使用getImageData接口獲取圖片的像素點，然后基于像素點實現動畫效果，封裝成一個簡單的lib
<!DOCTYPE html><html> <head> <title>particle image</title> <meta charset="utf-8" /> <style> #logo { margin-left:20px; margin-top:20px; width:160px; height:48px; background:url('./images/logo.png'); /*border: 1px solid red;*/ } </style> <script type="text/javascript" src="ParticleImage.js"></script> <script> window.onload = function() { ParticleImage.create("logo", "./images/logo.png", "fast"); }; </script> </head> <body> <div id="logo"></div> </body></html>ParticleImage.js
/*The MIT License (MIT) Copyright (c) 2015 arest Permission is hereby granted, free of charge, to any person obtaining a copy ofthis software and associated documentation files (the "Software"), to deal inthe Software without restriction, including without limitation the rights touse, copy, modify, merge, publish, distribute, sublicense, and/or sell copies ofthe Software, and to permit persons to whom the Software is furnished to do so,subject to the following conditions: The above copyright notice and this permission notice shall be included in allcopies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS ORIMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESSFOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS ORCOPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHERIN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR INCONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.*/ /** * Add particle animation for image * usage: <script type="text/javascript" src="ParticleImage.js"></script> <script> window.onload = function() { // be sure to use image file in your own server (prevent CORS issue) ParticleImage.create("logo", "logo_s2.png", "fast"); }; </script> // in html file <div id="logo"></div> // you can set default background image as usual #logo { margin-left:20px; margin-top:20px; width:160px; height:48px; background:url('logo_s2.png'); } * * @author tianx.qin (rushi_wowen@163.com) * @file ParticleImage.js * @version 0.9 */var ParticleImage = (function(window) { var container = null, canvas = null; var ctx = null, _spirit = [], timer = null, cw = 0, ch = 0, // container width/height iw = 0, ih = 0, // image width/height mx = 0, my = 0, // mouse position bMove = true, MOVE_SPAN = 4, DEFAULT_ALPHA = 100, speed = 100, S = {"fast":10, "mid":100, "low":300}, ALPHA = 255 * 255; // spirit class var Spirit = function(data) { this.orginal = { pos: data.pos, x : data.x, y : data.y, r : data.r, g : data.g, b : data.b, a : data.a }; // change state, for animation this.current = { x : data.x, y : data.y, a : data.a }; }; /** * move spirit to original position */ Spirit.prototype.move = function() { var cur = this.current, orig = this.orginal; if ((cur.x === orig.x) && (cur.y === orig.y)) { //console.log("don't move:" + cur.y); return false; } //console.log("move:" + cur.y); var rand = 1 + Math.round(MOVE_SPAN * Math.random()); var offsetX = cur.x - orig.x, offsetY = cur.y - orig.y; var rad = offsetX == 0 ? 0 : offsetY / offsetX; var xSpan = cur.x < orig.x ? rand : cur.x > orig.x ? -rand : 0; cur.x += xSpan; var tempY = xSpan == 0 ? Math.abs(rand) : Math.abs(Math.round(rad * xSpan)); var ySpan = offsetY < 0 ? tempY : offsetY > 0 ? -tempY : 0; cur.y += ySpan; cur.a = ((cur.x === orig.x) && (cur.y === orig.y)) ? orig.a : DEFAULT_ALPHA; return true; }; /** * set random position */ Spirit.prototype.random = function(width, height) { var cur = this.current; cur.x = width + Math.round(width * 2 * Math.random()); this.current.y = height + Math.round(height * 2 * Math.random()); }; /** * set random positions for all spirits */ var _disorder = function() { var len = _spirit.length; for (var i = 0; i < len; i++) { _spirit[i].random(cw, ch); } }; /** * start to move spirit */ var _move = function() { var sprt = _spirit; var len = sprt.length; var isMove = false; // whether need to move for (var i = 0; i < len; i++) { if (sprt[i].move()) { isMove = true; } } isMove ? _redraw() : _stopTimer(); }; /** * redraw all spirits while animating */ var _redraw = function() { var