MD_YOSwechat/pages/threadedTree/modules/FloatingButton/index.js

Component({
    properties: {
        radius: Number //半径 单位px
    },
    data: {
        top: "550px",
        left: "345px",
        viewHeight: null
    },
    lifetimes: {
        attached: function () {
            let that = this;
            wx.getSystemInfo({
                success: (res => that.setData({
                    viewHeight: res.windowHeight
                }))
            });
        },
    },
    methods: {
        viewTouchMove(e) {
            let left = e.touches[0].pageX;
            if (left > (375 - this.data.radius)) left = 375 - (this.data.radius / 2);
            if (left < 0 + this.data.radius) left = 0 + this.data.radius;
            let top = e.touches[0].pageY;
            if (top < 0 + this.data.radius) top = 0 + this.data.radius;
            if (top > this.data.viewHeight - this.data.radius) top = this.data.viewHeight - this.data.radius;
            this.setData({
                left: left + 'px',
                top: top + 'px'
            })
        }
    }
})