---
title: FxOnScreenControlAPI
framework: Professional Video Applications
role: symbol
role_heading: Protocol
platforms: [fxplug 3.1+]
path: professional_video_applications/fxonscreencontrolapi
---

# FxOnScreenControlAPI

The FxOnScreenControlAPI protocol defines the methods the host application uses to draw controls and other user interface elements directly on the canvas where the user has applied the plug-in.

## Declaration

```swift
protocol FxOnScreenControlAPI
```

## Mentioned in

Adding onscreen controls to plug-ins

## Overview

Overview Plug-ins use protocol to direct manipulation of the object and is an intuitive means for users to interact with a plug-in. Use this API to transform points from the drawing space of the canvas or document to the pixel space of the object the user wants to manipulate, and vice-versa.

## Topics

### Converting Points Between Coordinate Spaces

- [convertPoint(fromSpace:fromX:fromY:toSpace:toX:toY:)](professional_video_applications/fxonscreencontrolapi/convertpoint(fromspace:fromx:fromy:tospace:tox:toy:).md)

## Relationships

### Inherited By

- [FxOnScreenControlAPI_v2](professional_video_applications/fxonscreencontrolapi_v2.md)
- [FxOnScreenControlAPI_v3](professional_video_applications/fxonscreencontrolapi_v3.md)
- [FxOnScreenControlAPI_v4](professional_video_applications/fxonscreencontrolapi_v4.md)

## See Also

### Onscreen Control APIs

- [FxOnScreenControl_v4](professional_video_applications/fxonscreencontrol_v4.md)
- [FxOnScreenControlAPI_v2](professional_video_applications/fxonscreencontrolapi_v2.md)
- [FxOnScreenControlAPI_v3](professional_video_applications/fxonscreencontrolapi_v3.md)
- [FxOnScreenControlAPI_v4](professional_video_applications/fxonscreencontrolapi_v4.md)