imgDataObj = ctx.createImageData(iw, ih); var imgData = imgDataObj.data; var sprt = _spirit; var len = sprt.length; //console.log("redraw image : " + len); for (var i = 0; i < len; i++) { var temp = sprt[i]; //console.log("item : " + JSON.stringify(temp)); var orig = temp.orginal; var cur = temp.current; var pos = (cur.y * iw + cur.x) * 4; imgData[pos] = orig.r; imgData[pos + 1] = orig.g; imgData[pos + 2] = orig.b; imgData[pos + 3] = cur.a; } ctx.putImageData(imgDataObj, 0, 0); }; /** * add mousemove/mouseclick event */ var _addMouseEvent = function(c) { c.addEventListener("mouseenter", function(e) { //console.log("e.y:" + e.clientY + ", " + container.offsetTop); _startTimer(); }); c.addEventListener("click", function() { // disorder all spirits and start animation _startTimer(); }); }; /** * calculate all pixels of the logo image */ var _checkImage = function(imgUrl, callback) { // var tempCanvas = document.getElementById("temp"); //canvas.width = width; //canvas.height = height; var proc = function(image) { var w = image.width, h = image.height; iw = w, ih = h; //console.log("proc image " + image + "," + w + "," + h); canvas = _createCanvas(); // hide container background container.style.backgroundPosition = (-w) + "px"; container.style.backgroundRepeat = "no-repeat"; ctx.drawImage(image, 0, 0); // this may cause security error for CORS issue try { var imgData = ctx.getImageData(0, 0, w, h); var arrData = imgData.data; for (var i = 0; i < arrData.length; i += 4) { var r = arrData[i], g = arrData[i + 1], b = arrData[i + 2], a = arrData[i + 3]; if (r > 0 || g > 0 || b > 0 || a > 0) { var pos = i / 4; _spirit.push(new Spirit({ x : pos % w, y : Math.floor(pos / w), r : r, g : g, b : b, a : a })); } } return true; } catch (e) { // do nothing return false; } //return out; }; var img = new Image(); img.src = imgUrl; if (img.complete || img.complete === undefined) { proc(img) && callback && callback(); } else { img.onload = function() { proc(img) && callback && callback(); }; } }; // use "requestAnimationFrame" to create a timer, need browser support var _timer = function(func, dur) { //console.log("speed is " + dur); var timeLast = null; var bStop = false; var bRunning = false; // prevent running more than once var _start = function() { if (func) { if (! timeLast) { timeLast = Date.now(); func(); } else { var current = Date.now(); if (current - timeLast >= dur) { timeLast = current; func(); } } } if (bStop) { return; } requestAnimationFrame(_start); }; var _stop = function() { bStop = true; }; return { start : function() { if (bRunning) { //console.log("already running.."); return; } //console.log("start running.."); bRunning = true; bStop = false; _disorder(); _start(); }, stop : function() { _stop(); bRunning = false; } }; }; var _startTimer = function() { if (! timer) { timer = _timer(function() { bMove && _move(); }, speed); } timer.start(); }; var _stopTimer = function() { timer && timer.stop(); }; /** * start process */ var _create = function(imgUrl) { _checkImage(imgUrl, function() { //_createSpirits(); _addMouseEvent(canvas); //_startTimer(); }); }; var _setSpeed = function(s) { S[s] && (speed = S[s]); }; /** * check whether browser supports canvas */ var _support = function() { try { document.createElement("canvas").getContext("2d"); return true; } catch (e) { return false; } }; /** * create a canvas element */ var _createCanvas = function() { var cav = document.createElement("canvas"); cav.width = iw; cav.height = ih; container.appendChild(cav); ctx = cav.getContext("2d"); return cav; }; /** * initialize container params */ var _init = function(c, s) { if ((! c) || (! _support())) { // DIV id doesn't exist return false; } container = c; cw = c.clientWidth; ch = c.clientHeight; s && _setSpeed(s); return true; }; /** * export */ return { "create" : function(cId, imgUrl, s) { // user can set move speed by 's'['fast','mid','low'] _init(document.getElementById(cId), s) && _create(imgUrl); } };})(window);以上所述就是本文的全部內容了，希望大家能夠喜歡。
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