Gantt Chart

A Gantt chart displays tasks as horizontal bars spanning a time range, making it easy to see schedule, duration, sequence, and overlap at a glance. Tasks can be organized into named phases or groups, which receive colored header rows and distinct bar colors drawn from the category10 palette.

kuva's GanttPlot adds three features beyond basic scheduling:

• Progress fill — a darker inner region shows completion fraction; tasks not yet started are shown at full opacity without a progress fill.
• Milestone diamonds — single-point events (deadlines, sign-offs, launches) render as ◆ markers rather than bars.
• Now line — a dashed vertical reference line marks the current date or time.

Import path: kuva::plot::GanttPlot

Basic usage

Add tasks with .with_task(label, start, end). Without groups, all bars share the default color and appear in insertion order.

#![allow(unused)]
fn main() {
use kuva::plot::GanttPlot;
use kuva::backend::svg::SvgBackend;
use kuva::render::render::render_multiple;
use kuva::render::layout::Layout;
use kuva::render::plots::Plot;

let gantt = GanttPlot::new()
    .with_task("Literature review", 0.0,  4.0)
    .with_task("Data collection",   2.0,  8.0)
    .with_task("Analysis",          7.0, 12.0)
    .with_task("Write-up",         11.0, 16.0);

let plots = vec![Plot::Gantt(gantt)];
let layout = Layout::auto_from_plots(&plots)
    .with_title("Research Project")
    .with_x_label("Week");

let svg = SvgBackend.render_scene(&render_multiple(plots, layout));
std::fs::write("gantt.svg", svg).unwrap();
}

Labels are drawn inside the bar when there is enough room; otherwise they appear to the right of the bar. The right margin is automatically expanded so outside labels are never clipped.

Groups and phases

Use .with_task_group(group, label, start, end) to assign tasks to named groups. Each group gets a shaded header row and a distinct bar color from the category10 palette. Tasks within a group appear in insertion order immediately below their header.

#![allow(unused)]
fn main() {
use kuva::plot::GanttPlot;
use kuva::render::plots::Plot;
use kuva::backend::svg::SvgBackend;
use kuva::render::render::render_multiple;
use kuva::render::layout::Layout;

let gantt = GanttPlot::new()
    .with_task_group("Discovery", "User research",    0.0,  3.0)
    .with_task_group("Discovery", "Competitive audit",1.0,  4.0)
    .with_task_group("Design",    "Wireframes",       3.5,  6.0)
    .with_task_group("Design",    "Prototyping",      5.0,  8.0)
    .with_task_group("Build",     "Frontend",         7.0, 12.0)
    .with_task_group("Build",     "Backend",          6.0, 11.0);

let plots = vec![Plot::Gantt(gantt)];
let layout = Layout::auto_from_plots(&plots)
    .with_title("Product Development")
    .with_x_label("Week");
}

Use .with_group_order(groups) to control phase order explicitly. Groups not listed follow in insertion order.

#![allow(unused)]
fn main() {
use kuva::plot::GanttPlot;
use kuva::render::plots::Plot;
let gantt = GanttPlot::new()
    .with_group_order(["Build", "Discovery", "Design"])  // Build appears first
    .with_task_group("Discovery", "Research",   0.0, 3.0)
    .with_task_group("Design",    "Wireframes", 2.0, 5.0)
    .with_task_group("Build",     "Dev",        4.0, 9.0);
}

Progress fills and the now line

.with_task_group_progress(group, label, start, end, fraction) draws a darker inner fill showing how much of the task is complete. The fraction is clamped to [0.0, 1.0].

.with_now_line(value) draws a dashed red vertical reference line at the given x position — useful for marking today's date.

