Diagram: State Machine¶

State machines are suitable for DFAs, process states, and life-cycle flows. States are circles (double-circles for accepting states). Transitions are arrows, optionally curved to avoid overlaps.

Minimal example¶

import engrapha_notes as en
import engrapha_diagrams as ed

sm = ed.StateMachine(width=380, height=180,
                      caption="Fig 6: Connection States")

sm.state("closed", "CLOSED", initial=True)
sm.state("listen", "LISTEN")
sm.state("estab", "ESTABLISHED", accepting=True)

sm.transition("closed", "listen", label="passive open")
sm.transition("listen", "estab",  label="receive SYN")
sm.transition("estab",  "closed", label="RST received")
sm.transition("listen", "listen", label="retransmit")

en.add(sm.as_flowable())
en.build_doc("state.pdf")

Curved transitions¶

Offset bidirectional edges so they do not overlap:

sm.transition("A", "B", label="event1")
sm.transition("B", "A", label="event2")  # auto-offsets both

Provide an explicit offset to control curvature:

sm.transition("A", "C", label="detour", offset=80.0)

Positive offsets bend one way, negative offsets the other.

Self loops¶

A transition where from_id == to_id draws an arc loop:

sm.transition("A", "A", label="loop")

Pills¶

Enable pill-shaped label bubbles on transitions:

sm.transition("A", "B", label="START", pill=True)

Initial / accepting¶

sm.state("s0", "Start", initial=True)     # Filled dot + arrow
sm.state("s3", "End",  accepting=True)    # Double ring

Auto layout¶

auto_layout() tries to fit transitions without overlap and switches to vertical mode when horizontal fits poorly.

Parameters reference¶

Parameter	Default	Purpose
`direction`	`"LR"` (auto-switches to `"TB"`)	`"TB"` or `"LR"`
`state_r`	`22.0`	Default state circle radius
`state_label_max_width`	`82.0`	Text width cap
`transition_label_max_width`	`96.0`	Label width cap