Unity Animator Support

AutoLayout responds to Unity’s Animator the same way LayoutGroup does: drop an Animator on the GameObject, record curves against the AutoLayout fields you want to animate, and the layout reflows on every Animator update. Play mode and the Animation Window scrub-preview in the Editor both work.

Animator clip ──▶ writes m_Linear.Gap ──▶ OnDidApplyAnimationProperties
                                        ─▶ AutoLayout diffs against snapshot
                                        ─▶ marks PositionX dirty
                                        ─▶ adapter reflows children

What you can animate

Anything Unity’s Animator can keyframe on the AutoLayout component:

Category	Fields (Animation Window property path)
Size	m_Width.Value, m_Width.Type, m_Height.Value, m_Height.Type
Spacing	m_Padding.Left/Right/Top/Bottom, m_Margin.Left/Right/Top/Bottom
Linear	m_Linear.Gap, m_Linear.WrapGap, m_Linear.MainAxisAlign, m_Linear.CrossAxisAlign, m_Linear.Wrap, m_Linear.ReverseChildren
Grid	m_Grid.Columns, m_Grid.Rows, m_Grid.ColumnGap, m_Grid.RowGap, m_Grid.Flow, m_Grid.HorizontalAlign, m_Grid.VerticalAlign
Grid item	m_GridItem.Column, m_GridItem.Row, m_GridItem.ColumnSpan, m_GridItem.RowSpan
Constraints	m_Constraints.MinWidth/MaxWidth/MinHeight/MaxHeight
Structural	m_LayoutType, m_Placement, m_Visibility, m_Overflow, m_LayoutOrder

Float curves work as expected. Enum fields like m_LayoutType and m_Visibility can be keyframed with discrete (Tangent → Constant) curves.

Setting up a clip

1. Add an Animator to the GameObject that has AutoLayout.
2. Create an AnimationClip (or open the Animation Window with the GO selected).
3. Pick the property you want to animate from the Add Property dropdown — Unity exposes the serialized fields under the AutoLayout entry.
4. Record curves. Loop the clip. Done.

Everything that follows is just nice-to-haves.

Animate AutoLayout fields, not the RectTransform

AutoLayout drives the RectTransform’s sizeDelta and anchoredPosition via DrivenRectTransformTracker. If you animate the RectTransform directly, AutoLayout’s next reflow overwrites the keyframe.

Wrong:

RectTransform.m_SizeDelta.x  ───▶ overwritten by AutoLayout
RectTransform.m_AnchoredPosition.x ───▶ overwritten by AutoLayout

Right:

AutoLayout.m_Width.Value  ───▶ AutoLayout reads this and applies to sizeDelta
AutoLayout.m_Margin.Left  ───▶ AutoLayout reads this and applies to anchoredPosition

If you need to animate a property AutoLayout doesn’t control (scale, rotation, color), keep using the RectTransform / Image / TMP_Text bindings — those aren’t driven.

Animator vs declarative Transitions

AutoLayout has a declarative Transitions system for CSS-style animations that fire when you change a property from code. Per property, pick one or the other — not both:

	Use Animator when…	Use Transitions when…
Workflow	You’re a designer who lives in the Animation Window	You’re a programmer writing setter-driven UI
Trigger	Animator state transitions, timeline events	Property setter from script
Curve authoring	Visual, key-framed	EasePreset / AnimationCurve per rule
What it animates	Inputs and outputs (anything serialized)	Engine-aware: Width/Height even reflow siblings during the tween

If you keyframe m_Linear.Gap in an Animator clip and set a Transition rule on Gap, the Animator wins — it writes the field directly, bypassing the setter the transition system intercepts.

Calling from non-Animator animation libraries

DOTween, FairyGUI, custom tween systems — anything that mutates the private backing fields directly — won’t trigger a layout rebuild by itself. Call the public hook after your write:

DOTween.To(() => layout.m_Linear.Gap, x =>
{
    // Direct field write via reflection or unsafe code — bypasses setter.
    SetGapFieldDirectly(layout, x);
    layout.NotifyAnimatorPropertiesApplied();
}, 50f, 0.4f);

For 95% of DOTween use cases you don’t need this — just animate through the public setter (layout.Gap = x), which already calls MarkLayoutDirty. NotifyAnimatorPropertiesApplied is the escape hatch when something else (typically a clip-driven system) writes the field for you.

Performance

The hook fires every frame the Animator is updating the component — typically 60Hz. Each fire runs a structural diff (~50 field comparisons) against a per-component snapshot, then emits the narrowest DirtyType mask covering the changes (SizeX, LayoutSettings, PositionY, …). On clip plateaus where the curve produces an unchanged value, the diff short-circuits and no dirty mark is emitted — the loop pause cost is just the comparison itself.

Sizing-type flips (e.g. Fill ↔ Pixels via a discrete curve) route through the dependency-flag invalidation path so sibling Fill redistribution stays coherent. Structural flips (LayoutType, Placement, Visibility.Collapsed) escalate to a full island recalc.

Edit-mode preview

OnDidApplyAnimationProperties fires in the Editor too — the Animation Window scrub-preview shows the layout reflowing in real time as you drag the timeline. No need to enter Play mode just to check that a clip looks right.

Demo scene

Tools → AutoLayout PRO → Generate Animator Demo Scene builds a minimal example: a Row container with m_Linear.Gap and m_Padding.Left pulsing on a 2-second loop. Open the generated scene and press Play to see the breathe effect.