javascript 線(xiàn)性漸變二

更新時(shí)間：2009年10月14日 21:33:20 作者：

上部分我們逐一分析了各瀏覽器的可行方法，這部分將搞鼓出一個(gè)統(tǒng)一的類(lèi)來(lái)實(shí)現(xiàn)跨瀏覽器的線(xiàn)性漸變。

先來(lái)IE的，這是最大的用戶(hù)群，如果這部分開(kāi)發(fā)不出來(lái)，基本可以說(shuō)不用做了。IE雖然有Gradient濾鏡，但對(duì)比其他瀏覽器的實(shí)現(xiàn)特弱，沒(méi)有多重漸變（stop-color），不能實(shí)現(xiàn)角度漸變，而且還經(jīng)常失效。我的思路是這樣，假如有一個(gè)帶文本的DIV，要實(shí)現(xiàn)多重線(xiàn)性漸變，我們首先得把它里面的文本取出來(lái)，然后里面放幾個(gè)DIV，有幾重就放幾個(gè)，然后把它們漸變。如果是垂直漸變，這好辦，什么也不用做，只需設(shè)置其濾鏡與各個(gè)高就行了。如果水平，就讓其浮動(dòng)或絕對(duì)定位，放到適當(dāng)?shù)奈恢?，設(shè)置其濾鏡與寬。但漸變?yōu)V鏡竟然會(huì)在浮動(dòng)后或定位后失效，這是在使用透明濾鏡時(shí)聞所未聞的。沒(méi)有辦法，祭出上古神器table。但設(shè)置長(zhǎng)與寬時(shí)，使用style來(lái)設(shè)置是不頂用的，一定要用DOM屬性。漸變則由它的td元素負(fù)責(zé)。為了去除table元素與td元素之間，td元素與其內(nèi)容之間的空白，我們還得用到cellPadding與cellSpacing。

<!doctype html> <title>javascript線(xiàn)性漸變 by 司徒正美</title> <meta charset="utf-8"/> <meta name="keywords" content="javascript線(xiàn)性漸變 by 司徒正美" /> <meta name="description" content="javascript線(xiàn)性漸變 by 司徒正美" /> <style type="text/css"> #gradient{ width:800px; height:200px; border:1px solid red; } </style> <script type="text/javascript"> //④使用IE濾鏡實(shí)現(xiàn)漸變 function setFilter(el,start,end,type){ el.style.filter = "progid:DXImageTransform.Microsoft.Gradient(enabled='true',startColorstr="+start+",GradientType="+type+", endColorstr="+end+")"; } //③每個(gè)漸變體的實(shí)現(xiàn)，是用table還是div function createStop(parent,top,left,width,height,type){ if(type){ var table = document.createElement("table"); parent.appendChild(table); var tr = table.insertRow(0), td = tr.insertCell(0) table.height = height+"px"; table.width = width+"px"; table.cellPadding = 0; table.cellSpacing = 0; table.style.cssText = "position:absolute;top:"+top+"px;left:"+left+"px" td.innerHTML =" "; return td; } var div = document.createElement("div"); parent.appendChild(div); div.style.height = height+"px"; div.style.width = width+"px"; return div; } //②漸變的具體實(shí)現(xiàn)，確定要使用多少漸變體，每個(gè)漸變體的顏色（是漸變色還是純色）與長(zhǎng)寬坐標(biāo) var IEgradient = function(entity,stops,width,height,type){ var offset,color,beforeColor,stopWidth,stopHeight,left,top,stop; for(var i=0,j=0,l=stops.length;i<l;i++,j++){ offset = stops[i].split(",")[0]; color = stops[i].split(",")[1]; stopWidth = (offset/100 * width).toFixed(1); stopHeight = (offset/100 * height).toFixed(1); switch(i){ case 0 : beforeColor = color; left = stopWidth; top = stopHeight; if(offset != 0){ //插入一個(gè)純色的table stop = type? createStop(entity,0,0,stopWidth,height,type) : createStop(entity,0,0,width,stopHeight,type); stop.style.backgroundColor = color; } break; case l-1: //先插入一個(gè)漸變的table var w2 = ((100-offset)/100 * width).toFixed(1), h2 = ((100-offset)/100 * height).toFixed(1), stop = type? createStop(entity,0,left,width - left -w2,height,type): createStop(entity,0,0,width,height - top -h2,type); setFilter(stop,beforeColor,color,type); if(offset != 100){ //再插入一個(gè)純色的table var stop2 = type? createStop(entity,0,stopWidth,w2,height,type): createStop(entity,0,0,width,h2,type); stop2.style.backgroundColor = color; } break; default : //插入一個(gè)漸變的table stop = type ? createStop(entity,0,left,stopWidth - left,height,type) : createStop(entity,0,0,width,stopHeight-top,type); setFilter(stop,beforeColor,color,type); beforeColor = color; left = stopWidth; top = stopHeight; break; } } } //①漸變的主體函數(shù) var gradient = function(id){ var entity = document.getElementById(id), options = arguments[1] || {}, width = options.width, height = options.height, type = options.type , stops = options["color-stop"]; entity.style.position = "relative"; var content = entity.innerHTML; entity.innerHTML = ""; //向目標(biāo)對(duì)象進(jìn)行漸變。 IEgradient(entity,stops,width,height,type); //把原來(lái)的內(nèi)容重新加入的目標(biāo)對(duì)象。 var contentDiv = document.createElement("div"); contentDiv.style.cssText = "position:absolute;top:0;left:0"; contentDiv.innerHTML = content; entity.appendChild(contentDiv); } window.onload = function(){ gradient("gradient",{width:800,height:200,type:1,"color-stop":["0,red","16,orange","32,yellow","48,green","64,blue","80,indigo","100,violet"]}) } </script> <div   class="5jxb7lb"   id="gradient">javascript線(xiàn)性漸變 by 司徒正美 實(shí)現(xiàn)多重水平漸變效果</div> <p">必須在IE中才能看到效果！</p>

