laya-coreui-es/build/es/layaAir/laya/resource/Bitmap.js

laya核心库、ui库es版本，剔除了媒体、TTF等功能。基于 LayaAir-release_2.12.0 修改

import { Resource } from "./Resource";
export class Bitmap extends Resource {
    get width() {
        return this._width;
    }
    set width(width) {
        this._width = width;
    }
    get height() {
        return this._height;
    }
    set height(height) {
        this._height = height;
    }
    constructor() {
        super();
        this._width = -1;
        this._height = -1;
    }
    _getSource() {
        throw "Bitmap: must override it.";
    }
}