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refactor(chart): move render.rs items to render/

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This commit is contained in:
aiongg
2026-10-26 19:04:52 +00:00
parent c5098a0765
commit 3813413b65
7 changed files with 1679 additions and 1647 deletions
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crates/chart/src/render.rs
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crates/chart/src/render/cartesian.rs
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use super::frame::{Bx, CatAxis, ValAxis, frame, on, value_range};
use super::legend::{cat_label, plot_kind};
use super::lines::{decimate, draw_markers, draw_runs};
use super::trend::{draw_trend_labels, draw_trendlines, max_backward, max_forward, max_forward_slots, supports_trendline};
use super::*;
// ---------------------------------------------------------------- cartesian (column/bar/line/area/combo)
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
enum Fam {
Col,
ColStack,
Col100,
Line,
LineStack,
Area,
AreaStack,
Area100,
}
fn family(k: ChartKind) -> Fam {
use ChartKind::*;
match k {
ColumnStacked | BarStacked => Fam::ColStack,
ColumnStacked100 | BarStacked100 => Fam::Col100,
Line | LineMarkers | Scatter | ScatterLines | Radar | Stock => Fam::Line,
LineStacked => Fam::LineStack,
Area => Fam::Area,
AreaStacked => Fam::AreaStack,
AreaStacked100 => Fam::Area100,
_ => Fam::Col,
}
}
/// Families stacked to 100%: each category's values are shares of its total.
fn is_100(f: Fam) -> bool {
matches!(f, Fam::Col100 | Fam::Area100)
}
fn is_col(f: Fam) -> bool {
matches!(f, Fam::Col | Fam::ColStack | Fam::Col100)
}
fn is_line(f: Fam) -> bool {
matches!(f, Fam::Line | Fam::LineStack)
}
pub(super) fn cartesian(ctx: &mut Ctx, chart: &Chart, data: &ChartData, area: Bx, horizontal: bool) {
let ncat = data.categories.len().max(data.series.iter().map(|s| s.values.len()).max().unwrap_or(0)).min(MAX_CATS);
if ncat == 0 {
return;
}
let kinds: Vec<ChartKind> = data.series.iter().map(|s| if horizontal { chart.kind } else { plot_kind(chart, s) }).collect();
let fams: Vec<Fam> = kinds.iter().map(|k| family(*k)).collect();
let any_primary = data.series.iter().any(|s| !s.secondary);
let sec: Vec<bool> = data.series.iter().map(|s| s.secondary && any_primary && !horizontal).collect();
// Totals for 100% stacking, per axis and family (100% columns and 100% areas stack apart).
let mut totals: Vec<((bool, Fam), Vec<f64>)> = Vec::new();
for (i, s) in data.series.iter().enumerate() {
let fam = fams.get(i).copied().unwrap_or(Fam::Col);
if is_100(fam) {
let key = (sec.get(i).copied().unwrap_or(false), fam);
let p = match totals.iter().position(|(k, _)| *k == key) {
Some(p) => p,
None => {
totals.push((key, vec![0.0; ncat]));
totals.len() - 1
}
};
for (j, v) in s.values.iter().take(ncat).enumerate() {
if let (Some(v), Some(t)) = (v, totals.get_mut(p).and_then(|(_, t)| t.get_mut(j))) {
*t += v.abs();
}
}
}
}
// A value's share of its category's total, for the 100% families.
let share = |key: (bool, Fam), j: usize, v: f64| {
let t = totals.iter().find(|(k, _)| *k == key).and_then(|(_, t)| t.get(j)).copied().unwrap_or(0.0);
if t > 0.0 { v / t } else { 0.0 }
};
// Stack accumulators keyed by (axis, family): positive and negative running sums.
let mut stacks: Vec<((bool, Fam), Vec<f64>, Vec<f64>)> = Vec::new();
let mut spans: Vec<Vec<Option<(f64, f64)>>> = Vec::with_capacity(data.series.len());
for (i, s) in data.series.iter().enumerate() {
let fam = fams.get(i).copied().unwrap_or(Fam::Col);
let a = sec.get(i).copied().unwrap_or(false);
let stacked = matches!(fam, Fam::ColStack | Fam::Col100 | Fam::LineStack | Fam::AreaStack | Fam::Area100);
let key = (a, fam);
let si = if stacked {
match stacks.iter().position(|(k, _, _)| *k == key) {
Some(p) => Some(p),
None => {
stacks.push((key, vec![0.0; ncat], vec![0.0; ncat]));
Some(stacks.len() - 1)
}
}
} else {
None
};
let mut row = Vec::with_capacity(ncat);
for j in 0..ncat {
let v = s.values.get(j).copied().flatten();
let span = match (si.and_then(|p| stacks.get_mut(p)), fam) {
(Some((_, pos, neg)), Fam::ColStack | Fam::Col100) => v.and_then(|v| {
let v = if fam == Fam::Col100 { share(key, j, v) } else { v };
let acc = if v >= 0.0 { pos.get_mut(j) } else { neg.get_mut(j) }?;
let base = *acc;
*acc += v;
Some((base, *acc))
}),
(Some((_, pos, _)), _) => {
let v = v.unwrap_or(0.0);
let v = if fam == Fam::Area100 { share(key, j, v) } else { v };
pos.get_mut(j).map(|acc| {
let base = *acc;
*acc = clean(*acc + v);
(base, *acc)
})
}
(None, _) => v.map(|v| (0.0, v)),
};
row.push(span);
}
spans.push(row);
}
// Axis scales.
let mut axes: Vec<(Scale, Fmt)> = Vec::new();
for axis in [false, true] {
let members: Vec<usize> = (0..data.series.len()).filter(|i| sec.get(*i).copied().unwrap_or(false) == axis).collect();
if members.is_empty() {
continue;
}
let force_zero = members.iter().any(|i| fams.get(*i).is_some_and(|f| !is_line(*f)));
let all100 = members.iter().all(|i| fams.get(*i).is_some_and(|f| is_100(*f)));
let range = value_range(members.iter().flat_map(|i| {
let line = fams.get(*i).is_some_and(|f| is_line(*f));
spans.get(*i).into_iter().flatten().flatten().flat_map(move |(b, t)| if line { vec![*t] } else { vec![*b, *t] })
}));
let (lo, hi) = range.unwrap_or((0.0, 0.0));
let (scale, fmt) = if all100 {
(fixed_scale(if lo < -1e-9 { -1.0 } else { 0.0 }, if hi > 1e-9 || lo >= -1e-9 { 1.0 } else { 0.0 }, 0.2), Fmt::new("0%"))
} else {
let code = members.first().and_then(|i| data.series.get(*i)).map(|s| s.number_format.as_str()).unwrap_or("General");
(nice_scale(lo, hi, force_zero), Fmt::new(code))
};
axes.push((scale, fmt));
if !axis && sec.iter().all(|s| !s) {
break;
}
}
let Some((s1, f1)) = axes.first() else { return };
let y1 = ValAxis { scale: *s1, fmt: f1 };
let y2 = axes.get(1).map(|(s, f)| ValAxis { scale: *s, fmt: f });
// A forward forecast on a category axis adds empty category slots after the data.
let fwd = data
.series
.iter()
.enumerate()
.filter(|(i, _)| kinds.get(*i).is_some_and(|k| supports_trendline(*k)))
.map(|(_, s)| max_forward(s))
.fold(0.0, f64::max);
let ncat_slots = ncat.saturating_add(fwd.min(max_forward_slots(ncat)).ceil() as usize).min(MAX_CATS.max(ncat));
let labels: Vec<String> = (0..ncat_slots).map(|j| if j < ncat { cat_label(data, j) } else { String::new() }).collect();
// Outer levels padded to the slots (forecast slots stay in the last group).
let outer: Vec<Vec<String>> =
data.category_levels.iter().map(|l| (0..ncat_slots).map(|j| l.get(j).cloned().unwrap_or_default()).collect()).collect();
let plot = frame(ctx, area, CatAxis::Labels(&labels, &outer), &y1, y2.as_ref(), horizontal, chart.gridlines);
if !plot.ok() {
return;
}
let scale_of = |i: usize| -> Scale { if sec.get(i).copied().unwrap_or(false) { y2.as_ref().map(|a| a.scale).unwrap_or(*s1) } else { *s1 } };
let cat_len = if horizontal { plot.h } else { plot.w };
let cw = cat_len / ncat_slots as f32;
let center = |j: usize| if horizontal { plot.bottom() - (j as f32 + 0.5) * cw } else { plot.x + (j as f32 + 0.5) * cw };
let vpos = |v: f64, sc: &Scale| if horizontal { plot.x + sc.frac(v) * plot.w } else { plot.bottom() - sc.frac(v) * plot.h };
// Column slots: each clustered series gets one, each stack group shares one.
let mut slot_keys: Vec<(bool, Fam, usize)> = Vec::new();
let mut slot_of = vec![0usize; data.series.len()];
for (i, f) in fams.iter().enumerate() {
if !is_col(*f) {
continue;
}
let a = sec.get(i).copied().unwrap_or(false);
let key = if *f == Fam::Col { (a, *f, i) } else { (a, *f, usize::MAX) };
let k = match slot_keys.iter().position(|k| *k == key) {
Some(p) => p,
None => {
slot_keys.push(key);
slot_keys.len() - 1
}
};
if let Some(s) = slot_of.get_mut(i) {
*s = k;
}
}
let nslots = slot_keys.len().max(1) as f32;
let bw = cw / (nslots + 1.5);
let labels_on = chart.data_labels && ncat <= MAX_LABELS;
// Area labels wait until every area is filled, so a later (stacked) area can't paint over them.
let mut area_labels = Vec::new();
// Areas first, then columns, then lines on top.
