drawlib.charts.gantt

2D Gantt project schedule and roadmap chart builder supporting section banners, progress-filled task bars, diamond milestones, orthogonal task dependencies, and vertical timeline markers. Import from drawlib.charts.gantt (from drawlib.charts.gantt import Dependency, GanttChart, Marker, Milestone, Section, Task).

from drawlib.canvas import save, setup
from drawlib.charts.gantt import GanttChart
from drawlib.shapes import rectangle
from drawlib.styles import Colors, Styles

setup(width=120, height=54)

card_style = Styles.Neutral.patch(shape_r=2.0, shape_line_color=Colors.Gray4, shape_fill_color=Colors.White)
rectangle((60.0, 27.0), width=110.0, height=46.0, style=card_style)

chart = GanttChart(
    columns=["Apr", "May", "Jun", "Jul", "Aug"],
    axis_line_style=Styles.MutedDashed,
    axis_text_style=Styles.Black.patch(text_size=10.5),
    grid_style=Styles.MutedThin,
    header_style=Styles.Neutral,
    zebra_style=Styles.NeutralFlat,
    progress_text_style=Styles.WhiteBold.patch(text_size=10.0),
    width=102.0,
    label_width=29.0,
    header_height=5.5,
    row_height=4.8,
    bar_radius=0.9,
    title="Platform Release Schedule (Q2–Q3)",
    title_style=Styles.BlackBold.patch(text_size=12.0),
)

chart.add_section("Core Architecture", text_style=Styles.BlackBold.patch(text_size=10.5))
t1 = chart.add_task("Protocol Spec", start="Apr", end=1.1, style=Styles.PrimaryFlat, progress=1.0)
t2 = chart.add_task("Storage Engine", start=1.1, end=2.6, style=Styles.PrimaryFlat, progress=0.75)
t3 = chart.add_task(
    "gRPC Gateway",
    start=2.5,
    end=4.1,
    style=Styles.SecondaryFlat,
    progress=0.50,
)
chart.add_milestone("GA Launch", at=4.5, style=Styles.PrimaryFlat)

chart.add_dependency(t1, t2)
chart.add_dependency(t2, t3)
chart.add_marker(at=2.25, style=Styles.DarkDashed, label="Today", label_style=Styles.WhiteBold.patch(text_size=10.0))

chart.draw(xy=(9.0, 6.0))
save()

classDependency#

Mutable data model representing an orthogonal connector arrow linking two scheduled Task rows in a GanttChart.

• Visibility Cascading: Automatically hidden whenever either from_task or to_task has show=False or draw_ratio == 0.0.

class Dependency:
    def __init__(
        self,
        from_task: Task,
        to_task: Task,
        style: Style | None = None,
        show: bool = True,
    ) -> None: ...

Parameters & Attributes#

typeDrawDirection#

Spatial partial-rendering direction used with Task.draw_ratio (0.0 to 1.0) for progressive schedule animations.

DrawDirection = Literal["bottom_to_top", "left_to_right"]

classGanttChart#

2D Gantt project schedule chart builder stacking sections, tasks, and milestones top-to-bottom across horizontal timeline columns.

• Coordinate Anchor: Bottom-Left (x0, y0) by default in draw(xy=..., align="bottom_left"), or geometric center when align="center".
• Time Coordinate Indexing (start, end, at): Accepts either an exact column name from columns (start="Apr" = left edge, end="Apr" = right edge, at="Jun" = column midpoint) or a float column offset (0.0 = left edge of column 0, 1.5 = midpoint of column 1).

class GanttChart:
    def __init__(
        self,
        *,
        columns: list[str],
        axis_line_style: Style,
        axis_text_style: Style | None = None,
        header_style: Style | None = None,
        grid_style: Style | None = None,
        zebra_style: Style | None = None,
        progress_text_style: Style | None = None,
        background_style: Style | None = None,
        title: str = "",
        title_style: Style | None = None,
        width: float = 90.0,
        height: float | None = None,
        row_height: float = 4.5,
        header_height: float = 5.5,
        label_width: float = 24.0,
        bar_radius: float = 0.8,
    ) -> None: ...

