Source: packages/display/src/Container.js

packages/display/src/Container.js

import { settings } from '@pixi/settings';
import { removeItems } from '@pixi/utils';
import DisplayObject from './DisplayObject';

function sortChildren(a, b)
{
    if (a.zIndex === b.zIndex)
    {
        return a._lastSortedIndex - b._lastSortedIndex;
    }

    return a.zIndex - b.zIndex;
}

/**
 * A Container represents a collection of display objects.
 *
 * It is the base class of all display objects that act as a container for other objects (like Sprites).
 *
 *```js
 * let container = new PIXI.Container();
 * container.addChild(sprite);
 * ```
 *
 * @class
 * @extends PIXI.DisplayObject
 * @memberof PIXI
 */
export default class Container extends DisplayObject
{
    constructor()
    {
        super();

        /**
         * The array of children of this container.
         *
         * @member {PIXI.DisplayObject[]}
         * @readonly
         */
        this.children = [];

        /**
         * If set to true, the container will sort its children by zIndex value
         * when updateTransform() is called, or manually if sortChildren() is called.
         *
         * This actually changes the order of elements in the array, so should be treated
         * as a basic solution that is not performant compared to other solutions,
         * such as @link https://github.com/pixijs/pixi-display
         *
         * Also be aware of that this may not work nicely with the addChildAt() function,
         * as the zIndex sorting may cause the child to automatically sorted to another position.
         *
         * @see PIXI.settings.SORTABLE_CHILDREN
         *
         * @member {boolean}
         */
        this.sortableChildren = settings.SORTABLE_CHILDREN;

        /**
         * Should children be sorted by zIndex at the next updateTransform call.
         * Will get automatically set to true if a new child is added, or if a child's zIndex changes.
         *
         * @member {boolean}
         */
        this.sortDirty = false;

        /**
         * Fired when a DisplayObject is added to this Container.
         *
         * @event PIXI.Container#childAdded
         * @param {PIXI.DisplayObject} child - The child added to the Container.
         * @param {PIXI.Container} container - The container that added the child.
         * @param {number} index - The children's index of the added child.
         */

        /**
         * Fired when a DisplayObject is removed from this Container.
         *
         * @event PIXI.DisplayObject#removedFrom
         * @param {PIXI.DisplayObject} child - The child removed from the Container.
         * @param {PIXI.Container} container - The container that removed removed the child.
         * @param {number} index - The former children's index of the removed child
         */
    }

    /**
     * Overridable method that can be used by Container subclasses whenever the children array is modified
     *
     * @protected
     */
    onChildrenChange()
    {
        /* empty */
    }

    /**
     * Adds one or more children to the container.
     *
     * Multiple items can be added like so: `myContainer.addChild(thingOne, thingTwo, thingThree)`
     *
     * @param {...PIXI.DisplayObject} child - The DisplayObject(s) to add to the container
     * @return {PIXI.DisplayObject} The first child that was added.
     */
    addChild(child)
    {
        const argumentsLength = arguments.length;

        // if there is only one argument we can bypass looping through the them
        if (argumentsLength > 1)
        {
            // loop through the arguments property and add all children
            // use it the right way (.length and [i]) so that this function can still be optimized by JS runtimes
            for (let i = 0; i < argumentsLength; i++)
            {
                this.addChild(arguments[i]);
            }
        }
        else
        {
            // if the child has a parent then lets remove it as PixiJS objects can only exist in one place
            if (child.parent)
            {
                child.parent.removeChild(child);
            }

            child.parent = this;
            this.sortDirty = true;

            // ensure child transform will be recalculated
            child.transform._parentID = -1;

            this.children.push(child);

            // ensure bounds will be recalculated
            this._boundsID++;

            // TODO - lets either do all callbacks or all events.. not both!
            this.onChildrenChange(this.children.length - 1);
            this.emit('childAdded', child, this, this.children.length - 1);
            child.emit('added', this);
        }

        return child;
    }

    /**
     * Adds a child to the container at a specified index. If the index is out of bounds an error will be thrown
     *
     * @param {PIXI.DisplayObject} child - The child to add
     * @param {number} index - The index to place the child in
     * @return {PIXI.DisplayObject} The child that was added.
