Class LayoutRebuilder

Wrapper class for managing layout rebuilding of CanvasElement.

Inheritance
object
LayoutRebuilder
Implements
Inherited Members
Namespace: UnityEngine.UI
Assembly: UnityEngine.UI.dll
Syntax
public class LayoutRebuilder : ICanvasElement

Properties

transform

The Transform this LayoutRebuilder is targeting for rebuild.

Declaration
public Transform transform { get; }
Property Value
Type Description
Transform

Methods

Equals(object)

Does the passed rebuilder point to the same CanvasElement.

Declaration
public override bool Equals(object obj)
Parameters
Type Name Description
object obj

The other object to compare
Returns
Type Description
bool

Are they equal
Overrides

ForceRebuildLayoutImmediate(RectTransform)

Forces an immediate rebuild of the layout element and child layout elements affected by the calculations.

Declaration
public static void ForceRebuildLayoutImmediate(RectTransform layoutRoot)
Parameters
Type Name Description
RectTransform layoutRoot

The layout element to perform the layout rebuild on.
Remarks

Normal use of the layout system should not use this method. Instead MarkLayoutForRebuild should be used instead, which triggers a delayed layout rebuild during the next layout pass. The delayed rebuild automatically handles objects in the entire layout hierarchy in the correct order, and prevents multiple recalculations for the same layout elements. However, for special layout calculation needs, ::ref::ForceRebuildLayoutImmediate can be used to get the layout of a sub-tree resolved immediately. This can even be done from inside layout calculation methods such as ILayoutController.SetLayoutHorizontal orILayoutController.SetLayoutVertical. Usage should be restricted to cases where multiple layout passes are unavaoidable despite the extra cost in performance.

GetHashCode()

Returns the instance ID of the target transform as a hash code.

Declaration
public override int GetHashCode()
Returns
Type Description
int

The instance ID of the target transform.
Overrides

GraphicUpdateComplete()

Called when the graphic update is complete.

Declaration
public void GraphicUpdateComplete()

IsDestroyed()

Has the native representation of this LayoutRebuilder been destroyed?

Declaration
public bool IsDestroyed()
Returns
Type Description
bool

True if the target transform has been destroyed.

IsLayoutRebuildPending(Transform)

Checks whether a layout rebuild is queued for an element.

Declaration
public static bool IsLayoutRebuildPending(Transform transform)
Parameters
Type Name Description
Transform transform

The element to query.
Returns
Type Description
bool

True if a layout rebuild is queued for the element's layout root, otherwise false.
Remarks

Unity resolves the element to the layout root that owns its rebuild, so a child of a layout group reports true whenever an ancestor layout is queued. An element that takes part in no layout always reports false. A false result doesn't mean the geometry is final, because a script can mark the element dirty again later in the same frame.

Examples
using UnityEngine;
using UnityEngine.UI; // Required when using UI elements.

public class TooltipPositionerExample : MonoBehaviour
{
    public RectTransform tooltip;

    // Places the tooltip above its target, once the tooltip's own layout has settled.
    public void PositionAbove(RectTransform target)
    {
        // A queued rebuild means the tooltip size is not final, so wait for a later frame.
        if (LayoutRebuilder.IsLayoutRebuildPending(tooltip))
            return;

        float offset = (tooltip.rect.height + target.rect.height) * 0.5f;
        tooltip.position = target.position + new Vector3(0f, offset, 0f);
    }
}

LayoutComplete()

Called when the layout rebuild is complete. Returns this instance to the rebuilder pool.

Declaration
public void LayoutComplete()

MarkLayoutForRebuild(RectTransform)

Mark the given RectTransform as needing it's layout to be recalculated during the next layout pass.

Declaration
public static void MarkLayoutForRebuild(RectTransform rect)
Parameters
Type Name Description
RectTransform rect

Rect to rebuild.

Rebuild(CanvasUpdate)

Rebuilds the layout during the CanvasUpdate.Layout update stage.

Declaration
public void Rebuild(CanvasUpdate executing)
Parameters
Type Name Description
CanvasUpdate executing

The canvas update stage currently being executed.

ToString()

Returns a descriptive string showing the target transform's name.

Declaration
public override string ToString()
Returns
Type Description
string

A string describing this LayoutRebuilder.
Overrides

Implements