for pass in 0..3 {
for (i, s) in data.series.iter().enumerate() {
let fam = fams.get(i).copied().unwrap_or(Fam::Col);
let want = match pass {
0 => matches!(fam, Fam::Area | Fam::AreaStack | Fam::Area100),
1 => is_col(fam),
_ => is_line(fam),
};
if !want {
continue;
}
let sc = scale_of(i);
let fmt = Fmt::new(&s.number_format);
let row = match spans.get(i) {
Some(r) => r,
None => continue,
};
match pass {
0 => {
let mut top = Vec::with_capacity(ncat * 2);
let mut base = Vec::with_capacity(ncat);
for (j, sp) in row.iter().enumerate() {
let (b, t) = sp.unwrap_or((0.0, 0.0));
let c = center(j);
top.push([c, vpos(t, &sc)]);
base.push([c, vpos(b, &sc)]);
// Source values (not stack totals), just above the top edge like the line labels.
if labels_on
&& sp.is_some()
&& let Some(v) = s.values.get(j).copied().flatten()
{
area_labels.push((c, vpos(t, &sc) - 5.0, fmt.format(v, None)));
}
}
if top.len() == 1 {
// A single point: give it some width.
if let (Some(t), Some(b)) = (top.first().copied(), base.first().copied()) {
top = vec![[t[0] - cw * 0.3, t[1]], [t[0] + cw * 0.3, t[1]]];
base = vec![[b[0] - cw * 0.3, b[1]], [b[0] + cw * 0.3, b[1]]];
}
}
let top = decimate(top, MAX_LINE_PTS * 2);
let base = decimate(base, MAX_LINE_PTS * 2);
let mut poly = top;
poly.extend(base.into_iter().rev());
if poly.len() >= 3 {
ctx.out.push(Prim::Polygon { pts: poly, fill: s.color, stroke: None });
}
}
1 => {
let k = slot_of.get(i).copied().unwrap_or(0) as f32;
for (j, sp) in row.iter().enumerate() {
let Some((b, t)) = sp else { continue };
let (pb, pt) = (vpos(*b, &sc), vpos(*t, &sc));
let c = center(j);
let lo = pb.min(pt);
let len = (pb - pt).abs();
if horizontal {
let y = c + nslots * bw / 2.0 - (k + 1.0) * bw;
ctx.rect(lo, y, len, bw, s.color, None);
} else {
let x = c - nslots * bw / 2.0 + k * bw;
ctx.rect(x, lo, bw, len, s.color, None);
}
if labels_on && let Some(v) = s.values.get(j).copied().flatten() {
let t = fmt.format(v, None);
let stacked = fam != Fam::Col;
let mid = (pb + pt) / 2.0;
if horizontal {
let y = c + nslots * bw / 2.0 - (k + 0.5) * bw;
if stacked {
ctx.text(mid, y, &t, LABEL_SIZE, on(s.color), HAlign::Center, VAlign::Middle);
} else if v >= 0.0 {
ctx.text(pb.max(pt) + 3.0, y, &t, LABEL_SIZE, TEXT, HAlign::Left, VAlign::Middle);
} else {
ctx.text(lo - 3.0, y, &t, LABEL_SIZE, TEXT, HAlign::Right, VAlign::Middle);
}
} else {
let x = c - nslots * bw / 2.0 + (k + 0.5) * bw;
if stacked {
ctx.text(x, mid, &t, LABEL_SIZE, on(s.color), HAlign::Center, VAlign::Middle);
} else if v >= 0.0 {
ctx.text(x, lo - 2.0, &t, LABEL_SIZE, TEXT, HAlign::Center, VAlign::Bottom);
} else {
ctx.text(x, lo + len + 2.0, &t, LABEL_SIZE, TEXT, HAlign::Center, VAlign::Top);
}
}
}
}
}
_ => {
let pts: Vec<Option<[f32; 2]>> = row.iter().enumerate().map(|(j, sp)| sp.map(|(_, t)| [center(j), vpos(t, &sc)])).collect();
draw_runs(ctx, &pts, s.color, 2.25, s.smooth.then_some(plot));
let k = kinds.get(i).copied().unwrap_or(ChartKind::Line);
if k == ChartKind::LineMarkers && cw >= 3.0 {
draw_markers(ctx, pts.iter().flatten().copied(), 3.5, s.color);
}
if labels_on {
for (j, p) in pts.iter().enumerate() {
if let (Some(p), Some(v)) = (p, s.values.get(j).copied().flatten()) {
ctx.text(p[0], p[1] - 5.0, &fmt.format(v, None), LABEL_SIZE, TEXT, HAlign::Center, VAlign::Bottom);
}
}
}
}
}
}
for (x, y, t) in area_labels.drain(..) {
ctx.text(x, y, &t, LABEL_SIZE, TEXT, HAlign::Center, VAlign::Bottom);
}
}
// Trendlines on top: x is the category number 1..n.
let mut trend_labels = Vec::new();
for (i, s) in data.series.iter().enumerate() {
if s.trendlines.is_empty() || !kinds.get(i).is_some_and(|k| supports_trendline(*k)) {
continue;
}
let sc = scale_of(i);
let pts: Vec<(f64, f64)> = s.values.iter().take(ncat).enumerate().filter_map(|(j, v)| v.map(|v| ((j + 1) as f64, v))).collect();
let frac = |x: f64, y: f64| ((x - 0.5) / ncat_slots as f64, (y - sc.min) / (sc.max - sc.min));
let px = |(fx, fy): (f64, f64)| {
if horizontal {
[plot.x + fy as f32 * plot.w, plot.bottom() - fx as f32 * plot.h]
} else {
[plot.x + fx as f32 * plot.w, plot.bottom() - fy as f32 * plot.h]
}
};
draw_trendlines(ctx, s, &pts, &frac, &px, &mut trend_labels, (0.5, ncat_slots as f64 + 0.5));
}
draw_trend_labels(ctx, plot, &trend_labels);
}
// ---------------------------------------------------------------- scatter & bubble
pub(super) fn scatter(ctx: &mut Ctx, chart: &Chart, data: &ChartData, area: Bx) {
let pts_of = |s: &SeriesData| -> Vec<Option<(f64, f64)>> {
s.values
.iter()
.enumerate()
.map(|(j, v)| {
let x = match &s.x {
Some(xs) => xs.get(j).copied().flatten(),
None => Some((j + 1) as f64),
};
match (x, v) {
(Some(x), Some(y)) => Some((x, *y)),
_ => None,
}
})
.collect()
};
let all: Vec<Vec<Option<(f64, f64)>>> = data.series.iter().map(pts_of).collect();
let Some((mut xlo, mut xhi)) = value_range(all.iter().flatten().flatten().map(|p| p.0)) else { return };
// Forecasts extend the x axis to the trendline's ends.
for (s, pts) in data.series.iter().zip(&all) {
if let Some((lo, hi)) = value_range(pts.iter().flatten().map(|p| p.0)).filter(|_| !s.trendlines.is_empty()) {
xlo = xlo.min(lo - max_backward(s));
xhi = xhi.max(hi + max_forward(s));
}
}
let Some((ylo, yhi)) = value_range(all.iter().flatten().flatten().map(|p| p.1)) else { return };
let xs = nice_scale(xlo, xhi, false);
let ys = nice_scale(ylo, yhi, false);
let fx = Fmt::new("General");
let fy = Fmt::new(data.series.first().map(|s| s.number_format.as_str()).unwrap_or("General"));
let plot = frame(ctx, area, CatAxis::Numeric(xs, &fx), &ValAxis { scale: ys, fmt: &fy }, None, false, chart.gridlines);
if !plot.ok() {
return;
}
let map = |(x, y): (f64, f64)| [plot.x + xs.frac(x) * plot.w, plot.bottom() - ys.frac(y) * plot.h];
let bubble = chart.kind == ChartKind::Bubble;
let rmax = plot.w.min(plot.h) * 0.12;
for (s, pts) in data.series.iter().zip(&all) {
let px: Vec<Option<[f32; 2]>> = pts.iter().map(|p| p.map(map)).collect();
if bubble {
let sizes = s.sizes.as_deref().unwrap_or(&[]);
let smax = sizes.iter().flatten().fold(0.0f64, |a, b| a.max(*b));
let mut bubbles: Vec<([f32; 2], f64)> = px
.iter()
.enumerate()
.filter_map(|(j, p)| {
let sz = if sizes.is_empty() { Some(1.0) } else { sizes.get(j).copied().flatten() };
match (p, sz) {
(Some(p), Some(sz)) if sz > 0.0 => Some((*p, sz)),
_ => None,
}
})
.take(MAX_MARKERS)
.collect();
bubbles.sort_by(|a, b| b.1.total_cmp(&a.1));
let smax = if sizes.is_empty() { 1.0 } else { smax };
let fill = [s.color[0], s.color[1], s.color[2], 0xC0];
for (p, sz) in bubbles {
let r = ((sz / smax).sqrt() as f32 * rmax).max(1.0);
ctx.out.push(Prim::Circle { cx: p[0], cy: p[1], r, fill: Some(fill), stroke: Some((WHITE, 0.75)) });
}
} else {
let lines = chart.kind == ChartKind::ScatterLines || s.kind == ChartKind::ScatterLines;
if lines {
draw_runs(ctx, &px, s.color, 2.0, s.smooth.then_some(plot));
}
if !lines || px.len() <= 500 {
draw_markers(ctx, px.iter().flatten().copied(), 3.5, s.color);
}
}
if chart.data_labels && pts.len() <= MAX_LABELS {
for (p, raw) in px.iter().zip(pts) {
if let (Some(p), Some((_, y))) = (p, raw) {
ctx.text(p[0], p[1] - 6.0, &fy.format(*y, None), LABEL_SIZE, TEXT, HAlign::Center, VAlign::Bottom);
}
}
}
}
let mut trend_labels = Vec::new();
for (s, pts) in data.series.iter().zip(&all) {
if s.trendlines.is_empty() {
continue;
}
let pts: Vec<(f64, f64)> = pts.iter().flatten().copied().collect();
let frac = |x: f64, y: f64| ((x - xs.min) / (xs.max - xs.min), (y - ys.min) / (ys.max - ys.min));
let px = |(fx, fy): (f64, f64)| [plot.x + fx as f32 * plot.w, plot.bottom() - fy as f32 * plot.h];
draw_trendlines(ctx, s, &pts, &frac, &px, &mut trend_labels, (xs.min, xs.max));
}
draw_trend_labels(ctx, plot, &trend_labels);
}
crates/chart/src/render/frame.rs
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use super::*;
#[derive(Clone, Copy, Debug)]
pub(super) struct Bx {
pub(super) x: f32,
pub(super) y: f32,
pub(super) w: f32,
pub(super) h: f32,
}
impl Bx {
pub(super) fn right(&self) -> f32 {
self.x + self.w
}
pub(super) fn bottom(&self) -> f32 {
self.y + self.h
}
pub(super) fn ok(&self) -> bool {
self.w.is_finite() && self.h.is_finite() && self.w > 4.0 && self.h > 4.0
}
pub(super) fn cx(&self) -> f32 {
self.x + self.w / 2.0
}
pub(super) fn cy(&self) -> f32 {
self.y + self.h / 2.0
}
}
/// Text colour readable on `fill`.
