今天是个好日子，2014年5月20日，表白的最佳时机，虽说孩子已经四岁、结婚已经五年，但是也不可以偷懒，于是有了这个效果。
水平有限，浏览器兼容不好，请大家使用chrome浏览器获得最佳效果。
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程序猿and程序媛，大胆秀出你的爱吧。利用html5 canvas实现动态的文字粒子效果，效果如下。
实现原理
1. canvas里面实现描边文字
2. 利用getImageData获得描边文字的像素矩阵
3. 将粒子效果绑定在描边文字上
整个效果如下。
html文件非常简单。
<canvas id="canvas" width="1000" height="600"></canvas>css文件如下。
body { background: #000; text-align: center; font-family: "simhei"}canvas { margin: auto; position: absolute; left: 0; right:0; top: 0; bottom: 0;}js文件至关重要了。
BLUR = false; PULSATION = true;PULSATION_PERIOD = 1000;PARTICLE_RADIUS = 6; /* disable blur before using blink */ BLINK = false; GLOBAL_PULSATION = false; QUALITY = 2; /* 0 - 5 */ /* set false if you prefer rectangles */ARC = true; /* trembling + blur = fun */TREMBLING = 0; /* 0 - infinity */ FANCY_FONT = "Arial"; BACKGROUND = "#000"; BLENDING = true; /* if empty the text will be a random number */var TEXT;num = 0;TEXTArray = ["海庆", "深爱", "春玲", "直到","永远"];QUALITY_TO_FONT_SIZE = [10, 12, 40, 50, 200, 350];QUALITY_TO_SCALE = [20, 6, 4, 1, 0.9, 0.5];QUALITY_TO_TEXT_POS = [10, 20, 40, 60, 170, 280];window.onload = function () { document.body.style.backgroundColor = BACKGROUND; var canvas = document.getElementById("canvas"); var ctx = canvas.getContext("2d"); var W = canvas.width; var H = canvas.height; var tcanvas = document.createElement("canvas"); var tctx = tcanvas.getContext("2d"); tcanvas.width = W; tcanvas.height = H; total_area = W * H; total_particles = 1000; single_particle_area = total_area / total_particles; area_length = Math.sqrt(single_particle_area); var particles = []; for (var i = 1; i <= total_particles; i++) { particles.push(new particle(i)); } function particle(i) { this.r = Math.round(Math.random() * 255 | 0); this.g = Math.round(Math.random() * 255 | 0); this.b = Math.round(Math.random() * 255 | 0); this.alpha = 1; this.x = (i * area_length) % W; this.y = (i * area_length) / W * area_length; /* randomize delta to make particles sparkling */ this.deltaOffset = Math.random() * PULSATION_PERIOD | 0; this.radius = 0.1 + Math.random() * 2; } var positions = []; function new_positions() { TEXT = TEXTArray[num]; if (num < TEXTArray.length - 1) { num++; } else { num = 0; } //alert(TEXT); tctx.fillStyle = "white"; tctx.fillRect(0, 0, W, H) tctx.fill(); tctx.font = "bold " + QUALITY_TO_FONT_SIZE[QUALITY] + "px " + FANCY_FONT; tctx.strokeStyle = "black"; tctx.fillStyle="#f00"; tctx.strokeText(TEXT,20, 60); //tctx.fillText(TEXT,30, 50); image_data = tctx.getImageData(0, 0, W, H); pixels = image_data.data; positions = []; for (var i = 0; i < pixels.length; i = i + 2) { if (pixels[i] != 255) { position = { x: (i / 2 % W | 0) * QUALITY_TO_SCALE[QUALITY] | 0, y: (i / 2 / W | 0) * QUALITY_TO_SCALE[QUALITY] | 0 } positions.push(position); } } get_destinations(); } function draw() { var now = Date.now(); ctx.globalCompositeOperation = "source-over"; if (BLUR) ctx.globalAlpha = 0.1; else if (!BLUR && !BLINK) ctx.globalAlpha = 1.0; ctx.fillStyle = BACKGROUND; ctx.fillRect(0, 0, W, H) if (BLENDING) ctx.globalCompositeOperation = "lighter"; for (var i = 0; i < particles.length; i++) { p = particles[i]; if (isNaN(p.x)) continue ctx.beginPath(); ctx.fillStyle = "rgb(" + p.r + ", " + p.g + ", " + p.b + ")"; ctx.fillStyle = "rgba(" + p.r + ", " + p.g + ", " + p.b + ", " + p.alpha + ")"; if (BLINK) ctx.globalAlpha = Math.sin(Math.PI * mod * 1.0); if (PULSATION) { /* this would be 0 -> 1 */ var mod = ((GLOBAL_PULSATION ? 0 : p.deltaOffset) + now) % PULSATION_PERIOD / PULSATION_PERIOD; mod = Math.sin(mod * Math.PI); } else var mod = 1; var offset = TREMBLING ? TREMBLING * (-1 + Math.random() * 2) : 0; var radius = PARTICLE_RADIUS * p.radius; if (!ARC) { ctx.fillRect(offset + p.x - mod * radius / 2 | 0, offset + p.y - mod * radius / 2 | 0, radius * mod, radius * mod); } else { ctx.arc(offset + p.x | 0, offset + p.y | 0, radius * mod, Math.PI * 2, false); ctx.fill(); } p.x += (p.dx - p.x) / 10; p.y += (p.dy - p.y) / 10; } } function get_destinations() { for (var i = 0; i < particles.length; i++) { pa = particles[i]; particles[i].alpha = 1; var distance = []; nearest_position = 0; if (positions.length) { for (var n = 0; n < positions.length; n++) { po = positions[n]; distance[n] = Math.sqrt((pa.x - po.x) * (pa.x - po.x) + (pa.y - po.y) * (pa.y - po.y)); if (n > 0) { if (distance[n] <= distance[nearest_position]) { nearest_position = n; } } } particles[i].dx = positions[nearest_position].x; particles[i].dy = positions[nearest_position].y; particles[i].distance = distance[nearest_position]; var po1 = positions[nearest_position]; for (var n = 0; n < positions.length; n++) { var po2 = positions[n]; distance = Math.sqrt((po1.x - po2.x) * (po1.x - po2.x) + (po1.y - po2.y) * (po1.y - po2.y)); if (distance <= 5) { positions.splice(n, 1); } } } else { //particles[i].alpha = 0; } } } function init() { new_positions(); setInterval(draw, 30); setInterval(new_positions, 2000); } init();};
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