CVDisplayLink Reference

Overview

A Core Video display link provides a separate high-priority thread to notify your application when a given display will need each frame. You can use a display link to easily synchronize with the refresh rate of a display. The display link API uses the Core Foundation class system internally to provide reference counting behavior and other useful properties.

Functions

CVDisplayLinkCreateWithActiveCGDisplays

Creates a display link capable of being used with all active displays.

CVReturn CVDisplayLinkCreateWithActiveCGDisplays (
   CVDisplayLinkRef *displayLinkOut
);

CVDisplayLinkCreateWithCGDisplay

Creates a display link for a single display.

CVReturn CVDisplayLinkCreateWithCGDisplay (
   CGDirectDisplayID displayID,
   CVDisplayLinkRef *displayLinkOut
);

CVDisplayLinkCreateWithCGDisplays

Creates a display link for an array of displays.

CVReturn CVDisplayLinkCreateWithCGDisplays (
   CGDirectDisplayID *displayArray,
   CFIndex count,
   CVDisplayLinkRef *displayLinkOut
);

CVDisplayLinkCreateWithOpenGLDisplayMask

Creates a display link from an OpenGL display mask.

CVReturn CVDisplayLinkCreateWithOpenGLDisplayMask (
   CGOpenGLDisplayMask mask,
   CVDisplayLinkRef *displayLinkOut
);

CVDisplayLinkGetActualOutputVideoRefreshPeriod

Retrieves the actual output refresh period of a display as measured by the host time base.

double CVDisplayLinkGetActualOutputVideoRefreshPeriod (
   CVDisplayLinkRef displayLink
);

CVDisplayLinkGetCurrentCGDisplay

Gets the current display associated with a display link.

CGDirectDisplayID CVDisplayLinkGetCurrentCGDisplay (
   CVDisplayLinkRef displayLink
);

CVDisplayLinkGetCurrentTime

Retrieves the current (“now”) time of a given display link.

CVReturn CVDisplayLinkGetCurrentTime (
   CVDisplayLinkRef displayLink,
   CVTimeStamp *outTime
);

CVDisplayLinkGetNominalOutputVideoRefreshPeriod

Retrieves the nominal refresh period of a display link.

CVTime CVDisplayLinkGetNominalOutputVideoRefreshPeriod (
   CVDisplayLinkRef displayLink
);

CVDisplayLinkGetOutputVideoLatency

Retrieves the nominal latency of a display link.

CVTime CVDisplayLinkGetOutputVideoLatency (
   CVDisplayLinkRef displayLink
);

CVDisplayLinkGetTypeID

Obtains the Core Foundation ID for the display link data type.

CFTypeID CVDisplayLinkGetTypeID (
   void
);

CVDisplayLinkIsRunning

Indicates whether a given display link is running.

Boolean CVDisplayLinkIsRunning (
   CVDisplayLinkRef displayLink
);

CVDisplayLinkRelease

Releases a display link.

void CVDisplayLinkRelease (
   CVDisplayLinkRef displayLink
);

CVDisplayLinkRetain

Retains a display link.

CVDisplayLinkRef CVDisplayLinkRetain (
   CVDisplayLinkRef displayLink
);

CVDisplayLinkSetCurrentCGDisplay

Sets the current display of a display link.

CVReturn CVDisplayLinkSetCurrentCGDisplay (
   CVDisplayLinkRef displayLink,
   CGDirectDisplayID displayID
);

CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext

Selects the display link most optimal for the current renderer of an OpenGL context.

CVReturn CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext (
   CVDisplayLinkRef displayLink,
   CGLContextObj cglContext,
   CGLPixelFormatObj cglPixelFormat
);

CVDisplayLinkSetOutputCallback

Sets the renderer output callback function.

CVReturn CVDisplayLinkSetOutputCallback (
   CVDisplayLinkRef displayLink,
   CVDisplayLinkOutputCallback callback,
   void *userInfo
);

CVDisplayLinkStart

Activates a display link.

CVReturn CVDisplayLinkStart (
   CVDisplayLinkRef displayLink
);

CVDisplayLinkStop

Stops a display link.

CVReturn CVDisplayLinkStop (
   CVDisplayLinkRef displayLink
);

CVDisplayLinkTranslateTime

Translates the time in the display link’s time base from one representation to another.

CVReturn CVDisplayLinkTranslateTime (
   CVDisplayLinkRef displayLink,
   const CVTimeStamp *inTime,
   CVTimeStamp *outTime
);

Callbacks

CVDisplayLinkOutputCallback

Defines a pointer to a display link output callback function, which is called whenever the display link wants the application to output a frame.

typedef CVReturn (*CVDisplayLinkOutputCallback)(
   CVDisplayLinkRef displayLink,
   const CVTimeStamp *inNow,
   const CVTimeStamp *inOutputTime,
   CVOptionFlags flagsIn,
   CVOptionFlags *flagsOut,
   void *displayLinkContext
   );

You would declare a display link output callback function named MyDisplayLinkCallback like this:

CVReturn MyDisplayLinkCallback (
   CVDisplayLinkRef displayLink,
   const CVTimeStamp *inNow,
   const CVTimeStamp *inOutputTime,
   CVOptionFlags flagsIn,
   CVOptionFlags *flagsOut,
   void *displayLinkContext
   );

Data Types

CVDisplayLinkRef

A reference to a display link object.

typedef struct __CVDisplayLink *CVDisplayLinkRef;

CVOptionFlags

The flags to be used for the display link output callback function.

typedef uint64_t CVOptionFlags;