Struct VirtualScrollSizingStrategy

Namespace

Nalu

Assembly

Nalu.Maui.VirtualScroll.dll

The sizing strategy of a VirtualScroll along its scrolling axis (the cross axis always follows the parent's constraint — a virtualized list cannot know the size of items it has not realized).

[TypeConverter(typeof(VirtualScrollSizingStrategyTypeConverter))]
public readonly record struct VirtualScrollSizingStrategy : IEquatable<VirtualScrollSizingStrategy>

Implements

IEquatable<VirtualScrollSizingStrategy>

Inherited Members

ValueType.Equals(object)

ValueType.GetHashCode()

object.Equals(object, object)

object.GetType()

object.ReferenceEquals(object, object)

Remarks

The three modes exist because measuring virtualized content is not free, so the cost is opt-in:

• Fill measures nothing at all — the content size is never consulted, which is why it stays the default.
• Max(double) is bounded by construction: only the items that fit within the cap participate, no matter how many the collection holds. Once the content reaches the cap the measured size is pinned there, so further content changes cannot move the parent and no re-measure is requested at all.
• Unbounded has no such damper: the whole content is laid out, and every content change re-measures. Use it for small, bounded collections.

Not supported on Windows, where the value is accepted but always behaves as Fill.

Properties

Fill

Takes the size offered by the parent without measuring the content (the default).

public static VirtualScrollSizingStrategy Fill { get; }

Property Value

VirtualScrollSizingStrategy

MaxExtent

Gets the maximum extent the content may grow to, in device-independent units. Only meaningful for Max; PositiveInfinity for the other modes.

public double MaxExtent { get; }

Property Value

double

Mode

Gets the sizing mode.

public VirtualScrollSizingMode Mode { get; }

Property Value

VirtualScrollSizingMode

Unbounded

Hugs the content with no limit — measures every item, and re-measures on every content change. Intended for small, bounded collections.

public static VirtualScrollSizingStrategy Unbounded { get; }

Property Value

VirtualScrollSizingStrategy

Methods

Max(double)

Hugs the content up to maxExtent device-independent units along the scrolling axis, then stops growing.

public static VirtualScrollSizingStrategy Max(double maxExtent)

Parameters

maxExtent double

The maximum extent; must be a positive, finite number.

Returns

VirtualScrollSizingStrategy

Exceptions

ArgumentOutOfRangeException

The extent is not a positive, finite number.

ToString()

Returns the fully qualified type name of this instance.

public override string ToString()

Returns

string

The fully qualified type name.

Operators

implicit operator VirtualScrollSizingStrategy(double)

Converts a positive number to a Max(double) strategy (and PositiveInfinity to Unbounded).

public static implicit operator VirtualScrollSizingStrategy(double maxExtent)

Parameters

maxExtent double

The maximum extent.

Returns

VirtualScrollSizingStrategy

implicit operator VirtualScrollSizingStrategy(string?)

Converts a string representation — "Fill", "Unbounded" or a number (which becomes Max(double)) — to a VirtualScrollSizingStrategy.

public static implicit operator VirtualScrollSizingStrategy(string? inputString)

Parameters

inputString string

The string representation.

Returns

VirtualScrollSizingStrategy

Exceptions

FormatException

The string is not a known mode nor a valid number.