历史版本8 :JS实现大屏旋转星空背景 返回文档
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目录:

1. 概述编辑

1.1 应用场景

大屏场景下给决策报表添加一个酷炫的旋转星空效果。

旋转星空.gif

1.2 实现思路

采用插入动态 GIF 背景图的方式是无法进行自适应的,所以直接用 JS 代码来制作效果更好。

2. 示例编辑

FineReport.frm为例,给 body 组件添加一个初始化后事件,JS 代码如下:

function background() {
$("body").prepend('<canvas id="canvas" style="position:absolute;z-index:-2;"></canvas>');
//在body中插入canvas画布,并置于底层
var canvas = document.getElementById('canvas'),
ctx = canvas.getContext('2d'),
w = canvas.width = window.innerWidth,
h = canvas.height = window.innerHeight,

hue = 217,
stars = [],
count = 0,
maxStars = 800;
//设置星星数量

var canvas2 = document.createElement('canvas'),
ctx2 = canvas2.getContext('2d');
canvas2.width = 100;
canvas2.height = 100;
var half = canvas2.width / 2,
gradient2 = ctx2.createRadialGradient(half, half, 0, half, half, half);
gradient2.addColorStop(0.025, '#fff');
gradient2.addColorStop(0.1, 'hsl(' + hue + ', 61%, 33%)');
gradient2.addColorStop(0.25, 'hsl(' + hue + ', 64%, 6%)');
gradient2.addColorStop(1, 'transparent');

ctx2.fillStyle = gradient2;
ctx2.beginPath();
ctx2.arc(half, half, half, 0, Math.PI * 2);
ctx2.fill();

function random(min, max) {
if (arguments.length < 2) {
max = min;
min = 0;
}

if (min > max) {
var hold = max;
max = min;
min = hold;
}

return Math.floor(Math.random() * (max - min + 1)) + min;
}

var Star = function() {

this.orbitRadius = random(w / 2 - 50);
this.radius = random(100, this.orbitRadius) / 10;
this.orbitX = w / 2;
this.orbitY = h / 2;
this.timePassed = random(0, maxStars);
this.speed = random(this.orbitRadius) / 500000;
//设置旋转速度
this.alpha = random(2, 10) / 10;

count++;
stars[count] = this;
}

Star.prototype.draw = function() {
var x = Math.sin(this.timePassed + 1) * this.orbitRadius + this.orbitX,
y = Math.cos(this.timePassed) * this.orbitRadius / 2 + this.orbitY,
twinkle = random(10);

if (twinkle === 1 && this.alpha > 0) {
this.alpha -= 0.05;
} else if (twinkle === 2 && this.alpha < 1) {
this.alpha += 0.05;
}

ctx.globalAlpha = this.alpha;
ctx.drawImage(canvas2, x - this.radius / 2, y - this.radius / 2, this.radius, this.radius);
this.timePassed += this.speed;
}

for (var i = 0; i < maxStars; i++) {
new Star();
}

function animation() {
ctx.globalCompositeOperation = 'source-over';
ctx.globalAlpha = 0.8;
ctx.fillStyle = 'hsla(' + hue + ', 64%, 6%, 1)';
ctx.fillRect(0, 0, w, h)

ctx.globalCompositeOperation = 'lighter';
for (var i = 1, l = stars.length; i < l; i++) {
stars[i].draw();
};

window.requestAnimationFrame(animation);
}
animation();
}
background();
$(window).resize(function() {
background();
})

3. 效果预览编辑

保存决策报表,点击表单预览,效果图如应用场景中所示。

注:不支持移动端。

4. 已完成模板编辑

已完成模板可参见:%FR_HOME%\webapps\webroot\WEB-INF\reportlets\doc\JS\表单JS实例\大屏旋转星空背景图.frm

点击下载模板:大屏旋转星空背景图.frm