---
source_files:
  - DTS Viewer/DTS.Viewer.Modules/DTS.Viewer.ViewerSettings/ViewModel/ViewerSettingsViewModel.cs
generated_at: "2026-04-16T13:49:48.286150+00:00"
model: "zai-org/GLM-5-FP8"
schema_version: 1
sha256: "f93455d3d5a535ba"
---

# Documentation: ViewerSettingsViewModel

## 1. Purpose

`ViewerSettingsViewModel` is a Prism-based view model for the Viewer Settings module within the DTS Viewer application. It manages user-configurable settings related to calibration behaviors, handles visibility states for settings UI elements, and coordinates with parent view models via event aggregation. The class serves as the binding context for `IViewerSettingsView` and participates in the application's region-based navigation system.

---

## 2. Public Interface

### Constructor

```csharp
public ViewerSettingsViewModel(
    IViewerSettingsView view, 
    IRegionManager regionManager, 
    IEventAggregator eventAggregator,
    IUnityContainer unityContainer)
```
Initializes the view model, sets the view's DataContext to itself, and creates `NotificationRequest` and `ConfirmationRequest` interaction requests.

### Methods

```csharp
public override void Initialize()
```
Empty override. No initialization logic performed.

```csharp
public override void Initialize(object parameter)
```
Sets `Parent` property from the provided parameter (cast to `IBaseViewModel`) and calls `Subscribe()` to register event handlers.

```csharp
public void PublishChanges()
```
Empty implementation. No behavior defined in source.

### Properties

| Property | Type | Description |
|----------|------|-------------|
| `View` | `IViewerSettingsView` | Gets/sets the associated view interface. |
| `Parent` | `IBaseViewModel` | Gets/sets the parent view model reference. |
| `NotificationRequest` | `InteractionRequest<Notification>` | Interaction request for notifications. |
| `ConfirmationRequest` | `InteractionRequest<Confirmation>` | Interaction request for confirmations (hides base member with `new`). |
| `HeaderInfo` | `string` | Returns constant string `"SettingsRegion"`. |
| `IsBusy` | `bool` | Gets/sets busy state (hides base member with `new`). |
| `IsDirty` | `bool` | Gets/sets dirty state (hides base member with `new`). |
| `IsNavigationIncluded` | `bool` | Gets/sets navigation inclusion flag (hides base member with `new`). |
| `CalibrationBehaviorSettingVisibility` | `Visibility` | Controls visibility of calibration behavior setting UI. Publishes `ViewerSettingsVisibilityChangedEvent` when changed. |
| `OverallSettingsVisibility` | `Visibility` | Computed property; returns `Visibility.Visible` if `CalibrationBehaviorSettingVisibility` is visible, otherwise `Visibility.Collapsed`. |
| `AvailableCalibrationBehaviors` | `DisplayedCalibrationBehavior[]` | Lazily-initialized, thread-safe array of three calibration behavior options: `_linearIfAvail`, `_nonLinearIfAvail`, `_useBothIfAvail`. |
| `CalibrationBehaviorSetting` | `DisplayedCalibrationBehavior` | Gets/sets the selected calibration behavior. Defaults to `CalibrationBehaviors.NonLinearIfAvailable`. Publishes `CalibrationBehaviorSettingChangedEvent` when changed. |

### Events

```csharp
public new event PropertyChangedEventHandler PropertyChanged
```
Hides base class event. Raised via `OnPropertyChanged(string)`.

---

## 3. Invariants

- **Default Calibration Behavior**: `_calibrationBehaviorSetting` is always initialized to `CalibrationBehaviors.NonLinearIfAvailable`.
- **OverallSettingsVisibility Dependency**: `OverallSettingsVisibility` is always `Visibility.Collapsed` when `CalibrationBehaviorSettingVisibility` is `Visibility.Collapsed`. It cannot be visible independently.
- **Thread Safety**: `AvailableCalibrationBehaviors` getter uses a lock (`MyLock`) to ensure thread-safe lazy initialization.
- **CalibrationBehaviorSetting Getter**: Always returns a matching `DisplayedCalibrationBehavior` from `AvailableCalibrationBehaviors` array, or `null` if no match found.
- **Event Subscription Timing**: Subscriptions occur only after `Initialize(object parameter)` is called, not in the constructor.

---

## 4. Dependencies

### External Dependencies (from imports)
- **Prism.Events** - `IEventAggregator` for pub/sub messaging
- **Prism.Regions** - `IRegionManager` for region-based navigation
- **Unity** - `IUnityContainer` for dependency injection
- **DTS.Common.Base** - `BaseViewModel<T>`, `IBaseViewModel`
- **DTS.Common.Classes.Sensors** - `DisplayedCalibrationBehavior`
- **DTS.Common.Enums.Sensors** - `CalibrationBehaviors` enum
- **DTS.Common.Events** - `CalibrationBehaviorSettingChangedEvent`, `CalibrationBehaviorSettableInViewerChangedEvent`, `ViewerSettingsVisibilityChangedEvent`
- **DTS.Common.Interactivity** - `InteractionRequest<T>`, `Notification`, `Confirmation`
- **DTS.Common.Interface** - `IViewerSettingsViewModel`
- **System.Windows** - `Visibility` enum

### Consumed Events
- `CalibrationBehaviorSettingChangedEvent` - payload: `CalibrationBehaviors`
- `CalibrationBehaviorSettableInViewerChangedEvent` - payload: `bool`

### Published Events
- `CalibrationBehaviorSettingChangedEvent` - published when `CalibrationBehaviorSetting` setter is invoked with a different value
- `ViewerSettingsVisibilityChangedEvent` - published when `CalibrationBehaviorSettingVisibility` is set

---

## 5. Gotchas

1. **Misleading XML Documentation**: The constructor's XML comment references `TestSummaryViewListModel`, which appears to be a copy-paste error from another class.

2. **Member Hiding with `new` Keyword**: Multiple members (`PropertyChanged`, `OnPropertyChanged`, `IsBusy`, `IsDirty`, `IsNavigationIncluded`, `ConfirmationRequest`) hide base class members using `new`. This breaks polymorphism—consumers casting to the base type will invoke base implementations, not these overrides.

3. **Empty `PublishChanges()` Method**: The method has no implementation. Its intended purpose is unclear from source alone.

4. **Cascading Visibility Notifications**: `OnPropertyChanged` has special logic—any property name ending with `"Visibility"` (except `"OverallSettingsVisibility"`) triggers an additional `OnPropertyChanged("OverallSettingsVisibility")` call. This side effect is not obvious from property setters alone.

5. **Potential Null Return**: `CalibrationBehaviorSetting` getter returns `null` if `_calibrationBehaviorSetting` does not match any item in `AvailableCalibrationBehaviors`. Callers should handle this possibility.

6. **No Unsubscribe Logic**: The class subscribes to events in `Subscribe()` but does not appear to unsubscribe. Potential memory leak if view model lifecycle is shorter than the event aggregator's.