使用SVG基本操作API的实例讲解

前面的话

本文将详细介绍svg基本操作api，并使用这些api制作实例效果

基础api

在javascript中，可以使用一些基本的api来对svg进行操作

【ns地址】

因为svg定义在其自身的命令空间下，而不是html的命名空间下，可以作为单独的xml文件存在。所以需要使用自身的ns地址

有两个常用的ns地址

var svg_ns = "http://www.w3.org/2000/svg";
var xlink_ns = http://www.w3.org/1999/xlink;

【创建图形】

document.createelementns(svg_ns,tagname);

【添加图形】

element.appendchild(childelement)

【设置/获取属性】

element.setattribute(name,value);
element.getattribute(name);

【设置xlink】

<a>、<textpath>等标签需要设置xlink属性

element.setattributens(xlink_ns,'xlink:href',value);

封装函数

将创建标签及添加属性的操作封闭成一个函数，方便复用

function createtag(tag,objattr){
 var otag = document.createelementns('http://www.w3.org/2000/svg',tag);
  for(var attr in objattr){
  if(attr == 'xlink:href'){
   otag.setattributens("http://www.w3.org/1999/xlink",attr,objattr[attr]);
  }else{
   otag.setattribute(attr,objattr[attr]);
  }  
  } 
 return otag;
}

下面通过该函数，创建一个圆形

<script>
function createtag(tag,objattr){
 var otag = document.createelementns('http://www.w3.org/2000/svg',tag);
  for(var attr in objattr){
  if(attr == 'xlink:href'){
   otag.setattributens("http://www.w3.org/1999/xlink",attr,objattr[attr]);
  }else{
   otag.setattribute(attr,objattr[attr]);
  }  
  } 
 return otag;
} 
var osvg = createtag('svg',{'version':'1.1','xmls':'http://www.w3.org/2000/svg',height:'70'});
var ocircle = createtag('circle',{'cx':'25','cy':'25','r':20,'fill':'pink'});
osvg.appendchild(ocircle);
document.body.appendchild(osvg);
</script>

