背景彩带动画插件ribbon.js
效果图：
插件ribbon.js代码如下：
/**
* Ribbons Class File.
* Creates low-poly ribbons background effect inside a target container.
*/
(function (name, factory)
{
if (typeof window === "object")
{
window[name] = factory();
}
})("Ribbons", function ()
{
var _w = window,
_b = document.body,//返回html dom中的body节点 即<body>
_d = document.documentElement;//返回html dom中的root 节点 即<html>
// random helper
var random = function ()
{
if (arguments.length === 1) // only 1 argument
{
if (Array.isArray(arguments[0])) // extract index from array
{
var index = Math.round(random(0, arguments[0].length - 1));
return arguments[0][index];
}
return random(0, arguments[0]); // assume numeric
} else
if (arguments.length === 2) // two arguments range
{
return Math.random() * (arguments[1] - arguments[0]) + arguments[0];
}
return 0; // default
};
// screen helper
var screenInfo = function (e)
{
var width = Math.max(0, _w.innerWidth || _d.clientWidth || _b.clientWidth || 0),
height = Math.max(0, _w.innerHeight || _d.clientHeight || _b.clientHeight || 0),
scrollx = Math.max(0, _w.pageXOffset || _d.scrollLeft || _b.scrollLeft || 0) - (_d.clientLeft || 0),
scrolly = Math.max(0, _w.pageYOffset || _d.scrollTop || _b.scrollTop || 0) - (_d.clientTop || 0);
return {
width: width,
height: height,
ratio: width / height,
centerx: width / 2,
centery: height / 2,
scrollx: scrollx,
scrolly: scrolly };
};
// mouse/input helper
var mouseInfo = function (e)
{
var screen = screenInfo(e),
mousex = e ? Math.max(0, e.pageX || e.clientX || 0) : 0,
mousey = e ? Math.max(0, e.pageY || e.clientY || 0) : 0;
return {
mousex: mousex,
mousey: mousey,
centerx: mousex - screen.width / 2,
centery: mousey - screen.height / 2 };
};
// point object
var Point = function (x, y)
{
this.x = 0;
this.y = 0;
this.set(x, y);
};
Point.prototype = {
constructor: Point,
set: function (x, y)
{
this.x = x || 0;
this.y = y || 0;
},
copy: function (point)
{
this.x = point.x || 0;
this.y = point.y || 0;
return this;
},
multiply: function (x, y)
{
this.x *= x || 1;
this.y *= y || 1;
return this;
},
divide: function (x, y)
{
this.x /= x || 1;
this.y /= y || 1;
return this;
},
add: function (x, y)
{
this.x += x || 0;
this.y += y || 0;
return this;
},
subtract: function (x, y)
{
this.x -= x || 0;
this.y -= y || 0;
return this;
},
clampX: function (min, max)
{
this.x = Math.max(min, Math.min(this.x, max));
return this;
},
clampY: function (min, max)
{
this.y = Math.max(min, Math.min(this.y, max));
return this;
},
flipX: function ()
{
this.x *= -1;
return this;
},
flipY: function ()
{
this.y *= -1;
return this;
} };
// class constructor
var Factory = function (options)
{
this._canvas = null;
this._context = null;
this._sto = null;
this._width = 0;
this._height = 0;
this._scroll = 0;
this._ribbons = [];
this._options = {
// ribbon color HSL saturation amount
colorSaturation: "80%",
// ribbon color HSL brightness amount
colorBrightness: "60%",
// ribbon color opacity amount
colorAlpha: 0.65,
// how fast to cycle through colors in the HSL color space
colorCycleSpeed: 6,
// where to start from on the Y axis on each side (top|min, middle|center, bottom|max, random)
verticalPosition: "center",
// how fast to get to the other side of the screen
horizontalSpeed: 200,
// how many ribbons to keep on screen at any given time
ribbonCount: 3,
// add stroke along with ribbon fill colors
strokeSize: 0,
// move ribbons vertically by a factor on page scroll
parallaxAmount: -0.5,
// add animation effect to each ribbon section over time
animateSections: true };
this._onDraw = this._onDraw.bind(this);
this._onResize = this._onResize.bind(this);
this._onScroll = this._onScroll.bind(this);
this.setOptions(options);
this.init();
};
// class prototype
Factory.prototype = {
constructor: Factory,
// Set and merge local options
setOptions: function (options)
{
if (typeof options === "object")
{
for (var key in options)
{
if (options.hasOwnProperty(key))
{
this._options[key] = options[key];
}
}
}
},
// Initialize the ribbons effect
init: function ()
{
try
{
this._canvas = document.createElement("canvas");
this._canvas.style["display"] = "block";
this._canvas.style["position"] = "fixed";
this._canvas.style["margin"] = "0";
this._canvas.style["padding"] = "0";
this._canvas.style["border"] = "0";
this._canvas.style["outline"] = "0";
this._canvas.style["left"] = "0";
this._canvas.style["top"] = "0";
this._canvas.style["width"] = "100%";
this._canvas.style["height"] = "100%";
this._canvas.style["z-index"] = "-1";
// this._canvas.style["background-color"]="#1f1f1f";
this._canvas.id = "bgCanvas";
this._onResize();
this._context = this._canvas.getContext("2d");
this._context.clearRect(0, 0, this._width, this._height);
