Added all required dependencies

6 files changed, 753 insertions, 0 deletions

diff --git a/vendor/github.com/issue9/identicon/LICENSE b/vendor/github.com/issue9/identicon/LICENSE
new file mode 100644
index 0000000000..e92d1181e5
--- /dev/null
+++ b/vendor/github.com/issue9/identicon/LICENSE
@@ -0,0 +1,22 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 caixw
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the 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 all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
diff --git a/vendor/github.com/issue9/identicon/README.md b/vendor/github.com/issue9/identicon/README.md
new file mode 100644
index 0000000000..a68c73bc4e
--- /dev/null
+++ b/vendor/github.com/issue9/identicon/README.md
@@ -0,0 +1,40 @@
+identicon [![Build Status](https://travis-ci.org/issue9/identicon.svg?branch=master)](https://travis-ci.org/issue9/identicon)
+======
+
+根据用户的IP、邮箱名等任意数据为用户产生漂亮的随机头像。
+
+![screenhost.1](https://raw.github.com/issue9/identicon/master/screenshot/1.png)
+![screenhost.4](https://raw.github.com/issue9/identicon/master/screenshot/4.png)
+![screenhost.5](https://raw.github.com/issue9/identicon/master/screenshot/5.png)
+![screenhost.6](https://raw.github.com/issue9/identicon/master/screenshot/6.png)
+![screenhost.7](https://raw.github.com/issue9/identicon/master/screenshot/7.png)
+
+```go
+// 根据用户访问的IP，为其生成一张头像
+img, _ := identicon.Make(128, color.NRGBA{},color.NRGBA{}, []byte("192.168.1.1"))
+fi, _ := os.Create("/tmp/u1.png")
+png.Encode(fi, img)
+fi.Close()
+
+// 或者
+ii, _ := identicon.New(128, color.NRGBA{}, color.NRGBA{}, color.NRGBA{}, color.NRGBA{})
+img := ii.Make([]byte("192.168.1.1"))
+img = ii.Make([]byte("192.168.1.2"))
+```
+
+### 安装
+
+```shell
+go get github.com/issue9/identicon
+```
+
+
+### 文档
+
+[![Go Walker](http://gowalker.org/api/v1/badge)](http://gowalker.org/github.com/issue9/identicon)
+[![GoDoc](https://godoc.org/github.com/issue9/identicon?status.svg)](https://godoc.org/github.com/issue9/identicon)
+
+
+### 版权
+
+本项目采用[MIT](http://opensource.org/licenses/MIT)开源授权许可证，完整的授权说明可在[LICENSE](LICENSE)文件中找到。
diff --git a/vendor/github.com/issue9/identicon/block.go b/vendor/github.com/issue9/identicon/block.go
new file mode 100644
index 0000000000..cbeff67e6a
--- /dev/null
+++ b/vendor/github.com/issue9/identicon/block.go
@@ -0,0 +1,438 @@
+// Copyright 2015 by caixw, All rights reserved
+// Use of this source code is governed by a MIT
+// license that can be found in the LICENSE file.
+
+package identicon
+
+import (
+	"image"
+	"sync"
+)
+
+var pool = sync.Pool{
+	New: func() interface{} { return make([]float64, 0, 10) },
+}
+
+var (
+	// 可以出现在中间的方块，一般为了美观，都是对称图像。
+	centerBlocks = []blockFunc{b0, b1, b2, b3}
+
+	// 所有方块
+	blocks = []blockFunc{b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, b10, b11, b12, b13, b14, b15, b16}
+)
+
+// 所有block函数的类型
+type blockFunc func(img *image.Paletted, x, y, size float64, angle int)
+
+// 将多边形points旋转angle个角度，然后输出到img上，起点为x,y坐标
+func drawBlock(img *image.Paletted, x, y, size float64, angle int, points []float64) {
+	if angle > 0 { // 0角度不需要转换
+		// 中心坐标与x,y的距离，方便下面指定中心坐标(x+m,y+m)，
+		// 0.5的偏移值不能少，否则坐靠右，非正中央
+		m := size/2 - 0.5
+		rotate(points, x+m, y+m, angle)
+	}
+
+	for i := x; i < x+size; i++ {
+		for j := y; j < y+size; j++ {
+			if pointInPolygon(i, j, points) {
+				img.SetColorIndex(int(i), int(j), 1)
+			}
+		}
+	}
+}
+
+// 全空白
+//
+//  --------
+//  |      |
+//  |      |
+//  |      |
+//  --------
+func b0(img *image.Paletted, x, y, size float64, angle int) {
+}
+
+// 全填充正方形
+//
+//  --------
+//  |######|
+//  |######|
+//  |######|
+//  --------
