public SpacingItemDecoration(StaggeredGridItemsLayout itemsLayout)
{
if (itemsLayout == null)
{
throw new ArgumentNullException(nameof(itemsLayout));
}
switch (itemsLayout)
{
case StaggeredGridItemsLayout gridItemsLayout:
_orientation = gridItemsLayout.Orientation;
_horizontalSpacing = gridItemsLayout.HorizontalItemSpacing;
_verticalSpacing = gridItemsLayout.VerticalItemSpacing;
_span = gridItemsLayout.Span;
break;
}
}
public override void Draw(CGRect rect)
{
base.Draw(rect);
GradientColorStackLayout stack = this.Element as GradientColorStackLayout;
CGColor startColor = stack.StartColor.ToCGColor();
CGColor centerColor = stack.CenterColor.ToCGColor();
CGColor endColor = stack.EndColor.ToCGColor();
float yCenter = stack.YCenter;
ItemsLayoutOrientation direction = stack.Direction;
bool hasCenterColor = stack.HasCenterColor;
CAGradientLayer gradientLayer = null;
if (direction == ItemsLayoutOrientation.Vertical)
{
gradientLayer = new CAGradientLayer();
}
if (direction == ItemsLayoutOrientation.Horizontal)
{
gradientLayer = new CAGradientLayer()
{
StartPoint = new CGPoint(0, 0.5),
EndPoint = new CGPoint(1, 0.5)
};
}
gradientLayer.Frame = rect;
if (hasCenterColor)
{
gradientLayer.Locations = new NSNumber[] { new NSNumber(0.5F), new NSNumber(yCenter), new NSNumber(1F) };
gradientLayer.Colors = new CGColor[] { startColor, centerColor, endColor };
}
else
{
gradientLayer.Locations = new NSNumber[] { new NSNumber(yCenter), new NSNumber(1F) };
gradientLayer.Colors = new CGColor[] { startColor, endColor };
}
NativeView.Layer.InsertSublayer(gradientLayer, 0);
}
public ObservableCodeCollectionViewGallery(ItemsLayoutOrientation orientation = ItemsLayoutOrientation.Vertical,
bool grid = true, int initialItems = 1000, bool addItemsWithTimer = false)
{
var layout = new Grid
{
RowDefinitions = new RowDefinitionCollection
{
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Star
}
}
};
IItemsLayout itemsLayout = grid
? new GridItemsLayout(3, orientation)
: new ListItemsLayout(orientation) as IItemsLayout;
var itemTemplate = ExampleTemplates.PhotoTemplate();
var collectionView = new CollectionView {
ItemsLayout = itemsLayout, ItemTemplate = itemTemplate, AutomationId = "collectionview"
};
public TemplateCodeCollectionViewGridGallery(ItemsLayoutOrientation orientation = ItemsLayoutOrientation.Vertical)
{
var layout = new Grid
{
RowDefinitions = new RowDefinitionCollection
{
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Star
}
}
};
var itemsLayout = new GridItemsLayout(2, orientation);
var itemTemplate = ExampleTemplates.PhotoTemplate();
var collectionView = new CollectionView {
ItemsLayout = itemsLayout, ItemTemplate = itemTemplate, AutomationId = "collectionview"
};
var generator = new ItemsSourceGenerator(collectionView, 100);
var spanSetter = new SpanSetter(collectionView);
layout.Children.Add(generator);
layout.Children.Add(spanSetter);
Grid.SetRow(spanSetter, 1);
layout.Children.Add(collectionView);
Grid.SetRow(collectionView, 2);
Content = layout;
spanSetter.UpdateSpan();
generator.GenerateItems();
}
ListViewBase CreateCarouselListLayout(ItemsLayoutOrientation layoutOrientation)
{
Windows.UI.Xaml.Controls.ListView listView;
if (layoutOrientation == ItemsLayoutOrientation.Horizontal)
{
listView = new FormsListView()
{
Style = (Windows.UI.Xaml.Style)UWPApp.Current.Resources["HorizontalCarouselListStyle"],
