ytLlive/ViewModels/index.md

# ViewModels — index

MVVM layer. See [`schema.md`](../schema.md) for the memory-map conventions.

| File | Purpose |
|------|---------|
| `MainViewModel.cs` | The app brain: scenes/elements collections + commands, stream state (`IsLive`/`IsOffline`/`IsConnected`), chat feed, overlays, layout save/open, **resolution dropdown** (`QualityOptions`, `SelectedQuality`, `ResolutionHelp`, `ApplyStreamQuality`) that computes the output rect over the 1920×1080 master (`OutputRectX/Y/W/H`, `DimRects`, `IsOutputCropped`, `ResolutionBadgeText`). Auth: loads the saved DPAPI session at startup (`LoadSavedSessionAsync`), `SignInAsync` feeds the GoLive dialog; **End Livestream signs out** (`StopStream` clears session + token — crash-safe). **Connected account:** top-bar avatar/name (`AccountAvatarUrl`/`AccountDisplayName` via `SyncConnectedAccount`, cleared on End). **Audio (KISS — the mic is the creator's only audio control; capture pipeline still pending):** the sound meter is a **READ-ONLY realtime level display**: fill = `Math.Min(1, AudioLevel * MicVolume)` (`MeterFillWidth`/`MeterBrush`, green→yellow→red, zone markers at 60%/80%), where `AudioLevel` (live input, 0 with no input) is fed by the audio mixer once capture lands and `MicVolume` acts as a gain on ambient noise; while the slider is dragged the bar previews the slider position (`SetVolumeAdjusting`), returning to the live level on release (0 with no input — clicking the meter does nothing); `MicVolume` (default 0.8) + read-only `MicMuted`/`MicMuteText`/`ToggleMicMuteCommand` — **MicVolume drives MicMuted** (muted ⇔ volume 0): sliding to 0 flips the speaker to muted, sliding up from 0 clears it; muting stores the prior volume, unmuting restores it (default 0.8 if unknown) and flashes the meter to the restored position ~300ms (`BeginVolumeFlash`/`EndVolumeFlash`); `MicSourceName` = picked voice source, shown left-justified inside the meter bar (the fill runs at 75% opacity so the text + ruler markings show through); `OpenMicPickerCommand`/`PickMicrophone()` open the `MicPickerDialog`; desktop/game audio is automatic (WASAPI loopback at unity, zero UI). **Webcam:** owns `CameraManager` (MediaCapture), `AddWebcamToActiveSceneAsync` (picker → default 480×270 bottom-right placement → acquire; the Windows camera picker ALWAYS opens so the creator chooses — never silently reuses the previous camera; picking a different camera swaps the app-wide identity via `SwapWebcamIdentityAsync`, same path as `ChangeWebcamAsync`; propagates the running shared bitmap via `CameraManager.GetPreviewBitmap` first, so a webcam added mid-session never renders a transparent container; greys out when the active scene already has a config via `CanAddWebcamToActiveScene`), `ChangeWebcamAsync` (device swap — `ReleaseAllAsync` old + re-acquire), `ShowWebcamInActiveScene` (reveal hidden config / empty-canvas right-click), `ReacquireWebcam` after layout load (re-propagates the shared bitmap to every config), `OnCameraPreviewBitmapChanged` forwards the shared bitmap into every `WebcamSceneConfig.VideoImageSource`; `SelectedElement` drives the preview overlay + `internal ClampWebcamToBounds(config, sceneName)` (per-scene size cap seam: 50%-per-dimension everywhere, half-screen-AREA in Chat via `MaxWebcamWidthFor`/`MaxWebcamHeightFor`). **Scenes (five-scene catalog):** empty DB seeds Starting/Live/BRB/Chat/Ending (`SceneCatalog.All`); `AddScene(name)` accepts only canonical, missing names; `MissingScenes`/`ShowAddScene` drive the "+" button (hidden once all five exist; its menu lists only the missing scenes via `AddSceneCommand`). **Screen backdrop (Live-only by policy):** owns `ScreenCaptureManager` + `ScreenCaptureSourceFactory` (WinRT GraphicsCapture), `internal static EnsureBackdrop` heals one per backdrop-enabled scene (gated on `Scene.HasBackdrop`), `ReacquireScreenCaptures`/`RefreshBackdropAutoCapture`/`NoteBackgroundWindow` key by full-screen game monitor or the **primary display** via `Win32FullScreenDetector` (`GetDisplays()`/`PrimaryMonitorIndex()`), `ChangeBackdropCaptureAsync` (OS picker) + `SetBackdropCapture(DisplayInfo)` (in-app "Capture Display"), `RedesignateBackdropAsync` re-targets all backdrops and releases orphaned sessions, `internal static EnforceBackdropPolicy` normalizes `Scene.HasBackdrop` by name on every load + strips lingering non-Live backdrops, `CanChangeBackdrop` gates the capture menu to Live (the only scene with a backdrop), `BackdropImage` hides the preview watermark (`ShowPreviewPlaceholder`) |
| `GoLiveViewModel.cs` | Start Stream dialog: **account row** (saved channel shown with Change Account, or Sign in to YouTube; Start gated on `IsSignedIn`/`IsBusy`) + title/description/visibility, start/cancel requests |
| `ReuseImageViewModel.cs` | Add Image dialog: candidate list (`ReuseImageCandidate`), reuse/new/cancel |
| `CameraPickerViewModel.cs` | Add Webcam dialog: async camera list (loading / has / none states), `UseRequested(CameraDeviceInfo)`/`CancelRequested` |
| `MicPickerViewModel.cs` | Select Microphone dialog (voice source): async mic list (loading / has / none states), `UseRequested(MicrophoneDeviceInfo)`/`CancelRequested` |
| `SocialsDialogViewModel.cs` | Social Media Site Promotion dialog (six fixed slots, `SocialSlotViewModel`): row 0 = YouTube sign-in gate (sign-in provider fills the channel, delete = sign-out); rows 1-5 validated entries / empty / freemium locks 2-5 (`isPremium` seam); `DetectService` → `ISocialValidator` on confirm (input snaps to text + real logo on success, red do-not + stays editable on failure); `CanSave` blocked while any slot edits/validates/errors; `BarEnabled` switch; commit via `CommittedEntries` + `BuildSocialsConfig()` (YouTube first) + `SaveRequested`/`CancelRequested`. WPF-free — the window owns the dialogs (delete confirm, sign-in gate) and calls `StartEdit`/`ConfirmEdit`/`DeleteSlotAsync`. |

Related: [`Models/index.md`](../Models/index.md) for the data; [`Services/index.md`](../Services/index.md)
for what the ViewModels drive; base class in [`Helpers/ViewModelBase.cs`](../Helpers/ViewModelBase.cs).