pdfboss-style 1.2.0

CSS-subset theme parsing for pdfboss Markdown-to-PDF composition
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

//! Theme: cascade of CSS rules into concrete styles by element type.

use pdfboss_write::Color;

use crate::parse::{parse_sheet, StyleError};
use crate::style::{Declared, Edges, Element, TextStyle};

pub(crate) const DEFAULT_CSS: &str = "\
body { font-family: helvetica; font-size: 11pt; line-height: 1.4; color: #000; margin: 72pt; text-align: left; }\n\
h1 { font-size: 2em; font-weight: bold; margin-top: 18pt; margin-bottom: 9pt; }\n\
h2 { font-size: 1.6em; font-weight: bold; margin-top: 14pt; margin-bottom: 7pt; }\n\
h3 { font-size: 1.3em; font-weight: bold; margin-top: 12pt; margin-bottom: 6pt; }\n\
h4 { font-size: 1.15em; font-weight: bold; margin-top: 11pt; margin-bottom: 6pt; }\n\
h5 { font-size: 1em; font-weight: bold; margin-top: 11pt; margin-bottom: 6pt; }\n\
h6 { font-size: 0.9em; font-weight: bold; margin-top: 11pt; margin-bottom: 6pt; }\n\
p { margin-bottom: 8pt; }\n\
code { font-family: courier; background-color: #f0f0f0; }\n\
pre { font-family: courier; font-size: 0.9em; background-color: #f0f0f0; margin-top: 8pt; margin-bottom: 8pt; padding: 8pt; }\n\
blockquote { margin-left: 24pt; margin-top: 8pt; margin-bottom: 8pt; color: #555; font-style: italic; }\n\
ul { margin-top: 4pt; margin-bottom: 8pt; }\n\
ol { margin-top: 4pt; margin-bottom: 8pt; }\n\
li { margin-bottom: 2pt; }\n\
table { margin-top: 8pt; margin-bottom: 8pt; }\n\
th { font-weight: bold; background-color: #e8e8e8; padding: 4pt; }\n\
td { padding: 4pt; }\n\
a { color: #0645ad; text-decoration: underline; }\n\
del { text-decoration: line-through; }\n\
hr { margin-top: 12pt; margin-bottom: 12pt; color: #999; }\n";

/// A theme: cascade of CSS rules resolved into concrete styles by element.
#[derive(Debug)]
pub struct Theme {
    decls: Vec<Declared>,
}

impl Theme {
    /// The default theme: built-in CSS styles.
    pub fn default_theme() -> Theme {
        let rules = parse_sheet(DEFAULT_CSS).expect("the built-in default theme parses");
        Theme::from_rules(Theme::empty(), rules)
    }

    /// Parse a user stylesheet and overlay it onto the default theme.
    /// Later rules override earlier rules for the same element.
    pub fn parse(css: &str) -> Result<Theme, StyleError> {
        Ok(Theme::from_rules(Theme::default_theme(), parse_sheet(css)?))
    }

    /// Create an empty theme with no declarations.
    fn empty() -> Theme {
        Theme {
            decls: vec![Declared::default(); Element::ALL.len()],
        }
    }

    /// Fold rules into a theme, with later rules overriding earlier ones.
    fn from_rules(mut theme: Theme, rules: Vec<crate::parse::Rule>) -> Theme {
        for rule in rules {
            for element in &rule.elements {
                theme.decls[*element as usize].merge(&rule.declared);
            }
        }
        theme
    }

    /// The declared properties for an element, as merged from all matching
    /// rules.
    pub fn declared(&self, e: Element) -> &Declared {
        &self.decls[e as usize]
    }

    /// The base text style for the theme: hard fallback overlaid by body
    /// element declarations.
    pub fn base(&self) -> TextStyle {
        TextStyle::base().apply(self.declared(Element::Body))
    }

    /// The margin edges for an element. Unset sides default to 0.0.
    pub fn margin(&self, e: Element) -> Edges {
        let d = self.declared(e);
        Edges {
            top: d.margin[0].unwrap_or(0.0),
            right: d.margin[1].unwrap_or(0.0),
            bottom: d.margin[2].unwrap_or(0.0),
            left: d.margin[3].unwrap_or(0.0),
        }
    }

    /// The padding edges for an element. Unset sides default to 0.0.
    pub fn padding(&self, e: Element) -> Edges {
        let d = self.declared(e);
        Edges {
            top: d.padding[0].unwrap_or(0.0),
            right: d.padding[1].unwrap_or(0.0),
            bottom: d.padding[2].unwrap_or(0.0),
            left: d.padding[3].unwrap_or(0.0),
        }
    }

    /// The background color for an element, if set.
    pub fn background(&self, e: Element) -> Option<Color> {
        self.declared(e).background
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn default_theme_parses_and_covers_body() {
        let theme = Theme::default_theme();
        let base = theme.base();
        assert_eq!(base.size, 11.0);
        assert_eq!(base.family, crate::style::FontFamily::Helvetica);
        assert_eq!(theme.margin(Element::Body).left, 72.0);
    }

    #[test]
    fn user_theme_overlays_defaults() {
        let theme = Theme::parse("h1 { color: #c00; }").unwrap();
        let h1 = theme.base().apply(theme.declared(Element::H1));
        assert_eq!(h1.color, Color::Rgb(0.8, 0.0, 0.0));
        assert!(
            h1.bold,
            "default h1 bold survives an overlay that only sets color"
        );
        assert_eq!(h1.size, 22.0, "default h1 2em of body 11pt survives");
    }

    #[test]
    fn later_rule_wins() {
        let theme = Theme::parse("p { color: #111; }\np { color: #222; }").unwrap();
        let p = theme.base().apply(theme.declared(Element::P));
        let expected = 0x22 as f32 / 255.0;
        assert_eq!(p.color, Color::Rgb(expected, expected, expected));
    }

    #[test]
    fn parse_error_location_passes_through() {
        let e = Theme::parse("h1 { font-size: 12px; }").unwrap_err();
        assert_eq!(e.line, 1);
    }
}