     */
    addChildAt(child, index)
    {
        if (index < 0 || index > this.children.length)
        {
            throw new Error(`${child}addChildAt: The index ${index} supplied is out of bounds ${this.children.length}`);
        }

        if (child.parent)
        {
            child.parent.removeChild(child);
        }

        child.parent = this;
        this.sortDirty = true;

        // ensure child transform will be recalculated
        child.transform._parentID = -1;

        this.children.splice(index, 0, child);

        // ensure bounds will be recalculated
        this._boundsID++;

        // TODO - lets either do all callbacks or all events.. not both!
        this.onChildrenChange(index);
        child.emit('added', this);
        this.emit('childAdded', child, this, index);

        return child;
    }

    /**
     * Swaps the position of 2 Display Objects within this container.
     *
     * @param {PIXI.DisplayObject} child - First display object to swap
     * @param {PIXI.DisplayObject} child2 - Second display object to swap
     */
    swapChildren(child, child2)
    {
        if (child === child2)
        {
            return;
        }

        const index1 = this.getChildIndex(child);
        const index2 = this.getChildIndex(child2);

        this.children[index1] = child2;
        this.children[index2] = child;
        this.onChildrenChange(index1 < index2 ? index1 : index2);
    }

    /**
     * Returns the index position of a child DisplayObject instance
     *
     * @param {PIXI.DisplayObject} child - The DisplayObject instance to identify
     * @return {number} The index position of the child display object to identify
     */
    getChildIndex(child)
    {
        const index = this.children.indexOf(child);

        if (index === -1)
        {
            throw new Error('The supplied DisplayObject must be a child of the caller');
        }

        return index;
    }

    /**
     * Changes the position of an existing child in the display object container
     *
     * @param {PIXI.DisplayObject} child - The child DisplayObject instance for which you want to change the index number
     * @param {number} index - The resulting index number for the child display object
     */
    setChildIndex(child, index)
    {
        if (index < 0 || index >= this.children.length)
        {
            throw new Error(`The index ${index} supplied is out of bounds ${this.children.length}`);
        }

        const currentIndex = this.getChildIndex(child);

        removeItems(this.children, currentIndex, 1); // remove from old position
        this.children.splice(index, 0, child); // add at new position

        this.onChildrenChange(index);
    }

    /**
     * Returns the child at the specified index
     *
     * @param {number} index - The index to get the child at
     * @return {PIXI.DisplayObject} The child at the given index, if any.
     */
    getChildAt(index)
    {
        if (index < 0 || index >= this.children.length)
        {
            throw new Error(`getChildAt: Index (${index}) does not exist.`);
        }

        return this.children[index];
    }

    /**
     * Removes one or more children from the container.
     *
     * @param {...PIXI.DisplayObject} child - The DisplayObject(s) to remove
     * @return {PIXI.DisplayObject} The first child that was removed.
     */
    removeChild(child)
    {
        const argumentsLength = arguments.length;

        // if there is only one argument we can bypass looping through the them
        if (argumentsLength > 1)
        {
            // loop through the arguments property and add all children
            // use it the right way (.length and [i]) so that this function can still be optimized by JS runtimes
            for (let i = 0; i < argumentsLength; i++)
            {
                this.removeChild(arguments[i]);
            }
        }
        else
        {
            const index = this.children.indexOf(child);

            if (index === -1) return null;

            child.parent = null;
            // ensure child transform will be recalculated
            child.transform._parentID = -1;
            removeItems(this.children, index, 1);

            // ensure bounds will be recalculated
            this._boundsID++;

            // TODO - lets either do all callbacks or all events.. not both!
            this.onChildrenChange(index);
            child.emit('removed', this);
            this.emit('childRemoved', child, this, index);
        }

        return child;
    }

    /**
     * Removes a child from the specified index position.
     *
     * @param {number} index - The index to get the child from
     * @return {PIXI.DisplayObject} The child that was removed.
