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Provide the EnableVirtualization property to the TabView control. #41

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Merged
merged 1 commit into from
Dec 4, 2024
Merged

Provide the EnableVirtualization property to the TabView control. #41

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113 changes: 111 additions & 2 deletions maui/src/TabView/Control/HorizontalContent/SfHorizontalContent.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,8 @@ internal partial class SfHorizontalContent : SfTabViewExt, ITouchListener, ITapG
bool? _isTowardsRight;
int _visibleItemCount;
int _currentIndex;
int _previousVisibleIndex;
int _nextVisibleIndex;
bool _isPreviousItemVisible;
bool _isNextItemVisible;
SelectionChangingEventArgs? _selectionChangingEventArgs;
Expand Down Expand Up @@ -103,6 +105,19 @@ internal partial class SfHorizontalContent : SfTabViewExt, ITouchListener, ITapG
typeof(double),
typeof(SfHorizontalContent),
100d);

/// <summary>
/// Identifies the <see cref="EnableVirtualization"/> bindable property.
/// </summary>
/// <value>
/// The identifier for <see cref="EnableVirtualization"/> bindable property.
/// </value>
internal static readonly BindableProperty EnableVirtualizationProperty =
BindableProperty.Create(
nameof(EnableVirtualization),
typeof(bool),
typeof(SfHorizontalContent),
false);
#endregion

#region Properties
Expand Down Expand Up @@ -155,6 +170,18 @@ internal IList? ItemsSource
set => SetValue(ItemsSourceProperty, value);
}

/// <summary>
/// Gets or sets a value indicating whether lazy loading is enabled during the initial load.
/// </summary>
/// <value>
/// It accepts the bool values and the default value is false.
/// </value>
internal bool EnableVirtualization
{
get => (bool)GetValue(EnableVirtualizationProperty);
set => SetValue(EnableVirtualizationProperty, value);
}

/// <summary>
/// Gets or sets the value that defines the content width of each tab header item.
/// </summary>
Expand Down Expand Up @@ -373,6 +400,11 @@ void ClearTabContent(SfTabItem tabItem, int index)
void UpdateSelectedIndex()
{
_isSelectionProcessed = true;
if (EnableVirtualization)
{
LoadItemsContent(SelectedIndex);
}

UpdateTabItemContentPosition();
}

Expand Down Expand Up @@ -439,10 +471,29 @@ void AddTabContentItems(SfTabItem item, int index = -1)
{
if (item.Content != null)
{
SfGrid parentGrid = CreateParentGrid(item);
SfGrid parentGrid = new();

if (!EnableVirtualization || (EnableVirtualization && !(index != SelectedIndex && item.IsVisible)))
{
parentGrid = CreateParentGrid(item);
}

if (index >= 0)
{
_horizontalStackLayout?.Children.Insert(index, parentGrid);
if (EnableVirtualization && index != SelectedIndex && item.IsVisible)
{
var content = new BoxView
{
WidthRequest = 0,
HeightRequest = 0,
Opacity = 0
};
_horizontalStackLayout?.Children.Insert(index, content);
}
else
{
_horizontalStackLayout?.Children.Insert(index, parentGrid);
}
}
else
{
Expand Down Expand Up @@ -849,6 +900,12 @@ void AdjustForFirstIndex(double difference)
{
if (_horizontalStackLayout != null && IsTowardsRight == true)
{
if (EnableVirtualization)
{
var index = _nextVisibleIndex;
LoadItemsContent(index);
}

#if !WINDOWS
if (((this as IVisualElementController).EffectiveFlowDirection & EffectiveFlowDirection.RightToLeft) != EffectiveFlowDirection.RightToLeft)
_horizontalStackLayout.TranslationX = Math.Clamp(_horizontalStackLayout.TranslationX + difference, -ContentWidth, 0);
Expand All @@ -866,6 +923,17 @@ void AdjustForMiddleIndices(double difference)
{
if (_isPreviousItemVisible && _isNextItemVisible)
{
if (EnableVirtualization)
{
int index = -1;
if (IsTowardsRight is not null)
{
index = IsTowardsRight == true ? _nextVisibleIndex : _previousVisibleIndex;
}

LoadItemsContent(index);
}

#if !WINDOWS
if (((this as IVisualElementController).EffectiveFlowDirection & EffectiveFlowDirection.RightToLeft) != EffectiveFlowDirection.RightToLeft)
_horizontalStackLayout.TranslationX = Math.Clamp(_horizontalStackLayout.TranslationX + difference, -ContentWidth * (_currentIndex + 1), -ContentWidth * (_currentIndex - 1));
Expand All @@ -877,6 +945,12 @@ void AdjustForMiddleIndices(double difference)
}
else if (_isPreviousItemVisible)
{
if (EnableVirtualization)
{
var index = _previousVisibleIndex;
LoadItemsContent(index);
}

#if !WINDOWS
if (((this as IVisualElementController).EffectiveFlowDirection & EffectiveFlowDirection.RightToLeft) != EffectiveFlowDirection.RightToLeft)
_horizontalStackLayout.TranslationX = Math.Clamp(_horizontalStackLayout.TranslationX + difference, -ContentWidth * _currentIndex, -ContentWidth * (_currentIndex - 1));
Expand All @@ -888,6 +962,12 @@ void AdjustForMiddleIndices(double difference)
}
else if (_isNextItemVisible)
{
if (EnableVirtualization)
{
var index = _nextVisibleIndex;
LoadItemsContent(index);
}

