static char help[] = "Demonstrates use of color map\n";

#include <petscsys.h>
#include <petscdraw.h>

int main(int argc, char **argv)
{
  PetscDraw   draw;
  PetscMPIInt size, rank;
  int         x = 0, y = 0, width = 256, height = 256, i;

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &argv, NULL, help));
  PetscCall(PetscDrawCreate(PETSC_COMM_WORLD, 0, "Title", x, y, width, height, &draw));
  PetscCall(PetscDrawSetFromOptions(draw));
  PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  for (i = rank; i < height; i += size) {
    PetscReal y = ((PetscReal)i) / (height - 1);
    PetscCall(PetscDrawLine(draw, 0.0, y, 1.0, y, i % 256));
  }
  PetscCall(PetscDrawFlush(draw));
  PetscCall(PetscDrawPause(draw));
  PetscCall(PetscDrawSave(draw));
  PetscCall(PetscDrawDestroy(&draw));
  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   build:
     requires: x

   test:
     output_file: output/empty.out

TEST*/