Go语言制作svg格式树形图的示例代码
作者：Hann Yang
SVG是可伸缩矢量图形 (Scalable Vector Graphics)，于2003年1月14日成为 W3C 推荐标准。本文将利用Go语言实现制作svg格式树形图，感兴趣的可以了解一下
最近一直在刷二叉树题目，但在要验证结果时，通常用中序遍历、层序遍历查看结果，验证起来没有画图来得直观，所有想到自己动手制作二叉树的树形图。 直接开干，先从svg入手：
什么是SVG
SVG定义
SVG是可伸缩矢量图形 (Scalable Vector Graphics)，于2003年1月14日成为 W3C 推荐标准。
SVG 用来定义用于网络的基于矢量的图形
SVG 使用 XML 格式定义图形
SVG 是万维网联盟的标准
SVG 与诸如 DOM 和 XSL 之类的 W3C 标准是一个整体
SVG优点
- SVG 可被非常多的工具读取和修改（比如记事本）
- SVG 与 JPEG 和 GIF 图像比起来，尺寸更小，且可压缩性更强。
- SVG 图像在放大或改变尺寸的情况下其图形质量不会有所损失
- SVG 图像可在任何的分辨率下被高质量地打印
- SVG 可在图像质量不下降的情况下被放大
- SVG 图像中的文本是可选的，同时也是可搜索的（很适合制作地图）
- SVG 可以与 JavaScript 技术一起运行
- SVG 是开放的标准
- SVG 文件是纯粹的 XML
预定义元素
- 矩形 <rect>
- 圆形 <circle>
- 椭圆 <ellipse>
- 直线 <line>
- 文字 <text>
- 路径 <path>
- 折线 <polyline>
- 多边形 <polygon>
制作二叉树的树形图，就使用圆形、直线、文字三种即可：
圆形 <circle>
<svg xmlns="http://www.w3.org/2000/svg" version="1.1"> <circle cx="150" cy="50" r="30" stroke="black" stroke-width="2" fill="red"/> </svg>
cx和cy属性定义圆点的x和y坐标；r属性定义圆的半径
如果省略cx和cy，圆的中心会被设置为(0, 0)
直线 <line>
<svg xmlns="http://www.w3.org/2000/svg" version="1.1"> <line x1="50" y1="50" x2="200" y2="200" style="stroke:red;stroke-width:2"/> </svg>
x1，y2 属性定义线条的起始端点坐标
x2，y2 属性定义线条的结束端点坐标
文字 <text>
<svg xmlns="http://www.w3.org/2000/svg" version="1.1"> <text x="30" y="150" fill="red">Welcome to Hann's HomePage</text> </svg>
x，y 属性定义文字左对齐显示时的起始坐标（居中对齐则是文字中间点）
fill 属性定义文字的颜色
结点SVG格式
根结点
由<circle>和<text>组成，存放结点的数据域
<g id="0,0">
<circle cx="400" cy="50" r="30" stroke="black" stroke-width="2" fill="orange" />
<text x="400" y="50" fill="red" font-size="20" text-anchor="middle" dominant-baseline="middle">1</text>
</g>
子树结点
比根结点多出<line>元素，用来表示父结点左或右指针的指向
<g id="1,0">
<circle cx="200" cy="170" r="30" stroke="black" stroke-width="2" fill="orange" />
<text x="200" y="170" fill="red" font-size="20" text-anchor="middle" dominant-baseline="middle">2</text>
<line x1="200" y1="140" x2="379" y2="71" style="stroke:black;stroke-width:2"/>
</g>
叶结点
与子树结点相同，为区别显示把<circle>填充色改为greenlight
<g id="1,1">
<circle cx="600" cy="170" r="30" stroke="black" stroke-width="2" fill="lightgreen" />
<text x="600" y="170" fill="red" font-size="20" text-anchor="middle" dominant-baseline="middle">3</text>
<line x1="600" y1="140" x2="421" y2="71" style="stroke:black;stroke-width:2"/>
</g>
结点坐标
坐标的确定
结点坐标确定，把二叉树还原成满二叉树，结点位置标记为：
[ [0,0], [1,0], [1,1], [2,0], [2,1], [2,2], [2,3], [3,0]......]，再用循环计算出各点坐标。
连线的夹角
实际上不用考虑连线夹角，只要计算出连线始终两端点的坐标即可：
结点文本
以字符串形式保存好属性变量的特征关键词，用于遍历二叉树时替换成实际数据：
func XmlNode(M, N, X, Y int, Data string, Color ...string) string {
var cColor, tColor string
R := 30
Node := `<Tab><g id="M,N">
<circle cx="X" cy="Y" r="RC" stroke="black" stroke-width="2" fill="COLOR" />
