kuva v0.3.0

[0.3.0] — 2026-06-19

Added

• Math in labels — any label (title, axis labels, TextPlot markdown bodies) may embed $...$ math written in LaTeX-ish syntax ($\sigma^2$, $\frac{a}{b}$, $\sqrt{x^2+y^2}$). Math regions are lowered to inline Unicode — Greek letters, operators, super/subscripts (all-or-nothing, with a clean x^(2q) fallback), \frac→a/b, \sqrt→√(…) — by every backend including the terminal. Zero dependencies, always on; a literal dollar is written \$. See Reference → Math in Labels.
• QuiverPlot — 2-D vector field rendered as arrows. Each arrow has a tail at (x, y) and a vector (u, v). Features: from_function() constructor for sampling a closure on a regular grid; auto-scaled arrow length (longest arrow ≈ one grid cell via a span/√n heuristic) or explicit with_scale; proportional arrow heads that make every arrow "look like an arrow" regardless of magnitude; three pivot modes (Tail, Middle, Tip); optional magnitude-driven colormap with automatic colorbar; tight_bounds opt-in for dense fields and independent with_clip_to_plot_area() for plot-area clipping; combo helper with_magnitude_colormap(cmap, label). CLI: kuva quiver.
• Pre-compiled release binaries — pushing a vX.Y.Z tag now builds standalone kuva CLI binaries (with the cli,full feature set: SVG + PNG + PDF) for Linux (x86_64 gnu/musl, aarch64), macOS (Intel + Apple Silicon) and Windows (x86_64), and attaches them with SHA-256 checksums to the matching GitHub Release. Users can download a binary and run it without installing Rust. See .github/workflows/release.yml (resolves #17).
• AxisLabelOverlap — collision-aware x-axis label thinning — Layout::with_x_label_overlap(AxisLabelOverlap) opts any plot into collision-aware x-axis labelling. Three modes: Allow (default — existing behaviour), Thin (left-to-right pass; skip any label whose estimated footprint overlaps the previous one), and Stagger (alternate two vertical offsets so adjacent labels no longer need horizontal clearance). Works with both upright and rotated (Layout::with_x_tick_rotate) labels. ManhattanPlot gains the convenience builder with_thin_overlapping_labels(). CLI: --x-label-overlap allow|thin|stagger on all subcommands.
• .parquet input for all CLI subcommands — all ~50 CLI subcommands can read .parquet files directly (extension sniffing), or detect parquet piped via stdin by magic bytes (PAR1 header/footer). Uses projected Arrow reads via ParquetRecordBatchReaderBuilder + ProjectionMask::roots() — only requested columns are decoded; 35–154× faster and 7–29× less memory than full-file row API on wide files. Gated behind --features parquet. (Community PR #79 by mud2monarch; extended to all subcommands in this release.)
• Horizontal mode for BarPlot, BoxPlot, ViolinPlot, RaincloudPlot — .with_horizontal(true) rotates any of these charts so categories appear on the Y-axis and values on the X-axis. Useful when category labels are long or when a horizontal layout reads more naturally. Slot-fraction width/gap builders work identically in both orientations. CLI: --horizontal flag added to kuva bar, kuva box, kuva violin, kuva raincloud.
• CLI multi-column --y extended — --y A,B,C (comma-separated column names or indices) is now supported on histogram, bar, strip, violin, box, density, and ridgeline in addition to the scatter and line subcommands added in v0.2.0. One series / group / ridge / curve is created per column; legend labels use column header names. Bar mode aggregates rows by --label-col (mean by default; --agg overrides). All existing --group-col / --value-col flags remain supported.
• Enclosed plots — AxisLine::Internal and AxisLine::Mirrored — Layout::with_axis_line(AxisLine) controls how axes are drawn. AxisLine::Open (renamed from the previous Left) draws a standard open axis; AxisLine::Internal draws tick marks inward; AxisLine::Mirrored draws ticks on both sides of the plot area. (PR #77.)
• embed_font Cargo feature — flate2 is now optional. The new embed_font feature gates font embedding in SVG output; the png and pdf features pull in flate2 for their own font loading; SVG-only builds no longer depend on it. The fonts module is gated on any(embed_font, png, pdf). (Adapted from PR #81 by Zodey-hub.)
• NetworkPlot enhancements — cubic-Bézier curved edges via .with_curves(true); inside-node label placement (labels drawn centred inside node circles for compact graphs); legend group color fix (group entries now use the correct per-group color rather than a single fallback).
• Bundled font variants (Bold, Oblique, Mono) — DejaVu Sans Bold, Oblique, and Mono TTFs are now bundled (gzip-compressed, inflated on first use via OnceLock). All three are gated behind #[cfg(any(feature = "png", feature = "pdf", feature = "embed_font"))] — SVG-only builds pay no binary-size cost. The embed_font @font-face block now embeds all four variants with correct font-weight/font-style descriptors so bold, italic, and code spans in TextPlot render correctly in self-contained SVGs.
• TextPlot code span markup — backtick syntax (`code`) is now parsed by parse_inline_markup and produces a TextSpan { code: true }. SVG renders code spans with font-family="DejaVu Sans Mono,monospace"; PNG/PDF use the bundled DejaVu Sans Mono font face.
• TextPlot full markup in PNG/PDF — bold, italic, and code spans now render correctly in PNG and PDF. Each span is drawn with the matching bundled font face (Bold / Oblique / Mono); text metrics are computed per-font so multi-style lines are correctly anchored.

