terrio 0.2.0

Pure-Rust geospatial raster, vector and point cloud data I/O: read, write, convert and reproject GIS formats without C dependencies
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
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283

//! KML styles and OGR feature style strings (`PEN(c:#FF0000FF,w:2.000000px);BRUSH(...)`), the
//! form GDAL gives feature styles in and keeps in an `OGR_STYLE` field.
//!
//! Reading converts `<Style>` elements as GDAL's LIBKML driver does: `LineStyle` to `PEN`,
//! `PolyStyle` to `BRUSH`, `IconStyle` to `SYMBOL` and `LabelStyle` to `LABEL`, colors from
//! KML's `aabbggrr` to `#RRGGBBAA`. A `StyleMap` stands for its `normal` style. Writing goes the
//! other way.

use super::xml::{self, Element};
use std::fmt::Write as _;

/// The name of the field holding feature styles.
pub const FIELD: &str = "OGR_STYLE";

/// A KML color (`aabbggrr`, optionally with `#`) as `#RRGGBBAA`.
fn color(kml: &str) -> Option<String> {
    let h = kml.trim().trim_start_matches('#');
    if h.len() != 8 || !h.chars().all(|c| c.is_ascii_hexdigit()) {
        return None;
    }
    let (a, b, g, r) = (&h[0..2], &h[2..4], &h[4..6], &h[6..8]);
    Some(format!("#{r}{g}{b}{a}").to_ascii_uppercase())
}

/// An OGR color (`#RRGGBB` or `#RRGGBBAA`) as KML's `aabbggrr`.
fn kml_color(ogr: &str) -> Option<String> {
    let h = ogr.trim().trim_start_matches('#');
    if !(h.len() == 6 || h.len() == 8) || !h.chars().all(|c| c.is_ascii_hexdigit()) {
        return None;
    }
    let a = if h.len() == 8 { &h[6..8] } else { "ff" };
    Some(format!("{a}{}{}{}", &h[4..6], &h[2..4], &h[0..2]).to_ascii_lowercase())
}

fn num(e: &Element, name: &str) -> Option<f64> {
    e.child_text(name)?.parse().ok()
}

/// A `<Style>` element as an OGR style string; `None` when it sets nothing.
pub fn from_kml(style: &Element) -> Option<String> {
    let mut tools = Vec::new();
    if let Some(l) = style.child("LineStyle") {
        let mut p = Vec::new();
        if let Some(c) = l.child_text("color").and_then(color) {
            p.push(format!("c:{c}"));
        }
        if let Some(w) = num(l, "width") {
            p.push(format!("w:{w:.6}px"));
        }
        tools.push(("PEN", p));
    }
    if let Some(poly) = style.child("PolyStyle") {
        tools.push(("BRUSH", poly.child_text("color").and_then(color).map(|c| vec![format!("fc:{c}")]).unwrap_or_default()));
    }
    if let Some(i) = style.child("IconStyle") {
        let mut p = Vec::new();
        if let Some(href) = i.child("Icon").and_then(|ic| ic.child_text("href")) {
            p.push(format!("id:\"{href}\""));
        }
        if let Some(a) = num(i, "heading") {
            p.push(format!("a:{a:.6}"));
        }
        if let Some(c) = i.child_text("color").and_then(color) {
            p.push(format!("c:{c}"));
        }
        if let Some(s) = num(i, "scale") {
            p.push(format!("s:{s:.6}"));
        }
        if let Some(h) = i.child("hotSpot") {
            for (k, a) in [("dx", "x"), ("dy", "y")] {
                if let Some(v) = h.attr(a).and_then(|v| v.trim().parse::<f64>().ok()) {
                    p.push(format!("{k}:{v:.6}"));
                }
            }
        }
        tools.push(("SYMBOL", p));
    }
    if let Some(l) = style.child("LabelStyle") {
        let mut p = Vec::new();
        if let Some(c) = l.child_text("color").and_then(color) {
            p.push(format!("c:{c}"));
        }
        if let Some(s) = num(l, "scale") {
            p.push(format!("w:{:.6}", s * 100.0));
        }
        tools.push(("LABEL", p));
    }
    let s: Vec<String> = tools.into_iter().filter(|(_, p)| !p.is_empty()).map(|(t, p)| format!("{t}({})", p.join(","))).collect();
    (!s.is_empty()).then(|| s.join(";"))
}