Parameters#

Methods & Properties#

add_dependency

def add_dependency(
    self,
    from_task: Task,
    to_task: Task,
    style: Style | None = None,
    *,
    show: bool = True,
) -> Dependency

Adds an orthogonal dependency arrow connecting from_task to to_task and returns the mutable Dependency instance.

add_marker

def add_marker(
    self,
    at: str | float,
    style: Style,
    label: str = "",
    label_style: Style | None = None,
    *,
    show: bool = True,
) -> Marker

Adds a full-height vertical reference line at at with an optional top badge (label + label_style) and returns the mutable Marker instance.

add_milestone

def add_milestone(
    self,
    name: str,
    at: str | float,
    style: Style,
    *,
    show: bool = True,
) -> Milestone

Adds a milestone row with a diamond marker anchored at at and returns the mutable Milestone instance.

add_section

def add_section(
    self,
    name: str,
    style: Style | None = None,
    text_style: Style | None = None,
    *,
    show: bool = True,
) -> Section

Adds a category section divider banner row and returns the mutable Section instance.

add_task

def add_task(
    self,
    name: str,
    start: str | float,
    end: str | float,
    style: Style,
    progress: float = 0.0,
    progress_text_style: Style | None = None,
    *,
    show: bool = True,
    draw_ratio: float = 1.0,
    draw_direction: DrawDirection = "left_to_right",
) -> Task

Adds a scheduled task bar spanning [start, end] with optional completion progress (0.0 to 1.0) and returns the mutable Task instance.

columns *(property)*

@property
def columns(self) -> list[str]

Returns a list copy of timeline column labels.

dependencies *(property)*

@property
def dependencies(self) -> list[Dependency]

Returns a list copy of registered Dependency arrows.

draw

def draw(
    self,
    xy: tuple[float, float] = (0.0, 0.0),
    *,
    width: float | None = None,
    height: float | None = None,
    align: Literal["bottom_left", "center"] = "bottom_left",
    scale: float = 1.0,
) -> None

Renders the Gantt chart onto the canvas anchored at xy (Bottom-Left (x0, y0) by default, or geometric center when align="center").

get_size

def get_size(self) -> tuple[float, float]

Computes and returns the total (width, height) dimensions of the chart container.

items *(property)*

@property
def items(self) -> list[Task | Section | Milestone]

Returns a list copy of registered schedule rows (Task, Section, Milestone) in top-to-bottom order.

markers *(property)*

@property
def markers(self) -> list[Marker]

Returns a list copy of registered vertical Marker reference lines.

classMarker#

Mutable data model representing a full-height vertical reference line across all schedule rows (e.g. "Today" or "Code Freeze").

class Marker:
    def __init__(
        self,
        at: str | float,
        style: Style,
        label: str = "",
        label_style: Style | None = None,
        show: bool = True,
    ) -> None: ...

Parameters & Attributes#

classMilestone#

Mutable data model representing a zero-duration diamond milestone event row in a GanttChart.

class Milestone:
    def __init__(
        self,
        name: str,
        at: str | float,
        style: Style,
        show: bool = True,
    ) -> None: ...

Parameters & Attributes#

classSection#

Mutable data model representing a full-width category section divider row in a GanttChart.

class Section:
    def __init__(
        self,
        name: str,
        style: Style | None = None,
        text_style: Style | None = None,
        show: bool = True,
    ) -> None: ...

Parameters & Attributes#

classTask#

Mutable data model representing a scheduled task bar spanning [start, end] in a GanttChart.

class Task:
    def __init__(
        self,
        name: str,
        start: str | float,
        end: str | float,
        style: Style,
        progress: float = 0.0,
        progress_text_style: Style | None = None,
        show: bool = True,
        draw_ratio: float = 1.0,
        draw_direction: DrawDirection = "left_to_right",
    ) -> None: ...

Parameters & Attributes#