+func b1(img *image.Paletted, x, y, size float64, angle int) {
+	isize := int(size)
+	ix := int(x)
+	iy := int(y)
+	for i := ix + 1; i < ix+isize; i++ {
+		for j := iy + 1; j < iy+isize; j++ {
+			img.SetColorIndex(i, j, 1)
+		}
+	}
+}
+
+// 中间小方块
+//  ----------
+//  |        |
+//  |  ####  |
+//  |  ####  |
+//  |        |
+//  ----------
+func b2(img *image.Paletted, x, y, size float64, angle int) {
+	l := size / 4
+	x = x + l
+	y = y + l
+
+	for i := x; i < x+2*l; i++ {
+		for j := y; j < y+2*l; j++ {
+			img.SetColorIndex(int(i), int(j), 1)
+		}
+	}
+}
+
+// 菱形
+//
+//  ---------
+//  |   #   |
+//  |  ###  |
+//  | ##### |
+//  |#######|
+//  | ##### |
+//  |  ###  |
+//  |   #   |
+//  ---------
+func b3(img *image.Paletted, x, y, size float64, angle int) {
+	m := size / 2
+	points := pool.Get().([]float64)[:0]
+
+	drawBlock(img, x, y, size, 0, append(points,
+		x+m, y,
+		x+size, y+m,
+		x+m, y+size,
+		x, y+m,
+		x+m, y,
+	))
+
+	pool.Put(points)
+}
+
+// b4
+//
+//  -------
+//  |#####|
+//  |#### |
+//  |###  |
+//  |##   |
+//  |#    |
+//  |------
+func b4(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	drawBlock(img, x, y, size, angle, append(points,
+		x, y,
+		x+size, y,
+		x, y+size,
+		x, y,
+	))
+
+	pool.Put(points)
+}
+
+// b5
+//
+//  ---------
+//  |   #   |
+//  |  ###  |
+//  | ##### |
+//  |#######|
+func b5(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	drawBlock(img, x, y, size, angle, append(points,
+		x+m, y,
+		x+size,
+		y+size,
+		x, y+size,
+		x+m, y,
+	))
+
+	pool.Put(points)
+}
+
+// b6 矩形
+//
+//  --------
+//  |###   |
+//  |###   |
+//  |###   |
+//  --------
+func b6(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	drawBlock(img, x, y, size, angle, append(points,
+		x, y,
+		x+m, y,
+		x+m, y+size,
+		x, y+size,
+		x, y,
+	))
+
+	pool.Put(points)
+}
+
+// b7 斜放的锥形
+//
+//  ---------
+//  | #     |
+//  |  ##   |
+//  |  #####|
+//  |   ####|
+//  |--------
+func b7(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	drawBlock(img, x, y, size, angle, append(points,
+		x, y,
+		x+size, y+m,
+		x+size, y+size,
+		x+m, y+size,
+		x, y,
+	))
+
+	pool.Put(points)
+}
+
+// b8 三个堆叠的三角形
+//
+//  -----------
+//  |    #    |
+//  |   ###   |
+//  |  #####  |
+//  |  #   #  |
+//  | ### ### |
+//  |#########|
+//  -----------
+func b8(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	mm := m / 2
+
+	// 顶部三角形
+	drawBlock(img, x, y, size, angle, append(points,
+		x+m, y,
+		x+3*mm, y+m,
+		x+mm, y+m,
+		x+m, y,
+	))
+
+	// 底下左边
+	drawBlock(img, x, y, size, angle, append(points[:0],
+		x+mm, y+m,
+		x+m, y+size,
+		x, y+size,
+		x+mm, y+m,
+	))
+
+	// 底下右边
+	drawBlock(img, x, y, size, angle, append(points[:0],
+		x+3*mm, y+m,
+		x+size, y+size,
+		x+m, y+size,
+		x+3*mm, y+m,
+	))
+
+	pool.Put(points)
+}
+
+// b9 斜靠的三角形
+//
+//  ---------
+//  |#      |
+//  | ####  |
+//  |  #####|
+//  |  #### |
+//  |   #   |
+//  ---------
+func b9(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	drawBlock(img, x, y, size, angle, append(points,
+		x, y,
+		x+size, y+m,
+		x+m, y+size,
+		x, y,
+	))
+
+	pool.Put(points)
+}
+
+// b10
+//
+//  ----------
+//  |    ####|
+//  |    ### |
+//  |    ##  |
+//  |    #   |
+//  |####    |
+//  |###     |
+//  |##      |
+//  |#       |
+//  ----------
+func b10(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	drawBlock(img, x, y, size, angle, append(points,
+		x+m, y,
+		x+size, y,
+		x+m, y+m,
+		x+m, y,
+	))
+
+	drawBlock(img, x, y, size, angle, append(points[:0],
+		x, y+m,
+		x+m, y+m,
+		x, y+size,
+		x, y+m,
+	))
+
+	pool.Put(points)
+}
+
+// b11 左上角1/4大小的方块
+//
+//  ----------
