参考链接：​​缩放模式​​ 代码

<!-- index.html -->

this.stage.scaleMode = egret.StageScaleMode.SHOW_ALL;
// this.stage.scaleMode = egret.StageScaleMode.NO_SCALE;
// this.stage.scaleMode = egret.StageScaleMode.NO_BORDER;
// this.stage.scaleMode = egret.StageScaleMode.EXACT_FIT;
// this.stage.scaleMode = egret.StageScaleMode.FIXED_WIDTH;
// this.stage.scaleMode = egret.StageScaleMode.FIXED_HEIGHT;
// this.stage.scaleMode = egret.StageScaleMode.FIXED_NARROW;
// this.stage.scaleMode = egret.StageScaleMode.FIXED_WIDTH;
const img = new egret.Bitmap(RES.getRes("bg_jpg"));
this.addChild(img);