pub(super) fn on(fill: Rgba) -> Rgba {
let l = 0.299 * fill[0] as f32 + 0.587 * fill[1] as f32 + 0.114 * fill[2] as f32;
if l < 150.0 { WHITE } else { DARK_TEXT }
}
pub(super) fn chart_title(chart: &Chart, data: &ChartData) -> Option<String> {
match &chart.title {
Some(t) => Some(t.trim().to_string()).filter(|t| !t.is_empty()),
None if data.series.len() == 1 => data.series.first().map(|s| s.name.clone()).filter(|t| !t.is_empty()),
None => None,
}
}
pub(super) fn axis_titles(ctx: &mut Ctx, chart: &Chart, mut area: Bx) -> Bx {
let lh = AXIS_TITLE_SIZE * 1.4 + 2.0;
if let Some(t) = chart.x_title.as_deref().map(str::trim).filter(|t| !t.is_empty()) {
let t = ctx.fit(t, AXIS_TITLE_SIZE, area.w);
ctx.text(area.cx(), area.bottom(), &t, AXIS_TITLE_SIZE, TEXT, HAlign::Center, VAlign::Bottom);
area.h -= lh;
}
if let Some(t) = chart.y_title.as_deref().map(str::trim).filter(|t| !t.is_empty()) {
let t = ctx.fit(t, AXIS_TITLE_SIZE, area.h);
if !t.is_empty() {
ctx.out.push(Prim::Text {
x: area.x,
y: area.cy(),
text: t,
size: AXIS_TITLE_SIZE,
color: TEXT,
bold: false,
align: HAlign::Center,
valign: VAlign::Top,
rotation: -PI / 2.0,
});
}
area.x += lh;
area.w -= lh;
}
area
}
// ---------------------------------------------------------------- axes frame
pub(super) enum CatAxis<'a> {
/// Category labels and, for a multi-level axis, the outer levels (nearest the labels first;
/// one entry per category, non-empty where a group starts).
Labels(&'a [String], &'a [Vec<String>]),
Numeric(Scale, &'a Fmt),
}
/// Groups of an outer category level: `(first, end)` index pairs, a group starting at every
/// non-empty entry (and at the first category).
fn level_groups(level: &[String], n: usize) -> Vec<(usize, usize)> {
let mut starts: Vec<usize> = (0..n).filter(|&j| j == 0 || level.get(j).is_some_and(|t| !t.is_empty())).collect();
starts.push(n);
starts.windows(2).filter_map(|w| Some((*w.first()?, *w.get(1)?))).collect()
}
pub(super) struct ValAxis<'a> {
pub(super) scale: Scale,
pub(super) fmt: &'a Fmt,
}
impl ValAxis<'_> {
fn labels(&self) -> Vec<(f64, String)> {
self.scale.ticks().into_iter().map(|v| (v, self.fmt.format(v, Some(self.scale.step)))).collect()
}
}
/// Draws gridlines, axis labels and the category axis line; returns the plot rectangle.
pub(super) fn frame(ctx: &mut Ctx, area: Bx, cat: CatAxis, y: &ValAxis, y2: Option<&ValAxis>, horizontal: bool, grid: bool) -> Bx {
let ls = LABEL_SIZE;
let lh = ls * 1.4;
let ylabels = y.labels();
let maxw = |ctx: &Ctx, l: &[(f64, String)]| l.iter().map(|(_, t)| ctx.tw(t, ls)).fold(0.0f32, f32::max);
if !horizontal {
let left = (maxw(ctx, &ylabels) + 6.0).min(area.w * 0.4);
let y2labels = y2.map(ValAxis::labels);
let right = match (&y2labels, &cat) {
(Some(l), _) => (maxw(ctx, l) + 6.0).min(area.w * 0.3),
(None, CatAxis::Numeric(s, f)) => (ctx.tw(&f.format(s.max, Some(s.step)), ls) / 2.0).min(area.w * 0.2),
_ => 4.0,
};
let levels = match &cat {
CatAxis::Labels(_, o) => o.len() as f32,
CatAxis::Numeric(..) => 0.0,
};
let plot = Bx { x: area.x + left, y: area.y + lh * 0.5, w: area.w - left - right, h: area.h - lh * 1.5 - 4.0 - lh * levels };
if !plot.ok() {
return plot;
}
for (v, t) in &ylabels {
let yy = plot.bottom() - y.scale.frac(*v) * plot.h;
if grid {
ctx.hline(plot.x, plot.right(), yy, GRID, 0.75);
}
ctx.text(plot.x - 4.0, yy, t, ls, TEXT, HAlign::Right, VAlign::Middle);
}
if let (Some(a), Some(l)) = (y2, &y2labels) {
for (v, t) in l {
let yy = plot.bottom() - a.scale.frac(*v) * plot.h;
ctx.text(plot.right() + 4.0, yy, t, ls, TEXT, HAlign::Left, VAlign::Middle);
}
}
let zero = if y.scale.min <= 0.0 && y.scale.max >= 0.0 { 0.0 } else { y.scale.min };
let y0 = plot.bottom() - y.scale.frac(zero) * plot.h;
ctx.hline(plot.x, plot.right(), y0, AXIS, 0.75);
match cat {
CatAxis::Labels(l, outer) => {
let n = l.len().max(1);
let cw = plot.w / n as f32;
let lw = l.iter().take(2000).map(|t| ctx.tw(t, ls)).fold(0.0f32, f32::max);
let k = (((lw + 6.0) / cw.max(1e-3)).ceil() as usize).clamp(1, n);
for (j, t) in l.iter().enumerate().step_by(k) {
let t = ctx.fit(t, ls, cw * k as f32 - 2.0);
ctx.text(plot.x + (j as f32 + 0.5) * cw, plot.bottom() + 3.0, &t, ls, TEXT, HAlign::Center, VAlign::Top);
}
// Outer levels, one row each below the labels: a group's name centred under its
// categories, and a separator at each group boundary down through the rows.
for (i, level) in outer.iter().enumerate() {
let top = plot.bottom() + 3.0 + lh * (i as f32 + 1.0);
for (first, end) in level_groups(level, n) {
let (x0, x1) = (plot.x + first as f32 * cw, plot.x + end as f32 * cw);
if let Some(t) = level.get(first).filter(|t| !t.is_empty()) {
let t = ctx.fit(t, ls, x1 - x0 - 2.0);
ctx.text((x0 + x1) / 2.0, top, &t, ls, TEXT, HAlign::Center, VAlign::Top);
}
if first > 0 {
ctx.vline(x0, plot.bottom(), top + lh - 2.0, AXIS, 0.75);
}
}
ctx.vline(plot.right(), plot.bottom(), top + lh - 2.0, AXIS, 0.75);
}
}
CatAxis::Numeric(s, f) => {
let ticks = s.ticks();
let labels: Vec<String> = ticks.iter().map(|v| f.format(*v, Some(s.step))).collect();
let lw = labels.iter().map(|t| ctx.tw(t, ls)).fold(0.0f32, f32::max);
let slot = plot.w / ticks.len().max(1) as f32;
let k = (((lw + 6.0) / slot.max(1e-3)).ceil() as usize).max(1);
for (v, t) in ticks.iter().zip(&labels).step_by(k) {
let xx = plot.x + s.frac(*v) * plot.w;
ctx.text(xx, plot.bottom() + 3.0, t, ls, TEXT, HAlign::Center, VAlign::Top);
}
if s.min <= 0.0 && s.max >= 0.0 {
let xx = plot.x + s.frac(0.0) * plot.w;
ctx.vline(xx, plot.y, plot.bottom(), AXIS, 0.75);
}
}
}
plot
} else {
let (labels, outer): (Vec<String>, &[Vec<String>]) = match cat {
CatAxis::Labels(l, o) => (l.to_vec(), o),
CatAxis::Numeric(..) => (vec![], &[]),
};
let lw = (labels.iter().take(2000).map(|t| ctx.tw(t, ls)).fold(0.0f32, f32::max) + 6.0).min(area.w * 0.35);
// Outer levels stand in columns left of the labels, each as wide as its longest name.
