Method _transitionCheckState

src/material/checkbox/checkbox.ts:360–389

(newState: TransitionCheckState)

  }

  private _transitionCheckState(newState: TransitionCheckState) {
    let oldState = this._currentCheckState;
    let element = this._getAnimationTargetElement();

    if (oldState === newState || !element) {
      return;
    }
    if (this._currentAnimationClass) {
      element.classList.remove(this._currentAnimationClass);
    }

    this._currentAnimationClass = this._getAnimationClassForCheckStateTransition(
      oldState,
      newState,
    );
    this._currentCheckState = newState;

    if (this._currentAnimationClass.length > 0) {
      element.classList.add(this._currentAnimationClass);

      // Remove the animation class to avoid animation when the checkbox is moved between containers
      const animationClass = this._currentAnimationClass;

      this._ngZone.runOutsideAngular(() => {
        setTimeout(() => {
          element!.classList.remove(animationClass);
        }, 1000);
      });
    }
  }

  private _emitChangeEvent() {
    this._controlValueAccessorChangeFn(this.checked);