/// The styles a document defines (`<Style>` and `<StyleMap>` with an id, anywhere), by id, as
/// OGR style strings. A style map stands for its `normal` style.
pub fn table(root: &Element) -> Vec<(String, String)> {
    let mut styles: Vec<(String, String)> = Vec::new();
    let mut maps: Vec<&Element> = Vec::new();
    fn walk<'a>(e: &'a Element, styles: &mut Vec<(String, String)>, maps: &mut Vec<&'a Element>) {
        for c in &e.children {
            match c.name.as_str() {
                "Style" => {
                    if let (Some(id), Some(s)) = (c.attr("id"), from_kml(c)) {
                        styles.push((id.to_string(), s));
                    }
                }
                "StyleMap" if c.attr("id").is_some() => maps.push(c),
                "Placemark" => {}
                _ => walk(c, styles, maps),
            }
        }
    }
    walk(root, &mut styles, &mut maps);
    for m in maps {
        let normal = m.children_named("Pair").find(|p| p.child_text("key") == Some("normal"));
        let s = normal.and_then(|p| match p.child("Style") {
            Some(st) => from_kml(st),
            None => {
                let url = p.child_text("styleUrl")?;
                let id = url.strip_prefix('#')?;
                styles.iter().find(|(k, _)| k == id).map(|(_, v)| v.clone())
            }
        });
        if let (Some(id), Some(s)) = (m.attr("id"), s) {
            styles.push((id.to_string(), s));
        }
    }
    styles
}

/// A placemark's style: its own `<Style>`, else its `styleUrl` resolved through the document's
/// styles (`@id` when the document does not define it; other documents' URLs as they are).
pub fn of_feature(f: &Element, table: &[(String, String)]) -> Option<String> {
    if let Some(s) = f.child("Style").and_then(from_kml) {
        return Some(s);
    }
    let url = f.child_text("styleUrl")?;
    match url.strip_prefix('#') {
        Some(id) => Some(table.iter().find(|(k, _)| k == id).map_or_else(|| format!("@{id}"), |(_, v)| v.clone())),
        None => Some(url.to_string()),
    }
}

/// Splits on `sep` outside quotes and parentheses.
fn split_top(s: &str, sep: char) -> Vec<&str> {
    let (mut out, mut depth, mut quoted, mut start) = (Vec::new(), 0i32, false, 0);
    for (i, c) in s.char_indices() {
        match c {
            '"' => quoted = !quoted,
            '(' if !quoted => depth += 1,
            ')' if !quoted => depth -= 1,
            c if c == sep && !quoted && depth == 0 => {
                out.push(&s[start..i]);
                start = i + c.len_utf8();
            }
            _ => {}
        }
    }
    out.push(&s[start..]);
    out
}

/// The tools of an OGR style string: `(name, [(param, value)])`.
fn tools(style: &str) -> Vec<(String, Vec<(String, String)>)> {
    split_top(style, ';')
        .into_iter()
        .filter_map(|t| {
            let t = t.trim();
            let open = t.find('(')?;
            let body = t[open + 1..].strip_suffix(')')?;
            let params = split_top(body, ',')
                .into_iter()
                .filter_map(|p| {
                    let (k, v) = p.split_once(':')?;
                    Some((k.trim().to_ascii_lowercase(), v.trim().trim_matches('"').to_string()))
                })
                .collect();
            Some((t[..open].trim().to_ascii_uppercase(), params))
        })
        .collect()
}

/// The leading number of a value such as `2.5px`.
fn value_num(v: &str) -> Option<f64> {
    let end = v.find(|c: char| !(c.is_ascii_digit() || c == '.' || c == '-' || c == '+' || c == 'e' || c == 'E')).unwrap_or(v.len());
    v[..end].parse().ok()
}

