绘制开放域需要在主域中设置画板大小，开放域中能少绘制就少绘制，
/**
* 绘制开放域数据
* @param {*} layout 用来显示开放域数据的Sprite
*/
function drawOpenData(layout: Laya.Sprite) {
var openDataContext = wx.getOpenDataContext()
var sharedCanvas = openDataContext.canvas
sharedCanvas.width = layout.width;
sharedCanvas.height = layout.height;
//先清空绘制
layout.graphics.clear(false);
//设置大小
var canvas = new Laya.Texture(sharedCanvas);
canvas.bitmap.alwaysChange = true;//小游戏使用，非常费，每帧刷新
layout.graphics.drawTexture(canvas);
}
