A cross-platform UI framework for .NET
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// This source file is adapted from the WinUI project.
// (https://github.com/microsoft/microsoft-ui-xaml)
//
// Licensed to The Avalonia Project under MIT License, courtesy of The .NET Foundation.
namespace Avalonia.Layout
{
/// <summary>
/// Represents the base class for an object that sizes and arranges child elements for a host
/// and and does not support virtualization.
/// </summary>
/// <remarks>
/// NonVirtualizingLayout is the base class for layouts that do not support virtualization. You
/// can inherit from it to create your own layout.
///
/// A non-virtualizing layout can measure and arrange child elements.
/// </remarks>
public abstract class NonVirtualizingLayout : AttachedLayout
{
/// <summary>
/// When overridden in a derived class, initializes any per-container state the layout
/// requires when it is attached to an ILayoutable container.
/// </summary>
/// <param name="context">
/// The context object that facilitates communication between the layout and its host
/// container.
/// </param>
protected internal virtual void InitializeForContextCore(LayoutContext context)
{
}
/// <summary>
/// When overridden in a derived class, removes any state the layout previously stored on
/// the ILayoutable container.
/// </summary>
/// <param name="context">
/// The context object that facilitates communication between the layout and its host
/// container.
/// </param>
protected internal virtual void UninitializeForContextCore(LayoutContext context)
{
}
/// <summary>
/// Provides the behavior for the "Measure" pass of the layout cycle. Classes can override
/// this method to define their own "Measure" pass behavior.
/// </summary>
/// <param name="context">
/// The context object that facilitates communication between the layout and its host
/// container.
/// </param>
/// <param name="availableSize">
/// The available size that this object can give to child objects. Infinity can be
/// specified as a value to indicate that the object will size to whatever content is
/// available.
/// </param>
/// <returns>
/// The size that this object determines it needs during layout, based on its calculations
/// of the allocated sizes for child objects or based on other considerations such as a
/// fixed container size.
/// </returns>
protected internal abstract Size MeasureOverride(
NonVirtualizingLayoutContext context,
Size availableSize);
/// <summary>
/// When implemented in a derived class, provides the behavior for the "Arrange" pass of
/// layout. Classes can override this method to define their own "Arrange" pass behavior.
/// </summary>
/// <param name="context">
/// The context object that facilitates communication between the layout and its host
/// container.
/// </param>
/// <param name="finalSize">
/// The final area within the container that this object should use to arrange itself and
/// its children.
/// </param>
/// <returns>The actual size that is used after the element is arranged in layout.</returns>
protected internal virtual Size ArrangeOverride(
NonVirtualizingLayoutContext context,
Size finalSize) => finalSize;
}
}