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safari，chrome與opera打算都用SVG實(shí)現(xiàn)。為了減少函數(shù)的長(zhǎng)度，特意搞了兩個(gè)輔助函數(shù)。

復(fù)制代碼代碼如下:

 
var createSVG = function(tag){ 
return document.createElementNS("http://www.w3.org/2000/svg",tag); 
}; 
var attr= function(node,bag){ 
for(var i in bag){ 
if(bag.hasOwnProperty(i)) 
node.setAttribute(i,bag[i]) 
} 
}; 
var COSgradient = function(entity,stops,width,height,type){ 
var svg = createSVG("svg"); 
attr(svg,{width:width+"px",height:height+"px"}) 
entity.appendChild(svg); 
. 
var defs = createSVG("defs"); 
svg.appendChild(defs); 
var linearGradient = createSVG("linearGradient"); 
defs.appendChild(linearGradient); 
attr(linearGradient,{id:"nasami",x1:"0%",y1:"0%"}) 
if(type){ 
attr(linearGradient,{x2:"100%",y2:"0%"}) 
}else{ 
attr(linearGradient,{x2:"0%",y2:"100%"}) 
} 
for(var i=0,j=0,l=stops.length;i<l;i++,j++){ 
var offset = stops[i].split(",")[0] + "%", 
color = stops[i].split(",")[1], 
stop = createSVG("stop"); 
attr(stop,{offset:offset,"stop-color":color}); 
linearGradient.appendChild(stop); 
} 
var rect = createSVG("rect"); 
svg.appendChild(rect); 
attr(rect,{x:"0px",y:"0px",width:width+"px",height:height+"px",fill:"url(#nasami)"}); 
} 

firefox則利用其私有屬性：

復(fù)制代碼代碼如下:

 
var FFgradient= function(entity,stops,width,height,type){ 
var cssText = ";background: -moz-linear-gradient(" 
cssText += type? "top,bottom," :"left,right,"; 
. 
for(var i=0,j=0,l=stops.length;i<l;i++,j++){ 
var offset = stops[i].split(",")[0] + "%", 
color = stops[i].split(",")[1]; 
cssText += "color-stop("+[offset,color]+")," 
} 
cssText = cssText.replace(/,$/,"")+") no-repeat;"; 
entity.style.cssText = cssText+"width:"+width+"px;height:"+height+"px;" 
} 

