前言
前面两章已经介绍怎么开发一个chrome插件和怎么使用vue搭建一个弹出框的chrome插件，这一章来实现页面元素选择的功能，效果如下图，鼠标放到元素上，元素会高亮：
主要实现思路，创建一个和页面一样宽高的蒙层，监听蒙层的鼠标移动事件，再使用elementFromPoint函数来获得当前鼠标所在位置的页面元素，具体实现如下：shelter.js这是主函数
import $ from 'jquery';
import validateSelect from './validateSelected';
import isContentElement from "./isContentElement";
//选择遮罩
export default class {
constructor() {
this.shelter = $("<div class='layuiex'></div>"); //选择过程中的div
this.shelter.attr("id", "__pAp_SpiderShelter");
this.block = $("<div class='layuiex'></div>");
this.lastSelectEl = null; //当前鼠标移动到元素
this.shelterInterval = null;
$(document.body).append(this.shelter);
$(document.body).append(this.block);
}
beginSelect(onDomClick, onContextMenu, callback) {
let that = this;
this.shelter.css("position", "absolute");
this.shelter.css("display", "block");
this.shelter.addClass("pAp_spider_Selecter_Block");
this.shelter.bind("click", onDomClick);
this.shelter.show();
this.shelter.css("width", "100%");
this.shelter.css("height", $(document).height() + "px");
this.shelter.css("left", "0");
this.shelter.css("top", "0");
this.shelter.mousemove(this.onShelterMouseMove(callback));
//初始化遮罩
function initCover() {
that.shelterInterval = setInterval(function() {
//如果遮罩层的高度小于页面高度，则将遮罩的高度设置成页面高度
if ($(document).height() > that.shelter.height()) {
that.hideCover();
that.showCover();
}
}, 500);
}
//鼠标移动到遮罩层上的时候，重置遮罩层
this.shelter.mouseover(function() {
if (that.shelterInterval) {
clearInterval(that.shelterInterval);
that.shelterInterval = null;
}
}).mouseout(initCover);
this.block.css("position", "absolute");
this.block.css("display", "block");
this.block.show();
this.showShelter(); //显示遮罩阴影
this.block.css("z-index", "19891009")
this.shelter.css("z-index", "19891010");
//绑定右键事件
document.oncontextmenu = onContextMenu;
//鼠标滚动事件，目的是防止页面滚动
$(this.shelter).on("mousewheel", function(evt) {
event.stopPropagation();
event.preventDefault();
var height = evt.originalEvent.wheelDelta;
if (!that.lastSelectEl) return;
var el = that.lastSelectEl.get(0);
while (el) {
if (el.scrollHeight > el.offsetHeight || el.tagName == "BODY") {
var lastTop = el.scrollTop;
el.scrollTop = el.scrollTop - height;
if (lastTop !== el.scrollTop) {
break;
}
}
el = el.parentElement;
}
});
initCover();
};
endSelect(callback) {
if (this.shelterInterval) {
clearInterval(this.shelterInterval);
this.shelterInterval = null;
}
this.shelter.unbind();
this.shelter.remove();
this.block.remove();
$(document).unbind();
document.oncontextmenu = function() {};
callback && callback();
};
showShelter() {
this.block.css("box-shadow", "0 0 20px #d4930d");
};
hideShelter() {
this.block.css("box-shadow", "none");
};
//鼠标移动时的操作
onShelterMouseMove(callback) {
let that = this;
var position = {
x: 0,
y: 0
};
return function(e) {
event.stopPropagation();
if (Math.abs(position.x - e.pageX) > 10 || Math.abs(position.y - e.pageY) > 10) {
//隐藏蒙层
that.hideCover();
//返回当前鼠标所在位置的最顶层元素，也就是鼠标所在的页面元素
var el = $(document.elementFromPoint(e.clientX, e.clientY));
//显示蒙层
that.showCover();
//如果是弹出框或者是遮罩则返回
if (!isContentElement(el)) return;
//如果元素中有我们生成的属性，则取父元素
if (!validateSelect(el)) {
el = el.parent();
}
if (!that.lastSelectEl || that.lastSelectEl.get(0) != el.get(0)) {
that.lastSelectEl = el;
}
position = {
x: e.pageX,
y: e.pageY
};
that.setPosition(el, that.block);
