The Get Region of Definition Action

	#include "ofxImageEffect.h"
	#define kOfxImageEffectActionGetRegionOfDefinition        "OfxImageEffectActionGetRegionOfDefinition"

  • handle handle to the instance, cast to an OfxImageEffectHandle ,
  • inArgs has the following properties...
  • outArgs has the following property which the plug-in may set...


The region of definition for an image effect is the rectangular section of the 2D image plane that it is capable of filling, given the state of its input clips and parameters. This action is used to calculate the RoD for a plugin instance at a given frame. For more details on regions of definition see Image Effect Architectures .

Note that hosts that have constant sized imagery need not call this action, only hosts that allow image sizes to vary need call this.

Return Values

  • kOfxStatOK, , the action was trapped and the RoD was set in the outArgs property set
  • kOfxStatReplyDefault, the action was not trapped and the host should use the default values
  • kOfxStatErrMemory, in which case the action may be called again after a memory purge
  • kOfxStatFailed, something wrong, but no error code appropriate, plugin to post message
  • kOfxStatErrFatal

Default Action

If the effect did not trap this, it means the host should use the default RoD instead, which depends on the context. This is...

  • generator context - defaults to the project window,
  • filter and paint contexts - defaults to the RoD of the 'Source' input clip at the given time,
  • transition context - defaults to the union of the RoDs of the 'SourceFrom' and 'SourceTo' input clips at the given time,
  • general context - defaults to the union of the RoDs of all the non optional input clips and the 'Source' input clip (if it exists and it is connected) at the given time, if none exist, then it is the project window
  • retimer context - defaults to the union of the RoD of the 'Source' input clip at the frame directly preceding the value of the 'SourceTime' double parameter and the frame directly after it