devtools_app 2.9.4

Published Aug 12, 2025

Web-based performance tooling for Dart and Flutter.

Timeline Code Architecture

View

The view has no awareness of the timeline data directly. It has access to the timeline data (frames, selected event, selected frame, cpu profile, etc.) through the TimelineController. The view receives updates from the TimelineController via streams.

Model

TimelineData stores the current data for the DevTools timeline. Its main components include frames, selectedFrame, selectedEvent, cpuProfileData, and traceEvents. This data is maintained by TimelineController.

Controller

The controller manages TimelineData and communicates with the view to give and receive data updates. It manages data processing via protocols TimelineProtocol (protocol for processing trace events and composing them into TimelineEvents and TimelineFrames) and CpuProfileProtocol (protocol for processing CpuProfileData and composing it into a structured tree of CpuStackFrames). The controller also communicates with TimelineService, which manages interactions between the Timeline and the VmService. TimelineController has no dependency on dart:html, making it easily testable.