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  3. FFrameGrabber

FFrameGrabber

Class responsible for resolving render target data for a specific viewport in an efficient manner Internally, the class uses a fixed array of resolution surfaces, and dispatches rendering commands to resolve the viewport render target into a specific index into this array.

API > API/Runtime > API/Runtime/MovieSceneCapture

Class responsible for resolving render target data for a specific viewport in an efficient manner Internally, the class uses a fixed array of resolution surfaces, and dispatches rendering commands to resolve the viewport render target into a specific index into this array. This means we can resolve the render target data without having to wait, or flush rendering commands.

   
Name FFrameGrabber
Type class
Header File /Engine/Source/Runtime/MovieSceneCapture/Public/FrameGrabber.h
Include Path #include "FrameGrabber.h"

Syntax

class FFrameGrabber

Constructors

Name Remarks Include Path Unreal Specifiers
Non-copyable FrameGrabber.h  

FFrameGrabber ( TSharedRef< FSceneViewport > Viewport,
FIntPoint DesiredBufferSize,
EPixelFormat InPixelFormat,
uint32 NumSurfaces
)

 Construct this frame grabber FrameGrabber.h  

Destructors

Name Remarks Include Path Unreal Specifiers

~FFrameGrabber()

 Destructor FrameGrabber.h  

Structs

Name Remarks
FResolveSurface Array of surfaces that we resolve the viewport RHI to. Fixed allocation - should never be resized

Variables

Protected

Name Type Remarks Include Path Unreal Specifiers
CapturedFrames TArray< FCapturedFrameData > Array of captured frames FrameGrabber.h  
CapturedFramesMutex FCriticalSection Lock to protect the above array FrameGrabber.h  
CurrentFrameIndex int32 Index into the above array to the next surface that we should use - only accessed on main thread FrameGrabber.h  
FrameGrabLatency int32   FrameGrabber.h  
OnBackBufferReadyToPresent FDelegateHandle Delegate handle for the OnBackBufferReadyToPresent event FrameGrabber.h  
OutstandingFrameCount FThreadSafeCounter The total number of frames we are currently waiting on FrameGrabber.h  
RenderThread_PendingFramePayloads TArray< FFramePayloadPtr > Only to be accessed from the render thread - array of frame payloads to be captured from the rendered slate window sorted first to last. FrameGrabber.h  
SlateRenderIndex int32 The index that we should capture the next rendered slate window into FrameGrabber.h  
State EFrameGrabberState   FrameGrabber.h  
Surfaces TArray< FResolveSurface >   FrameGrabber.h  
TargetSize FIntPoint The desired target size to resolve frames to FrameGrabber.h  
TargetWindowPtr void * Pointer to the window we want to capture. FrameGrabber.h  

Functions

Public

Name Remarks Include Path Unreal Specifiers

void CaptureThisFrame ( FFramePayloadPtr Payload
)

 Instruct the frame grabber capture this frame, when it receives an event from slate FrameGrabber.h  

TArray< FCapturedFrameData > GetCapturedFrames()

 Retrieve any frames we may have captured FrameGrabber.h  

bool HasOutstandingFrames()

 Check whether we have any outstanding frames or not FrameGrabber.h  

bool IsCapturingFrames()

 Check whether we're capturing frames or not FrameGrabber.h  

void Shutdown()

 Shut down this grabber, ensuring that any threaded operations are finished FrameGrabber.h  

void StartCapturingFrames()

 Instruct the frame grabber to start capturing frames FrameGrabber.h  

void StopCapturingFrames()

 Stop capturing frames FrameGrabber.h  

Protected

Name Remarks Include Path Unreal Specifiers

void OnBackBufferReadyToPresentCallback ( SWindow& SlateWindow,
const FTextureRHIRef& BackBuffer
)

 Callback for when a backbuffer is ready for reading (called on render thread) FrameGrabber.h  

void OnFrameReady ( int32 SurfaceIndex,
FColor* ColorBuffer,
int32 Width,
int32 Height
)

 Called when the specified surface index has been locked for reading with the render target data (called on render thread) FrameGrabber.h  

Operators

Name Remarks Include Path Unreal Specifiers

FFrameGrabber & operator= ( const FFrameGrabber&
)

   FrameGrabber.h  

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