+//  |####    |
+//  |####    |
+//  |####    |
+//  |        |
+//  |        |
+//  ----------
+func b11(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	drawBlock(img, x, y, size, angle, append(points,
+		x, y,
+		x+m, y,
+		x+m, y+m,
+		x, y+m,
+		x, y,
+	))
+
+	pool.Put(points)
+}
+
+// b12
+//
+//  -----------
+//  |         |
+//  |         |
+//  |#########|
+//  |  #####  |
+//  |    #    |
+//  -----------
+func b12(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	drawBlock(img, x, y, size, angle, append(points,
+		x, y+m,
+		x+size, y+m,
+		x+m, y+size,
+		x, y+m,
+	))
+
+	pool.Put(points)
+}
+
+// b13
+//
+//  -----------
+//  |         |
+//  |         |
+//  |    #    |
+//  |  #####  |
+//  |#########|
+//  -----------
+func b13(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	drawBlock(img, x, y, size, angle, append(points,
+		x+m, y+m,
+		x+size, y+size,
+		x, y+size,
+		x+m, y+m,
+	))
+
+	pool.Put(points)
+}
+
+// b14
+//
+//  ---------
+//  |   #   |
+//  | ###   |
+//  |####   |
+//  |       |
+//  |       |
+//  ---------
+func b14(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	drawBlock(img, x, y, size, angle, append(points,
+		x+m, y,
+		x+m, y+m,
+		x, y+m,
+		x+m, y,
+	))
+
+	pool.Put(points)
+}
+
+// b15
+//
+//  ----------
+//  |#####   |
+//  |###     |
+//  |#       |
+//  |        |
+//  |        |
+//  ----------
+func b15(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	drawBlock(img, x, y, size, angle, append(points,
+		x, y,
+		x+m, y,
+		x, y+m,
+		x, y,
+	))
+
+	pool.Put(points)
+}
+
+// b16
+//
+//  ---------
+//  |   #   |
+//  | ##### |
+//  |#######|
+//  |   #   |
+//  | ##### |
+//  |#######|
+//  ---------
+func b16(img *image.Paletted, x, y, size float64, angle int) {
+	points := pool.Get().([]float64)[:0]
+	m := size / 2
+	drawBlock(img, x, y, size, angle, append(points,
+		x+m, y,
+		x+size, y+m,
+		x, y+m,
+		x+m, y,
+	))
+
+	drawBlock(img, x, y, size, angle, append(points[:0],
+		x+m, y+m,
+		x+size, y+size,
+		x, y+size,
+		x+m, y+m,
+	))
+
+	pool.Put(points)
+}
diff --git a/vendor/github.com/issue9/identicon/doc.go b/vendor/github.com/issue9/identicon/doc.go
new file mode 100644
index 0000000000..adaf30a947
--- /dev/null
+++ b/vendor/github.com/issue9/identicon/doc.go
@@ -0,0 +1,37 @@
+// Copyright 2015 by caixw, All rights reserved.
+// Use of this source code is governed by a MIT
+// license that can be found in the LICENSE file.
+
+// 一个基于hash值生成随机图像的包。
+//
+// 关于identicon并没有统一的标准，一般用于在用户注册时，
+// 取用户的邮箱或是访问IP等数据(也可以是其它任何数据)，
+// 进行hash运算，之后根据hash数据，产生一张图像，
+// 这样即可以为用户产生一张独特的头像，又不会泄漏用户的隐藏。
+//
+// 在identicon中，把图像分成以下九个部分:
+//  -------------
+//  | 1 | 2 | 3 |
+//  -------------
+//  | 4 | 5 | 6 |
+//  -------------
+//  | 7 | 8 | 9 |
+//  -------------
+// 其中1、3、9、7为不同角度(依次增加90度)的同一张图片，
+// 2、6、8、4也是如此，这样可以保持图像是对称的，比较美观。
+// 5则单独使用一张图片。
+//
+//  // 根据用户访问的IP，为其生成一张头像
+//  img, _ := identicon.Make(128, color.NRGBA{},color.NRGBA{}, []byte("192.168.1.1"))
+//  fi, _ := os.Create("/tmp/u1.png")
+//  png.Encode(fi, img)
+//  fi.Close()
+//
+//  // 或者
+//  ii, _ := identicon.New(128, color.NRGBA{}, color.NRGBA{}, color.NRGBA{})
+//  img := ii.Make([]byte("192.168.1.1"))
+//  img = ii.Make([]byte("192.168.1.2"))
+//
+// NOTE: go test 会在当前目录的testdata文件夹下产生大量的随机图片。
+// 要运行测试，必须保证该文件夹是存在的，且有相应的写入权限。
+package identicon
diff --git a/vendor/github.com/issue9/identicon/identicon.go b/vendor/github.com/issue9/identicon/identicon.go
new file mode 100644
index 0000000000..c0b1db3b01
--- /dev/null
+++ b/vendor/github.com/issue9/identicon/identicon.go
@@ -0,0 +1,147 @@
+// Copyright 2015 by caixw, All rights reserved.
