Mermaid

一直比较喜欢用Markdown格式写点东西，如：记笔记、列计划等。但是当需要在Markdown中插入一些图片时，尤其是那些会经常发生变动的图片时（例如：流程图），简直痛不欲生，因为需要重新用工具修改图片后再链接进Markdown里。

如果能直接在Markdown里编写并生成图片，简直不要太开心。所幸这个问题已经有大佬给出了解决方案，那就是Mermaid。

个人理解：Mermaid是一种类似于Markdown中代码块高亮渲染的东西，可以把特定的纯文本渲染成对应的图片（流程图等）。Mermaid仅仅是一种渲染，并非Markdown的原生语法，所以，能不能看到图片以及图片最终呈现的样子，还要看对应的编辑器或页面是否对Mermaid进行支持及具体的渲染实现。

语法

在Markdown中嵌入Mermaid，语法与嵌入代码块的语法类似，即原先写c、java等的地方写为mermaid，之间写上具体的Mermaid内容即可。

```mermaid      # 开始
graph TD        # 类型
Start --> Stop  # 具体内容
```             # 结束

经渲染后如下：

graph TD
Start --> Stop

分类

1. 流程图

见上面的示例。

2. 时序图

sequenceDiagram
Alice->>John: Hello John, how are you?
John-->>Alice: Great!
Alice-)John: See you later!

sequenceDiagram
Alice->>John: Hello John, how are you?
John-->>Alice: Great!
Alice-)John: See you later!

3. 类图

classDiagram
Animal <|-- Duck
Animal <|-- Fish
Animal <|-- Zebra
Animal : +int age
Animal : +String gender
Animal: +isMammal()
Animal: +mate()
class Duck{
+String beakColor
+swim()
+quack()
}
class Fish{
-int sizeInFeet
-canEat()
}
class Zebra{
+bool is_wild
+run()
}

classDiagram
Animal <|-- Duck
Animal <|-- Fish
Animal <|-- Zebra
Animal : +int age
Animal : +String gender
Animal: +isMammal()
Animal: +mate()
class Duck{
+String beakColor
+swim()
+quack()
}
class Fish{
-int sizeInFeet
-canEat()
}
class Zebra{
+bool is_wild
+run()
}

4. 状态图

stateDiagram-v2
[*] --> Still
Still --> [*]

Still --> Moving
Moving --> Still
Moving --> Crash
Crash --> [*]

stateDiagram-v2
[*] --> Still
Still --> [*]

Still --> Moving
Moving --> Still
Moving --> Crash
Crash --> [*]

5. 关系图

erDiagram
CUSTOMER ||--o{ ORDER : places
ORDER ||--|{ LINE-ITEM : contains
CUSTOMER }|..|{ DELIVERY-ADDRESS : uses

erDiagram
CUSTOMER ||--o{ ORDER : places
ORDER ||--|{ LINE-ITEM : contains
CUSTOMER }|..|{ DELIVERY-ADDRESS : uses

6. 旅程图

journey
title My working day
section Go to work
Make tea: 5: Me
Go upstairs: 3: Me
Do work: 1: Me, Cat
section Go home
Go downstairs: 5: Me
Sit down: 5: Me

journey
title My working day
section Go to work
Make tea: 5: Me
Go upstairs: 3: Me
Do work: 1: Me, Cat
section Go home
Go downstairs: 5: Me
Sit down: 5: Me

7. 甘特图

gantt
title A Gantt Diagram
dateFormat  YYYY-MM-DD
section Section
A task           :a1, 2014-01-01, 30d
Another task     :after a1  , 20d
section Another
Task in sec      :2014-01-12  , 12d
another task      : 24d

gantt
title A Gantt Diagram
dateFormat  YYYY-MM-DD
section Section
A task           :a1, 2014-01-01, 30d
Another task     :after a1  , 20d
section Another
Task in sec      :2014-01-12  , 12d
another task      : 24d

8. 饼图

pie title Pets adopted by volunteers
"Dogs" : 386
"Cats" : 85
"Rats" : 15

pie title Pets adopted by volunteers
"Dogs" : 386
"Cats" : 85
"Rats" : 15

9. 需求图

requirementDiagram

requirement test_req {
id: 1
text: the test text.
risk: high
verifymethod: test
}

element test_entity {
type: simulation
}

test_entity - satisfies -> test_req

requirementDiagram

requirement test_req {
id: 1
text: the test text.
risk: high
verifymethod: test
}

element test_entity {
type: simulation
}

test_entity - satisfies -> test_req

10. git提交图

---
title: Example Git diagram
---
gitGraph
   commit
   commit
   branch develop
   checkout develop
   commit
   commit
   checkout main
   merge develop
   commit
   commit

---
title: Example Git diagram
---
gitGraph
   commit
   commit
   branch develop
   checkout develop
   commit
   commit
   checkout main
   merge develop
   commit
   commit

11. C4图

C4Context
  title System Context diagram for Internet Banking System
  Enterprise_Boundary(b0, "BankBoundary0") {
    Person(customerA, "Banking Customer A", "A customer of the bank, with personal bank accounts.")
    Person(customerB, "Banking Customer B")
    Person_Ext(customerC, "Banking Customer C", "desc")

    Person(customerD, "Banking Customer D", "A customer of the bank, <br/> with personal bank accounts.")

