Bars#

A bar is a record with a start and an end. The definition names the attributes and how the bar looks; the browser draws it.

->start('starts_on')->end('ends_on')   // defaults: starts_at, ends_at
->label('title')                        // an attribute (an enum reads as its label), or fn (Task $task): string
->color('priority')                     // an attribute (a colour name, or an enum implementing HasColor), or a closure
->progress('progress')                  // 0–100, an attribute or a closure

Colours are names (gray, sky, amber, emerald, rose… or your panel's primary, success, warning, danger, info, or a colour you registered on the panel, brand), a Filament palette such as Color::Sky (its 500 shade is drawn), an enum implementing HasColor, or a CSS colour: #0ea5e9, rgb(…), hsl(…), oklch(…) and the other colour functions with plain values, var(--my-colour). Anything else is dropped and the bar uses the panel's primary colour: the value ends up in the bar's style, so a colour taken from user data (a project's colour field) cannot bring declarations of its own (red; position: fixed…), on the server or in the browser. Without one, the bars use the panel's primary colour.

Whole days and moments#

The chart works in half-open ranges [start, end):

Whatever the browser does, the record is written back in the same convention: a whole-day record resized to end on the 9th gets ends_on = 2026-10-09. ->dateOnly() (or ->dateOnly(false)) overrides the detection for plain string columns. The tooltip follows the record too: whole days read as dates, moments as date and time.

Dates are handled as wall-clock times, never converted between zones, so a daylight-saving change never lengthens or shortens a bar (Time zones).

Milestones#

A record with a null end is a milestone: a diamond at its start, movable but not resizable. A datetime record whose end equals its start is one too. To decide yourself, give milestone() an attribute or a closure:

->milestone('is_milestone')
->milestone(fn (Task $task) => $task->type === TaskType::Milestone)

Whole-day records with starts_on == ends_on are one-day bars, not milestones, unless milestone() says otherwise. A record milestone() flags keeps whatever end it has: when the diamond is dragged, its end moves by the same number of days.

The Bar shape#

For anything beyond the three shortcuts, shape the bar in one closure. What it sets wins over label(), color() and progress():

use Packstub\Gantt\Bar;

->bar(fn (Task $task) => Bar::make()
    ->label($task->title)
    ->color($task->is_late ? 'danger' : $task->priority)
    ->progress($task->progress)
    ->tooltip($task->assignee?->name)
    ->url(TaskResource::getUrl('edit', ['record' => $task]))
    ->actions($task->is_locked ? ['view'] : ['view', 'edit', 'delete']))

Bars are plain data drawn in the browser, so a chart of a few hundred bars is a few kilobytes of JSON rather than a few hundred Blade components. Eager-load what the closures touch (->query(fn () => Task::query()->with('assignee'))).

Dependencies#

Tell the chart which bars a bar waits for and it draws an arrow from each predecessor's end to the bar's start (finish-to-start):

->dependencies('depends_on')     // a JSON or array column holding the predecessors' keys
->dependencies('predecessors')   // a relation to them (BelongsToMany, HasMany), eager-loaded with the bars
->dependencies(fn (Task $task) => $task->blockers->pluck('id'))   // or a closure returning keys or models

The arrows are drawn, not enforced: a successor that starts before its predecessor ends gets a dashed arrow in the danger colour, and nothing is rescheduled or refused. To refuse such a move, say so in canMove(). An arrow needs both bars on the chart: a predecessor outside the window, filtered out or in a folded group draws none. The arrows follow a bar while it is dragged. Their colours are --ps-gantt-arrow and --ps-gantt-arrow-late (Styling).

Order#

Bars inside a group are ordered by their start; sortBy('priority', 'desc') orders them by another attribute. Records without a start are left out.