###### tags: `linux2022`

# graphviz note

## 初始宣告
一開始要用 graph 或 diagraph來宣告圖底，箭頭符號不一樣

// 無向圖
graph{
    a--b;
}
// 有向圖
digraph{
    a->b;
}

## 全域描述
如果想套模板到所有點上，可以用 `node` `edge` 來宣告全部的樣式

digraph{
    node [color=orange];
    edge [color=red];
    a->b;
}

digraph{
    node [color=orange];
    edge [color=red];
    a->b;
}

## 圖片方向 rankdir
設定箭頭方向和排版方向性 [document](https://graphviz.org/docs/attrs/rankdir/)

rankdir = LR; //left to right
rankdir = TB; //top to bottom
rankdir = BT; //bottom to top

digraph{
    rankdir = LR; //left to right
    a->b;
    label = "LR"
}

digraph{
    label = "RL"
    rankdir = RL; //left to right
    a->b;
}

## Attributes
用`[]`把參數框起來，每個參數間用逗號隔開 [document](https://graphviz.org/doc/info/attrs.html)

### fillcolor

當`style = filled` 時，設定節點內的顏色

digraph{
    a [style=filled, fillcolor = red];
}

digraph{
    a [style=filled, fillcolor = red];
}

### dir
箭頭方向性 [document](https://graphviz.org/docs/attrs/dir/)

digraph{
    a->b [dir=both];
    c->d [dir=one];
}

digraph{
    a->b [dir=both];
    c->d [dir=one];
}

### label
文字

digraph{
    a [label="node"];
    a->b[label="  arrow"]
}

digraph{
    a [label="node"];
    a->b[label="  arrow"]
}

### shape
指定 node 或 arrow 形狀
+ [arrowshape](https://graphviz.org/doc/info/arrows.html#primitive-shapes)
+ [node shape](https://graphviz.org/doc/info/shapes.html)

digraph{
    edge [dir=both];
    a [shape=egg];
    a->b [arrowhead=box, arrowtail=tee];
}

digraph{
    edge [dir=both];
    a [shape=egg];
    a->b [arrowhead=box, arrowtail=tee];
}

特別的是，Record-based 的 node 可以用特殊語法來宣告

digraph structs {
    node [shape=record];
    struct1 [label="<f0> left|<f1> mid&#92; dle|<f2> right"];
    struct2 [label="<f0> one|<f1> two"];
    struct1:f1 -> struct2:f0;
    struct1:f2 -> struct3:here;
}

digraph structs {
    node [shape=record];
    struct1 [label="<f0> left|<f1> mid&#92; dle|<f2> right"];
    struct2 [label="<f0> one|<f1> two"];
    struct1:f1 -> struct2:f0;
    struct1:f2 -> struct3:here;
}

也能用html語法，而ports參數能為節點分區，也可再指定要指在 ewsn 東西南北方向

digraph{
    node1
    [   
        shape = none;
        style = none;
        label = <<table border="0" cellspacing="0">
                    <tr><td port="hlink" border="1" bgcolor="#FFC382">hlink</td></tr>
                    <tr><td port="dlink" border="1" bgcolor="#FFC382">dlink</td></tr>
                    <tr><td border="1"> xxx</td></tr>
                    <tr><td border="1"> xxx</td></tr>

                </table>>
    ]
    node2->node1:hlink:w;
    node2->node1:dlink:e;
}

digraph{
    node1
    [   
        shape = none;
        style = none;
        label = <<table border="0" cellspacing="0">
                    <tr><td port="hlink" border="1" bgcolor="#FFC382">hlink</td></tr>
                    <tr><td port="dlink" border="1" bgcolor="#FFC382">dlink</td></tr>
                    <tr><td border="1"> xxx</td></tr>
                    <tr><td border="1"> xxx</td></tr>

                </table>>
    ]
    node2->node1:hlink:w;
    node2->node1:dlink:e;
}

## rank
調整排序 [document](https://graphviz.org/docs/attrs/rank/)

digraph{
    a;b;c;
    {rank=same; a b c}
    d;e;
    {rank=same; d e}
    a->e
}

digraph{
    a;b;c;
    {rank=same; a b c}
    d;e;
    {rank=same; d e}
    a->e;
}

## subgraph
在graph中開一個子圖，需以 `cluster` 為開頭

digraph{
    c->d;
    subgraph cluster_1 {
        a->b;
        color=red;
    }
}

## reference

+ [lk list](https://stackoverflow.com/questions/50494263/circular-list-in-graphviz-or-how-to-bend-the-edge)

+ [double pointer ](https://stackoverflow.com/questions/38410370/edge-pointing-at-edge-with-graphviz-and-dot)