不過(guò)今天研磨一下，發(fā)現(xiàn)firefox還是支持SVG的線(xiàn)性漸變的，因此糾正我原來(lái)的觀(guān)點(diǎn)。上面的函數(shù)只是作用一種實(shí)現(xiàn)手段放在這里，它并沒(méi)有整合到我最終的版本中（雖然它比SVG實(shí)現(xiàn)短很多。）這樣一來(lái)，在老一點(diǎn)版本的firefox中我們也能實(shí)現(xiàn)線(xiàn)性漸變了。
下面這個(gè)運(yùn)行框里的漸變效果可在所有主流瀏覽器中正常運(yùn)作。

<!doctype html> <title>javascript線(xiàn)性漸變 by 司徒正美</title> <meta charset="utf-8"/> <meta name="keywords" content="javascript線(xiàn)性漸變 by 司徒正美" /> <meta name="description" content="javascript線(xiàn)性漸變 by 司徒正美" /> <style type="text/css"> #gradient{ width:800px; height:100px; border:1px solid red; } </style> <script type="text/javascript"> var attr= function(node,bag){ for(var i in bag){ if(bag.hasOwnProperty(i)) node.setAttribute(i,bag[i]) } }; //④使用IE濾鏡實(shí)現(xiàn)漸變 function setFilter(el,start,end,type){ el.style.filter = "progid:DXImageTransform.Microsoft.Gradient(enabled='true',startColorstr="+start+",GradientType="+type+", endColorstr="+end+")"; } //③每個(gè)漸變體的實(shí)現(xiàn)，是用table還是div function createStop(parent,top,left,width,height,type){ if(type){ var table = document.createElement("table"); parent.appendChild(table); var tr = table.insertRow(0), td = tr.insertCell(0) attr(table,{height:height+"px",width:width+"px",cellPadding:0,cellSpacing:0}) css(table,{position:"absolute",top:top+"px",left:left+"px"}); td.innerHTML =" "; return td; } var div = document.createElement("div"); parent.appendChild(div); css(div,{height:height+"px",width:width+"px"}) return div; }; var createSVG = function(tag){ return document.createElementNS("http://www.w3.org/2000/svg",tag); }; var css = function(node,bag){ var str = ";" for(var i in bag){ if(bag.hasOwnProperty(i)) str += i+":"+bag[i]+";"; } node.style.cssText = str; } var SVGgradient = function(entity,stops,width,height,type){ var svg = createSVG("svg"); attr(svg,{width:width+"px",height:height+"px"}) entity.appendChild(svg); var defs = createSVG("defs"); svg.appendChild(defs); var linearGradient = createSVG("linearGradient"); defs.appendChild(linearGradient); attr(linearGradient,{id:"nasami",x1:"0%",y1:"0%"}) if(type){ attr(linearGradient,{x2:"100%",y2:"0%"}) }else{ attr(linearGradient,{x2:"0%",y2:"100%"}) } for(var i=0,j=0,l=stops.length;i<l;i++,j++){ var offset = stops[i].split(",")[0] + "%", color = stops[i].split(",")[1], stop = createSVG("stop"); attr(stop,{offset:offset,"stop-color":color}); linearGradient.appendChild(stop); } var rect = createSVG("rect"); svg.appendChild(rect); attr(rect,{x:"0px",y:"0px",width:width+"px",height:height+"px",fill:"url(#nasami)"}); } //②漸變的具體實(shí)現(xiàn)，確定要使用多少漸變體，每個(gè)漸變體的顏色（是漸變色還是純色）與長(zhǎng)寬坐標(biāo) var IEgradient = function(entity,stops,width,height,type){ var offset,color,beforeColor,stopWidth,stopHeight,left,top,stop; for(var i=0,j=0,l=stops.length;i<l;i++,j++){ offset = stops[i].split(",")[0]; color = stops[i].split(",")[1]; stopWidth = (offset/100 * width).toFixed(1); stopHeight = (offset/100 * height).toFixed(1); switch(i){ case 0 : beforeColor = color; left = stopWidth; top = stopHeight; if(offset != 0){ //插入一個(gè)純色的table stop = type? createStop(entity,0,0,stopWidth,height,type) : createStop(entity,0,0,width,stopHeight,type); css(stop,{background:color}); } break; case l-1: //先插入一個(gè)漸變的table var w2 = ((100-offset)/100 * width).toFixed(1), h2 = ((100-offset)/100 * height).toFixed(1), stop = type? createStop(entity,0,left,width - left -w2,height,type): createStop(entity,0,0,width,height - top -h2,type); setFilter(stop,beforeColor,color,type); if(offset != 100){ //再插入一個(gè)純色的table var stop2 = type? createStop(entity,0,stopWidth,w2,height,type): createStop(entity,0,0,width,h2,type); css(stop2,{background:color}); } break; default : //插入一個(gè)漸變的table stop = type ? createStop(entity,0,left,stopWidth - left,height,type) : createStop(entity,0,0,width,stopHeight-top,type); setFilter(stop,beforeColor,color,type); beforeColor = color; left = stopWidth; top = stopHeight; break; } } } //①漸變的主體函數(shù) var gradient = function(id){ var entity = document.getElementById(id), options = arguments[1] || {}, width = options.width, height = options.height, type = options.type , stops = options["color-stop"]; css(entity,{position:"relative"}); var content = entity.innerHTML; entity.innerHTML = ""; !+"\v1"? IEgradient(entity,stops,width,height,type): SVGgradient(entity,stops,width,height,type) var contentDiv = document.createElement("div"); css(contentDiv,{position:"absolute",top:0,left:0}) contentDiv.innerHTML = content; entity.appendChild(contentDiv); } window.onload = function(){ gradient("gradient",{width:800,height:100,type:1,"color-stop":["0,red","16,orange","32,yellow","48,green","64,blue","80,indigo","100,violet"]}) } </script> <div   class="zfvtjxb"   id="gradient">javascript線(xiàn)性漸變 by 司徒正美 實(shí)現(xiàn)多重水平漸變效果</div> https://developer.mozilla.org/en/SVG/Tutorial/Fill_Stroke_and_Gradients