<text x="X" y="Y" fill="TextColor" font-size="20" text-anchor="middle"
dominant-baseline="middle">DATA</text>
<ROOT/>
</g><CrLf>`
if len(Color) == 0 {
cColor, tColor = "orange", "red"
} else if len(Color) == 1 {
cColor, tColor = Color[0], "red"
} else {
cColor, tColor = Color[0], Color[1]
}
Node = strings.Replace(Node, "M", strconv.Itoa(M), 1)
Node = strings.Replace(Node, "N", strconv.Itoa(N), 1)
Node = strings.Replace(Node, "X", strconv.Itoa(X), 2)
Node = strings.Replace(Node, "Y", strconv.Itoa(Y), 2)
Node = strings.Replace(Node, "RC", strconv.Itoa(R), 1)
Node = strings.Replace(Node, "DATA", Data, 1)
Node = strings.Replace(Node, "COLOR", cColor, 1)
Node = strings.Replace(Node, "TextColor", tColor, 1)
Node = strings.Replace(Node, "<CrLf>", "\n", -1)
Node = strings.Replace(Node, "<Tab>", "\t", -1)
Node = strings.Replace(Node, "\n\t\t", " ", -1)
return Node
}二叉树转SVG
遍历二叉树对应的满二叉树，读出数据域并计算坐标，转成svg格式：
格式转换
func (bt *biTree) Xml4Tree() string {
var Xml, Node string
Head := "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/" +
"1999/xlink\" version=\"1.1\" width=\"Width\" height=\"Height\">\nCONTENT</svg>"
Line := `<line x1="X1" y1="Y1" x2="X2" y2="Y2" style="stroke:black;stroke-width:2"/>`
Link := `<a xlink:href="https://blog.csdn.net/boysoft2002" target="_blank">
<text x="5" y="20" fill="blue">Hann's CSDN Homepage</text></a>`
List := bt.LevelNullwith()
Levels := len(List)
for i := Levels - 1; i >= 0; i-- {
negative := -1
TmpXml := ""
for j := 0; j < Pow2(i); j++ {
t := Pow2(Levels - i - 1)
x, y := 50*(2*t*j+t), 120*i+50
if List[i][j] != nil {
fillColor := "orange"
if i == Levels-1 || i > 0 && i < Levels-1 &&
List[i+1][j*2] == nil && List[i+1][j*2+1] == nil {
fillColor = "lightgreen"
}
TmpStr := ""
switch List[i][j].(type) {
case int:
TmpStr = strconv.Itoa(List[i][j].(int))
case float64:
TmpStr = strconv.FormatFloat(List[i][j].(float64), 'g', -1, 64)
case string:
TmpStr = List[i][j].(string)
default:
TmpStr = "Error Type"
}
Xml = XmlNode(i, j, x, y, TmpStr, fillColor)
}
if i > 0 {
line1 := strings.Replace(Line, "X1", strconv.Itoa(x), 1)
line1 = strings.Replace(line1, "Y1", strconv.Itoa(y-30), 1)
negative *= -1
x0, y0 := 21, 21
x += 50*negative*(2*t*j%2+t) - negative*x0
line1 = strings.Replace(line1, "X2", strconv.Itoa(x), 1)
line1 = strings.Replace(line1, "Y2", strconv.Itoa(y-120+y0), 1)
Xml = strings.Replace(Xml, "<ROOT/>", line1, 1)
}
if List[i][j] != nil {
TmpXml += Xml
}
}
Node = TmpXml + Node
}
Xml = strings.Replace(Head, "CONTENT", Node, 1)
Xml = strings.Replace(Xml, "Width", strconv.Itoa(Pow2(Levels)*50), 1)
Xml = strings.Replace(Xml, "Height", strconv.Itoa(Levels*120), 1)
Xml = strings.Replace(Xml, "<ROOT/>", Link, 1)
return Xml
}写入文件、调取浏览
//......