ItemsPanel = (ItemsPanelTemplate)UWPApp.Current.Resources["HorizontalListItemsPanel"]
};
}
else
{
listView = new FormsListView()
{
Style = (Windows.UI.Xaml.Style)UWPApp.Current.Resources["VerticalCarouselListStyle"]
};
}
return(listView);
}
ListViewBase CreateCarouselListLayout(ItemsLayoutOrientation layoutOrientation)
{
Windows.UI.Xaml.Controls.ListView listView;
if (layoutOrientation == ItemsLayoutOrientation.Horizontal)
{
listView = new FormsListView()
{
Style = (Windows.UI.Xaml.Style)UWPApp.Current.Resources["HorizontalCarouselListStyle"],
ItemsPanel = (ItemsPanelTemplate)UWPApp.Current.Resources["HorizontalListItemsPanel"]
};
}
else
{
listView = new FormsListView()
{
Style = (Windows.UI.Xaml.Style)UWPApp.Current.Resources["VerticalCarouselListStyle"]
};
}
listView.Padding = new Windows.UI.Xaml.Thickness(Carousel.PeekAreaInsets.Left, Carousel.PeekAreaInsets.Top, Carousel.PeekAreaInsets.Right, Carousel.PeekAreaInsets.Bottom);
return(listView);
}
public CarouselCodeGallery(ItemsLayoutOrientation orientation)
{
On <iOS>().SetLargeTitleDisplay(LargeTitleDisplayMode.Never);
_scrollInfoLabel.MaxLines = 1;
_scrollInfoLabel.LineBreakMode = LineBreakMode.TailTruncation;
_orientation = orientation;
Title = $"CarouselView (Code, {orientation})";
var nItems = 5;
var layout = new Grid
{
RowDefinitions = new RowDefinitionCollection
{
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Star
}
}
};
var itemsLayout =
new LinearItemsLayout(orientation)
{
SnapPointsType = SnapPointsType.MandatorySingle,
SnapPointsAlignment = SnapPointsAlignment.Center
};
var itemTemplate = ExampleTemplates.CarouselTemplate();
var carouselView = new CarouselView
{
ItemsLayout = itemsLayout,
ItemTemplate = itemTemplate,
Position = 2,
Margin = new Thickness(0, 10, 0, 10),
BackgroundColor = Color.LightGray,
AutomationId = "TheCarouselView"
};
if (orientation == ItemsLayoutOrientation.Horizontal)
{
carouselView.PeekAreaInsets = new Thickness(30, 0, 30, 0);
}
else
{
carouselView.PeekAreaInsets = new Thickness(0, 30, 0, 30);
}
carouselView.Scrolled += CarouselView_Scrolled;
StackLayout stacklayoutInfo = GetReadOnlyInfo(carouselView);
var generator = new ItemsSourceGenerator(carouselView, initialItems: nItems, itemsSourceType: ItemsSourceType.ObservableCollection);
layout.Children.Add(generator);
var positionControl = new PositionControl(carouselView, nItems);
layout.Children.Add(positionControl);
var spacingModifier = new SpacingModifier(carouselView.ItemsLayout, "Update Spacing");
layout.Children.Add(spacingModifier);
layout.Children.Add(stacklayoutInfo);
var stckPeek = new StackLayout {
Orientation = StackOrientation.Horizontal
};
stckPeek.Children.Add(new Label {
Text = "Peek"
});
var padi = new Slider
{
Maximum = 100,
Minimum = 0,
Value = 30,
WidthRequest = 100,
BackgroundColor = Color.Pink
};
padi.ValueChanged += (s, e) => {
var peek = padi.Value;
if (orientation == ItemsLayoutOrientation.Horizontal)
{
carouselView.PeekAreaInsets = new Thickness(peek, 0, peek, 0);
}
else
{
carouselView.PeekAreaInsets = new Thickness(0, peek, 0, peek);
}
};
stckPeek.Children.Add(padi);
stacklayoutInfo.Children.Add(stckPeek);
stacklayoutInfo.Children.Add(_scrollInfoLabel);
var content = new Grid();
content.Children.Add(carouselView);
#if DEBUG
// Uncomment this line to add a helper to visualize the center of each element.