+// Use of this source code is governed by a MIT
+// license that can be found in the LICENSE file.
+
+package identicon
+
+import (
+	"crypto/md5"
+	"fmt"
+	"image"
+	"image/color"
+)
+
+const (
+	minSize       = 16 // 图片的最小尺寸
+	maxForeColors = 32 // 在New()函数中可以指定的最大颜色数量
+)
+
+// Identicon 用于产生统一尺寸的头像。
+// 可以根据用户提供的数据，经过一定的算法，自动产生相应的图案和颜色。
+type Identicon struct {
+	foreColors []color.Color
+	backColor  color.Color
+	size       int
+	rect       image.Rectangle
+}
+
+// 声明一个Identicon实例。
+// size表示整个头像的大小。
+// back表示前景色。
+// fore表示所有可能的前景色，会为每个图像随机挑选一个作为其前景色。
+// NOTE:前景色不要与背景色太相近。
+func New(size int, back color.Color, fore ...color.Color) (*Identicon, error) {
+	if len(fore) == 0 || len(fore) > maxForeColors {
+		return nil, fmt.Errorf("前景色数量必须介于[1]~[%v]之间，当前为[%v]", maxForeColors, len(fore))
+	}
+
+	if size < minSize {
+		return nil, fmt.Errorf("参数size的值(%v)不能小于%v", size, minSize)
+	}
+
+	return &Identicon{
+		foreColors: fore,
+		backColor:  back,
+		size:       size,
+
+		// 画布坐标从0开始，其长度应该是size-1
+		rect: image.Rect(0, 0, size, size),
+	}, nil
+}
+
+// 根据data数据产生一张唯一性的头像图片。
+func (i *Identicon) Make(data []byte) image.Image {
+	h := md5.New()
+	h.Write(data)
+	sum := h.Sum(nil)
+
+	// 第一个方块
+	index := int(sum[0]+sum[1]+sum[2]+sum[3]) % len(blocks)
+	b1 := blocks[index]
+
+	// 第二个方块
+	index = int(sum[4]+sum[5]+sum[6]+sum[7]) % len(blocks)
+	b2 := blocks[index]
+
+	// 中间方块
+	index = int(sum[8]+sum[9]+sum[10]+sum[11]) % len(centerBlocks)
+	c := centerBlocks[index]
+
+	// 旋转角度
+	angle := int(sum[12]+sum[13]+sum[14]) % 4
+
+	// 根据最后一个字段，获取前景颜色
+	index = int(sum[15]) % len(i.foreColors)
+
+	p := image.NewPaletted(i.rect, []color.Color{i.backColor, i.foreColors[index]})
+	drawBlocks(p, i.size, c, b1, b2, angle)
+	return p
+}
+
+// 根据data数据产生一张唯一性的头像图片。
+// size 头像的大小。
+// back, fore头像的背景和前景色。
+func Make(size int, back, fore color.Color, data []byte) (image.Image, error) {
+	if size < minSize {
+		return nil, fmt.Errorf("参数size的值(%v)不能小于%v", size, minSize)
+	}
+
+	h := md5.New()
+	h.Write(data)
+	sum := h.Sum(nil)
+
+	// 第一个方块
+	index := int(sum[0]+sum[1]+sum[2]+sum[3]) % len(blocks)
+	b1 := blocks[index]
+
+	// 第二个方块
+	index = int(sum[4]+sum[5]+sum[6]+sum[7]) % len(blocks)
+	b2 := blocks[index]
+
+	// 中间方块
+	index = int(sum[8]+sum[9]+sum[10]+sum[11]) % len(centerBlocks)
+	c := centerBlocks[index]
+
+	// 旋转角度
+	angle := int(sum[12]+sum[13]+sum[14]+sum[15]) % 4
+
+	// 画布坐标从0开始，其长度应该是size-1
+	p := image.NewPaletted(image.Rect(0, 0, size, size), []color.Color{back, fore})
+	drawBlocks(p, size, c, b1, b2, angle)
+	return p, nil
+}
+
+// 将九个方格都填上内容。
+// p为画板。
+// c为中间方格的填充函数。
+// b1,b2为边上8格的填充函数。
