merman-render 0.6.2

Headless layout + SVG renderer for Mermaid (parity-focused; upstream SVG goldens).
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183

//! Flowchart SVG defs and marker emission.

use std::fmt::Write as _;

use super::super::util::{escape_xml, escape_xml_display};
use super::{FlowchartRenderCtx, flowchart_resolve_stroke_for_marker};

pub(in crate::svg::parity::flowchart) struct FlowchartDefs<'a> {
    diagram_id: &'a str,
    extra_marker_colors: Vec<String>,
}

pub(in crate::svg::parity::flowchart) fn prepare_flowchart_defs<'a>(
    diagram_id: &'a str,
    ctx: &FlowchartRenderCtx<'_>,
) -> FlowchartDefs<'a> {
    FlowchartDefs {
        diagram_id,
        extra_marker_colors: collect_edge_marker_colors(ctx),
    }
}

impl FlowchartDefs<'_> {
    pub(in crate::svg::parity::flowchart) fn push_base_markers(&self, out: &mut String) {
        push_base_markers(out, self.diagram_id);
    }

    pub(in crate::svg::parity::flowchart) fn push_extra_markers(&self, out: &mut String) {
        push_extra_markers(out, self.diagram_id, &self.extra_marker_colors);
    }
}

fn push_base_markers(out: &mut String, diagram_id: &str) {
    let id = escape_xml(diagram_id);
    let _ = write!(
        out,
        r#"<marker id="{}_flowchart-v2-pointEnd" class="marker flowchart-v2" viewBox="0 0 10 10" refX="5" refY="5" markerUnits="userSpaceOnUse" markerWidth="8" markerHeight="8" orient="auto"><path d="M 0 0 L 10 5 L 0 10 z" class="arrowMarkerPath" style="stroke-width: 1; stroke-dasharray: 1, 0;"/></marker>"#,
        id.as_str()
    );
    let _ = write!(
        out,
        r#"<marker id="{}_flowchart-v2-pointStart" class="marker flowchart-v2" viewBox="0 0 10 10" refX="4.5" refY="5" markerUnits="userSpaceOnUse" markerWidth="8" markerHeight="8" orient="auto"><path d="M 0 5 L 10 10 L 10 0 z" class="arrowMarkerPath" style="stroke-width: 1; stroke-dasharray: 1, 0;"/></marker>"#,
        id.as_str()
    );
    let _ = write!(
        out,
        r#"<marker id="{}_flowchart-v2-circleEnd" class="marker flowchart-v2" viewBox="0 0 10 10" refX="11" refY="5" markerUnits="userSpaceOnUse" markerWidth="11" markerHeight="11" orient="auto"><circle cx="5" cy="5" r="5" class="arrowMarkerPath" style="stroke-width: 1; stroke-dasharray: 1, 0;"/></marker>"#,
        id.as_str()
    );
    let _ = write!(
        out,
        r#"<marker id="{}_flowchart-v2-circleStart" class="marker flowchart-v2" viewBox="0 0 10 10" refX="-1" refY="5" markerUnits="userSpaceOnUse" markerWidth="11" markerHeight="11" orient="auto"><circle cx="5" cy="5" r="5" class="arrowMarkerPath" style="stroke-width: 1; stroke-dasharray: 1, 0;"/></marker>"#,
        id.as_str()
    );
    let _ = write!(
        out,
        r#"<marker id="{}_flowchart-v2-crossEnd" class="marker cross flowchart-v2" viewBox="0 0 11 11" refX="12" refY="5.2" markerUnits="userSpaceOnUse" markerWidth="11" markerHeight="11" orient="auto"><path d="M 1,1 l 9,9 M 10,1 l -9,9" class="arrowMarkerPath" style="stroke-width: 2; stroke-dasharray: 1, 0;"/></marker>"#,
        id.as_str()
    );
    let _ = write!(
        out,
        r#"<marker id="{}_flowchart-v2-crossStart" class="marker cross flowchart-v2" viewBox="0 0 11 11" refX="-1" refY="5.2" markerUnits="userSpaceOnUse" markerWidth="11" markerHeight="11" orient="auto"><path d="M 1,1 l 9,9 M 10,1 l -9,9" class="arrowMarkerPath" style="stroke-width: 2; stroke-dasharray: 1, 0;"/></marker>"#,
        id.as_str()
    );
}