/// The KML of a style: the body of a `<Style>` element (its sub-styles), empty when the string
/// sets nothing KML can hold.
pub fn to_kml(style: &str) -> String {
    let mut s = String::new();
    let get = |p: &[(String, String)], k: &str| p.iter().find(|(n, _)| n == k).map(|(_, v)| v.clone());
    for (tool, p) in tools(style) {
        match tool.as_str() {
            "SYMBOL" => {
                s.push_str("<IconStyle>");
                if let Some(c) = get(&p, "c").and_then(|c| kml_color(&c)) {
                    let _ = write!(s, "<color>{c}</color>");
                }
                if let Some(v) = get(&p, "s").and_then(|v| value_num(&v)) {
                    let _ = write!(s, "<scale>{v}</scale>");
                }
                if let Some(v) = get(&p, "a").and_then(|v| value_num(&v)) {
                    let _ = write!(s, "<heading>{v}</heading>");
                }
                if let Some(id) = get(&p, "id").filter(|id| !id.starts_with("ogr-sym-")) {
                    let _ = write!(s, "<Icon><href>{}</href></Icon>", xml::escape(&id));
                }
                if let (Some(x), Some(y)) = (get(&p, "dx").and_then(|v| value_num(&v)), get(&p, "dy").and_then(|v| value_num(&v))) {
                    let _ = write!(s, "<hotSpot x=\"{x}\" y=\"{y}\" xunits=\"fraction\" yunits=\"fraction\"/>");
                }
                s.push_str("</IconStyle>");
            }
            "LABEL" => {
                s.push_str("<LabelStyle>");
                if let Some(c) = get(&p, "c").and_then(|c| kml_color(&c)) {
                    let _ = write!(s, "<color>{c}</color>");
                }
                if let Some(v) = get(&p, "w").and_then(|v| value_num(&v)) {
                    let _ = write!(s, "<scale>{}</scale>", v / 100.0);
                }
                s.push_str("</LabelStyle>");
            }
            "PEN" => {
                s.push_str("<LineStyle>");
                if let Some(c) = get(&p, "c").and_then(|c| kml_color(&c)) {
                    let _ = write!(s, "<color>{c}</color>");
                }
                if let Some(v) = get(&p, "w").and_then(|v| value_num(&v)) {
                    let _ = write!(s, "<width>{v}</width>");
                }
                s.push_str("</LineStyle>");
            }
            "BRUSH" => {
                s.push_str("<PolyStyle>");
                if let Some(c) = get(&p, "fc").and_then(|c| kml_color(&c)) {
                    let _ = write!(s, "<color>{c}</color>");
                }
                s.push_str("</PolyStyle>");
            }
            _ => {}
        }
    }
    s
}

/// Whether a style value refers to a style rather than describing one: `@name`, or another
/// document's URL.
pub fn is_reference(v: &str) -> bool {
    v.starts_with('@') || !v.contains('(')
}

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

    #[test]
    fn converts_like_gdal() {
        let doc = xml::parse(
            r#"<kml><Document>
            <Style id="s1"><IconStyle><color>ff00ff00</color><scale>1.1</scale><heading>45</heading><Icon><href>http://x/i.png</href></Icon><hotSpot x="0.5" y="0" xunits="fraction" yunits="fraction"/></IconStyle><LabelStyle><color>ff0000ff</color><scale>1.5</scale></LabelStyle></Style>
            <Style id="s2"><LineStyle><color>7f00ffff</color><width>3.5</width></LineStyle><PolyStyle><color>4000ff00</color><fill>1</fill></PolyStyle></Style>
            <StyleMap id="m"><Pair><key>normal</key><styleUrl>#s2</styleUrl></Pair><Pair><key>highlight</key><styleUrl>#s1</styleUrl></Pair></StyleMap>
            </Document></kml>"#,
        )
        .unwrap();
        let t = table(&doc);
        let get = |k: &str| t.iter().find(|(n, _)| n == k).map(|(_, v)| v.as_str());
        // As GDAL's LIBKML driver gives them.
        assert_eq!(
            get("s1"),
            Some(
                r#"SYMBOL(id:"http://x/i.png",a:45.000000,c:#00FF00FF,s:1.100000,dx:0.500000,dy:0.000000);LABEL(c:#FF0000FF,w:150.000000)"#
            )
        );
        assert_eq!(get("s2"), Some("PEN(c:#FFFF007F,w:3.500000px);BRUSH(fc:#00FF0040)"));
        assert_eq!(get("m"), get("s2"));
        // Back to KML, and again to the same string.
        let back = xml::parse(&format!("<Style>{}</Style>", to_kml(get("s1").unwrap()))).unwrap();
        assert_eq!(from_kml(&back).as_deref(), get("s1"));
        let back = xml::parse(&format!("<Style>{}</Style>", to_kml(get("s2").unwrap()))).unwrap();
        assert_eq!(from_kml(&back).as_deref(), get("s2"));
    }
}