Go语言制作svg格式树形图的示例代码

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2023-02-03
golang基于errgroup实现并发调用的方法
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目录
  • 什么是SVG
  • SVG定义
  • SVG优点
  • 预定义元素
  • 圆形 <circle>
  • 直线 <line>
  • 文字 <text>
  • 结点SVG格式
  • 根结点
  • 子树结点
  • 叶结点
  • 结点坐标
  • 结点文本
  • 二叉树转SVG
  • 全部源代码

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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