let level_w: Vec<f32> =
outer.iter().map(|l| (l.iter().take(2000).map(|t| ctx.tw(t, ls)).fold(0.0f32, f32::max) + 6.0).min(area.w * 0.15)).collect();
let levels_w: f32 = level_w.iter().sum();
let right = ylabels.last().map(|(_, t)| ctx.tw(t, ls) / 2.0).unwrap_or(0.0).min(area.w * 0.2) + 2.0;
let plot = Bx { x: area.x + lw + levels_w, y: area.y + 2.0, w: area.w - lw - levels_w - right, h: area.h - lh - 6.0 };
if !plot.ok() {
return plot;
}
let vw = maxw(ctx, &ylabels);
let slot = plot.w / ylabels.len().max(1) as f32;
let k = (((vw + 6.0) / slot.max(1e-3)).ceil() as usize).max(1);
for (i, (v, t)) in ylabels.iter().enumerate() {
let xx = plot.x + y.scale.frac(*v) * plot.w;
if grid {
ctx.vline(xx, plot.y, plot.bottom(), GRID, 0.75);
}
if i % k == 0 {
ctx.text(xx, plot.bottom() + 3.0, t, ls, TEXT, HAlign::Center, VAlign::Top);
}
}
let zero = if y.scale.min <= 0.0 && y.scale.max >= 0.0 { 0.0 } else { y.scale.min };
let x0 = plot.x + y.scale.frac(zero) * plot.w;
ctx.vline(x0, plot.y, plot.bottom(), AXIS, 0.75);
let n = labels.len().max(1);
let ch = plot.h / n as f32;
let k = ((lh / ch.max(1e-3)).ceil() as usize).clamp(1, n);
for (j, t) in labels.iter().enumerate().step_by(k) {
let t = ctx.fit(t, ls, lw - 6.0);
ctx.text(plot.x - 4.0, plot.bottom() - (j as f32 + 0.5) * ch, &t, ls, TEXT, HAlign::Right, VAlign::Middle);
}
// Outer levels: a group's name centred beside its categories, separators at the
// boundaries running right to the axis.
let mut x1 = plot.x - lw;
for (level, w) in outer.iter().zip(&level_w) {
let x0 = x1 - w;
for (first, end) in level_groups(level, n) {
let (y0, y1) = (plot.bottom() - end as f32 * ch, plot.bottom() - first as f32 * ch);
if let Some(t) = level.get(first).filter(|t| !t.is_empty()) {
let t = ctx.fit(t, ls, w - 4.0);
ctx.text((x0 + x1) / 2.0, (y0 + y1) / 2.0, &t, ls, TEXT, HAlign::Center, VAlign::Middle);
}
if first > 0 {
ctx.hline(x0, plot.x, y1, AXIS, 0.75);
}
}
ctx.hline(x0, plot.x, plot.y, AXIS, 0.75);
x1 = x0;
}
plot
}
}
pub(super) fn value_range(it: impl Iterator<Item = f64>) -> Option<(f64, f64)> {
it.fold(None, |acc, v| match acc {
None => Some((v, v)),
Some((a, b)) => Some((a.min(v), b.max(v))),
})
}
crates/chart/src/render/kinds.rs
+505
View File
@@ -0,0 +1,505 @@
use super::frame::{Bx, CatAxis, ValAxis, frame, on, value_range};
use super::legend::{cat_label, point_color};
use super::*;
// ---------------------------------------------------------------- histogram
pub(super) fn histogram(ctx: &mut Ctx, chart: &Chart, data: &ChartData, area: Bx) {
let Some(s) = data.series.first() else { return };
let vals: Vec<f64> = s.values.iter().flatten().copied().collect();
let Some((lo, hi)) = value_range(vals.iter().copied()) else { return };
let n = vals.len();
let span = hi - lo;
let mut bins = ((n as f64).sqrt().ceil() as usize).clamp(1, 100);
if !(span.is_finite() && span > 0.0) {
bins = 1;
}
let width = if bins == 1 && span.partial_cmp(&0.0) != Some(std::cmp::Ordering::Greater) { 1.0 } else { span / bins as f64 };
// Upper edge of each bin, exactly as shown in the labels below. Bins are right-inclusive (the first is closed on both sides), so a value
// equal to an edge belongs to the bin that ends there.
let edges: Vec<f64> = (0..bins).map(|b| if b + 1 == bins { hi.max(lo + b as f64 * width) } else { lo + (b + 1) as f64 * width }).collect();
let mut counts = vec![0usize; bins];
for v in &vals {
let b = edges.partition_point(|e| e < v).min(bins - 1);
if let Some(c) = counts.get_mut(b) {
*c += 1;
}
}
let f = Fmt::new(&s.number_format);
let labels: Vec<String> = (0..bins)
.map(|b| {
let a = lo + b as f64 * width;
let e = edges.get(b).copied().unwrap_or(a);
let open = if b == 0 { '[' } else { '(' };
format!("{open}{}, {}]", f.format(a, Some(width / 10.0)), f.format(e, Some(width / 10.0)))
})
.collect();
let maxc = counts.iter().copied().max().unwrap_or(0) as f64;
let ys = nice_scale(0.0, maxc, true);
let fc = Fmt::new("General");
let plot = frame(ctx, area, CatAxis::Labels(&labels, &[]), &ValAxis { scale: ys, fmt: &fc }, None, false, chart.gridlines);
if !plot.ok() {
return;
}
let cw = plot.w / bins as f32;
for (b, c) in counts.iter().enumerate() {
let top = plot.bottom() - ys.frac(*c as f64) * plot.h;
let x = plot.x + b as f32 * cw;
ctx.rect(x, top, cw, plot.bottom() - top, s.color, Some((WHITE, 0.75)));
if chart.data_labels {
ctx.text(x + cw / 2.0, top - 2.0, &c.to_string(), LABEL_SIZE, TEXT, HAlign::Center, VAlign::Bottom);
}
}
}
// ---------------------------------------------------------------- waterfall
pub(super) fn waterfall(ctx: &mut Ctx, chart: &Chart, data: &ChartData, area: Bx) {
let Some(s) = data.series.first() else { return };
let mut ncat = data.categories.len().max(s.values.len()).min(MAX_CATS);
if ncat == 0 {
return;
}
let mut labels: Vec<String> = (0..ncat).map(|j| cat_label(data, j)).collect();
let mut vals: Vec<f64> = (0..ncat).map(|j| s.values.get(j).copied().flatten().unwrap_or(0.0)).collect();
let mut is_total = vec![false; ncat];
let last_total = labels.last().is_some_and(|l| l.to_lowercase().contains("total"));
if let Some(t) = is_total.last_mut() {
*t = last_total;
}
if !last_total {
labels.push("Total".into());
vals.push(0.0);
is_total.push(true);
ncat += 1;
}
let mut bars = Vec::with_capacity(ncat);
let mut cum = 0.0f64;
for (j, v) in vals.iter().enumerate() {
if is_total.get(j).copied().unwrap_or(false) {
let total = if last_total && j + 1 == ncat && *v != 0.0 { *v } else { cum };
bars.push((0.0, total, 0u8));
cum = total;
} else {
let top = clean(cum + v);
bars.push((cum, top, if *v >= 0.0 { 1 } else { 2 }));
cum = top;
}
}
let (lo, hi) = value_range(bars.iter().flat_map(|(b, t, _)| [*b, *t])).unwrap_or((0.0, 0.0));
let ys = nice_scale(lo, hi, true);
let f = Fmt::new(&s.number_format);
let plot = frame(ctx, area, CatAxis::Labels(&labels, &[]), &ValAxis { scale: ys, fmt: &f }, None, false, chart.gridlines);
if !plot.ok() {
return;
}
let cw = plot.w / ncat as f32;
let bw = cw / 1.5;
let vy = |v: f64| plot.bottom() - ys.frac(v) * plot.h;
for (j, (b, t, kind)) in bars.iter().enumerate() {
let color = match kind {
1 => UP,
2 => DOWN,
_ => s.color,
};
let x = plot.x + (j as f32 + 0.5) * cw - bw / 2.0;
let (yb, yt) = (vy(*b), vy(*t));
ctx.rect(x, yb.min(yt), bw, (yb - yt).abs().max(0.5), color, None);
if j + 1 < bars.len() && ncat <= 500 {
ctx.out.push(Prim::Line { pts: vec![[x + bw, yt], [x + cw, yt]], color: AXIS, width: 0.75, dash: true });
}
if chart.data_labels && ncat <= MAX_LABELS {
let v = if *kind == 0 { *t } else { t - b };
ctx.text(x + bw / 2.0, yb.min(yt) - 2.0, &f.format(v, None), LABEL_SIZE, TEXT, HAlign::Center, VAlign::Bottom);
}
}
}
// ---------------------------------------------------------------- funnel
pub(super) fn funnel(ctx: &mut Ctx, chart: &Chart, data: &ChartData, area: Bx) {
let Some(s) = data.series.first() else { return };
let n = data.categories.len().max(s.values.len()).min(MAX_CATS);
if n == 0 {
return;
}
let vals: Vec<f64> = (0..n).map(|j| s.values.get(j).copied().flatten().unwrap_or(0.0).abs()).collect();
let max = vals.iter().copied().fold(0.0f64, f64::max);
if max.is_nan() || max <= 0.0 {
return;
}
let labels: Vec<String> = (0..n).map(|j| cat_label(data, j)).collect();
let lw = (labels.iter().take(2000).map(|t| ctx.tw(t, LABEL_SIZE)).fold(0.0f32, f32::max) + 8.0).min(area.w * 0.35);
let plot = Bx { x: area.x + lw, w: area.w - lw, ..area };
if !plot.ok() {
return;
}
let slot = plot.h / n as f32;
let bh = slot * 0.85;
let f = Fmt::new(&s.number_format);
let show = slot >= LABEL_SIZE * 0.9;
for (j, v) in vals.iter().enumerate() {
let bw = (*v / max) as f32 * plot.w;