for index, text := range texts {
svgFile := "./biTree0" + strconv.Itoa(index+1) + ".svg"
file, err1 = os.Create(svgFile)
if err1 != nil {
panic(err1)
}
_, err1 = io.WriteString(file, text)
if err1 != nil {
panic(err1)
}
file.Close()
exec.Command("cmd", "/c", "start", svgFile).Start()
//Linux 代码：
//exec.Command("xdg-open", svgFile).Start()
//Mac 代码：
//exec.Command("open", svgFile).Start()
}
//......全部源代码
package main
import (
"fmt"
"io"
"os"
"os/exec"
"strconv"
"strings"
)
type btNode struct {
Data interface{}
Lchild *btNode
Rchild *btNode
}
type biTree struct {
Root *btNode
}
func Build(data interface{}) *biTree {
var list []interface{}
if data == nil {
return &biTree{}
}
switch data.(type) {
case []interface{}:
list = append(list, data.([]interface{})...)
default:
list = append(list, data)
}
if len(list) == 0 {
return &biTree{}
}
node := &btNode{Data: list[0]}
list = list[1:]
Queue := []*btNode{node}
for len(list) > 0 {
if len(Queue) == 0 {
//panic("Given array can not build binary tree.")
return &biTree{Root: node}
}
cur := Queue[0]
val := list[0]
Queue = Queue[1:]
if val != nil {
cur.Lchild = &btNode{Data: val}
if cur.Lchild != nil {
Queue = append(Queue, cur.Lchild)
}
}
list = list[1:]
if len(list) > 0 {
val := list[0]
if val != nil {
cur.Rchild = &btNode{Data: val}
if cur.Rchild != nil {
Queue = append(Queue, cur.Rchild)
}
}
list = list[1:]
}
}
return &biTree{Root: node}
}
func (bt *biTree) AppendNode(data interface{}) {
root := bt.Root
if root == nil {
bt.Root = &btNode{Data: data}
return
}
Queue := []*btNode{root}
for len(Queue) > 0 {
cur := Queue[0]
Queue = Queue[1:]
if cur.Lchild != nil {
Queue = append(Queue, cur.Lchild)
} else {
cur.Lchild = &btNode{Data: data}
return
}
if cur.Rchild != nil {
Queue = append(Queue, cur.Rchild)
} else {
cur.Rchild = &btNode{Data: data}
break
}
}
}
func Copy(bt *biTree) *biTree {
root := bt.Root
if root == nil {
return &biTree{}
}
node := &btNode{Data: root.Data}
Queue1, Queue2 := []*btNode{root}, []*btNode{node}
for len(Queue1) > 0 {
p1, p2 := Queue1[0], Queue2[0]
Queue1, Queue2 = Queue1[1:], Queue2[1:]
if p1.Lchild != nil {
Node := &btNode{Data: p1.Lchild.Data}
p2.Lchild = Node
Queue1 = append(Queue1, p1.Lchild)
Queue2 = append(Queue2, Node)
}
if p1.Rchild != nil {
Node := &btNode{Data: p1.Rchild.Data}
p2.Rchild = Node
Queue1 = append(Queue1, p1.Rchild)
Queue2 = append(Queue2, Node)
}
}
return &biTree{Root: node}
}
func Mirror(bt *biTree) *biTree {
root := bt.Root
if root == nil {
return &biTree{}
}
node := &btNode{Data: root.Data}
Queue1, Queue2 := []*btNode{root}, []*btNode{node}
for len(Queue1) > 0 {
p1, p2 := Queue1[0], Queue2[0]
Queue1, Queue2 = Queue1[1:], Queue2[1:]
if p1.Lchild != nil {
Node := &btNode{Data: p1.Lchild.Data}
p2.Rchild = Node
Queue1 = append(Queue1, p1.Lchild)
Queue2 = append(Queue2, Node)
}
if p1.Rchild != nil {
Node := &btNode{Data: p1.Rchild.Data}
p2.Lchild = Node
Queue1 = append(Queue1, p1.Rchild)
Queue2 = append(Queue2, Node)
}
}
return &biTree{Root: node}
}
func (bt *biTree) BForder2D() [][]interface{} {
var res [][]interface{}
root := bt.Root
if root == nil {
return res
}
Queue := []*btNode{root}
for len(Queue) > 0 {
Nodes := []interface{}{}
Levels := len(Queue)
for Levels > 0 {
cur := Queue[0]
