微信小程序image自适应宽高完全显示

<image style="height: 200rpx;width: 200rpx;" src="https://gitee.com/xiaojisengren/tuchuang/raw/master/test/redPacketSuccess.png" mode="aspectFit" />

<image style="height: 200rpx;width: 200rpx;" src="https://gitee.com/xiaojisengren/tuchuang/raw/master/test/activityBackground.png" mode="aspectFit" />

给定image宽高就行,设置mode为aspectFit,就可以自适应完全显示长边了