Fixed

• Tick generation overflow (#80) — generate_ticks used an absolute loop guard end + 1e-8; on sub-1e-8 data ranges (e.g. values in the 1e-10 range) the guard was never reached and the loop could produce millions of ticks or run indefinitely. Fixed with a relative tolerance step.abs() * 1e-6 plus scale-invariant significant-figure rounding.
• Y-axis label centering without title (#83) — the y-axis label y-position was computed from the canvas centre (height / 2); when no title was present this placed the label above the plot midpoint. Corrected to margin_top + plot_height() / 2.
• Legend box right-padding — the auto-sizing formula max_chars * 7.2 + 35 underestimated required box width, clipping long labels at larger font sizes or scale factors. Updated to max_chars * 8.5 + 41.
• Negative values in CLI numeric flags — --y-min, --y-max, --x-min, --x-max, --x-tick-step, --y-tick-step now accept negative numbers (e.g. --x-min -1.5) without being misinterpreted as unknown flags. Fixed via allow_hyphen_values = true on the relevant arguments.
• BrickPlot multifigure bleed — row heights are now normalized to a consistent pixel height when BrickPlot is placed inside a Figure panel, preventing render bleed into adjacent cells.
• group_by performance — changed from O(n²) to O(n) using a HashMap + insertion-order Vec. Affects all CLI subcommands that use --color-by or grouped input.

Changed

• PNG backend — new raster pipeline — PngBackend now uses a direct RGBA pixel-buffer rasterizer with fontdue text rendering. The previous resvg-based SVG round-trip path is removed. Renders are faster and no longer depend on resvg or usvg. PngBackend retains its existing public API as a compatibility shim over the new RasterBackend.
• BrickPlot legend improvements — new builders with_legend_columns(n) (fixed column count) and with_legend_max_entries(n) (cap before overflow); legend entries per column are now evenly distributed. Prevents legend overflow when many repeat motifs are present.
• Refactor: render_utils::arrow_head_path — factored a shared arrow-head triangle helper now used by QuiverPlot, NetworkPlot (directed-edge arrowheads), and TextAnnotation arrows. Eliminates three inlined copies of the same geometry.
• Refactor: colorbar_linear helper in render/plots.rs — consolidates six near-identical Arc<Fn> closures that built linearly-normalized colorbars across Heatmap, DotPlot, DicePlot, Contour, Clustermap, and (new) Quiver. The 3-D colorbar_from_z path also routes through it now.

Pull Requests

• doc updates, and small tweaks to png raster backend by @Psy-Fer in #86
• manhattan: opt-in thinning of overlapping chromosome labels by @wdecoster in #82
• ci: build and publish release binaries on version tags by @wdecoster in #85
• Add QuiverPlot — 2-D vector field plot (re-submit of #70) by @gabo515 in #87
• feat: add support for enclosed plots with internal and mirrored ticks by @Ryan-D-Gast in #77
• Add unicode math shorthand for $...$ regions in labels by @gabo515 in #89
• Add parquet for scatter plots in CLI by @mud2monarch in #79
• Dev merge for v0.3.0 by @Psy-Fer in #90

New Contributors

• @wdecoster made their first contribution in #82
• @Ryan-D-Gast made their first contribution in #77
• @mud2monarch made their first contribution in #79

Full Changelog: v0.2.0...v0.3.0