css3+js: 局部高斯模糊的实现
前两篇文介绍了css3的过滤器filter用来实现图片的高斯模糊效果,还有js拖拽的功能。
要实现局部模糊就要把两者结合起来,计算位移就可以了。
实现原理
原理其实很简单,就是两张图的叠加。底部一张清晰的图,上面一个高斯模糊过的图,局部显示与下面的图片无缝重合,这样看起来就行下面的图片部分模糊了一样。
代码
<style type="text/css">
#box{
position:relative;
width:500px;
height:500px;
background: url('xxx.jpg') no-repeat;
}
#target{
position:absolute;
left:0px;
top:0px;
width:100px;
height:100px;
background: inherit; //继承父元素的background属性
}
</style>
<div id="#box">
<div id="#target">
</div>
</div>
var bar = document.getElementById("bar");
var target = document.getElementById("target");
startDrag(target,target, function(x,y){
eleDrag.style.backgroundPosition = (-1 * x) + "px " + (-1 * y) + "px";
});
为实现局部模糊的回调
var eleDrag = document.getElementById("box");
if (eleDrag) {
startDrag(eleDrag, eleDrag, function(x, y) {
eleDrag.style.backgroundPosition = (-1 * x) + "px " + (-1 * y) + "px";
});
}*/
var getCss = function(o,key){
return o.currentStyle? o.currentStyle[key] : document.defaultView.getComputedStyle(o,false)[key];
};
// 拖拽
var startDrag = function(bar, target, callback){
var params = {
left: 0,
top: 0,
currentX: 0,
currentY: 0,
flag: false
};
if(getCss(target, "left") !== "auto"){
params.left = getCss(target, "left");
}
if(getCss(target, "top") !== "auto"){
params.top = getCss(target, "top");
}
bar.onmousedown = function(event){
params.flag = true;
if(!event){
event = window.event;
bar.onselectstart = function(){
return false;
}
}
var e = event;
params.currentX = e.clientX;
params.currentY = e.clientY;
};
document.onmouseup = function(){
params.flag = false;
if(getCss(target, "left") !== "auto"){
params.left = getCss(target, "left");
}
if(getCss(target, "top") !== "auto"){
params.top = getCss(target, "top");
}
};
document.onmousemove = function(event){
var e = event ? event: window.event;
if(params.flag){
var nowX = e.clientX, nowY = e.clientY;
var disX = nowX - params.currentX, disY = nowY - params.currentY;
target.style.left = parseInt(params.left) + disX + "px";
target.style.top = parseInt(params.top) + disY + "px";
if (typeof callback == "function") {
callback((parseInt(params.left) || 0) + disX, (parseInt(params.top) || 0) + disY);
}
if (event.preventDefault) {
event.preventDefault();
}
return false;
}
}
};
以上就是局部模糊的实现方法。可以直接套用。
借鉴于张鑫旭大神