Implementation Notes

This chapter is written for developers working on the library itself. It provides technical background information about internal implementation details, code structure, and platform-specific behavior that are intentionally not part of the public API documentation.

Important

The pages in this chapter describe internal behavior and design decisions intended for contributors and maintainers. If you are using the library in an application, start with the usage guides and API reference instead.

We do our best to update implementation notes when the described implementation changes, nevertheless, please carefully validate against the actual implementation first, before doing any changes.

Windows Backend

Follow how the Windows console is initialized, how key input is processed, how the screen size is detected, and how termination state is restored.

Windows Backend
POSIX Backend

Explore the POSIX terminal setup, raw key input handling, TTY probing, and the pipe-based signal forwarding mechanism.

POSIX Backend
Action Scheduling

Follow how surface-local scheduled actions are stored, turned into events, delivered on the UI thread, and connected to dirty-driven rendering.

Action Scheduling
Invocation and Event Threads

Understand how generic invocation events move work onto the UI thread or a managed worker thread, and how cooperative shutdown is coordinated.

Invocation and Event Threads
UI Paint System

Follow how dirty surfaces become clipped paint calls, how opacity chooses the repaint base, and how overlapping siblings are composed in order.

UI Paint System
UI Scrollable Areas

Understand the scroll metric helpers, managed child containers, visibility filtering, viewports, scroll areas, and custom-painted scroll surfaces.

UI Scrollable Areas
Paragraph Layout and Painting

Trace how paragraphs are tokenized, wrapped into physical lines, and finally painted into terminal buffers.

Paragraph Layout and Painting
TextNodeRenderer

Follow how rich-text nodes are planned into linear render blocks, how list prefixes are attached, and how plain-string and terminal output diverge.

TextNodeRenderer
Remapped Buffer

Understand how remap tables, storage layout, and resize paths work together to keep row- and column-oriented edits efficient.

RemappedBuffer
String Sharing

Follow how String, StringView, shared backing storage, and copy-on-write detaches fit together.

String Sharing
Stack Layout

Follow how stack children receive their initial sizes, how free space is distributed, and how overflow is reduced in ordered shrink passes.

Stack Layout
Unicode Width System

Understand how the Unicode width table is generated, queried, and consistently applied during terminal layout.

Unicode Width System