2:  #include <petsc/private/viewerimpl.h>

  4: /*@
  5:    PetscViewerGetSubViewer - Creates a new PetscViewer (same type as the old)
  6:     that lives on a subcommunicator

  8:     Collective on PetscViewer

 10:    Input Parameter:
 11: .  viewer - the PetscViewer to be reproduced

 13:    Output Parameter:
 14: .  outviewer - new PetscViewer

 16:    Level: advanced

 18:    Notes: Call PetscViewerRestoreSubViewer() to return this PetscViewer, NOT PetscViewerDestroy()

 20:      This is most commonly used to view a sequential object that is part of a
 21:     parallel object. For example block Jacobi PC view could use this to obtain a
 22:     PetscViewer that is used with the sequential KSP on one block of the preconditioner.

 24:    Concepts: PetscViewer^sequential version

 26: .seealso: PetscViewerSocketOpen(), PetscViewerASCIIOpen(), PetscViewerDrawOpen(), PetscViewerRestoreSubViewer()
 27: @*/
 28: PetscErrorCode  PetscViewerGetSubViewer(PetscViewer viewer,MPI_Comm comm,PetscViewer *outviewer)
 29: {
 31:   PetscMPIInt    size;

 36:   MPI_Comm_size(PetscObjectComm((PetscObject)viewer),&size);
 37:   if (size == 1) {
 38:     PetscObjectReference((PetscObject)viewer);
 39:     *outviewer = viewer;
 40:   } else if (viewer->ops->getsubviewer) {
 41:     (*viewer->ops->getsubviewer)(viewer,comm,outviewer);
 42:   } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_SUP,"Cannot get SubViewer PetscViewer for type %s",((PetscObject)viewer)->type_name);
 43:   PetscViewerASCIIPushSynchronized(viewer);
 44:   return(0);
 45: }

 47: /*@
 48:    PetscViewerRestoreSubViewer - Restores a new PetscViewer obtained with PetscViewerGetSubViewer().

 50:     Collective on PetscViewer

 52:    Input Parameters:
 53: +  viewer - the PetscViewer that was reproduced
 54: -  outviewer - new PetscViewer

 56:    Level: advanced

 58:    Notes: Call PetscViewerGetSubViewer() to get this PetscViewer, NOT PetscViewerCreate()

 60: .seealso: PetscViewerSocketOpen(), PetscViewerASCIIOpen(), PetscViewerDrawOpen(), PetscViewerGetSubViewer()
 61: @*/
 62: PetscErrorCode  PetscViewerRestoreSubViewer(PetscViewer viewer,MPI_Comm comm,PetscViewer *outviewer)
 63: {
 65:   PetscMPIInt    size;


 70:   MPI_Comm_size(PetscObjectComm((PetscObject)viewer),&size);
 71:   if (size == 1) {
 72:     PetscObjectDereference((PetscObject)viewer);
 73:     if (outviewer) *outviewer = NULL;
 74:   } else if (viewer->ops->restoresubviewer) {
 75:     (*viewer->ops->restoresubviewer)(viewer,comm,outviewer);
 76:   }
 77:   PetscViewerASCIIPopSynchronized(viewer);
 78:   return(0);
 79: }