//content.Children.Add(CreateDebuggerLines());
#endif
layout.Children.Add(content);
Grid.SetRow(positionControl, 1);
Grid.SetRow(stacklayoutInfo, 2);
Grid.SetRow(spacingModifier, 3);
Grid.SetRow(content, 4);
Content = layout;
generator.CollectionChanged += (sender, e) => {
positionControl.UpdatePositionCount(generator.Count);
};
generator.GenerateItems();
}
public static bool IsListViewItemVisible(FrameworkElement element, FrameworkElement container, ItemsLayoutOrientation itemsLayoutOrientation)
{
if (element == null || container == null)
{
return(false);
}
if (element.Visibility != Visibility.Visible)
{
return(false);
}
var elementBounds = element.TransformToVisual(container).TransformBounds(new Rect(0, 0, element.ActualWidth, element.ActualHeight));
var containerBounds = new Rect(0, 0, container.ActualWidth, container.ActualHeight);
switch (itemsLayoutOrientation)
{
case ItemsLayoutOrientation.Vertical:
return(elementBounds.Top < containerBounds.Bottom && elementBounds.Bottom > containerBounds.Top);
default:
return(elementBounds.Left < containerBounds.Right && elementBounds.Right > containerBounds.Left);
}
;
}
public static (int firstVisibleItemIndex, int lastVisibleItemIndex, int centerItemIndex) GetVisibleIndexes(this ListViewBase listViewBase, ItemsLayoutOrientation itemsLayoutOrientation, bool goingNext)
{
int firstVisibleItemIndex = -1;
int lastVisibleItemIndex = -1;
var itemsPanel = (listViewBase.ItemsPanelRoot as ItemsStackPanel);
if (itemsPanel != null)
{
firstVisibleItemIndex = itemsPanel.FirstVisibleIndex;
lastVisibleItemIndex = itemsPanel.LastVisibleIndex;
}
else
{
var scrollViewer = listViewBase.GetFirstDescendant <ScrollViewer>();
var presenters = listViewBase.GetChildren <ListViewItemPresenter>();
if (presenters != null || scrollViewer == null)
{
int count = 0;
foreach (ListViewItemPresenter presenter in presenters)
{
if (IsListViewItemVisible(presenter, scrollViewer, itemsLayoutOrientation))
{
if (firstVisibleItemIndex == -1)
{
firstVisibleItemIndex = count;
}
lastVisibleItemIndex = count;
}
count++;
}
}
}
double center = (lastVisibleItemIndex + firstVisibleItemIndex) / 2.0;
int centerItemIndex = goingNext ? (int)Math.Ceiling(center) : (int)Math.Floor(center);
return(firstVisibleItemIndex, lastVisibleItemIndex, centerItemIndex);
}
public ListItemsLayout(ItemsLayoutOrientation orientation) : base(orientation)
{
}
public ObservableCodeCollectionViewGallery(ItemsLayoutOrientation orientation = ItemsLayoutOrientation.Vertical,
bool grid = true)
{
var layout = new Grid
{
RowDefinitions = new RowDefinitionCollection
{
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Star
}
}
};
IItemsLayout itemsLayout = grid
? new GridItemsLayout(3, orientation)
: new ListItemsLayout(orientation) as IItemsLayout;
var itemTemplate = ExampleTemplates.PhotoTemplate();
var collectionView = new CollectionView {
ItemsLayout = itemsLayout, ItemTemplate = itemTemplate
};
var generator = new ItemsSourceGenerator(collectionView);
var remover = new ItemRemover(collectionView);
var adder = new ItemAdder(collectionView);
var replacer = new ItemReplacer(collectionView);
var mover = new ItemMover(collectionView);
layout.Children.Add(generator);
layout.Children.Add(remover);
Grid.SetRow(remover, 1);
layout.Children.Add(adder);
Grid.SetRow(adder, 2);
layout.Children.Add(replacer);
Grid.SetRow(replacer, 3);
layout.Children.Add(mover);
Grid.SetRow(mover, 4);
layout.Children.Add(collectionView);
Grid.SetRow(collectionView, 5);
Content = layout;
generator.GenerateObservableCollection();
}
public ObservableCodeCollectionViewGallery(ItemsLayoutOrientation orientation = ItemsLayoutOrientation.Vertical,
bool grid = true, int initialItems = 1000, bool addItemsWithTimer = false, ItemsUpdatingScrollMode scrollMode = ItemsUpdatingScrollMode.KeepItemsInView)
{
var layout = new Grid
{
RowDefinitions = new RowDefinitionCollection
{
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Star
}
}
};
IItemsLayout itemsLayout = grid
? new GridItemsLayout(3, orientation)
: new LinearItemsLayout(orientation) as IItemsLayout;
var itemTemplate = ExampleTemplates.PhotoTemplate();
var collectionView = new CollectionView {
ItemsLayout = itemsLayout, ItemTemplate = itemTemplate,
AutomationId = "collectionview", Header = "This is the header", ItemsUpdatingScrollMode = scrollMode
};
var generator = new ItemsSourceGenerator(collectionView, initialItems, ItemsSourceType.ObservableCollection);
var remover = new ItemRemover(collectionView);
var adder = new ItemAdder(collectionView);
var replacer = new ItemReplacer(collectionView);
var mover = new ItemMover(collectionView);
var inserter = new ItemInserter(collectionView);
layout.Children.Add(generator);
layout.Children.Add(remover);