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再把它做成類(lèi)。扼要說(shuō)明一下：它的第一個(gè)參數(shù)為IE，第二個(gè)為哈希。哈希中的各參數(shù)都為必選的，width，height的單位為px；type為0或者1，0代表垂直，1為水平；color-stop代表漸變體，由一個(gè)字符串?dāng)?shù)組構(gòu)成，每個(gè)字符串都是由數(shù)字加逗號(hào)加顏色值組成，數(shù)字表代偏移量，單位為%，顏色值可以是red,green等名詞，也可以是六位或三位的哈希值。漸變體至少要有一個(gè)。

復(fù)制代碼代碼如下:

 
new Gradient("gradient",{width:800,height:100,type:0,"color-stop":["0,red", 
3."16,orange","32,yellow","48,green","64,blue","80,indigo","100,violet"]}) 

<!doctype html> <title>javascript線(xiàn)性漸變 by 司徒正美</title> <meta charset="utf-8"/> <meta name="keywords" content="javascript線(xiàn)性漸變 by 司徒正美" /> <meta name="description" content="javascript線(xiàn)性漸變 by 司徒正美" /> <style type="text/css"> .gradient{ width:800px; height:100px; } </style> <script type="text/javascript"> var Gradient = function(id){ var entity = document.getElementById(id), options = arguments[1] || {}, width = options.width, height = options.height, type = options.type , stops = options["color-stop"]; this.init(entity,stops,width,height,type); } Gradient.prototype ={ constructor: Gradient, init: function(entity,stops,width,height,type) { this.css(entity,{position:"relative"}); var content = entity.innerHTML; entity.innerHTML = ""; !+"\v1"? this.IEgradient(entity,stops,width,height,type): this.SVGgradient(entity,stops,width,height,type) var contentDiv = document.createElement("div"); this.css(contentDiv,{position:"absolute",top:0,left:0}) contentDiv.innerHTML = content; entity.appendChild(contentDiv); }, css: function(node,bag){ var str = ";" for(var i in bag){ if(bag.hasOwnProperty(i)) str += i+":"+bag[i]+";"; } node.style.cssText = str; }, attr: function(node,bag){ for(var i in bag){ if(bag.hasOwnProperty(i)) node.setAttribute(i,bag[i]) } }, createSVG:function(tag){ return document.createElementNS("http://www.w3.org/2000/svg",tag); }, setFilter:function(el,start,end,type){ el.style.filter = "progid:DXImageTransform.Microsoft.Gradient(enabled='true',startColorstr="+ start+",GradientType="+type+", endColorstr="+end+")"; }, createStop:function(parent,top,left,width,height,type){ if(type){ var table = document.createElement("table"); parent.appendChild(table); var tr = table.insertRow(0), td = tr.insertCell(0) this.attr(table,{height:height+"px",width:width+"px",cellPadding:0,cellSpacing:0}) this.css(table,{position:"absolute",top:top+"px",left:left+"px"}); td.innerHTML =" "; return td; } var div = document.createElement("div"); parent.appendChild(div); this.css(div,{height:height+"px",width:width+"px"}) return div; }, IEgradient:function(entity,stops,width,height,type){ var offset,color,beforeColor,stopWidth,stopHeight,left,top,stop; for(var i=0,j=0,l=stops.length;i<l;i++,j++){ offset = stops[i].split(",")[0]; color = this.hex(stops[i].split(",")[1]); stopWidth = (offset/100 * width).toFixed(1); stopHeight = (offset/100 * height).toFixed(1); switch(i){ case 0 : beforeColor = color; left = stopWidth; top = stopHeight; if(offset != 0){ //插入一個(gè)純色的table stop = type? this.createStop(entity,0,0,stopWidth,height,type) : this.createStop(entity,0,0,width,stopHeight,type); this.css(stop,{background:color}); } break; case l-1: //先插入一個(gè)漸變的table var w2 = ((100-offset)/100 * width).toFixed(1), h2 = ((100-offset)/100 * height).toFixed(1), stop = type? this.createStop(entity,0,left,width - left -w2,height,type): this.createStop(entity,0,0,width,height - top -h2,type); this.setFilter(stop,beforeColor,color,type); if(offset != 100){ //再插入一個(gè)純色的table var stop2 = type? this.createStop(entity,0,stopWidth,w2,height,type): this.createStop(entity,0,0,width,h2,type); this.css(stop2,{background:color}); } break; default : //插入一個(gè)漸變的table stop = type ? this.createStop(entity,0,left,stopWidth - left,height,type) : this.createStop(entity,0,0,width,stopHeight-top,type); this.setFilter(stop,beforeColor,color,type); beforeColor = color; left = stopWidth; top = stopHeight; break; } } }, SVGgradient:function(entity,stops,width,height,type){ var svg = this.createSVG("svg"), id = "id" + (new Date().getTime()* Math.random()).toFixed(0); this.attr(svg,{width:width+"px",height:height+"px"}) entity.appendChild(svg); var defs = this.createSVG("defs"); svg.appendChild(defs); var linearGradient = this.createSVG("linearGradient"); defs.appendChild(linearGradient); this.attr(linearGradient,{id:id,x1:"0%",y1:"0%"}) if(type){ this.attr(linearGradient,{x2:"100%",y2:"0%"}) }else{ this.attr(linearGradient,{x2:"0%",y2:"100%"}) } for(var i=0,j=0,l=stops.length;i<l;i++,j++){ var offset = stops[i].split(",")[0] + "%", color = this.hex(stops[i].split(",")[1]), stop = this.createSVG("stop"); this.attr(stop,{offset:offset,"stop-color":color}); linearGradient.appendChild(stop); } var rect = this.createSVG("rect"); svg.appendChild(rect); this.attr(rect,{x:"0px",y:"0px",width:width+"px",height:height+"px", fill:"url(#"+linearGradient.getAttribute("id")+")"}); }, hex:function(value){ if(/^#/.test(value)){ value = value.replace('#', ''); return "#" + (value.length == 3 ? value.replace(/^(\w)(\w)(\w)$/, '$1$1$2$2$3$3') : value); } return value; } } window.onload = function(){ new Gradient("text1",{width:800,height:100,type:1,"color-stop":["0,red","16,orange","32,yellow","48,green","64,blue","80,indigo","100,violet"]}) new Gradient("text2",{width:800,height:100,type:0,"color-stop":["0,red","16,orange","32,yellow","48,green","64,blue","80,indigo","100,violet"]}) } </script> <div   class="h5vth5x"   id="text1" class="gradient">javascript線(xiàn)性漸變 by 司徒正美 實(shí)現(xiàn)多重水平漸變效果</div>  <div   class="rhvxlxt"   id="text2" class="gradient">javascript線(xiàn)性漸變 by 司徒正美 實(shí)現(xiàn)多重垂直漸變效果</div>

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