Interface IVirtualizingScrollInfo

Namespace

Icy.UI

Assembly

IcyUI.dll

Lets a ScrollViewer delegate extent/offset/viewport handling to its Content, instead of fully measuring and arranging it, when that content can realize only the portion of itself that's actually visible.

public interface IVirtualizingScrollInfo

Extension Methods

PropertyReferencesExtensions.ContainsProperty(object, IPropertyReference)

Remarks

Mirrors WPF's ScrollViewer → IScrollInfo → VirtualizingStackPanel delegation. IcyUI has no separate virtualizing-panel type - ItemsControl implements this interface directly, since nothing else in the roadmap needs virtualized layout independent of an items list.

Properties

ExtentHeight

Gets this content's full natural height, estimated or exact depending on how much of it has actually been measured so far.

float ExtentHeight { get; }

Property Value

float

ExtentWidth

Gets this content's full natural width, estimated or exact depending on how much of it has actually been measured so far.

float ExtentWidth { get; }

Property Value

float

Methods

OnViewportChanged(float, float, float, float)

Called by the host ScrollViewer whenever the offset or viewport size it's presenting this content through may have changed - the single point where this content decides what to realize, de-realize, and how to position it.

void OnViewportChanged(float horizontalOffset, float verticalOffset, float viewportWidth, float viewportHeight)

Parameters

horizontalOffset float

How far the viewport is scrolled horizontally.

verticalOffset float

How far the viewport is scrolled vertically.

viewportWidth float

The visible viewport's width.

viewportHeight float

The visible viewport's height.

Events

ScrollToVerticalOffsetRequested

Occurs when this content asks its host ScrollViewer to scroll to an absolute vertical offset - for example to bring one of its items into view (see ScrollIntoView(int)).

event EventHandler<float>? ScrollToVerticalOffsetRequested

Event Type

EventHandler<float>

Remarks

The event's float payload is the new VerticalOffset, not a delta. The host clamps it to its scrollable range.

VerticalOffsetCorrectionRequested

Occurs when this content needs its host ScrollViewer to adjust VerticalOffset by a specific amount, so on-screen content doesn't visibly jump when something already realized (and positioned above the current viewport) changes size.

event EventHandler<float>? VerticalOffsetCorrectionRequested

Event Type

EventHandler<float>

Remarks

The event's float payload is the delta to apply (VerticalOffset += delta), not an absolute new value.