// 拖拽实现
// 属性 包含拖拽盒子的大盒子 拖拽的盒子 盒子的坐标位置
class Touch {
constructor(outerBox, move) {
this.outerBox = outerBox //包含的盒子
this.move = move //移动的盒子
this.point = { //坐标位置
x: parseInt(this.getStyle(move).left) || 0,
y: parseInt(this.getStyle(move).top) || 0
} //基础坐标为0,0
this.handlerDown()
}
//获取样式的方法
getStyle(element) {
return window.getComputedStyle ? window.getComputedStyle(element, '') :
element.currentStyle
}
//按下
handlerDown(){
this.move.onmousedown = (e)=>{
e = e || window.event
//获取第一次按下的位置
let currentX = e.offsetX
let currentY = e.offsetY
//调用移动的方法
this.handlerMove(currentX,currentY)
//调用弹起的方法
this.handlerUp()
}
}
//弹起
handlerUp(){
document.onmouseup = ()=>{
this.outerBox.onmousemove = null
}
}
//移动
handlerMove(currentX,currentY){
//给大盒子添加移动事件
this.outerBox.onmousemove = (e) => {
e = e || window.event
//大盒子在页面上的位置
let { x, y } = this.getPagePoint(this.outerBox)
//获取移动的位置 - 大盒子在页面上的位置 - 当前按下位置
let { targetX, targetY } = {
targetX: e.pageX - x - currentX,
targetY: e.pageY - y - currentY
}
let { maxX, maxY } = {基于面向的拖拽实现放大镜
maxX: this.outerBox.offsetWidth - this.move.offsetWidth,
maxY: this.outerBox.offsetHeight - this.move.offsetHeight
}
//区间判断
if (targetX < 0) {
targetX = 0
}
if (targetX > maxX) {
targetX = maxX
}
if (targetY < 0) {
targetY = 0
}
if (targetY > maxY) {
targetY = maxY
}
//将对应的位置设置进去
this.point = { x: targetX, y: targetY }
this.setMovePoint()
}
}
setMovePoint() {
//设置
this.move.style.left = this.point.x + 'px'
this.move.style.top = this.point.y + 'px'
}
getPagePoint(element) {
let x = 0
let y = 0
while (element.offsetParent) {
x += element.offsetLeft
y += element.offsetTop
element = element.offsetParent
}
return { x, y }
}
}