Grid.SetRow(remover, 1);
layout.Children.Add(adder);
Grid.SetRow(adder, 2);
layout.Children.Add(replacer);
Grid.SetRow(replacer, 3);
layout.Children.Add(mover);
Grid.SetRow(mover, 4);
layout.Children.Add(inserter);
Grid.SetRow(inserter, 5);
layout.Children.Add(collectionView);
Grid.SetRow(collectionView, 6);
Content = layout;
if (addItemsWithTimer)
{
generator.GenerateEmptyObservableCollectionAndAddItemsEverySecond();
}
else
{
generator.GenerateItems();
}
}
public static (int firstVisibleItemIndex, int lastVisibleItemIndex, int centerItemIndex) GetVisibleIndexes(ListViewBase listViewBase, ItemsLayoutOrientation itemsLayoutOrientation)
{
int firstVisibleItemIndex = -1;
int lastVisibleItemIndex = -1;
int centerItemIndex = -1;
var scrollViewer = listViewBase.GetFirstDescendant <ScrollViewer>();
var presenters = listViewBase.GetChildren <ListViewItemPresenter>();
if (presenters != null || scrollViewer == null)
{
int count = 0;
foreach (ListViewItemPresenter presenter in presenters)
{
if (CollectionViewExtensions.IsListViewItemVisible(presenter, scrollViewer, itemsLayoutOrientation))
{
if (firstVisibleItemIndex == -1)
{
firstVisibleItemIndex = count;
}
lastVisibleItemIndex = count;
}
count++;
}
centerItemIndex = (lastVisibleItemIndex + firstVisibleItemIndex) / 2;
}
return(firstVisibleItemIndex, lastVisibleItemIndex, centerItemIndex);
}
protected ItemsLayout(ItemsLayoutOrientation orientation)
{
CollectionView.VerifyCollectionViewFlagEnabled(constructorHint: nameof(ItemsLayout));
Orientation = orientation;
}
public CustomLinearItemsLayout([CustomParameter("Orientation")] ItemsLayoutOrientation orientation) : base(orientation)
{
}
protected virtual ItemsViewScrolledEventArgs ComputeVisibleIndexes(ItemsViewScrolledEventArgs args, ItemsLayoutOrientation orientation, bool advancing)
{
var(firstVisibleItemIndex, lastVisibleItemIndex, centerItemIndex) = GetVisibleIndexes(orientation, advancing);
args.FirstVisibleItemIndex = firstVisibleItemIndex;
args.CenterItemIndex = centerItemIndex;
args.LastVisibleItemIndex = lastVisibleItemIndex;
return(args);
}
public SwipeItemsLayout(ItemsLayoutOrientation orientation) : base(orientation)
{
}
public ObservableMultiItemCollectionViewGallery(ItemsLayoutOrientation orientation = ItemsLayoutOrientation.Vertical,
bool grid = true, int initialItems = 1000, bool withIndex = false)
{
var layout = new Grid
{
RowDefinitions = new RowDefinitionCollection
{
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Auto
},
new RowDefinition {
Height = GridLength.Star
}
}
};
var itemsLayout = grid
? new GridItemsLayout(3, orientation)
: new ListItemsLayout(orientation) as IItemsLayout;
var itemTemplate = ExampleTemplates.PhotoTemplate();
var collectionView = new CollectionView {
ItemsLayout = itemsLayout, ItemTemplate = itemTemplate, AutomationId = "collectionview"
};
var generator = new ItemsSourceGenerator(collectionView, initialItems, ItemsSourceType.MultiTestObservableCollection);
var remover = new MultiItemRemover(collectionView, withIndex);
var adder = new MultiItemAdder(collectionView, withIndex);
var replacer = new MultiItemReplacer(collectionView);
var mover = new MultiItemMover(collectionView);
layout.Children.Add(generator);
layout.Children.Add(remover);
Grid.SetRow(remover, 1);
layout.Children.Add(adder);
Grid.SetRow(adder, 2);
layout.Children.Add(replacer);
Grid.SetRow(replacer, 3);
layout.Children.Add(mover);
Grid.SetRow(mover, 4);
layout.Children.Add(collectionView);
Grid.SetRow(collectionView, 5);
Content = layout;
generator.GenerateItems();
}
protected ItemsLayout([Parameter("Orientation")] ItemsLayoutOrientation orientation)
{
Orientation = orientation;
}
public StaggeredGridItemsLayout([Parameter("Orientation")] ItemsLayoutOrientation orientation) : base(orientation)
{
}
protected override ItemsViewScrolledEventArgs ComputeVisibleIndexes(ItemsViewScrolledEventArgs args, ItemsLayoutOrientation orientation, bool advancing)
{
args = base.ComputeVisibleIndexes(args, orientation, advancing);
if (Element.Loop)
{
args.FirstVisibleItemIndex %= ItemCount;
args.CenterItemIndex %= ItemCount;
args.LastVisibleItemIndex %= ItemCount;
}
return(args);
}
public StaggeredGridItemsLayout(int span, [Parameter("Orientation")] ItemsLayoutOrientation orientation) : base(span, orientation)
{
}
public LinearItemsLayout([Parameter("Orientation")] ItemsLayoutOrientation orientation) : base(orientation)
{
}
public static TCollectionView GridStyle <TCollectionView>(this TCollectionView collection, ItemsLayoutOrientation orientation, int span, int spacing) where TCollectionView : CollectionView
{
collection.ItemsLayout = new GridItemsLayout(orientation)
{
Span = span,
VerticalItemSpacing = spacing,
HorizontalItemSpacing = spacing,
};
return(collection);
}