let x = plot.x + (plot.w - bw) / 2.0;
let y = plot.y + j as f32 * slot + (slot - bh) / 2.0;
if bw > 0.0 {
ctx.rect(x, y, bw, bh, s.color, None);
}
if show {
let yc = y + bh / 2.0;
if chart.data_labels {
let t = f.format(s.values.get(j).copied().flatten().unwrap_or(0.0), None);
let color = if ctx.tw(&t, LABEL_SIZE) + 4.0 <= bw { on(s.color) } else { TEXT };
ctx.text(plot.cx(), yc, &t, LABEL_SIZE, color, HAlign::Center, VAlign::Middle);
}
let l = ctx.fit(labels.get(j).map(String::as_str).unwrap_or(""), LABEL_SIZE, lw - 8.0);
ctx.text(plot.x - 6.0, yc, &l, LABEL_SIZE, TEXT, HAlign::Right, VAlign::Middle);
}
}
}
// ---------------------------------------------------------------- pie, doughnut, sunburst
pub(super) fn pie(ctx: &mut Ctx, chart: &Chart, data: &ChartData, area: Bx, inner: f32, names: bool) {
let Some(s) = data.series.first() else { return };
let vals: Vec<f64> = s.values.iter().take(MAX_CATS).map(|v| v.map(f64::abs).unwrap_or(0.0)).collect();
let total: f64 = vals.iter().sum();
if !(total.is_finite() && total > 0.0) {
return;
}
let (cx, cy) = (area.cx(), area.cy());
let r = area.w.min(area.h) / 2.0 * 0.92;
if r < 2.0 {
return;
}
let ri = r * inner;
let f = Fmt::new(&s.number_format);
let mut a = 0.0f32;
let mut labels = Vec::new();
for (j, v) in vals.iter().enumerate() {
let sweep = (*v / total) as f32 * TAU;
if sweep > 1e-4 {
let fill = point_color(data, j);
ctx.out.push(Prim::Wedge { cx, cy, r_outer: r, r_inner: ri, a0: a, a1: (a + sweep).min(TAU), fill, stroke: Some((WHITE, 1.5)) });
if (chart.data_labels || names) && vals.len() <= MAX_LABELS {
let t = if names { cat_label(data, j) } else { f.format(s.values.get(j).copied().flatten().unwrap_or(0.0), None) };
let mid = a + sweep / 2.0;
let rr = if ri > 0.0 { (r + ri) / 2.0 } else { r * 0.65 };
let room = sweep * rr;
if ctx.tw(&t, LABEL_SIZE) <= room.max(r - ri) && room >= LABEL_SIZE {
labels.push((cx + rr * mid.sin(), cy - rr * mid.cos(), t, on(fill)));
}
}
}
a += sweep;
}
for (x, y, t, c) in labels {
ctx.text(x, y, &t, LABEL_SIZE, c, HAlign::Center, VAlign::Middle);
}
}
// ---------------------------------------------------------------- treemap
fn worst(row: &[f64], side: f64) -> f64 {
let s: f64 = row.iter().sum();
if s <= 0.0 || side <= 0.0 {
return f64::INFINITY;
}
let (mn, mx) = row.iter().fold((f64::INFINITY, 0.0f64), |(a, b), v| (a.min(*v), b.max(*v)));
let s2 = s * s;
let w2 = side * side;
(w2 * mx / s2).max(s2 / (w2 * mn))
}
/// Squarified treemap layout of (index, area) items, sorted descending, into `r`.
fn squarify(items: &[(usize, f64)], r: Bx) -> Vec<(usize, Bx)> {
let total: f64 = items.iter().map(|i| i.1).sum();
let area = (r.w as f64) * (r.h as f64);
if !(total > 0.0 && area > 0.0) {
return vec![];
}
let scale = area / total;
let mut out = Vec::with_capacity(items.len());
let mut rem = r;
let mut row: Vec<(usize, f64)> = Vec::new();
let mut i = 0;
let layout = |row: &[(usize, f64)], rem: &mut Bx, out: &mut Vec<(usize, Bx)>| {
let s: f64 = row.iter().map(|x| x.1).sum();
if s <= 0.0 {
return;
}
if rem.w >= rem.h {
let cw = (s / rem.h.max(1e-6) as f64) as f32;
let mut y = rem.y;
for (j, a) in row {
let h = (*a / cw.max(1e-6) as f64) as f32;
out.push((*j, Bx { x: rem.x, y, w: cw, h }));
y += h;
}
rem.x += cw;
rem.w = (rem.w - cw).max(0.0);
} else {
let rh = (s / rem.w.max(1e-6) as f64) as f32;
let mut x = rem.x;
for (j, a) in row {
let w = (*a / rh.max(1e-6) as f64) as f32;
out.push((*j, Bx { x, y: rem.y, w, h: rh }));
x += w;
}
rem.y += rh;
rem.h = (rem.h - rh).max(0.0);
}
};
while let Some(&(j, v)) = items.get(i) {
let a = v * scale;
let side = rem.w.min(rem.h) as f64;
let cur: Vec<f64> = row.iter().map(|x| x.1).collect();
let mut with = cur.clone();
with.push(a);
if row.is_empty() || worst(&with, side) <= worst(&cur, side) {
row.push((j, a));
i += 1;
} else {
layout(&row, &mut rem, &mut out);
row.clear();
}
}
if !row.is_empty() {
layout(&row, &mut rem, &mut out);
}
out
}
pub(super) fn treemap(ctx: &mut Ctx, chart: &Chart, data: &ChartData, area: Bx) {
let Some(s) = data.series.first() else { return };
let mut items: Vec<(usize, f64)> =
s.values.iter().take(MAX_MARKERS).enumerate().filter_map(|(j, v)| v.filter(|v| *v > 0.0).map(|v| (j, v))).collect();
items.sort_by(|a, b| b.1.total_cmp(&a.1));
let f = Fmt::new(&s.number_format);
for (j, b) in squarify(&items, area) {
let fill = point_color(data, j);
ctx.rect(b.x, b.y, b.w, b.h, fill, Some((WHITE, 1.5)));
if b.w > 24.0 && b.h > LABEL_SIZE * 1.6 {
let name = ctx.fit(&cat_label(data, j), LABEL_SIZE, b.w - 8.0);
ctx.text(b.x + 4.0, b.y + 4.0, &name, LABEL_SIZE, on(fill), HAlign::Left, VAlign::Top);
if chart.data_labels && b.h > LABEL_SIZE * 3.2 {
let v = items.iter().find(|x| x.0 == j).map(|x| x.1).unwrap_or(0.0);
let t = ctx.fit(&f.format(v, None), LABEL_SIZE, b.w - 8.0);
ctx.text(b.x + 4.0, b.y + 4.0 + LABEL_SIZE * 1.4, &t, LABEL_SIZE, on(fill), HAlign::Left, VAlign::Top);
}
}
}
}
// ---------------------------------------------------------------- radar
pub(super) fn radar(ctx: &mut Ctx, chart: &Chart, data: &ChartData, area: Bx) {
let ncat = data.categories.len().max(data.series.iter().map(|s| s.values.len()).max().unwrap_or(0)).min(1000);
if ncat == 0 {
return;
}
let labels: Vec<String> = (0..ncat).map(|j| cat_label(data, j)).collect();
let lw = labels.iter().map(|t| ctx.tw(t, LABEL_SIZE)).fold(0.0f32, f32::max).min(area.w * 0.2);
let r = ((area.w - 2.0 * (lw + 8.0)).min(area.h - 2.0 * (LABEL_SIZE * 1.4 + 6.0)) / 2.0).max(0.0);
if r < 5.0 {
return;
}
let (cx, cy) = (area.cx(), area.cy());
let (lo, hi) = value_range(data.series.iter().flat_map(|s| s.values.iter().flatten().copied())).unwrap_or((0.0, 0.0));
let sc = nice_scale(lo, hi, true);
let f = Fmt::new(data.series.first().map(|s| s.number_format.as_str()).unwrap_or("General"));
let ang = |j: usize| j as f32 / ncat as f32 * TAU;
let pt = |a: f32, rr: f32| [cx + rr * a.sin(), cy - rr * a.cos()];
let ticks = sc.ticks();
let spacing = r / ticks.len().saturating_sub(1).max(1) as f32;
let every = ((LABEL_SIZE * 1.3 / spacing.max(1e-3)).ceil() as usize).max(1);
for (ti, t) in ticks.into_iter().enumerate() {
let rr = sc.frac(t) * r;
if rr > 0.5 && chart.gridlines {
let mut ring: Vec<[f32; 2]> = (0..ncat).map(|j| pt(ang(j), rr)).collect();
if ncat < 3 {
ring = (0..=48).map(|k| pt(k as f32 / 48.0 * TAU, rr)).collect();
} else if let Some(p) = ring.first().copied() {
ring.push(p);
}
ctx.line(ring, GRID, 0.75);
}
if ti % every == 0 {
ctx.text(cx - 3.0, cy - rr, &f.format(t, Some(sc.step)), LABEL_SIZE * 0.9, TEXT, HAlign::Right, VAlign::Middle);
}
}
let step = ncat.div_ceil(72).max(1);
for j in (0..ncat).step_by(step) {
let a = ang(j);
ctx.line(vec![[cx, cy], pt(a, r)], GRID, 0.75);
let p = pt(a, r + 6.0);
let (sa, ca) = (a.sin(), a.cos());
let align = if sa > 0.1 {
HAlign::Left
} else if sa < -0.1 {
HAlign::Right
} else {
HAlign::Center
};
let valign = if ca > 0.1 {
VAlign::Bottom
} else if ca < -0.1 {
VAlign::Top
} else {
VAlign::Middle
};
let t = ctx.fit(labels.get(j).map(String::as_str).unwrap_or(""), LABEL_SIZE, lw.max(20.0));
ctx.text(p[0], p[1], &t, LABEL_SIZE, TEXT, align, valign);
}
for s in &data.series {
let mut pts: Vec<[f32; 2]> = (0..ncat).map(|j| pt(ang(j), sc.frac(s.values.get(j).copied().flatten().unwrap_or(sc.min)) * r)).collect();
if let Some(p) = pts.first().copied() {
pts.push(p);
}
ctx.line(pts, s.color, 2.0);
}
}
// ---------------------------------------------------------------- box & whisker
fn quantile(sorted: &[f64], q: f64, method: QuartileMethod) -> f64 {
let n = sorted.len();
if n == 0 {
return 0.0;
}
// Clamp exclusive ranks for short samples so one or two points remain drawable.