#![allow(unused)]
fn main() {
use kuva::plot::GanttPlot;
use kuva::render::plots::Plot;
use kuva::backend::svg::SvgBackend;
use kuva::render::render::render_multiple;
use kuva::render::layout::Layout;

let gantt = GanttPlot::new()
    .with_task_group_progress("Q1", "API design",   0.0,  3.0, 1.0)   // done
    .with_task_group_progress("Q1", "Auth service", 1.0,  4.0, 1.0)   // done
    .with_task_group_progress("Q2", "Dashboard",    3.0,  7.0, 0.65)  // in progress
    .with_task_group_progress("Q2", "Reporting",    4.0,  8.0, 0.25)  // early
    .with_task_group("Q3", "Mobile app",            7.0, 11.0)        // not started
    .with_task_group("Q3", "Performance",           8.0, 12.0)
    .with_now_line(5.5);

let plots = vec![Plot::Gantt(gantt)];
let layout = Layout::auto_from_plots(&plots)
    .with_title("Engineering Roadmap — progress at week 5.5")
    .with_x_label("Week");
}

Milestones

.with_milestone(label, at) and .with_milestone_group(group, label, at) add diamond markers at a single point in time. Milestone labels are always drawn to the right of the diamond in bold, and the right margin is automatically widened to fit them.

#![allow(unused)]
fn main() {
use kuva::plot::GanttPlot;
use kuva::render::plots::Plot;
use kuva::backend::svg::SvgBackend;
use kuva::render::render::render_multiple;
use kuva::render::layout::Layout;

let gantt = GanttPlot::new()
    .with_task_group("Planning",  "Requirements",  0.0,  2.0)
    .with_task_group("Planning",  "Architecture",  1.0,  3.0)
    .with_milestone_group("Planning", "Sign-off",  3.0)
    .with_task_group("Execution", "Core build",    3.0,  9.0)
    .with_task_group("Execution", "Integration",   7.0, 11.0)
    .with_milestone_group("Execution", "Code freeze", 11.0)
    .with_task_group("Launch",    "Testing",      10.0, 13.0)
    .with_milestone("Public launch", 14.0)
    .with_now_line(7.0);

let plots = vec![Plot::Gantt(gantt)];
let layout = Layout::auto_from_plots(&plots)
    .with_title("Software Release Plan")
    .with_x_label("Week");
}

Showcase — clinical trial timeline

The example below uses every major feature: explicit group_order, progress fills on pre-trial tasks, in-progress recruitment bars, ungrouped treatment arms, per-group and free-floating milestones, and a now line marking the current month.

#![allow(unused)]
fn main() {
use kuva::plot::GanttPlot;
use kuva::render::plots::Plot;
use kuva::backend::svg::SvgBackend;
use kuva::render::render::render_multiple;
use kuva::render::layout::Layout;

let gantt = GanttPlot::new()
    .with_group_order(["Pre-trial", "Recruitment", "Treatment", "Analysis"])
    .with_task_group_progress("Pre-trial",   "Protocol writing",     0.0,  3.0, 1.0)
    .with_task_group_progress("Pre-trial",   "IRB approval",         2.0,  5.0, 1.0)
    .with_task_group_progress("Pre-trial",   "Site selection",       3.0,  6.0, 1.0)
    .with_milestone_group("Pre-trial",       "Trial start",          6.0)
    .with_task_group_progress("Recruitment", "Screening",            6.0, 12.0, 0.75)
    .with_task_group_progress("Recruitment", "Enrollment",           7.0, 14.0, 0.45)
    .with_task_group("Treatment",            "Arm A (n=150)",       12.0, 24.0)
    .with_task_group("Treatment",            "Arm B (n=150)",       12.0, 24.0)
    .with_milestone_group("Treatment",       "Interim analysis",    18.0)
    .with_task_group("Analysis",             "Data lock",           23.0, 26.0)
    .with_task_group("Analysis",             "Statistical analysis",25.0, 30.0)
    .with_task_group("Analysis",             "Report writing",      28.0, 34.0)
    .with_milestone("Primary endpoint", 24.0)
    .with_milestone("Submission",       35.0)
    .with_now_line(16.0)
    .with_bar_height(0.55);

let plots = vec![Plot::Gantt(gantt)];
let layout = Layout::auto_from_plots(&plots)
    .with_title("Phase III Clinical Trial Timeline")
    .with_x_label("Month")
    .with_width(800.0)
    .with_height(520.0);

let svg = SvgBackend.render_scene(&render_multiple(plots, layout));
std::fs::write("trial.svg", svg).unwrap();
}

GanttPlot API reference

Task builders

Display builders