Remove noise lines

(they are very distinc paths in length and size and can easily be filtered out by any script, they do not benefit us)

README.md

@@ -51,7 +51,6 @@ If no option is passed, you will get a random string of four characters and corr
   
 * `size`: 4 // size of random string  
 * `ignoreChars`: '0o1i' // filter out some characters like 0o1i  
-* `noise`: 1 // number of noise lines  
 * `color`: true // characters will have distinct colors instead of grey, true if background option is set  
 * `background`: '#cc9966' // background color of the svg image  
 
@@ -80,7 +79,7 @@ See the following api.
 Gain access to global setting object. 
 It is used for create and createMathExpr api as the default options.  
   
-In addition to size, noise, color, and background, you can also set the following property:
+In addition to size, color, and background, you can also set the following property:
 * `width`: number // width of captcha
 * `height`: number // height of captcha
 * `fontSize`: number // captcha text size

README_CN.md

@@ -51,7 +51,6 @@ app.get('/captcha', function (req, res) {
   
 * `size`: 4 // 验证码长度  
 * `ignoreChars`: '0o1i' // 验证码字符中排除 0o1i  
-* `noise`: 1 // 干扰线条的数量  
 * `color`: true // 验证码的字符是否有颜色，默认没有，如果设定了背景，则默认有  
 * `background`: '#cc9966' // 验证码图片背景颜色  
 
@@ -74,7 +73,7 @@ text 属性上是算数式的结果。不过用法和之前是完全一样的。
 这是全局配置对象。 
 create和createMathExpr接口的默认配置就是使用的这个对象。  
   
-除了 size, noise, color, 和 background 之外，你还可以修改以下属性：
+除了 size, color, 和 background 之外，你还可以修改以下属性：
 * `width`: number // width of captcha
 * `height`: number // height of captcha
 * `fontSize`: number // captcha text size
@@ -106,4 +105,4 @@ create和createMathExpr接口的默认配置就是使用的这个对象。
 这样的路径，没有text标签。所以SVG验证码可能比的图片普通验证码要更难识别，因为你必须先做SVG到其它格式的转化。
 
 ## License
-[MIT](LICENSE.md)
+[MIT](LICENSE.md)

index.d.ts

@@ -41,11 +41,6 @@ declare class ConfigObject {
 	 * filter out some characters
 	 */
 	ignoreChars?: string;
-	/**
-	 * default: 1
-	 * number of noise lines
-	 */
-	noise?: number;
 	/**
 	 * default: white
 	 * background color of svg image

lib/index.js

@@ -5,25 +5,6 @@ const optionMngr = require('./option-manager');
 
 const opts = optionMngr.options;
 
-const getLineNoise = function (width, height, options) {
-	const hasColor = options.color;
-	const noiseLines = [];
-	const min = options.inverse ? 7 : 1;
-	const max = options.inverse ? 15 : 9;
-	let i = -1;
-
-	while (++i < options.noise) {
-		const start = `${random.int(1, 21)} ${random.int(1, height - 1)}`;
-		const end = `${random.int(width - 21, width - 1)} ${random.int(1, height - 1)}`;
-		const mid1 = `${random.int((width / 2) - 21, (width / 2) + 21)} ${random.int(1, height - 1)}`;
-		const mid2 = `${random.int((width / 2) - 21, (width / 2) + 21)} ${random.int(1, height - 1)}`;
-		const color = hasColor ? random.color() : random.greyColor(min, max);
-		noiseLines.push(`<path d="M${start} C${mid1},${mid2},${end}" stroke="${color}" fill="none"/>`);
-	}
-
-	return noiseLines;
-};
-
 const getText = function (text, width, height, options) {
 	const len = text.length;
 	const spacing = (width - 2) / (len + 1);
@@ -58,8 +39,7 @@ const createCaptcha = function (text, options) {
 	const bgRect = bg ?
 		`<rect width="100%" height="100%" fill="${bg}"/>` : '';
 	const paths =
-		[].concat(getLineNoise(width, height, options))
-			.concat(getText(text, width, height, options))
+		[].concat(getText(text, width, height, options))
 			.sort(() => Math.random() - 0.5)
 			.join('');
 	const start = `<svg xmlns="http://www.w3.org/2000/svg" width="${width}" height="${height}" viewBox="0,0,${width},${height}">`;

lib/option-manager.js

@@ -11,7 +11,6 @@ const descender = font.descender;
 const options = {
 	width: 150,
 	height: 50,
-	noise: 1,
 	color: false,
 	background: '',
 	size: 4,