let pos = match method {
QuartileMethod::Inclusive => q * (n - 1) as f64,
QuartileMethod::Exclusive => (q * (n as f64 + 1.0) - 1.0).clamp(0.0, (n - 1) as f64),
};
let i = pos.floor() as usize;
let frac = pos - i as f64;
let a = sorted.get(i).copied().unwrap_or(0.0);
let b = sorted.get(i + 1).copied().unwrap_or(a);
a + (b - a) * frac
}
pub(super) fn box_whisker(ctx: &mut Ctx, chart: &Chart, data: &ChartData, area: Bx) {
let labels: Vec<String> = data.series.iter().map(|s| s.name.clone()).collect();
let Some((lo, hi)) = value_range(data.series.iter().flat_map(|s| s.values.iter().flatten().copied())) else { return };
let ys = nice_scale(lo, hi, false);
let f = Fmt::new(data.series.first().map(|s| s.number_format.as_str()).unwrap_or("General"));
let plot = frame(ctx, area, CatAxis::Labels(&labels, &[]), &ValAxis { scale: ys, fmt: &f }, None, false, chart.gridlines);
if !plot.ok() {
return;
}
let n = data.series.len().max(1);
let cw = plot.w / n as f32;
let bw = (cw * 0.4).min(80.0);
let vy = |v: f64| plot.bottom() - ys.frac(v) * plot.h;
for (i, s) in data.series.iter().enumerate() {
let mut v: Vec<f64> = s.values.iter().flatten().copied().collect();
if v.is_empty() {
continue;
}
v.sort_by(f64::total_cmp);
let method = chart.series.get(i).map(|s| s.quartiles).unwrap_or_default();
let (q1, med, q3) = (quantile(&v, 0.25, method), quantile(&v, 0.5, method), quantile(&v, 0.75, method));
let iqr = q3 - q1;
let (flo, fhi) = (q1 - 1.5 * iqr, q3 + 1.5 * iqr);
let wlo = v.iter().copied().find(|x| *x >= flo).unwrap_or(q1);
let whi = v.iter().rev().copied().find(|x| *x <= fhi).unwrap_or(q3);
let mean = v.iter().sum::<f64>() / v.len() as f64;
let c = plot.x + (i as f32 + 0.5) * cw;
ctx.vline(c, vy(whi), vy(q3), s.color, 1.25);
ctx.vline(c, vy(q1), vy(wlo), s.color, 1.25);
ctx.hline(c - bw / 4.0, c + bw / 4.0, vy(whi), s.color, 1.25);
ctx.hline(c - bw / 4.0, c + bw / 4.0, vy(wlo), s.color, 1.25);
let (yt, yb) = (vy(q3), vy(q1));
ctx.rect(c - bw / 2.0, yt, bw, (yb - yt).max(0.5), s.color, None);
ctx.hline(c - bw / 2.0, c + bw / 2.0, vy(med), WHITE, 1.5);
let (mx, my, d) = (c, vy(mean), 3.0);
ctx.line(vec![[mx - d, my - d], [mx + d, my + d]], WHITE, 1.25);
ctx.line(vec![[mx - d, my + d], [mx + d, my - d]], WHITE, 1.25);
for o in v.iter().filter(|x| **x < flo || **x > fhi).take(MAX_MARKERS) {
ctx.out.push(Prim::Circle { cx: c, cy: vy(*o), r: 2.5, fill: None, stroke: Some((s.color, 1.0)) });
}
}
}
// ---------------------------------------------------------------- stock
pub(super) fn stock(ctx: &mut Ctx, chart: &Chart, data: &ChartData, area: Bx) {
let ncat = data.categories.len().max(data.series.iter().map(|s| s.values.len()).max().unwrap_or(0)).min(MAX_CATS);
if ncat == 0 {
return;
}
let labels: Vec<String> = (0..ncat).map(|j| cat_label(data, j)).collect();
let Some((lo, hi)) = value_range(data.series.iter().flat_map(|s| s.values.iter().flatten().copied())) else { return };
let ys = nice_scale(lo, hi, false);
let f = Fmt::new(data.series.first().map(|s| s.number_format.as_str()).unwrap_or("General"));
let plot = frame(ctx, area, CatAxis::Labels(&labels, &[]), &ValAxis { scale: ys, fmt: &f }, None, false, chart.gridlines);
if !plot.ok() {
return;
}
let ser = |k: usize| data.series.get(k);
let (open, high, low, close) = match data.series.len() {
0 => return,
1 => (None, None, None, ser(0)),
2 => (None, ser(0), ser(1), None),
3 => (None, ser(0), ser(1), ser(2)),
_ => (ser(0), ser(1), ser(2), ser(3)),
};
let get = |s: Option<&SeriesData>, j: usize| s.and_then(|s| s.values.get(j).copied().flatten());
let cw = plot.w / ncat as f32;
let tick = (cw * 0.25).max(1.0);
let vy = |v: f64| plot.bottom() - ys.frac(v) * plot.h;
for j in 0..ncat {
let c = plot.x + (j as f32 + 0.5) * cw;
if let (Some(h), Some(l)) = (get(high, j), get(low, j)) {
ctx.vline(c, vy(h), vy(l), STOCK, 1.25);
}
match (get(open, j), get(close, j)) {
(Some(o), Some(cl)) => {
let (yo, yc) = (vy(o), vy(cl));
let bw = (cw * 0.5).max(1.0);
let fill = if cl >= o { WHITE } else { STOCK };
ctx.rect(c - bw / 2.0, yo.min(yc), bw, (yo - yc).abs().max(0.75), fill, Some((STOCK, 1.0)));
}
(None, Some(cl)) => {
if high.is_some() {
ctx.hline(c, c + tick, vy(cl), STOCK, 1.25);
} else {
ctx.out.push(Prim::Circle { cx: c, cy: vy(cl), r: 2.5, fill: Some(STOCK), stroke: None });
}
}
_ => {}
}
}
}
#[cfg(test)]
mod quartile_tests {
use super::*;
#[test]
fn box_whisker_default_quartiles_are_exclusive() {
let values = [1.0, 2.0, 3.0, 4.0, 5.0, 6.0];
assert_eq!(quantile(&values, 0.25, QuartileMethod::default()), 1.75);
assert_eq!(quantile(&values, 0.5, QuartileMethod::default()), 3.5);
assert_eq!(quantile(&values, 0.75, QuartileMethod::default()), 5.25);
}
#[test]
fn quartile_methods_and_short_samples() {
for (values, exclusive, inclusive) in [
(vec![1., 2., 3.], (1., 3.), (1.5, 2.5)),
(vec![1., 2., 3., 4.], (1.25, 3.75), (1.75, 3.25)),
(vec![1., 2., 3., 4., 5.], (1.5, 4.5), (2., 4.)),
(vec![1., 2., 3., 4., 5., 6., 7.], (2., 6.), (2.5, 5.5)),
(vec![1., 1., 2., 3., 5., 8.], (1., 5.75), (1.25, 4.5)),
(vec![1., 2.], (1., 2.), (1.25, 1.75)),
(vec![1.], (1., 1.), (1., 1.)),
(vec![], (0., 0.), (0., 0.)),
] {
for (method, expected) in [(QuartileMethod::Exclusive, exclusive), (QuartileMethod::Inclusive, inclusive)] {
assert_eq!((quantile(&values, 0.25, method), quantile(&values, 0.75, method)), expected);
}
}
}
}
crates/chart/src/render/legend.rs
+161
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use super::frame::Bx;
use super::trend::supports_trendline;
use super::*;
/// How a legend entry's swatch is drawn.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Swatch {
Box,
Line,
LineMarker,
Marker,
}
/// The kind a series is drawn as (per-series kinds only apply to combo charts).
pub(super) fn plot_kind(chart: &Chart, s: &SeriesData) -> ChartKind {
if chart.kind == ChartKind::Combo { if s.kind == ChartKind::Combo { ChartKind::Line } else { s.kind } } else { chart.kind }
}
/// Colour of point `j` for charts that colour by point (pie, doughnut, treemap, sunburst).
pub(super) fn point_color(data: &ChartData, j: usize) -> Rgba {
match (j, data.series.first()) {
(0, Some(s)) => s.color,
_ => j.checked_rem(data.palette.len()).and_then(|k| data.palette.get(k)).copied().unwrap_or_else(|| series_color(&Theme::default(), j)),
}
}
fn first_len(data: &ChartData) -> usize {
data.series.first().map(|s| s.values.len()).unwrap_or(0)
}
pub(super) fn cat_label(data: &ChartData, j: usize) -> String {
data.categories.get(j).cloned().unwrap_or_else(|| (j + 1).to_string())
}
/// Legend entries (text, colour, swatch) `render` draws for this chart; empty when hidden.
