Grcov report - svg.rs

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//! SVG renderer. Uses plotters' `SVGBackend` and the shared `draw`

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//! dispatch in `draw.rs` so the canvas renderer produces identical

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//! layouts.

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use plotters::prelude::*;

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use crate::draw::draw_on;

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use crate::spec::ChartSpec;

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/// Render `spec` to an SVG string of the given dimensions. Drawing

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/// errors fall back to a minimal SVG with the chart title so a broken

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/// chart never fails a page render.

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#[must_use]

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pub fn render_svg(spec: &ChartSpec, width: u32, height: u32) -> String {

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    let mut buf = String::new();

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    let ok = {

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        let backend = SVGBackend::with_string(&mut buf, (width, height));

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        let root = backend.into_drawing_area();

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        draw_on(&root, spec).is_ok()

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};

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    if !ok || buf.is_empty() {

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        return format!(

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            "<svg xmlns=\"http://www.w3.org/2000/svg\" width=\"{width}\" height=\"{height}\">\

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                 <title>{}</title>\

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                 <text x=\"10\" y=\"20\" font-family=\"sans-serif\" font-size=\"14\">{}</text>\

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             </svg>",

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            escape_xml(&spec.title),

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            escape_xml(&spec.title),

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);

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buf

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fn escape_xml(s: &str) -> String {

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    s.replace('&', "&amp;")

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        .replace('<', "&lt;")

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        .replace('>', "&gt;")

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#[cfg(test)]

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mod tests {

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    use super::*;

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    use crate::spec::{ChartKind, Series, SeriesPoint};

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    fn sample(kind: ChartKind) -> ChartSpec {

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        ChartSpec {

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            title: "Test".to_string(),

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            kind,

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            x_label: "X".to_string(),

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            y_label: "Y".to_string(),

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            series: vec![Series {

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                label: "A".to_string(),

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                commodity_symbol: "USD".to_string(),

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                points: vec![

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                    SeriesPoint {

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                        x: "Jan".to_string(),

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                        y_num: 100,

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                        y_denom: 1,

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},

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                    SeriesPoint {

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                        x: "Feb".to_string(),

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                        y_num: 200,

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                        y_denom: 1,

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},

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],

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}],

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            notes: vec![],

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    #[test]

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    fn render_svg_emits_non_empty_svg_for_each_kind() {

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        for kind in [ChartKind::Bar, ChartKind::StackedBar, ChartKind::Line] {

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            let svg = render_svg(&sample(kind), 400, 300);

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            assert!(svg.contains("<svg"), "missing <svg for {kind:?}");

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            assert!(svg.contains("Test"), "title missing for {kind:?}");

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    #[test]

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    fn render_svg_includes_series_label() {

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        let svg = render_svg(&sample(ChartKind::Line), 400, 300);

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        // Plotters escapes text; "A" should appear at least once in

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        // the legend or axis.

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        assert!(svg.contains('A'), "series label missing");

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    #[test]

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    fn render_svg_empty_spec_is_safe() {

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        let spec = ChartSpec {

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            title: "Empty".to_string(),

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            kind: ChartKind::Bar,

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            x_label: String::new(),

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            y_label: String::new(),

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            series: vec![],

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            notes: vec![],

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};

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        let svg = render_svg(&spec, 400, 300);

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        assert!(svg.contains("<svg"));

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