTemplateWrapper != null && !isSettingsItem)
{
m_itemTemplateWrapper.RecycleElement(args);
}
else
{
UnlinkElementFromParent(args);
}
// Do not recycle SettingsItem
bool isSettingsItem = m_settingsItem != null && m_settingsItem == args.Element;
UnlinkElementFromParent(args);
if (m_itemTemplateWrapper != null && !isSettingsItem)
{
m_itemTemplateWrapper.RecycleElement(args);
}
}
}

private void UnlinkElementFromParent(ElementFactoryRecycleArgs args)
private void UnlinkElementFromParent(ElementFactoryRecycleArgs args)
{
// We want to unlink the containers from the parent repeater
// in case we are required to move it to a different repeater.
if (args.Parent is Panel panel)
{
// We want to unlink the containers from the parent repeater
// in case we are required to move it to a different repeater.
if (args.Parent is Panel panel)
var children = panel.Children;
var childIndex = children.IndexOf(args.Element);
if (childIndex >= 0)
{
var children = panel.Children;
var childIndex = children.IndexOf(args.Element);
if (childIndex >= 0)
{
children.RemoveAt(childIndex);
}
children.RemoveAt(childIndex);
}
}
}
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