pub fn legend_entries(chart: &Chart, data: &ChartData) -> Vec<(String, Rgba, Swatch)> {
if chart.legend == LegendPos::None {
return vec![];
}
match chart.kind {
ChartKind::Pie | ChartKind::Doughnut | ChartKind::Treemap | ChartKind::Sunburst => {
let n = first_len(data).min(MAX_CATS);
(0..n).map(|j| (cat_label(data, j), point_color(data, j), Swatch::Box)).collect()
}
ChartKind::Histogram | ChartKind::Funnel | ChartKind::Stock => vec![],
ChartKind::Waterfall => {
if data.series.is_empty() {
return vec![];
}
let total = data.series.first().map(|s| s.color).unwrap_or(TEXT);
vec![("Increase".into(), UP, Swatch::Box), ("Decrease".into(), DOWN, Swatch::Box), ("Total".into(), total, Swatch::Box)]
}
_ => {
let series = data.series.iter().take(MAX_SERIES);
let mut out: Vec<(String, Rgba, Swatch)> = series
.clone()
.map(|s| {
let sw = match plot_kind(chart, s) {
ChartKind::Line | ChartKind::LineStacked | ChartKind::Radar | ChartKind::ScatterLines => Swatch::Line,
ChartKind::LineMarkers => Swatch::LineMarker,
ChartKind::Scatter | ChartKind::Bubble => Swatch::Marker,
_ => Swatch::Box,
};
(s.name.clone(), s.color, sw)
})
.collect();
// Trendlines follow the series, named "Linear (Sales)" unless given a name.
for s in series.filter(|s| supports_trendline(plot_kind(chart, s))) {
for t in s.trendlines.iter().take(MAX_TRENDLINES) {
out.push((t.spec.name.clone().unwrap_or_else(|| auto_name(t.spec.kind, &s.name)), t.color, Swatch::Line));
}
}
out
}
}
}
// ---------------------------------------------------------------- legend
fn swatch_w(sw: Swatch, s: f32) -> f32 {
if sw == Swatch::Box { s } else { s * 2.0 }
}
fn draw_swatch(ctx: &mut Ctx, sw: Swatch, x: f32, yc: f32, s: f32, color: Rgba) {
match sw {
Swatch::Box => ctx.rect(x, yc - s / 2.0, s, s, color, None),
Swatch::Line => ctx.hline(x, x + 2.0 * s, yc, color, 2.0),
Swatch::LineMarker => {
ctx.hline(x, x + 2.0 * s, yc, color, 2.0);
ctx.out.push(Prim::Circle { cx: x + s, cy: yc, r: s * 0.35, fill: Some(color), stroke: None });
}
Swatch::Marker => ctx.out.push(Prim::Circle { cx: x + s, cy: yc, r: s * 0.4, fill: Some(color), stroke: None }),
}
}
pub(super) fn draw_legend(ctx: &mut Ctx, entries: &[(String, Rgba, Swatch)], pos: LegendPos, area: Bx) -> Bx {
let size = LABEL_SIZE;
let row_h = size * 1.6;
let s = size * 0.8;
let gap = 4.0;
let spacing = size * 1.3;
let item_w = |ctx: &Ctx, e: &(String, Rgba, Swatch)| swatch_w(e.2, s) + gap + ctx.tw(&e.0, size);
match pos {
LegendPos::None => area,
LegendPos::Top | LegendPos::Bottom => {
let max_rows = ((area.h * 0.3 / row_h).floor() as usize).max(1);
let mut rows: Vec<Vec<(usize, f32)>> = vec![vec![]];
let mut cur = 0.0f32;
for (i, e) in entries.iter().enumerate() {
let iw = item_w(ctx, e).min(area.w);
let need = if cur > 0.0 { spacing + iw } else { iw };
if cur > 0.0 && cur + need > area.w {
if rows.len() >= max_rows {
break;
}
rows.push(vec![]);
cur = 0.0;
}
cur += if cur > 0.0 { spacing + iw } else { iw };
if let Some(r) = rows.last_mut() {
r.push((i, iw));
}
}
let lh = rows.len() as f32 * row_h;
let y0 = if pos == LegendPos::Bottom { area.bottom() - lh } else { area.y };
for (ri, row) in rows.iter().enumerate() {
let total: f32 = row.iter().map(|(_, w)| w).sum::<f32>() + spacing * row.len().saturating_sub(1) as f32;
let mut x = area.x + (area.w - total).max(0.0) / 2.0;
let yc = y0 + ri as f32 * row_h + row_h / 2.0;
for &(i, iw) in row {
if let Some(e) = entries.get(i) {
draw_swatch(ctx, e.2, x, yc, s, e.1);
let sx = swatch_w(e.2, s) + gap;
let t = ctx.fit(&e.0, size, (iw - sx).max(0.0) + 0.5);
ctx.text(x + sx, yc, &t, size, TEXT, HAlign::Left, VAlign::Middle);
}
x += iw + spacing;
}
}
let used = lh + 4.0;
if pos == LegendPos::Bottom { Bx { h: area.h - used, ..area } } else { Bx { y: area.y + used, h: area.h - used, ..area } }
}
LegendPos::Left | LegendPos::Right => {
let colw = entries.iter().map(|e| item_w(ctx, e)).fold(0.0f32, f32::max).min(area.w * 0.35);
let max_rows = ((area.h / row_h).floor() as usize).max(1);
let n = entries.len().min(max_rows);
let lh = n as f32 * row_h;
let y0 = area.y + (area.h - lh).max(0.0) / 2.0;
let x0 = if pos == LegendPos::Right { area.right() - colw } else { area.x };
for (i, e) in entries.iter().take(n).enumerate() {
let yc = y0 + i as f32 * row_h + row_h / 2.0;
draw_swatch(ctx, e.2, x0, yc, s, e.1);
let sx = swatch_w(e.2, s) + gap;
let t = ctx.fit(&e.0, size, (colw - sx).max(0.0) + 0.5);
ctx.text(x0 + sx, yc, &t, size, TEXT, HAlign::Left, VAlign::Middle);
}
let used = colw + 8.0;
if pos == LegendPos::Right { Bx { w: area.w - used, ..area } } else { Bx { x: area.x + used, w: area.w - used, ..area } }
}
}
}
crates/chart/src/render/lines.rs
+157
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use super::frame::Bx;
use super::*;
// ---------------------------------------------------------------- helpers
/// Reduces a long polyline to first/min/max/last per pixel column.
pub(super) fn decimate(pts: Vec<[f32; 2]>, max: usize) -> Vec<[f32; 2]> {
if pts.len() <= max {
return pts;
}
let mut out = Vec::with_capacity(max * 2);
let mut i = 0;
while let Some(p) = pts.get(i) {
let col = p[0].floor();
let (start, mut mn, mut mx) = (i, i, i);
let mut k = i + 1;
while let Some(q) = pts.get(k) {
if q[0].floor() != col {
break;
}
if pts.get(mn).is_some_and(|m| q[1] < m[1]) {
mn = k;
}
if pts.get(mx).is_some_and(|m| q[1] > m[1]) {
mx = k;
}
k += 1;
}
let mut idx = [start, mn, mx, k - 1];
idx.sort_unstable();
let mut last = usize::MAX;
for ix in idx {
if ix != last
&& let Some(q) = pts.get(ix)
{
out.push(*q);
last = ix;
}
}
i = k;
}
if out.len() > max * 4 {
let step = out.len() / (max * 2) + 1;
let last = out.last().copied();
let mut s: Vec<[f32; 2]> = out.into_iter().step_by(step).collect();
if let Some(l) = last
&& s.last() != Some(&l)
{
s.push(l);
}
return s;
}
out
}
/// Draws a polyline split at gaps (`None`), decimated when long. With `smooth` (the plot box),
/// each run is interpolated with a Catmull-Rom spline so the line curves through the data points.
pub(super) fn draw_runs(ctx: &mut Ctx, pts: &[Option<[f32; 2]>], color: Rgba, width: f32, smooth: Option<Bx>) {
let mut run: Vec<[f32; 2]> = Vec::new();
for p in pts.iter().chain(std::iter::once(&None)) {
match p {
Some(p) => run.push(*p),
None => {
if run.len() >= 2 {
let r = decimate(std::mem::take(&mut run), MAX_LINE_PTS);
let r = match smooth {
Some(plot) => smooth_run(r, plot),
None => r,
};
ctx.line(r, color, width);
} else {
run.clear();
}
}
}
}
}
/// Catmull-Rom spline through `pts`: every segment gets the same number of sub-segments (up to
/// 100), chosen so the whole curve stays within `MAX_LINE_PTS * 2` points. Endpoints are
/// duplicated so the curve passes through the first and last points, and the curve is clamped
/// to the `plot` box (a spline overshoots its data near sharp turns).
fn smooth_run(pts: Vec<[f32; 2]>, plot: Bx) -> Vec<[f32; 2]> {
let n = pts.len();
if n < 3 {
return pts;
}
let cap = MAX_LINE_PTS * 2;
let steps = (cap / n).clamp(1, 100);
let mut out: Vec<[f32; 2]> = Vec::with_capacity(n.saturating_mul(steps).min(cap) + 1);
let at = |i: isize| -> [f32; 2] {
let j = i.clamp(0, n as isize - 1) as usize;
pts.get(j).copied().unwrap_or([0.0, 0.0])
};
let (x0, x1) = (plot.x.min(plot.right()), plot.x.max(plot.right()));
let (y0, y1) = (plot.y.min(plot.bottom()), plot.y.max(plot.bottom()));
let clip = |p: [f32; 2]| [p[0].clamp(x0, x1), p[1].clamp(y0, y1)];
for i in 0..n.saturating_sub(1) {
let (p0, p1, p2, p3) = (at(i as isize - 1), at(i as isize), at(i as isize + 1), at(i as isize + 2));
for s in 0..steps {
let t = s as f32 / steps as f32;
out.push(clip(catmull(p0, p1, p2, p3, t)));
}
}
out.push(clip(at(n as isize - 1)));
out
}
/// One Catmull-Rom point between `p1` and `p2` (uniform parameterisation), tangent-scaled by 0.5.