this._context.globalAlpha = this._options.colorAlpha;
window.addEventListener("resize", this._onResize);
window.addEventListener("scroll", this._onScroll);
document.body.appendChild(this._canvas);
}
catch (e) {
console.warn("Canvas Context Error: " + e.toString());
return;
}
this._onDraw();
},
// Create a new random ribbon and to the list
addRibbon: function ()
{
// movement data
var dir = Math.round(random(1, 9)) > 5 ? "right" : "left",
stop = 1000,
hide = 200,
min = 0 - hide,
max = this._width + hide,
movex = 0,
movey = 0,
startx = dir === "right" ? min : max,
starty = Math.round(random(0, this._height));
// asjust starty based on options
if (/^(top|min)$/i.test(this._options.verticalPosition))
{
starty = 0 + hide;
} else
if (/^(middle|center)$/i.test(this._options.verticalPosition))
{
starty = this._height / 2;
} else
if (/^(bottom|max)$/i.test(this._options.verticalPosition))
{
starty = this._height - hide;
}
// ribbon sections data
var ribbon = [],
point1 = new Point(startx, starty),
point2 = new Point(startx, starty),
point3 = null,
color = Math.round(random(0, 360)),
delay = 0;
// buils ribbon sections
while (true)
{
if (stop <= 0) break;stop--;
movex = Math.round((Math.random() * 1 - 0.2) * this._options.horizontalSpeed);
movey = Math.round((Math.random() * 1 - 0.5) * (this._height * 0.25));
point3 = new Point();
point3.copy(point2);
if (dir === "right")
{
point3.add(movex, movey);
if (point2.x >= max) break;
} else
if (dir === "left")
{
point3.subtract(movex, movey);
if (point2.x <= min) break;
}
// point3.clampY( 0, this._height );
ribbon.push({ // single ribbon section
point1: new Point(point1.x, point1.y),
point2: new Point(point2.x, point2.y),
point3: point3,
color: color,
delay: delay,
dir: dir,
alpha: 0,
phase: 0 });
point1.copy(point2);
point2.copy(point3);
delay += 4;
color += this._options.colorCycleSpeed;
}
this._ribbons.push(ribbon);
},
// Draw single section
_drawRibbonSection: function (section)
{
if (section)
{
if (section.phase >= 1 && section.alpha <= 0)
{
return true; // done
}
if (section.delay <= 0)
{
section.phase += 0.02;
section.alpha = Math.sin(section.phase) * 1;
section.alpha = section.alpha <= 0 ? 0 : section.alpha;
section.alpha = section.alpha >= 1 ? 1 : section.alpha;
if (this._options.animateSections)
{
var mod = Math.sin(1 + section.phase * Math.PI / 2) * 0.1;
if (section.dir === "right")
{
section.point1.add(mod, 0);
section.point2.add(mod, 0);
section.point3.add(mod, 0);
} else {
section.point1.subtract(mod, 0);
section.point2.subtract(mod, 0);
section.point3.subtract(mod, 0);
}
section.point1.add(0, mod);
section.point2.add(0, mod);
section.point3.add(0, mod);
}
} else
{section.delay -= 0.5;}
var s = this._options.colorSaturation,
l = this._options.colorBrightness,
c = "hsla(" + section.color + ", " + s + ", " + l + ", " + section.alpha + " )";
this._context.save();
if (this._options.parallaxAmount !== 0)
{
this._context.translate(0, this._scroll * this._options.parallaxAmount);
}
this._context.beginPath();
this._context.moveTo(section.point1.x, section.point1.y);
this._context.lineTo(section.point2.x, section.point2.y);
this._context.lineTo(section.point3.x, section.point3.y);
this._context.fillStyle = c;
this._context.fill();
if (this._options.strokeSize > 0)
{
this._context.lineWidth = this._options.strokeSize;
this._context.strokeStyle = c;
this._context.lineCap = "round";
this._context.stroke();
}
this._context.restore();
}
return false; // not done yet
},
// Draw ribbons
_onDraw: function ()
{
// cleanup on ribbons list to rtemoved finished ribbons
for (var i = 0, t = this._ribbons.length; i < t; ++i)
{
if (!this._ribbons[i])
{
this._ribbons.splice(i, 1);
}
}
// draw new ribbons
this._context.clearRect(0, 0, this._width, this._height);
for (var a = 0; a < this._ribbons.length; ++a) // single ribbon
{
var ribbon = this._ribbons[a],
numSections = ribbon.length,
numDone = 0;
for (var b = 0; b < numSections; ++b) // ribbon section
{
if (this._drawRibbonSection(ribbon[b]))
{
numDone++; // section done
}
}
if (numDone >= numSections) // ribbon done
{
this._ribbons[a] = null;
}
}
// maintain optional number of ribbons on canvas
if (this._ribbons.length < this._options.ribbonCount)
{
this.addRibbon();
}
requestAnimationFrame(this._onDraw);
},
// Update container size info
_onResize: function (e)
{
var screen = screenInfo(e);
this._width = screen.width;
this._height = screen.height;
if (this._canvas)
{
this._canvas.width = this._width;
this._canvas.height = this._height;
if (this._context)
{
this._context.globalAlpha = this._options.colorAlpha;
}
}
},
// Update container size info
_onScroll: function (e)
{
var screen = screenInfo(e);
this._scroll = screen.scrolly;
} };
// export
return Factory;
});
new Ribbons();