     */
    removeChildAt(index)
    {
        const child = this.getChildAt(index);

        // ensure child transform will be recalculated..
        child.parent = null;
        child.transform._parentID = -1;
        removeItems(this.children, index, 1);

        // ensure bounds will be recalculated
        this._boundsID++;

        // TODO - lets either do all callbacks or all events.. not both!
        this.onChildrenChange(index);
        child.emit('removed', this);
        this.emit('childRemoved', child, this, index);

        return child;
    }

    /**
     * Removes all children from this container that are within the begin and end indexes.
     *
     * @param {number} [beginIndex=0] - The beginning position.
     * @param {number} [endIndex=this.children.length] - The ending position. Default value is size of the container.
     * @returns {PIXI.DisplayObject[]} List of removed children
     */
    removeChildren(beginIndex = 0, endIndex)
    {
        const begin = beginIndex;
        const end = typeof endIndex === 'number' ? endIndex : this.children.length;
        const range = end - begin;
        let removed;

        if (range > 0 && range <= end)
        {
            removed = this.children.splice(begin, range);

            for (let i = 0; i < removed.length; ++i)
            {
                removed[i].parent = null;
                if (removed[i].transform)
                {
                    removed[i].transform._parentID = -1;
                }
            }

            this._boundsID++;

            this.onChildrenChange(beginIndex);

            for (let i = 0; i < removed.length; ++i)
            {
                removed[i].emit('removed', this);
                this.emit('childRemoved', removed[i], this, i);
            }

            return removed;
        }
        else if (range === 0 && this.children.length === 0)
        {
            return [];
        }

        throw new RangeError('removeChildren: numeric values are outside the acceptable range.');
    }

    /**
     * Sorts children by zIndex. Previous order is mantained for 2 children with the same zIndex.
     */
    sortChildren()
    {
        let sortRequired = false;

        for (let i = 0, j = this.children.length; i < j; ++i)
        {
            const child = this.children[i];

            child._lastSortedIndex = i;

            if (!sortRequired && child.zIndex !== 0)
            {
                sortRequired = true;
            }
        }

        if (sortRequired && this.children.length > 1)
        {
            this.children.sort(sortChildren);
        }

        this.sortDirty = false;
    }

    /**
     * Updates the transform on all children of this container for rendering
     */
    updateTransform()
    {
        if (this.sortableChildren && this.sortDirty)
        {
            this.sortChildren();
        }

        this._boundsID++;

        this.transform.updateTransform(this.parent.transform);

        // TODO: check render flags, how to process stuff here
        this.worldAlpha = this.alpha * this.parent.worldAlpha;

        for (let i = 0, j = this.children.length; i < j; ++i)
        {
            const child = this.children[i];

            if (child.visible)
            {
                child.updateTransform();
            }
        }
    }

    /**
     * Recalculates the bounds of the container.
     *
     */
    calculateBounds()
    {
        this._bounds.clear();

        this._calculateBounds();

        for (let i = 0; i < this.children.length; i++)
        {
            const child = this.children[i];

            if (!child.visible || !child.renderable)
            {
                continue;
            }

            child.calculateBounds();

            // TODO: filter+mask, need to mask both somehow
            if (child._mask)
            {
                child._mask.calculateBounds();
                this._bounds.addBoundsMask(child._bounds, child._mask._bounds);
            }
            else if (child.filterArea)
            {
                this._bounds.addBoundsArea(child._bounds, child.filterArea);
            }
            else
            {
                this._bounds.addBounds(child._bounds);
            }
        }

        this._lastBoundsID = this._boundsID;
    }

    /**
     * Recalculates the bounds of the object. Override this to
     * calculate the bounds of the specific object (not including children).