fn catmull(p0: [f32; 2], p1: [f32; 2], p2: [f32; 2], p3: [f32; 2], t: f32) -> [f32; 2] {
let t2 = t * t;
let t3 = t2 * t;
let mut o = [0.0f32; 2];
for k in 0..2 {
let (a0, a1, a2, a3) = (p0[k], p1[k], p2[k], p3[k]);
o[k] = 0.5 * ((2.0 * a1) + (-a0 + a2) * t + (2.0 * a0 - 5.0 * a1 + 4.0 * a2 - a3) * t2 + (-a0 + 3.0 * a1 - 3.0 * a2 + a3) * t3);
}
o
}
pub(super) fn draw_markers(ctx: &mut Ctx, pts: impl Iterator<Item = [f32; 2]>, r: f32, color: Rgba) {
let mut seen = HashSet::new();
for p in pts {
if seen.len() >= MAX_MARKERS {
break;
}
if seen.insert(((p[0] * 0.5) as i32, (p[1] * 0.5) as i32)) {
ctx.out.push(Prim::Circle { cx: p[0], cy: p[1], r, fill: Some(color), stroke: Some((WHITE, 0.75)) });
}
}
}
#[cfg(test)]
mod smooth_tests {
use super::*;
#[test]
fn long_runs_are_smoothed_uniformly_within_the_cap() {
let plot = Bx { x: 0.0, y: 0.0, w: 3000.0, h: 100.0 };
let pts: Vec<[f32; 2]> = (0..1500).map(|i| [i as f32 * 2.0, if i % 2 == 0 { 20.0 } else { 80.0 }]).collect();
let out = smooth_run(pts, plot);
assert!(out.len() <= MAX_LINE_PTS * 2 + 1, "{}", out.len());
// Two sub-segments per segment all the way to the end, not 100 each and then a straight tail.
assert_eq!(out.len(), 1499 * 2 + 1);
assert_eq!(out.last().copied(), Some([2998.0, 80.0]));
}
#[test]
fn spline_overshoot_is_clamped_to_the_plot() {
let plot = Bx { x: 0.0, y: 10.0, w: 300.0, h: 100.0 };
// A step right at the plot edges: Catmull-Rom overshoots past both.
let pts = vec![[0.0, 110.0], [100.0, 110.0], [110.0, 10.0], [200.0, 10.0], [300.0, 10.0]];
let out = smooth_run(pts, plot);
assert!(out.len() > 5);
assert!(out.iter().all(|p| (0.0..=300.0).contains(&p[0]) && (10.0..=110.0).contains(&p[1])));
}
}
crates/chart/src/render/trend.rs
+166
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use super::frame::{Bx, value_range};
use super::lines::decimate;
use super::*;
// ---------------------------------------------------------------- trendlines
/// Samples along a regression trendline.
const TREND_STEPS: usize = 200;
/// Whether series drawn as `k` show trendlines (Excel offers them on 2-D unstacked column,
/// bar, line, area, scatter and bubble charts).
pub fn supports_trendline(k: ChartKind) -> bool {
use ChartKind::*;
matches!(k, ColumnClustered | BarClustered | Line | LineMarkers | Area | Scatter | ScatterLines | Bubble)
}
/// A forecast distance as drawn: finite, non-negative and bounded.
fn forecast(v: f64) -> f64 {
if v.is_finite() && v > 0.0 { v.min(1e9) } else { 0.0 }
}
/// Most empty category slots a forward forecast may add after `ncat` categories: four times the
/// data (at least 32), and never past `MAX_CATS` in total. A larger forecast would shrink every
/// column to nothing.
pub(super) fn max_forward_slots(ncat: usize) -> f64 {
(ncat.saturating_mul(4).max(32)).min(MAX_CATS.saturating_sub(ncat)) as f64
}
/// Longest forward forecast among `s`'s regression trendlines.
pub(super) fn max_forward(s: &SeriesData) -> f64 {
s.trendlines.iter().filter(|t| !matches!(t.spec.kind, TrendlineKind::MovingAverage(_))).map(|t| forecast(t.spec.forward)).fold(0.0, f64::max)
}
/// Longest backward forecast among `s`'s regression trendlines.
pub(super) fn max_backward(s: &SeriesData) -> f64 {
s.trendlines.iter().filter(|t| !matches!(t.spec.kind, TrendlineKind::MovingAverage(_))).map(|t| forecast(t.spec.backward)).fold(0.0, f64::max)
}
/// Liang–Barsky: the part of segment `a`–`b` inside the unit square, with whether the start and
/// end were cut.
#[allow(clippy::type_complexity)]
fn clip_segment(a: (f64, f64), b: (f64, f64)) -> Option<((f64, f64), (f64, f64), bool, bool)> {
let (dx, dy) = (b.0 - a.0, b.1 - a.1);
let (mut t0, mut t1) = (0.0f64, 1.0f64);
for (p, q) in [(-dx, a.0), (dx, 1.0 - a.0), (-dy, a.1), (dy, 1.0 - a.1)] {
if p == 0.0 {
if q < 0.0 {
return None;
}
} else {
let r = q / p;
if p < 0.0 {
if r > t1 {
return None;
}
t0 = t0.max(r);
} else {
if r < t0 {
return None;
}
t1 = t1.min(r);
}
}
}
Some(((a.0 + t0 * dx, a.1 + t0 * dy), (a.0 + t1 * dx, a.1 + t1 * dy), t0 > 0.0, t1 < 1.0))
}
/// Clips a sampled polyline in plot fractions (`None` = gap) to the plot box (the unit
/// square), returning the visible runs.
fn clip_unit(pts: &[Option<(f64, f64)>]) -> Vec<Vec<(f64, f64)>> {
const LIM: f64 = 1e9;
let ok = |p: &(f64, f64)| p.0.is_finite() && p.1.is_finite();
let cl = |p: (f64, f64)| (p.0.clamp(-LIM, LIM), p.1.clamp(-LIM, LIM));
let mut runs: Vec<Vec<(f64, f64)>> = Vec::new();
let mut run: Vec<(f64, f64)> = Vec::new();
for w in pts.windows(2) {
let seg = match w {
[Some(a), Some(b)] if ok(a) && ok(b) => clip_segment(cl(*a), cl(*b)),
_ => None,
};
match seg {
Some((p, q, cut_start, cut_end)) => {
if cut_start || run.is_empty() {
if run.len() >= 2 {
runs.push(std::mem::take(&mut run));
}
run.clear();
run.push(p);
}
run.push(q);
if cut_end {
runs.push(std::mem::take(&mut run));
}
}
None => {
if run.len() >= 2 {
runs.push(std::mem::take(&mut run));
}
run.clear();
}
}
}
if run.len() >= 2 {
runs.push(run);
}
runs
}
/// Draws `s`'s trendlines fitted to its plotted points `pts` (data x, y). `frac` maps data to
/// fractions of the plot box (0..1 inside, along the x and y axes), `px` fractions to pixels.
/// Equation and R² label lines are appended to `labels`. Degenerate fits draw nothing.
pub(super) fn draw_trendlines(
ctx: &mut Ctx,
s: &SeriesData,
pts: &[(f64, f64)],
frac: &dyn Fn(f64, f64) -> (f64, f64),
px: &dyn Fn((f64, f64)) -> [f32; 2],
labels: &mut Vec<String>,
window: (f64, f64),
) {
let Some((xlo, xhi)) = value_range(pts.iter().map(|p| p.0)) else { return };
for t in s.trendlines.iter().take(MAX_TRENDLINES) {
let spec = &t.spec;
let samples: Vec<Option<(f64, f64)>> = match spec.kind {
TrendlineKind::MovingAverage(p) => moving_average(pts, p).into_iter().map(|(x, y)| Some(frac(x, y))).collect(),
_ => {
let Some(fit) = fit_trendline(spec, pts) else { continue };
// Sample only the part of the forecast that is on the plot.
let (lo, hi) = ((xlo - forecast(spec.backward)).max(window.0), (xhi + forecast(spec.forward)).min(window.1));
if spec.display_equation {
labels.push(fit.equation());
}
if spec.display_r_squared {
labels.push(fit.r_squared());
}
(0..=TREND_STEPS)
.map(|i| {
let x = lo + (hi - lo) * i as f64 / TREND_STEPS as f64;
fit.eval(x).map(|y| frac(x, y))
})
.collect()
}
};
let width = spec.width.filter(|w| w.is_finite()).unwrap_or(1.5).clamp(0.25, 12.0);
let dash = spec.dash != Some(LineDash::Solid);
for run in clip_unit(&samples) {
let line = decimate(run.into_iter().map(px).collect(), MAX_LINE_PTS);
if line.len() >= 2 {
ctx.out.push(Prim::Line { pts: line, color: t.color, width, dash });
}
}
}
}
/// Trendline equation / R² labels, stacked in the plot's top-right corner.
pub(super) fn draw_trend_labels(ctx: &mut Ctx, plot: Bx, labels: &[String]) {
let lh = LABEL_SIZE * 1.3;
for (i, t) in labels.iter().enumerate() {
let y = plot.y + 4.0 + i as f32 * lh;
if y + lh > plot.bottom() {
break;
}
let t = ctx.fit(t, LABEL_SIZE, plot.w - 8.0);
ctx.text(plot.right() - 4.0, y, &t, LABEL_SIZE, TEXT, HAlign::Right, VAlign::Top);
}
}