Selection → Visualization Flow

Overview

Selecting an item in the project tree triggers a chain of typed events that ultimately renders a plot in the Plot1DView widget. The chain is fully decoupled: no layer holds a direct reference to any other layer; each component publishes an event and relies on the EventBroker singleton to deliver it to the next stage.

Two variants exist depending on what was selected:

• RawScan selected — scan data must be converted into a plottable form before rendering (full chain)

• Plot selected — a pre-built plot object is retrieved directly and forwarded to the renderer, skipping the conversion step

Participants

Five components take part, each with a single responsibility:

• Project tree — translates user interaction into a generic selection event

• Load presenter — collects the selected identifiers and publishes a focus event

• Project model — resolves each identifier to a typed domain object and re-publishes a type-specific event

• Plot model — converts raw scan domain objects into renderable plot objects and re-publishes for the renderer (RawScan path only)

• Plotter presenter + view — clears the canvas and renders each plot object

RawScan Selection — Full Chain

        sequenceDiagram
    participant User
    participant TreeViewWidget
    participant LoadRawScanPresenter
    participant EventBroker
    participant TaviProjectModel
    participant PlotModel
    participant PlotterPresenter
    participant Plot1DView

    User ->> TreeViewWidget: clicks scan node
    TreeViewWidget ->> LoadRawScanPresenter: selection signal (Qt)
    LoadRawScanPresenter ->> LoadRawScanPresenter: collect selected identifiers
    LoadRawScanPresenter ->> EventBroker: publish focus event

    EventBroker ->> TaviProjectModel: handle focus event
    TaviProjectModel ->> TaviProjectModel: resolve identifiers → RawScan objects
    TaviProjectModel ->> EventBroker: publish raw-scan focus event

    EventBroker ->> PlotModel: handle raw-scan focus event
    PlotModel ->> PlotModel: extract axes data from scan
    PlotModel ->> PlotModel: build plot objects
    PlotModel ->> EventBroker: publish plot focus event

    EventBroker ->> PlotterPresenter: handle plot focus event
    PlotterPresenter ->> Plot1DView: clear canvas
    loop for each plot object
        PlotterPresenter ->> Plot1DView: append plot
    end
    Plot1DView ->> Plot1DView: redraw canvas
    

Plot Selection — Short-Circuit Chain

When the selected identifier resolves to a pre-built plot object, TaviProjectModel publishes the plot focus event directly. PlotModel is never invoked.

        sequenceDiagram
    participant User
    participant TreeViewWidget
    participant LoadRawScanPresenter
    participant EventBroker
    participant TaviProjectModel
    participant PlotterPresenter
    participant Plot1DView

    User ->> TreeViewWidget: clicks plot node
    TreeViewWidget ->> LoadRawScanPresenter: selection signal (Qt)
    LoadRawScanPresenter ->> EventBroker: publish focus event

    EventBroker ->> TaviProjectModel: handle focus event
    TaviProjectModel ->> TaviProjectModel: resolve identifiers → Plot objects
    TaviProjectModel ->> EventBroker: publish plot focus event

    EventBroker ->> PlotterPresenter: handle plot focus event
    PlotterPresenter ->> Plot1DView: clear canvas
    PlotterPresenter ->> Plot1DView: append plot
    Plot1DView ->> Plot1DView: redraw canvas
    

Key Design Decisions

Typed event routing in the project model

The project model dispatches to different downstream events based on the runtime type of each resolved object. This keeps the upstream trigger generic — the caller does not need to know whether it selected a scan or a plot — while allowing downstream consumers to specialize.

PlotModel as an adapter

PlotModel exists to convert raw scan domain objects into plot view-model objects. This keeps rendering concerns out of both the domain model and the view layer.

Clear-before-append semantics

The plotter presenter always clears the canvas before appending. Every plot focus event represents a replacement, not an addition. Overplot behaviour (accumulating multiple series on the same axes) requires a separate code path.

Mixed selection limitation

If a user selects both scan and plot identifiers simultaneously, the project model publishes both a raw-scan focus event and a plot focus event. Because the plot model reacts to the raw-scan event by publishing another plot focus event, the plotter presenter receives two plot focus events in sequence and clears the canvas between them. Only the final group survives — a known consequence of the clear-before-append design.