Window System

OSSIM's window system provides a fully interactive desktop window experience including drag, resize, minimize, maximize, snap, tabbed hosting, and animated transitions.

Window Lifecycle

Spawning

Windows are created via WindowManager::SpawnWindow(ChromeClass, Params). Each window receives:

• A unique FGuid window ID
• Cascade positioning: Default position (100,100) offset by 30px × (CascadeIndex mod 10) to prevent window stacking.
• Z-order assignment via GetNextZOrder().

States (EWindowState)

• Normal: Standard draggable/resizable window.
• Minimized: Window hidden from view, icon remains in taskbar.
• Maximized: Window fills the desktop work area.

Controls

• Close: Terminates the associated process via ProcessManager::TerminateProcess.
• Minimize: Hides the window with a scale/fade animation.
• Maximize: Expands to fill the desktop work area, hides taskbar overlay.
• Snap: Snap to half/full via WindowManager::SnapWindow.

Window Widget (UWindowWidget)

Bind Points (all optional)

Interaction

• Drag: Click and drag the title bar.
• Resize: 8 directional edges/corners (EResizeDirection).
• Focus: Click anywhere on the window to bring to front.
• Double-click title: Toggle maximize.
• Min/Max size constraints: MinSize=(200,150), MaxSize=(3840,2160).

Tabbed Hosting

Windows support hosting multiple app instances in tabs:

• SupportsTabbedApps — Whether the window supports tabs.
• AddHostedTab(App, Content, Title) — Add a new tab.
• OpenAppInNewTab(AppClass) — Launch a new app instance in a tab.
• SwitchToHostedTab(ByPID) — Activate a specific tab.
• CloseHostedTab(ByPID) — Close a tab and terminate its process.
• RefreshHostedTabsUI() — Rebuild the tab bar.
• TerminateHostedApps() — Close all hosted tabs.

Tab Button Widget: UTabButtonWidget with bind points for MainTabButton, TabText, CloseButton.

Animations

Window transitions use FWidgetTransitionController:

enum EWidgetTransitionState { Hidden, Entering, Visible, Exiting }

FWidgetTransitionStyle defaults:

• Enter: 0.25s duration, ease exponent 3.0
• Exit: 0.2s duration, ease exponent 2.5
• Scale: Hidden=(0.95,0.95) → Visible=(1,1)
• Opacity: Hidden=0 → Visible=1

Window-Specific Animations

• AnimateMinimize / AnimateRestore — Lerp to target position/size via Tick (AnimSpeed=20).

Window Container

UWindowContainerWidget hosts all windows on a UCanvasPanel. It subscribes to WindowManager::OnWindowOpened to add new windows to the canvas.

Taskbar Integration

The UTaskbarWidget maintains:

• AppIconGroupMap<FString, UAppIconWidget*> — Groups windows by app.
• WindowToGroupMap<FGuid, FString> — Maps window IDs to app groups.
• MaximizedWindowIds: TSet — Tracks maximized windows to auto-hide the taskbar overlay.

Window Group Flyout

When an app has multiple windows, clicking its taskbar icon opens SWindowGroupFlyout — a Slate popup showing mock window chrome tiles with close buttons and live icon thumbnails.