fn marker_color_id(color: &str) -> String {
    // Mermaid's DOM marker id coloring logic (Mermaid@11.12.2) uses:
    // `strokeColor.replace(/[^\dA-Za-z]/g, '_')`
    //
    // Important: this does not trim whitespace. As a result, values like `" orange"` (leading
    // space captured from `style="...stroke: orange;..."`) produce a leading `_` in the color id,
    // which in turn yields a `__orange` suffix in the final marker id.
    let raw = color.trim_end_matches(';');
    if raw.trim().is_empty() {
        return String::new();
    }
    let mut out = String::with_capacity(raw.len());
    for ch in raw.chars() {
        if ch.is_ascii_alphanumeric() {
            out.push(ch);
        } else {
            out.push('_');
        }
    }
    out
}

#[inline]
pub(in crate::svg::parity::flowchart) fn write_flowchart_marker_id_xml(
    out: &mut String,
    diagram_id: &str,
    base: &str,
    color: Option<&str>,
) {
    let _ = write!(out, "{}", escape_xml_display(diagram_id));
    out.push('_');
    out.push_str(base);

    let Some(color) = color else {
        return;
    };
    let raw = color.trim_end_matches(';');
    if raw.trim().is_empty() {
        return;
    }
    out.push('_');
    for ch in raw.chars() {
        if ch.is_ascii_alphanumeric() {
            out.push(ch);
        } else {
            out.push('_');
        }
    }
}

fn push_extra_markers(out: &mut String, diagram_id: &str, colors: &[String]) {
    for c in colors {
        let cid = marker_color_id(c);
        if cid.is_empty() {
            continue;
        }

        let _ = write!(
            out,
            r#"<marker id="{}_flowchart-v2-pointEnd_{}" class="marker flowchart-v2" viewBox="0 0 10 10" refX="5" refY="5" markerUnits="userSpaceOnUse" markerWidth="8" markerHeight="8" orient="auto"><path d="M 0 0 L 10 5 L 0 10 z" class="arrowMarkerPath" style="stroke-width: 1; stroke-dasharray: 1, 0;" stroke="{}" fill="{}"/></marker>"#,
            escape_xml(diagram_id),
            escape_xml(&cid),
            escape_xml_display(c.trim()),
            escape_xml_display(c.trim())
        );
    }
}

fn collect_edge_marker_colors(ctx: &FlowchartRenderCtx<'_>) -> Vec<String> {
    let mut seen: std::collections::HashSet<String> = std::collections::HashSet::new();
    let mut out: Vec<String> = Vec::new();

    for e in ctx.edges_by_id.values() {
        let mut found: Option<String> = None;
        for raw in ctx.default_edge_style.iter().chain(e.style.iter()) {
            // Mirror upstream behavior: `strokeColor` is extracted from `style="...stroke:...;..."`
            // without trimming, and then marker ids use `replace(/[^\dA-Za-z]/g, '_')`.
            //
            // Our style declarations may include a leading space (e.g. ` stroke: orange`), so we
            // only trim the key side.
            let s = raw.trim_start();
            let Some(rest) = s.strip_prefix("stroke:") else {
                continue;
            };
            let cid = marker_color_id(rest);
            if cid.is_empty() {
                continue;
            }
            if seen.insert(cid) {
                found = Some(rest.to_string());
            }
            break;
        }

        if found.is_none() && !e.classes.is_empty() {
            let stroke = flowchart_resolve_stroke_for_marker(
                ctx.class_defs,
                &e.classes,
                &ctx.default_edge_style,
                &e.style,
            );
            if let Some(stroke) = stroke {
                let cid = marker_color_id(&stroke);
                if !cid.is_empty() && seen.insert(cid) {
                    found = Some(stroke);
                }
            }
        }

        if let Some(v) = found {
            out.push(v);
        }
    }

    out.sort();
    out
}