Queue = Queue[1:]
Nodes = append(Nodes, cur.Data)
Levels--
if cur.Lchild != nil {
Queue = append(Queue, cur.Lchild)
}
if cur.Rchild != nil {
Queue = append(Queue, cur.Rchild)
}
}
res = append(res, Nodes)
}
return res
}
func (bt *biTree) LevelNullwith(Fills ...interface{}) [][]interface{} {
var Nodes [][]interface{}
var Fill0 interface{}
if len(Fills) == 0 {
Fill0 = nil
} else if len(Fills) == 1 {
Fill0 = Fills[0]
} else {
panic("Error: number of parameters is greater than 1")
}
root := bt.Root
if root == nil {
return Nodes
}
Count := 0
Queue := []*btNode{root}
for len(Queue) > 0 {
nodes := []interface{}{}
Level := len(Queue)
for Level > 0 {
cur := Queue[0]
Queue = Queue[1:]
nodes = append(nodes, cur.Data)
Count++
Level--
if cur.Lchild != nil {
Queue = append(Queue, cur.Lchild)
}
if cur.Rchild != nil {
Queue = append(Queue, cur.Rchild)
}
}
Nodes = append(Nodes, nodes)
}
newbiTree := Copy(bt)
for i := 1; i < Pow2(len(Nodes))-Count; i++ {
newbiTree.AppendNode(Fill0)
}
return newbiTree.BForder2D()
}
func XmlNode(M, N, X, Y int, Data string, Color ...string) string {
var cColor, tColor string
R := 30
Node := `<Tab><g id="M,N">
<circle cx="X" cy="Y" r="RC" stroke="black" stroke-width="2" fill="COLOR" />
<text x="X" y="Y" fill="TextColor" font-size="20" text-anchor="middle"
dominant-baseline="middle">DATA</text>
<ROOT/>
</g><CrLf>`
if len(Color) == 0 {
cColor, tColor = "orange", "red"
} else if len(Color) == 1 {
cColor, tColor = Color[0], "red"
} else {
cColor, tColor = Color[0], Color[1]
}
Node = strings.Replace(Node, "M", strconv.Itoa(M), 1)
Node = strings.Replace(Node, "N", strconv.Itoa(N), 1)
Node = strings.Replace(Node, "X", strconv.Itoa(X), 2)
Node = strings.Replace(Node, "Y", strconv.Itoa(Y), 2)
Node = strings.Replace(Node, "RC", strconv.Itoa(R), 1)
Node = strings.Replace(Node, "DATA", Data, 1)
Node = strings.Replace(Node, "COLOR", cColor, 1)
Node = strings.Replace(Node, "TextColor", tColor, 1)
Node = strings.Replace(Node, "<CrLf>", "\n", -1)
Node = strings.Replace(Node, "<Tab>", "\t", -1)
Node = strings.Replace(Node, "\n\t\t", " ", -1)
return Node
}
func Pow2(x int) int { //x>=0
res := 1
for i := 0; i < x; i++ {
res *= 2
}
return res
}
func Xml4Full(Levels int) string {
var Xml, Node string
Head := "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/" +
"1999/xlink\" version=\"1.1\" width=\"Width\" height=\"Height\">\nCONTENT</svg>"
Line := `<line x1="X1" y1="Y1" x2="X2" y2="Y2" style="stroke:black;stroke-width:2"/>`
Link := `<a xlink:href="https://blog.csdn.net/boysoft2002" rel="external nofollow" rel="external nofollow" target="_blank">
<text x="5" y="20" fill="blue">Hann's CSDN Homepage</text></a>`
for i := 0; i < Levels; i++ {
negative := -1
for j := 0; j < Pow2(i); j++ {
t := Pow2(Levels - i - 1)
x, y := 50*(2*t*j+t), 120*i+50
if Levels != 1 && i == Levels-1 {
Xml = XmlNode(i, j, x, y, strconv.Itoa(Pow2(i)+j), "lightgreen")
} else {
Xml = XmlNode(i, j, x, y, strconv.Itoa(Pow2(i)+j))
}
if i > 0 {
line1 := strings.Replace(Line, "X1", strconv.Itoa(x), 1)
line1 = strings.Replace(line1, "Y1", strconv.Itoa(y-30), 1)
negative *= -1
x0, y0 := 21, 21
//过连线起始端的半径与纵轴线夹角取45度时x,y坐标修正值21,21[30/1.414]
//取30度时 x0,y0:= 15,30-26；取60度时 x0,y0:= 26[15*1.732],15
