Source: tiny/core/textures/RenderTexture.js

import BaseRenderTexture from './BaseRenderTexture';
import Texture from './Texture';

/**
 * A RenderTexture is a special texture that allows any 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 = (new Tiny.Application()).renderer;
 * let renderTexture = Tiny.RenderTexture.create(800, 600);
 * let sprite = Tiny.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 = Tiny.RenderTexture.create(100, 100);
 *
 * renderer.render(sprite, renderTexture);  // Renders to center of RenderTexture
 * ```
 *
 * @class
 * @extends Tiny.Texture
 * @memberof Tiny
 */
export default class RenderTexture extends Texture {
  /**
   * @param {Tiny.BaseRenderTexture} baseRenderTexture - The renderer used for this RenderTexture
   * @param {Tiny.Rectangle} [frame] - The rectangle frame of the texture to show
   */
  constructor(baseRenderTexture, frame) {
    /**
     * The base texture object that this texture uses
     *
     * @member {BaseTexture}
     */
    super(
      baseRenderTexture,
      frame
    );

    /**
     * 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=Tiny.settings.SCALE_MODE] - See {@link Tiny.SCALE_MODES} for possible values
   * @param {number} [resolution=1] - The resolution / device pixel ratio of the texture being generated
   * @return {Tiny.RenderTexture} The new render texture
   */
  static create(width, height, scaleMode, resolution) {
    return new RenderTexture(new BaseRenderTexture(width, height, scaleMode, resolution));
  }
}