plantuml/plantuml

[Packetdiag] fix `rotate`, allow `same_height` optional, ...

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#2,530 opened on Feb 15, 2026

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Description

Context

To follow:

Wanted feature

Here is a wanted feature in order to:

  • fix rotate
  • center vertically/horizontally all labels
  • allow same_height optional (same_height = true)

to be conform with the original form:

Not working Example

@startpacketdiag
{
  colwidth = 32
  node_height = 72

  0-15: Source Port
  16-31: Destination Port
  32-63: Sequence Number
  64-95: Acknowledgment Number
  96-99: Data Offset
  100-105: Reserved
  106: URG [rotate = 270]
  107: ACK [rotate = 270]
  108: PSH [rotate = 270]
  109: RST [rotate = 270]
  110: SYN [rotate = 270]
  111: FIN [rotate = 270]
  112-127: Window
  128-143: Checksum
  144-159: Urgent Pointer
  160-191: (Options and Padding)
  192-223: data [colheight = 3]
}
@endpacketdiag

(FYI @kolulu23) Regards, Th.

Contributor guide

Research direction
Examine the packetdiag rendering code in PlantUML, focusing on label positioning and rotation. Fix the rotate functionality, implement center alignment, and add support for the optional 'same height' parameter.
Tech stack
java
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Java
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70