实例

下面通过svg基本操作api，创建一个可交互的svg实例

<style>
#box{
 height: 300px;
 width: 300px;
 background: hsl(20,40%,90%);
 background-image:linear-gradient(90deg,#fb3 11px,transparent 0),
 linear-gradient(90deg,#ab4 23px,transparent 0),
 linear-gradient(90deg,#655 41px,transparent 0);
 background-size: 41px 100%,61px 100%,83px 100%; 
} 
</style>
<div id="box"></div>
<script>
var osvg = createtag('svg',{'version':'1.1','xmls':'http://www.w3.org/2000/svg',height:'100%',width:'100%'});
var obox = document.getelementbyid('box');
var w = parseint(getcomputedstyle(obox).width);
var h = parseint(getcomputedstyle(obox).height);
var appearance = {
 'dis':h/3,
 'r0':h/8,'r':h/10,
 'x0':w/2,'y0':h/2,
 'fontsize':h/20,
 'bg0':'hsla(0,0%,100%,.6)','bg':'hsla(0,0%,100%,.3)',
 'color0':'hsl(210,13%,30%)','color':'hsl(210,13%,30%)',
 'bordercolor0':'rgba(0,0,0,0.3)','bordercolor':'rgba(0,0,0,0.3)',
 'strokwidth0':3,'strokwidth':2,
 'linecolor':'rgba(0,0,0,0.3)','linewidth':1,'linedashed':'5,5'
}
var data = {
 text:'前端开发',
 children:[
  {text:'html',url:'http://www.cnblogs.com/xiaohuochai/p/5203223.html'},
  {text:'css',url:'http://www.cnblogs.com/xiaohuochai/p/5249139.html'},
  {text:'js',url:'http://www.cnblogs.com/xiaohuochai/p/5613593.html'},
  {text:'es6',url:'http://www.cnblogs.com/xiaohuochai/p/7233392.html'},
  {text:'http',url:'http://www.cnblogs.com/xiaohuochai/p/6392010.html'},
  {text:'nodejs',url:'http://www.cnblogs.com/xiaohuochai/p/6940560.html'},
  {text:'前端工具',url:'http://www.cnblogs.com/xiaohuochai/p/6666415.html'},
 ], 
}
addchildentags();
addcentertag();
obox.appendchild(osvg);
function createtag(tag,objattr){
 var otag = document.createelementns('http://www.w3.org/2000/svg',tag);
  for(var attr in objattr){
  if(attr == 'xlink:href'){
   otag.setattributens("http://www.w3.org/1999/xlink",attr,objattr[attr]);
  }else{
   otag.setattribute(attr,objattr[attr]);
  }  
  } 
 return otag;
} 
function addcentertag(){
 var og = createtag('g',{'style':'cursor:default'});
 var ocircle = createtag('circle',{'cx':appearance.x0,'cy':appearance.y0,'r':appearance.r0,'fill':appearance.bg0,'stroke':appearance.bordercolor0,'stroke-width':appearance.strokwidth0});
 var otext = createtag('text',{'x':appearance.x0,'y':appearance.y0,'font-size':appearance.fontsize,'text-anchor':'middle','dominant-baseline':'middle','stroke-width':appearance.strokwidth0});
 otext.innerhtml = data.text;
 og.appendchild(ocircle);
 og.appendchild(otext);
 osvg.appendchild(og);
}
function addchildentags(){
 var children = data.children;
 var length = children.length;
 var deg = (360/length)*(2*math.pi)/360;
 for(var i = 0; i < children.length;i++){
  var cos = math.cos(deg*i - 90);
  var sin = math.sin(deg*i - 90);
  var x = appearance.x0 + appearance.dis*cos;
  var y = appearance.y0 + appearance.dis*sin;
  var oa = createtag('a',{'xlink:href':children[i].url,'target':'_black'}); 
  var og = createtag('g',{'style':'cursor:pointer'}); 
  og.index = i;    
  var oline = createtag('line',{'x1':x-appearance.r*cos,y1:y-appearance.r*sin,x2:appearance.x0+appearance.r0*cos,y2:appearance.y0+appearance.r0*sin,'stroke':appearance.linecolor,'stroke-width':appearance.linewidth,'stroke-dasharray':appearance.linedashed,'style':'transition:.5s'});
  var olinehelper = createtag('line',{'x1':x-appearance.r*cos,y1:y-appearance.r*sin,x2:appearance.x0+appearance.r0*cos,y2:appearance.y0+appearance.r0*sin,'stroke':'transparent','stroke-width':10});  
  var ocircle = createtag('circle',{'cx':x,'cy':y,'r':appearance.r,'fill':appearance.bg,'stroke':appearance.bordercolor,'stroke-width':appearance.strokwidth,'class':'frostedglass'});
  var otext = createtag('text',{'x':x,'y':y,'font-size':appearance.fontsize,'text-anchor':'middle','dominant-baseline':'middle','stroke-width':appearance.strokwidth,fill:appearance.color});
  otext.innerhtml = children[i].text; 
  og.appendchild(oline);
  og.appendchild(olinehelper);   
  og.appendchild(ocircle);     
  og.appendchild(otext);
  oa.appendchild(og);
  osvg.appendchild(oa);
  og.onmouseenter = function(){
   elasticmove(this,appearance.r*1.2);
   var line = this.children[0];
   line.removeattribute('stroke-dasharray');
   line.setattribute('stroke-width',appearance.linewidth*3);
   line.setattribute('x1',appearance.x0+(appearance.dis - appearance.r0)*math.cos(deg*this.index - 90));
   line.setattribute('y1',appearance.y0+(appearance.dis - appearance.r0)*math.sin(deg*this.index - 90));
  }
  og.onmouseleave = function(){
   elasticmove(this,appearance.r);
   var line = this.children[0];
   line.setattribute('stroke-width',appearance.linewidth);
   line.setattribute('stroke-dasharray',appearance.linedashed);
   line.setattribute('x1',appearance.x0+(appearance.dis - appearance.r)*math.cos(deg*this.index - 90));
   line.setattribute('y1',appearance.y0+(appearance.dis - appearance.r)*math.sin(deg*this.index - 90));   
  }   
 }
}
function elasticmove(obj,str){
 var circle = obj.getelementsbytagname('circle')[0];
 var r0 = circle.getattribute('r');
 var r = number(str);
 //声明步长值
 var step = 0;
 //声明弹性距离
 var len = r - r0;
 //声明弹性系数
 var k = 0.7;
 //声明损耗系数
 var z= 0.7;
 //声明当前值
 var cur = r0;
 clearinterval(circle.timer);
 circle.timer = setinterval(function(){
  //获取当前值cur
  cur = circle.getattribute('r');
  //更新弹性距离
  len = r - cur;
  //弹力影响
  step += len*k;
  //阻力影响
  step = step*z;
  //赋值
  circle.setattribute('r',number(cur) + step);
  //当元素的步长值接近于0，并且弹性距离接近于0时，停止定时器
  if(math.round(step) == 0 && math.round(len) == 0){
   circle.setattribute('r',r);
   clearinterval(circle.timer); 
  } 
 },30);
}
</script>

以上这篇使用svg基本操作api的实例讲解就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。