callback && callback(that.lastSelectEl);
}
}
}
setShelterPosition(el) {
this.setPosition(el, this.shelter);
}
/**
* 把选择框设置当当前选择元素的位置
* @param {Jquery Dom Element} el 选择的元素
* @param {Jquery Dom Element} shelter 遮罩层
*/
setPosition(el, shelter) {
if ((el.width() == 0 || el.height() == 0) && el.get(0).tagName == 'A' && el.children().length) {
that.setPosition(el.children().eq(0), shelter);
return;
}
var paddingObject = {
left: parseInt(el.css("padding-left")),
top: parseInt(el.css("padding-top")),
right: parseInt(el.css("padding-right")),
bottom: parseInt(el.css("padding-bottom"))
};
var _width = 0,
_height = 0;
if (!isNaN(paddingObject.left)) {
_width += paddingObject.left;
}
if (!isNaN(paddingObject.right)) {
_width += paddingObject.right;
}
if (!isNaN(paddingObject.top)) {
_height += paddingObject.top;
}
if (!isNaN(paddingObject.bottom)) {
_height += paddingObject.bottom;
}
var top = parseInt(el.offset().top);
var height = el.height() + _height;
var availHeight = $(document).height() - top;
height = height > availHeight ? availHeight : height;
var obj = {
"left": parseInt(el.offset().left) + "px",
"top": top + "px",
"width": el.width() + _width,
"height": height
};
shelter.css(obj);
};
hideCover() {
this.block.css("z-index", "-2")
this.shelter.css("z-index", "-1");
this.shelter.css("display", "none");
this.block.css("display", "none");
};
showCover() {
this.shelter.css("display", "block");
this.block.css("display", "block");
this.block.css("z-index", "19891009")
this.shelter.css("z-index", "19891010");
var height = $(document).height();
this.shelter.css("width", "100%");
this.shelter.css("height", height + "px");
this.shelter.css("left", "0");
this.shelter.css("top", "0");
};
setBlockCss(key, value) {
this.block.css(key, value);
}
setShelterCss(key, value) {
this.shelter.css(key, value);
}
}
validateSelected.js确保所选择的元素是页面本身的元素
import $ from 'jquery';
/**
* 判断是否有我们生成的元素，即被我们标记为选中的元素
* @param {*} element
*/
export default function(element) {
var el = $(element);
if (el.attr("__pAp_select")) {
return false;
}
if (el.hasClass("__pAp_selectrow")) {
return false;
}
return true;
};
isContentElement.js这个函数的作用也是确保所选择的的元素是页面自有的元素
import $ from 'jquery';
/*
判断是否内容元素，也就是判断是不是我们的弹出框或者是遮罩
*/
export default function(element) {
var expectClasses = [".layuiex", ".layuiex-layer", ".layuiex-layer-shade", ".layuiex-layer-moves", ".pAp_spider_Selecter_Block"];
for (var _i = 0; _i < expectClasses.length; _i++) {
var els = $(expectClasses[_i]);
for (var a = 0; a < els.length; a++) {
//$.contains( container, contained )
//检测一个元素包含在另一个元素之内
//container Element类型 指定可能包含其他元素的祖辈容器元素。
//contained Element类型 指定可能被其他元素包含的后代元素。
if ($.contains(els.eq(a).get(0), element) || els.eq(a).get(0) == element) {
return false;
}
}
}
return true;
};
这样页面选择函数就写完了，下面就是引用了，在main.js中添加函数
import Vue from 'vue';
import $ from "jquery";
import './layer/layer.css';
import layer from './layer/layer';
import shelter from './js/selector/shelter';
Vue.config.productionTip = false;
let shelterUi = new shelter();
......
new Vue({
el: "#__paApa_container",
components: {},
data() {
return {
selectedEl: null
};
},
mounted() {
let that = this;
shelterUi.beginSelect(that.onDomClick, null,
function(selectedEl) {
that.selectedEl = selectedEl;
});
},
methods: {
onDomClick() {
console.log('点击');
}
}
});
以上就完成了页面选择功能