LayoutConstraint¶

Overview¶

Abstract supertype for layout constraints. Provides a lot of assistance to layout handling, including adding/removing listeners, and reentrancy detection/loop prevention.

We'll also handle reentrancy somewhat specially. If code tries to enter a layout reentrantly (while a layout is already executing), we'll instead IGNORE this second one (and set a flag). Once our first layout is done, we'll attempt to run the layout again. In case the subtype needs to lock multiple times (if a layout is FORCED), we have an integer count of how many "layout" calls we're in (_layoutLockCount). Once this reaches zero, we're effectively unlocked and not inside any layout calls.

NOTE: This can still trigger infinite loops nominally (if every layout call triggers another layout call), but we have a practical assertion limit that will stop this and flag it as an error.

@author Jonathan Olson <jonathan.olson@colorado.edu>

Class LayoutConstraint¶

import { LayoutConstraint } from 'scenerystack/scenery';

Instance Methods¶

layout()¶

(protected)

NOTE: DO NOT call from places other than super.layout() in overridden layout() OR from the existing call in updateLayout(). Doing so would break the lock mechanism. NOTE: Cannot be marked as abstract due to how mixins work

updateLayout()¶

Updates the layout of this constraint. Called automatically during initialization, when children change (if resize is true), or when client wants to call this public method for any reason.

dispose()¶

Releases references

Instance Properties¶

ancestorNode : Node¶

(readonly)

The Node in whose local coordinate frame our layout computations are done.

Source Code¶

See the source for LayoutConstraint.ts in the scenery repository.