Method setChildIndex

packages/fairygui/src/core/GComponent.ts:250–268

* Set child index * 设置子对象索引

(child: GObject, index: number)

     * 设置子对象索引
     */
    public setChildIndex(child: GObject, index: number): void {
        const oldIndex = this._children.indexOf(child);
        if (oldIndex === -1) {
            throw new Error('Not a child of this container');
        }

        if (child.sortingOrder !== 0) {
            return;
        }

        const count = this._children.length;
        if (this._sortingChildCount > 0) {
            if (index > count - this._sortingChildCount - 1) {
                index = count - this._sortingChildCount - 1;
            }
        }

        this.moveChild(child, oldIndex, index);
    }

    /**
     * Set child index before another child