x += 50*negative*(2*t*j%2+t) - negative*x0
line1 = strings.Replace(line1, "X2", strconv.Itoa(x), 1)
line1 = strings.Replace(line1, "Y2", strconv.Itoa(y-120+y0), 1)
Xml = strings.Replace(Xml, "<ROOT/>", line1, 1)
}
Node += Xml
}
}
Xml = strings.Replace(Head, "CONTENT", Node, 1)
Xml = strings.Replace(Xml, "Width", strconv.Itoa(Pow2(Levels)*50), 1)
Xml = strings.Replace(Xml, "Height", strconv.Itoa(Levels*120), 1)
Xml = strings.Replace(Xml, "<ROOT/>", Link, 1)
return Xml
}
func (bt *biTree) Xml4Tree() string {
var Xml, Node string
Head := "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/" +
"1999/xlink\" version=\"1.1\" width=\"Width\" height=\"Height\">\nCONTENT</svg>"
Line := `<line x1="X1" y1="Y1" x2="X2" y2="Y2" style="stroke:black;stroke-width:2"/>`
Link := `<a xlink:href="https://blog.csdn.net/boysoft2002" rel="external nofollow" rel="external nofollow" target="_blank">
<text x="5" y="20" fill="blue">Hann's CSDN Homepage</text></a>`
List := bt.LevelNullwith()
Levels := len(List)
for i := Levels - 1; i >= 0; i-- {
negative := -1
TmpXml := ""
for j := 0; j < Pow2(i); j++ {
t := Pow2(Levels - i - 1)
x, y := 50*(2*t*j+t), 120*i+50
if List[i][j] != nil {
fillColor := "orange"
if i == Levels-1 || i > 0 && i < Levels-1 &&
List[i+1][j*2] == nil && List[i+1][j*2+1] == nil {
fillColor = "lightgreen"
}
TmpStr := ""
switch List[i][j].(type) {
case int:
TmpStr = strconv.Itoa(List[i][j].(int))
case float64:
TmpStr = strconv.FormatFloat(List[i][j].(float64), 'g', -1, 64)
case string:
TmpStr = List[i][j].(string)
default:
TmpStr = "Error Type"
}
Xml = XmlNode(i, j, x, y, TmpStr, fillColor)
}
if i > 0 {
line1 := strings.Replace(Line, "X1", strconv.Itoa(x), 1)
line1 = strings.Replace(line1, "Y1", strconv.Itoa(y-30), 1)
negative *= -1
x0, y0 := 21, 21
x += 50*negative*(2*t*j%2+t) - negative*x0
line1 = strings.Replace(line1, "X2", strconv.Itoa(x), 1)
line1 = strings.Replace(line1, "Y2", strconv.Itoa(y-120+y0), 1)
Xml = strings.Replace(Xml, "<ROOT/>", line1, 1)
}
if List[i][j] != nil {
TmpXml += Xml
}
}
Node = TmpXml + Node
}
Xml = strings.Replace(Head, "CONTENT", Node, 1)
Xml = strings.Replace(Xml, "Width", strconv.Itoa(Pow2(Levels)*50), 1)
Xml = strings.Replace(Xml, "Height", strconv.Itoa(Levels*120), 1)
Xml = strings.Replace(Xml, "<ROOT/>", Link, 1)
return Xml
}
func main() {
var file *os.File
var err1 error
list1 := []interface{}{"-", "*", 6, "+", 3, nil, nil, 2, 8}
list2 := []interface{}{1, 2, 3, 4, 5, nil, 6, 7, 8}
tree1 := Build(list1)
tree2 := Build(list2)
tree3 := Mirror(tree2)
texts := []string{tree1.Xml4Tree(), tree2.Xml4Tree(), tree3.Xml4Tree(), Xml4Full(4)}
for index, text := range texts {
svgFile := "./biTree0" + strconv.Itoa(index+1) + ".svg"
file, err1 = os.Create(svgFile)
if err1 != nil {
panic(err1)
}
_, err1 = io.WriteString(file, text)
if err1 != nil {
panic(err1)
}
file.Close()
exec.Command("cmd", "/c", "start", svgFile).Start()
//Linux 代码：
//exec.Command("xdg-open", svgFile).Start()
//Mac 代码：
//exec.Command("open", svgFile).Start()
}
fmt.Println("Welcome to my homepage: https://blog.csdn.net/boysoft2002")
exec.Command("cmd", "/c", "start", "https://blog.csdn.net/boysoft2002").Start()
}至此，已达成自己的预想结果，算法实在有点笨拙，但总算成功了。
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