Source: core/textures/RenderTexture.js

import BaseRenderTexture from './BaseRenderTexture';
import Texture from './Texture';
/**
 * A RenderTexture is a special texture that allows any PixiJS display object to be rendered to it.
 *
 * __Hint__: All DisplayObjects (i.e. Sprites) that render to a RenderTexture should be preloaded
 * otherwise black rectangles will be drawn instead.
 *
 * A RenderTexture takes a snapshot of any Display Object given to its render method. For example:
 *
 * ```js
 * let renderer = PIXI.autoDetectRenderer(1024, 1024);
 * let renderTexture = PIXI.RenderTexture.create(800, 600);
 * let sprite = PIXI.Sprite.fromImage("spinObj_01.png");
 *
 * sprite.position.x = 800/2;
 * sprite.position.y = 600/2;
 * sprite.anchor.x = 0.5;
 * sprite.anchor.y = 0.5;
 *
 * renderer.render(sprite, renderTexture);
 * ```
 *
 * The Sprite in this case will be rendered using its local transform. To render this sprite at 0,0
 * you can clear the transform
 *
 * ```js
 *
 * sprite.setTransform()
 *
 * let renderTexture = new PIXI.RenderTexture.create(100, 100);
 *
 * renderer.render(sprite, renderTexture);  // Renders to center of RenderTexture
 * ```
 *
 * @class
 * @extends PIXI.Texture
 * @memberof PIXI
 */
export default class RenderTexture extends Texture
{
    /**
     * @param {PIXI.BaseRenderTexture} baseRenderTexture - The renderer used for this RenderTexture
     * @param {PIXI.Rectangle} [frame] - The rectangle frame of the texture to show
     */
    constructor(baseRenderTexture, frame)
    {
        // support for legacy..
        let _legacyRenderer = null;
        if (!(baseRenderTexture instanceof BaseRenderTexture))
        {
            /* eslint-disable prefer-rest-params, no-console */
            const width = arguments[1];
            const height = arguments[2];
            const scaleMode = arguments[3];
            const resolution = arguments[4];
            // we have an old render texture..
            console.warn(`Please use RenderTexture.create(${width}, ${height}) instead of the ctor directly.`);
            _legacyRenderer = arguments[0];
            /* eslint-enable prefer-rest-params, no-console */
            frame = null;
            baseRenderTexture = new BaseRenderTexture(width, height, scaleMode, resolution);
        }
        /**
         * The base texture object that this texture uses
         *
         * @member {BaseTexture}
         */
        super(
            baseRenderTexture,
            frame
        );
        this.legacyRenderer = _legacyRenderer;
        /**
         * This will let the renderer know if the texture is valid. If it's not then it cannot be rendered.
         *
         * @member {boolean}
         */
        this.valid = true;
        this._updateUvs();
    }
    /**
     * Resizes the RenderTexture.
     *
     * @param {number} width - The width to resize to.
     * @param {number} height - The height to resize to.
     * @param {boolean} doNotResizeBaseTexture - Should the baseTexture.width and height values be resized as well?
     */
    resize(width, height, doNotResizeBaseTexture)
    {
        width = Math.ceil(width);
        height = Math.ceil(height);
        // TODO - could be not required..
        this.valid = (width > 0 && height > 0);
        this._frame.width = this.orig.width = width;
        this._frame.height = this.orig.height = height;
        if (!doNotResizeBaseTexture)
        {
            this.baseTexture.resize(width, height);
        }
        this._updateUvs();
    }
    /**
     * A short hand way of creating a render texture.
     *
     * @param {number} [width=100] - The width of the render texture
     * @param {number} [height=100] - The height of the render texture
     * @param {number} [scaleMode=PIXI.settings.SCALE_MODE] - See {@link PIXI.SCALE_MODES} for possible values
     * @param {number} [resolution=1] - The resolution / device pixel ratio of the texture being generated
     * @return {PIXI.RenderTexture} The new render texture
     */
    static create(width, height, scaleMode, resolution)
    {
        return new RenderTexture(new BaseRenderTexture(width, height, scaleMode, resolution));
    }
}