public class Gantt

A Gantt chart of a ProjectModel: the tree of tasks in a table on the left, a bar for each against a time axis on the right, the links between them, and under them how much of every resource the plan asks for.

WorkCalendar calendar = new WorkCalendar();
// A duration is working time: a day of it is the calendar's hours.
long day = calendar.getMillisPerDay();
ProjectModel project = new ProjectModel(calendar, System.currentTimeMillis());
GanttTask design = new GanttTask("design", "Design", 5 * day);
GanttTask build = new GanttTask("build", "Build", 10 * day);
project.addTask(design).addTask(build);
project.link(design, build);
project.update();

Form form = new Form("Plan", new BorderLayout());
form.add(BorderLayout.CENTER, new Gantt(project));
form.show();

The chart draws its rows and keeps no component for each, so a plan of thousands of tasks scrolls as one of ten does. Time zooms with a pinch, with the wheel and the control key held, or with zoomIn, zoomOut and zoomToFit.

Editing

A bar is dragged to move it and by its end to change its duration. With a mouse that is a plain drag; on a touch screen a drag scrolls, so a long press picks the bar up. The selected task shows a marker under its bar, dragged to set how much of it is done, and a dot after its end, dragged onto another bar to make that one depend on it.

A task the project schedules is not placed by a drag: the drag sets a “start no earlier than” constraint, and the task then starts there or later if its predecessors say so. A manually scheduled task is given the dates as they are. Every change is offered to the listeners first, which may refuse it, and then the project is scheduled again and the bars slide to where they now are. A summary task follows its children and is not dragged. The table is not edited in place: a double tap is reported to GanttListener#taskOpened, for an application’s own editor.

Under a mouse the bar the pointer is over lights up together with the links into and out of it, the row is marked in the table and in the chart, the cursor says what a drag would do and a tooltip gives the task’s dates and progress. A bar that is picked up lifts over a shadow.

setAnimationTime stops the clock these run by, for a screenshot or a test of a moment in the middle of one.

Resources

setLoadVisible(true) shows the load of every resource under the chart. A stretch over the resource’s capacity is drawn in GanttOverload. level() delays tasks until no resource is asked for more than it has, as far as that can be done.

Styling

GanttRow is a row, with its selected style the selected one, and GanttSummaryRow the row of a summary task; GanttHeader the time axis and the titles of the table. The bars are GanttBar, with GanttBarProgress the part done, GanttBarCritical, GanttSummaryBar and GanttMilestone; GanttBaseline is the plan as it was captured. GanttLink and GanttLinkCritical give the links their foreground colour, GanttLoad and GanttOverload the resource load. A task that names a UIID or a colour of its own is painted with that.