    System(SystemAA, "Internet Banking System", "Allows customers to view information about their bank accounts, and make payments.")

    Enterprise_Boundary(b1, "BankBoundary") {

      SystemDb_Ext(SystemE, "Mainframe Banking System", "Stores all of the core banking information about customers, accounts, transactions, etc.")

      System_Boundary(b2, "BankBoundary2") {
        System(SystemA, "Banking System A")
        System(SystemB, "Banking System B", "A system of the bank, with personal bank accounts. next line.")
      }

      System_Ext(SystemC, "E-mail system", "The internal Microsoft Exchange e-mail system.")
      SystemDb(SystemD, "Banking System D Database", "A system of the bank, with personal bank accounts.")

      Boundary(b3, "BankBoundary3", "boundary") {
        SystemQueue(SystemF, "Banking System F Queue", "A system of the bank.")
        SystemQueue_Ext(SystemG, "Banking System G Queue", "A system of the bank, with personal bank accounts.")
      }
    }
  }

  BiRel(customerA, SystemAA, "Uses")
  BiRel(SystemAA, SystemE, "Uses")
  Rel(SystemAA, SystemC, "Sends e-mails", "SMTP")
  Rel(SystemC, customerA, "Sends e-mails to")

  UpdateElementStyle(customerA, $fontColor="red", $bgColor="grey", $borderColor="red")
  UpdateRelStyle(customerA, SystemAA, $textColor="blue", $lineColor="blue", $offsetX="5")
  UpdateRelStyle(SystemAA, SystemE, $textColor="blue", $lineColor="blue", $offsetY="-10")
  UpdateRelStyle(SystemAA, SystemC, $textColor="blue", $lineColor="blue", $offsetY="-40", $offsetX="-50")
  UpdateRelStyle(SystemC, customerA, $textColor="red", $lineColor="red", $offsetX="-50", $offsetY="20")

  UpdateLayoutConfig($c4ShapeInRow="3", $c4BoundaryInRow="1")

C4Context
  title System Context diagram for Internet Banking System
  Enterprise_Boundary(b0, "BankBoundary0") {
    Person(customerA, "Banking Customer A", "A customer of the bank, with personal bank accounts.")
    Person(customerB, "Banking Customer B")
    Person_Ext(customerC, "Banking Customer C", "desc")

    Person(customerD, "Banking Customer D", "A customer of the bank, <br/> with personal bank accounts.")

    System(SystemAA, "Internet Banking System", "Allows customers to view information about their bank accounts, and make payments.")

    Enterprise_Boundary(b1, "BankBoundary") {

      SystemDb_Ext(SystemE, "Mainframe Banking System", "Stores all of the core banking information about customers, accounts, transactions, etc.")

      System_Boundary(b2, "BankBoundary2") {
        System(SystemA, "Banking System A")
        System(SystemB, "Banking System B", "A system of the bank, with personal bank accounts. next line.")
      }

      System_Ext(SystemC, "E-mail system", "The internal Microsoft Exchange e-mail system.")
      SystemDb(SystemD, "Banking System D Database", "A system of the bank, with personal bank accounts.")

      Boundary(b3, "BankBoundary3", "boundary") {
        SystemQueue(SystemF, "Banking System F Queue", "A system of the bank.")
        SystemQueue_Ext(SystemG, "Banking System G Queue", "A system of the bank, with personal bank accounts.")
      }
    }
  }

  BiRel(customerA, SystemAA, "Uses")
  BiRel(SystemAA, SystemE, "Uses")
  Rel(SystemAA, SystemC, "Sends e-mails", "SMTP")
  Rel(SystemC, customerA, "Sends e-mails to")

  UpdateElementStyle(customerA, $fontColor="red", $bgColor="grey", $borderColor="red")
  UpdateRelStyle(customerA, SystemAA, $textColor="blue", $lineColor="blue", $offsetX="5")
  UpdateRelStyle(SystemAA, SystemE, $textColor="blue", $lineColor="blue", $offsetY="-10")
  UpdateRelStyle(SystemAA, SystemC, $textColor="blue", $lineColor="blue", $offsetY="-40", $offsetX="-50")
  UpdateRelStyle(SystemC, customerA, $textColor="red", $lineColor="red", $offsetX="-50", $offsetY="20")

  UpdateLayoutConfig($c4ShapeInRow="3", $c4BoundaryInRow="1")

12. 思维导图

mindmap
  root((mindmap))
    Origins
      Long history
      ::icon(fa fa-book)
      Popularisation
        British popular psychology author Tony Buzan
    Research
      On effectiveness<br/>and features
      On Automatic creation
        Uses
            Creative techniques
            Strategic planning
            Argument mapping
    Tools
      Pen and paper
      Mermaid

mindmap
  root((mindmap))
    Origins
      Long history
      ::icon(fa fa-book)
      Popularisation
        British popular psychology author Tony Buzan
    Research
      On effectiveness<br/>and features
      On Automatic creation
        Uses
            Creative techniques
            Strategic planning
            Argument mapping
    Tools
      Pen and paper
      Mermaid

图片能否正常显示，还要看具体的Mermaid实现版本。

mermaid学习笔记之——初识