     *
     * @protected
     */
    _calculateBounds()
    {
        // FILL IN//
    }

    /**
     * Renders the object using the WebGL renderer
     *
     * @param {PIXI.Renderer} renderer - The renderer
     */
    render(renderer)
    {
        // if the object is not visible or the alpha is 0 then no need to render this element
        if (!this.visible || this.worldAlpha <= 0 || !this.renderable)
        {
            return;
        }

        // do a quick check to see if this element has a mask or a filter.
        if (this._mask || (this.filters && this.filters.length))
        {
            this.renderAdvanced(renderer);
        }
        else
        {
            this._render(renderer);

            // simple render children!
            for (let i = 0, j = this.children.length; i < j; ++i)
            {
                this.children[i].render(renderer);
            }
        }
    }

    /**
     * Render the object using the WebGL renderer and advanced features.
     *
     * @protected
     * @param {PIXI.Renderer} renderer - The renderer
     */
    renderAdvanced(renderer)
    {
        renderer.batch.flush();

        const filters = this.filters;
        const mask = this._mask;

        // push filter first as we need to ensure the stencil buffer is correct for any masking
        if (filters)
        {
            if (!this._enabledFilters)
            {
                this._enabledFilters = [];
            }

            this._enabledFilters.length = 0;

            for (let i = 0; i < filters.length; i++)
            {
                if (filters[i].enabled)
                {
                    this._enabledFilters.push(filters[i]);
                }
            }

            if (this._enabledFilters.length)
            {
                renderer.filter.push(this, this._enabledFilters);
            }
        }

        if (mask)
        {
            renderer.mask.push(this, this._mask);
        }

        // add this object to the batch, only rendered if it has a texture.
        this._render(renderer);

        // now loop through the children and make sure they get rendered
        for (let i = 0, j = this.children.length; i < j; i++)
        {
            this.children[i].render(renderer);
        }

        renderer.batch.flush();

        if (mask)
        {
            renderer.mask.pop(this, this._mask);
        }

        if (filters && this._enabledFilters && this._enabledFilters.length)
        {
            renderer.filter.pop();
        }
    }

    /**
     * To be overridden by the subclasses.
     *
     * @protected
     * @param {PIXI.Renderer} renderer - The renderer
     */
    _render(renderer) // eslint-disable-line no-unused-vars
    {
        // this is where content itself gets rendered...
    }

    /**
     * Removes all internal references and listeners as well as removes children from the display list.
     * Do not use a Container after calling `destroy`.
     *
     * @param {object|boolean} [options] - Options parameter. A boolean will act as if all options
     *  have been set to that value
     * @param {boolean} [options.children=false] - if set to true, all the children will have their destroy
     *  method called as well. 'options' will be passed on to those calls.
     * @param {boolean} [options.texture=false] - Only used for child Sprites if options.children is set to true
     *  Should it destroy the texture of the child sprite
     * @param {boolean} [options.baseTexture=false] - Only used for child Sprites if options.children is set to true
     *  Should it destroy the base texture of the child sprite
     */
    destroy(options)
    {
        super.destroy();

        this.sortDirty = false;

        const destroyChildren = typeof options === 'boolean' ? options : options && options.children;

        const oldChildren = this.removeChildren(0, this.children.length);

        if (destroyChildren)
        {
            for (let i = 0; i < oldChildren.length; ++i)
            {
                oldChildren[i].destroy(options);
            }
        }
    }

    /**
     * The width of the Container, setting this will actually modify the scale to achieve the value set
     *
     * @member {number}
     */
    get width()
    {
        return this.scale.x * this.getLocalBounds().width;
    }

    set width(value) // eslint-disable-line require-jsdoc
    {
        const width = this.getLocalBounds().width;

        if (width !== 0)
        {
            this.scale.x = value / width;
        }
        else
        {
            this.scale.x = 1;
        }

        this._width = value;
    }

    /**
     * The height of the Container, setting this will actually modify the scale to achieve the value set
     *
     * @member {number}
     */
    get height()
    {
        return this.scale.y * this.getLocalBounds().height;
    }

    set height(value) // eslint-disable-line require-jsdoc
    {
        const height = this.getLocalBounds().height;

        if (height !== 0)
        {
            this.scale.y = value / height;
        }
        else
        {
            this.scale.y = 1;
        }

        this._height = value;
    }
}

// performance increase to avoid using call.. (10x faster)
Container.prototype.containerUpdateTransform = Container.prototype.updateTransform;