css-sprite
為紀(jì)念美國現(xiàn)代舞舞蹈家瑪莎·葛蘭姆誕辰，Google Doodle推出了一款極其炫酷的LOGO葫掉，整個(gè)LOGO使用CSS Sprite技術(shù)赤屋，利用一個(gè)初始圖片和一張畫滿各個(gè)動(dòng)作的拼接圖片碍岔，實(shí)現(xiàn)了動(dòng)畫畏线，而非傳統(tǒng)的GIF動(dòng)畫圖像。
效果
CSS Sprite簡(jiǎn)介
CSS Sprites(css精靈)方篮，是一種網(wǎng)頁圖片應(yīng)用處理方式名秀。它允許你將一個(gè)頁面涉及到的所有零星圖片都包含到一張大圖中去，這樣一來藕溅，當(dāng)訪問該頁面時(shí)匕得，載入的圖片就不會(huì)像以前那樣一幅一幅地慢慢顯示出來了。
限制：不高于200KB的單張圖片
整合處理圖片的目的是減少請(qǐng)求次數(shù)巾表，如果每一張圖片都向服務(wù)器發(fā)送請(qǐng)求汁掠，即影響服務(wù)器負(fù)載也影響頁面性能。
CSS Sprite原理
CSS Sprites的原理就是把網(wǎng)頁中用到的小圖標(biāo)集币、圖片類集中整合到一張圖片中考阱。
再利用CSS中的背景屬性
- background-image
- background-repeat
- background-position
當(dāng)需要顯示指定圖片時(shí)，定位到圖片相應(yīng)位置即可
Google粘土動(dòng)畫
實(shí)現(xiàn)步驟：
1鞠苟、準(zhǔn)備素材乞榨，設(shè)計(jì)動(dòng)畫的每一幀圖片并整合成一張圖片
2、監(jiān)聽點(diǎn)擊事件執(zhí)行動(dòng)畫
3当娱、根據(jù)延遲時(shí)間設(shè)置圖片背景位置以顯示下一幀圖片
素材
HTML
<div>
<div style="display:flex;align-items:flex-end;">
<div style="width:135px;height:156px;background:url(/images/css-sprite/blockheads.png) 0 0;" id="blockheads"></div>
<div style="width:65px;height:102px;background:url(/images/css-sprite/prickle.png) 0 0;" id="prickle"></div>
<div style="width:67px;height:144px;background:url(/images/css-sprite/goo.png) 0 0;" id="goo"></div>
<div style="width:98px;height:156px;background:url(/images/css-sprite/gumby.png) 0 0;" id="gumby"></div>
<div style="width:75px;height:108px;background:url(/images/css-sprite/pokey.png) 0 0;" id="pokey"></div>
</div>
</div>
JS
<script>
class Sprite {
constructor(opt) {
this.element = document.getElementById(opt.element);
this.url = opt.url;
this.delay = 1000 / (opt.speed || 20);
this.defaultBackground = this.element.style.background;
this.defalutUrl = this.element.style.backgroundImage;
this.step = 0;
this.width = this.element.clientWidth;
this.height = this.element.clientHeight;
let img = new Image();
img.onload = () => {
this.cols = parseInt(img.width / this.width);
this.rows = parseInt(img.height / this.height);
this.frames = this.cols * this.rows;
this.element.onclick = () => {
this.play();
};
};
img.src = this.url;
}
play() {
if (this.playing) {
return;
}
this.playing = true;
this.next();
}
next() {
this.step++;
if (this.step > this.frames) {
this.stop();
return;
}
let x = this.step % this.cols;
let y = parseInt(this.step / this.rows);
if (this.step % this.rows > 0) {
y++;
}
var position = "-" + (x - 1) * this.width + "px -" + (y - 1) * this.height + "px";
this.element.style.background = "url(" + this.url + ") " + position;
setTimeout(() => {
this.next();
}, this.delay);
}
stop() {
this.step = 0;
this.playing = false;
this.element.style.background = this.defaultBackground;
}
}
window.addEventListener('load', () => {
new Sprite({
element: 'blockheads',
url:'/images/css-sprite/blockheads.png'
});
new Sprite({
element: 'prickle',
url:'/images/css-sprite/prickle.png'
});
new Sprite({
element: 'goo',
url:'/images/css-sprite/goo.png'
});
new Sprite({
element: 'gumby',
url:'/images/css-sprite/gumby.png'
});
new Sprite({
element: 'pokey',
url:'/images/css-sprite/pokey.png'
});
});
</script>
Google舞蹈者
實(shí)現(xiàn)步驟：
1吃既、準(zhǔn)備素材，收集舞蹈者每一個(gè)動(dòng)作集成到一張圖片
2跨细、初始化每一個(gè)動(dòng)作的位置
3鹦倚、定時(shí)動(dòng)態(tài)創(chuàng)建div元素設(shè)置背景位置和元素位置
素材
HTML
<div id="graham-logo" style="position:relative;height:150px;"></div>
JS
(function () {
window.google={};
if (!google.doodle) google.doodle = {};
var d = [
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],
e = d.length,
f, g, h, i, j = -1,
c = document.getElementById("graham-logo"),
l = function () {
var a = d[f];
if (c && a[0]) {
var b = document.createElement("div");
b.id = "graham-logo" + f;
b.style.position = "absolute";
b.style.left = a[0] + "px";
b.style.top = a[1] + "px";
b.style.width = a[2] + "px";
b.style.height = a[3] + "px";
b.style.background = "url(/images/css-sprite/graham-sprite.png) no-repeat " + -g + "px " + -h + "px";
a[3] > i && (i = a[3]);
a[4] ? (g = 0, h += i, i = 0) : g += a[2];
c.appendChild(b);
++f;
f < e && (j = window.setTimeout(l, 83))
}
},
m = function () {
google.doodle.a = !1;
i = h = g = f = 0;
j != -1 && (window.clearTimeout(j), j = -1);
c.innerHTML = "";
j = window.setTimeout(l, 83)
};
c.addEventListener ? c.addEventListener("click", m, !1) : c.attachEvent("onclick", m);
if (!google.doodle.a) {
google.doodle.a = !0;
var n = document.createElement("img");
n.addEventListener ? n.addEventListener("load", m, !1) : n.attachEvent("onload", m);
n.src = "/images/css-sprite/graham-sprite.png"
}
})();
總結(jié)
希望大家可以通過本文的Google動(dòng)畫實(shí)現(xiàn)了解到一些CSS Sprite技術(shù)，CSS Sprite是前端優(yōu)化的一部分冀惭，合理的利用好可以提高網(wǎng)頁的性能震叙，也可以豐富網(wǎng)頁內(nèi)容掀鹅。
