ScreenOverlay

ScreenOverlay refers to a graphical layer that is drawn on top of the main content on a screen. Overlay content can include user interface elements, alerts, captions, chat tools, or HUDs that remain visible while the user interacts with underlying applications. Overlays are common in media players, game tools, screen recording software, accessibility features, and augmented reality apps. They are usually implemented as a separate window or as a composited texture that renders after the underlying content, allowing the overlay to appear above other visuals without altering the underlying UI.

In Android, Screen Overlay is frequently used to describe the permission that allows an app to draw over other apps. The Draw over other apps or SYSTEM_ALERT_WINDOW permission enables features such as chat bubbles, screen dimming, or on-screen assistive tools. Overlays can interfere with security and usability by capturing touch input or masking important UI, so many platforms limit their use on sensitive screens (for example, when entering passwords). Users typically manage this capability in settings, often granting or revoking per-app access; newer versions emphasize explicit user consent and a clear purpose.

In other environments, screen overlays are implemented through layered windows or graphics APIs (such as DirectX, OpenGL, or platform-specific toolkits). They are used by streaming software, screen capture tools, game overlays, and accessibility aids. Performance considerations include rendering cost, input handling, and z-order management, while accessibility and usability concerns focus on visibility, contrast, and the potential to obscure critical content.

Common considerations for ScreenOverlay include ensuring non-intrusiveness, respecting user preferences, and balancing functionality with security and performance.