+// angle为b1,b2的起始旋转角度。
+func drawBlocks(p *image.Paletted, size int, c, b1, b2 blockFunc, angle int) {
+	// 每个格子的长宽。先转换成float，再计算！
+	blockSize := float64(size) / 3
+	twoBlockSize := 2 * blockSize
+
+	incr := func() { // 增加angle的值，但不会大于3
+		angle++
+		if angle > 3 {
+			angle = 0
+		}
+	}
+
+	c(p, blockSize, blockSize, blockSize, 0)
+
+	b1(p, 0, 0, blockSize, angle)
+	b2(p, blockSize, 0, blockSize, angle)
+
+	incr()
+	b1(p, twoBlockSize, 0, blockSize, angle)
+	b2(p, twoBlockSize, blockSize, blockSize, angle)
+
+	incr()
+	b1(p, twoBlockSize, twoBlockSize, blockSize, angle)
+	b2(p, blockSize, twoBlockSize, blockSize, angle)
+
+	incr()
+	b1(p, 0, twoBlockSize, blockSize, angle)
+	b2(p, 0, blockSize, blockSize, angle)
+}
diff --git a/vendor/github.com/issue9/identicon/polygon.go b/vendor/github.com/issue9/identicon/polygon.go
new file mode 100644
index 0000000000..06759c31a5
--- /dev/null
+++ b/vendor/github.com/issue9/identicon/polygon.go
@@ -0,0 +1,69 @@
+// Copyright 2015 by caixw, All rights reserved.
+// Use of this source code is governed by a MIT
+// license that can be found in the LICENSE file.
+
+package identicon
+
+var (
+	// 4个元素分别表示cos(0),cos(90),cos(180),cos(270)
+	cos = []float64{1, 0, -1, 0}
+
+	// 4个元素分别表示sin(0),sin(90),sin(180),sin(270)
+	sin = []float64{0, 1, 0, -1}
+)
+
+// 将points中的所有点，以x,y为原点旋转angle个角度。
+// angle取值只能是[0,1,2,3]，分别表示[0，90，180，270]
+func rotate(points []float64, x, y float64, angle int) {
+	if angle < 0 || angle > 3 {
+		panic("rotate:参数angle必须0,1,2,3三值之一")
+	}
+
+	for i := 0; i < len(points); i += 2 {
+		px := points[i] - x
+		py := points[i+1] - y
+		points[i] = px*cos[angle] - py*sin[angle] + x
+		points[i+1] = px*sin[angle] + py*cos[angle] + y
+	}
+}
+
+// 判断某个点是否在多边形之内，不包含构成多边形的线和点
+// x,y 需要判断的点坐标
+// points 组成多边形的所顶点，每两个元素表示一点顶点，其中最后一个顶点必须与第一个顶点相同。
+func pointInPolygon(x float64, y float64, points []float64) bool {
+	if len(points) < 8 { // 只有2个以上的点，才能组成闭合多边形
+		return false
+	}
+
+	// 大致算法如下：
+	// 把整个平面以给定的测试点为原点分两部分:
+	// - y>0，包含(x>0 && y==0)
+	// - y<0，包含(x<0 && y==0)
+	// 依次扫描每一个点，当该点与前一个点处于不同部分时（即一个在y>0区，一个在y<0区），
+	// 则判断从前一点到当前点是顺时针还是逆时针（以给定的测试点为原点），如果是顺时针r++，否则r--。
+	// 结果为：2==abs(r)。
+
+	r := 0
+	x1, y1 := points[0], points[1]
+	prev := (y1 > y) || ((x1 > x) && (y1 == y))
+	for i := 2; i < len(points); i += 2 {
+		x2, y2 := points[i], points[i+1]
+		curr := (y2 > y) || ((x2 > x) && (y2 == y))
+
+		if curr == prev {
+			x1, y1 = x2, y2
+			continue
+		}
+
+		mul := (x1-x)*(y2-y) - (x2-x)*(y1-y)
+		if mul > 0 {
+			r++
+		} else if mul < 0 {
+			r--
+		}
+		x1, y1 = x2, y2
+		prev = curr
+	}
+
+	return r == 2 || r == -2
+}