#if !WINDOWS
if (((this as IVisualElementController).EffectiveFlowDirection & EffectiveFlowDirection.RightToLeft) != EffectiveFlowDirection.RightToLeft)
_horizontalStackLayout.TranslationX = Math.Clamp(_horizontalStackLayout.TranslationX + difference, -ContentWidth * (_currentIndex + 1), -ContentWidth * _currentIndex);
Expand All @@ -904,6 +984,15 @@ void AdjustForLastIndex(double difference)
{
if (_horizontalStackLayout != null)
{
if (EnableVirtualization)
{
var index = _previousVisibleIndex;
if (IsTowardsRight is false)
{
LoadItemsContent(index);
}
}

#if !WINDOWS
if (((this as IVisualElementController).EffectiveFlowDirection & EffectiveFlowDirection.RightToLeft) != EffectiveFlowDirection.RightToLeft)
_horizontalStackLayout.TranslationX = Math.Clamp(_horizontalStackLayout.TranslationX + difference, -ContentWidth * (_visibleItemCount - 1), -ContentWidth * (_visibleItemCount - 2));
Expand All @@ -915,6 +1004,24 @@ void AdjustForLastIndex(double difference)
}
}

/// <summary>
/// This method is used to replace the placeholder view with a tab item when the EnableVirtualization is true.
/// </summary>
/// <param name="index">This index position of the child in the HorizontalStackLayout to replaced with a tab item.</param>
void LoadItemsContent(int index)
{
if (_horizontalStackLayout != null)
{
if (Items is not null && index >= 0 && index < _horizontalStackLayout.Children.Count && _horizontalStackLayout.Children[index] is BoxView)
{
SfGrid parentGrid = CreateParentGrid(Items[index]);
_horizontalStackLayout?.Children.RemoveAt(index);
_horizontalStackLayout?.Children.Insert(index, parentGrid);
UpdateDynamicChanges();
}
}
}

/// <summary>
/// This method is used to update the tab item position after swipe complete.
/// </summary>
Expand Down Expand Up @@ -1377,6 +1484,7 @@ void UpdateVisibilityWithoutTemplate()
if (Items[i].IsVisible == true)
{
_isNextItemVisible = true;
_nextVisibleIndex = i;
break;
}
}
Expand All @@ -1386,6 +1494,7 @@ void UpdateVisibilityWithoutTemplate()
if (Items[i].IsVisible == true)
{
_isPreviousItemVisible = true;
_previousVisibleIndex = i;
break;
}
}
Expand Down
6 changes: 5 additions & 1 deletion maui/src/TabView/Control/SfTabBar.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -720,7 +720,11 @@ internal void UpdateSelectedIndex(int newIndex, int oldIndex)
{
if (newIndex != -1)
{
_isSelectionProcessed = true;
if (IsLoaded)
{
_isSelectionProcessed = true;
}

UpdateSelectedTabItemIsSelected(newIndex, oldIndex);
UpdateTabIndicatorWidth();
if (_tabSelectionChangedEventArgs != null)
Expand Down
51 changes: 51 additions & 0 deletions maui/src/TabView/Control/SfTabView.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -306,6 +306,17 @@ public class SfTabView : ContentView, IParentThemeElement
BindingMode.Default,
null);

/// <summary>
/// Identifies the <see cref="EnableVirtualization"/> bindable property.
/// </summary>
public static readonly BindableProperty EnableVirtualizationProperty =
BindableProperty.Create(
nameof(EnableVirtualization),
typeof(bool),
typeof(SfTabView),
false,
propertyChanged: OnEnableVirtualizationChanged);

static readonly BindableProperty IsContentTransitionEnabledProperty =
BindableProperty.Create(
nameof(IsContentTransitionEnabled),
Expand Down Expand Up @@ -1257,6 +1268,32 @@ public double ContentTransitionDuration
set => SetValue(ContentTransitionDurationProperty, value);
}

/// <summary>
/// Gets or sets a value indicating whether lazy loading is enabled during the initial load.
/// </summary>
/// <value>
/// A boolean value indicating whether lazy loading is enabled. The default value is false.
/// </value>
/// <example>
/// Here is an example of how to set the <see cref="EnableVirtualization"/> property.
///
/// # [XAML](#tab/tabid-1)
/// <code><![CDATA[
/// <tabView:SfTabView EnableVirtualization="True" />
/// ]]></code>
///
/// # [C#](#tab/tabid-2)
/// <code><![CDATA[
/// SfTabView tabView = new SfTabView();
/// tabView.EnableVirtualization = true;
/// ]]></code>
/// </example>
public bool EnableVirtualization
{
get => (bool)GetValue(EnableVirtualizationProperty);
set => SetValue(EnableVirtualizationProperty, value);
}

/// <summary>
/// Gets or sets a value that can be used to customize the scroll button’s background color in the <see cref="SfTabView"/>.
/// </summary>
Expand Down Expand Up @@ -1557,6 +1594,11 @@ internal void RaiseSelectionChangingEvent(SelectionChangingEventArgs args)
/// </summary>
static void OnFontAutoScalingEnabledChanged(BindableObject bindable, object oldValue, object newValue) => (bindable as SfTabView)?.UpdateFontAutoScalingEnabled((Boolean)newValue);

/// <summary>
/// Handles changes to the <see cref="EnableVirtualization"/> property.
/// </summary>
static void OnEnableVirtualizationChanged(BindableObject bindable, object oldValue, object newValue) => (bindable as SfTabView)?.UpdateEnableVirtualization();

#endregion

#region Private Methods
Expand Down Expand Up @@ -1955,6 +1997,15 @@ void UpdateFontAutoScalingEnabled(bool newValue)
}
}

/// <summary>
/// Updates the enable virtualization.
/// </summary>
void UpdateEnableVirtualization()
{
if (_tabContentContainer != null)
_tabContentContainer.EnableVirtualization = EnableVirtualization;
}

/// <summary>
/// Gets the theme dictionary for the tab view.
/// </summary>
Expand Down