draw/utils/lgc.c

#include <petscviewer.h>
#include <petsc/private/drawimpl.h> /*I   "petscdraw.h"  I*/
PetscClassId PETSC_DRAWLG_CLASSID = 0;

/*@
  PetscDrawLGGetAxis - Gets the axis context associated with a line graph.
  This is useful if one wants to change some axis property, such as
  labels, color, etc. The axis context should not be destroyed by the
  application code.

  Not Collective, if lg is parallel then axis is parallel

  Input Parameter:
. lg - the line graph context

  Output Parameter:
. axis - the axis context

  Level: advanced

.seealso: `PetscDrawLGCreate()`, `PetscDrawAxis`, `PetscDrawLG`
@*/
PetscErrorCode PetscDrawLGGetAxis(PetscDrawLG lg, PetscDrawAxis *axis)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  PetscAssertPointer(axis, 2);
  *axis = lg->axis;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGGetDraw - Gets the draw context associated with a line graph.

  Not Collective, if lg is parallel then draw is parallel

  Input Parameter:
. lg - the line graph context

  Output Parameter:
. draw - the draw context

  Level: intermediate

.seealso: `PetscDrawLGCreate()`, `PetscDraw`, `PetscDrawLG`
@*/
PetscErrorCode PetscDrawLGGetDraw(PetscDrawLG lg, PetscDraw *draw)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  PetscAssertPointer(draw, 2);
  *draw = lg->win;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGSPDraw - Redraws a line graph and a scatter plot on the same `PetscDraw` they must share

  Collective

  Input Parameters:
+ lg   - the line graph context
- spin - the scatter plot

  Level: intermediate

  Developer Notes:
  This code cheats and uses the fact that the `PetscDrawLG` and `PetscDrawSP` structs are the same

.seealso: `PetscDrawLGDraw()`, `PetscDrawSPDraw()`
@*/
PetscErrorCode PetscDrawLGSPDraw(PetscDrawLG lg, PetscDrawSP spin)
{
  PetscDrawLG sp = (PetscDrawLG)spin;
  PetscReal   xmin, xmax, ymin, ymax;
  PetscBool   isnull;
  PetscMPIInt rank;
  PetscDraw   draw;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  PetscValidHeaderSpecific(sp, PETSC_DRAWLG_CLASSID, 2);
  PetscCall(PetscDrawIsNull(lg->win, &isnull));
  if (isnull) PetscFunctionReturn(PETSC_SUCCESS);
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)lg), &rank));

  draw = lg->win;
  PetscCall(PetscDrawCheckResizedWindow(draw));
  PetscCall(PetscDrawClear(draw));

  xmin = PetscMin(lg->xmin, sp->xmin);
  ymin = PetscMin(lg->ymin, sp->ymin);
  xmax = PetscMax(lg->xmax, sp->xmax);
  ymax = PetscMax(lg->ymax, sp->ymax);
  PetscCall(PetscDrawAxisSetLimits(lg->axis, xmin, xmax, ymin, ymax));
  PetscCall(PetscDrawAxisDraw(lg->axis));

  PetscDrawCollectiveBegin(draw);
  if (rank == 0) {
    int i, j, dim, nopts;
    dim   = lg->dim;
    nopts = lg->nopts;
    for (i = 0; i < dim; i++) {
      for (j = 1; j < nopts; j++) {
        PetscCall(PetscDrawLine(draw, lg->x[(j - 1) * dim + i], lg->y[(j - 1) * dim + i], lg->x[j * dim + i], lg->y[j * dim + i], PETSC_DRAW_BLACK + i));
        if (lg->use_markers) PetscCall(PetscDrawMarker(draw, lg->x[j * dim + i], lg->y[j * dim + i], PETSC_DRAW_RED));
      }
    }
    dim   = sp->dim;
    nopts = sp->nopts;
    for (i = 0; i < dim; i++) {
      for (j = 0; j < nopts; j++) PetscCall(PetscDrawMarker(draw, sp->x[j * dim + i], sp->y[j * dim + i], PETSC_DRAW_RED));
    }
  }
  PetscDrawCollectiveEnd(draw);

  PetscCall(PetscDrawFlush(draw));
  PetscCall(PetscDrawPause(draw));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGCreate - Creates a line graph data structure.

  Collective

  Input Parameters:
+ draw - the window where the graph will be made.
- dim  - the number of curves which will be drawn

  Output Parameter:
. outlg - the line graph context

  Level: intermediate

  Notes:
  The MPI communicator that owns the `PetscDraw` owns this `PetscDrawLG`, but the calls to set options and add points are ignored on all processes except the
  zeroth MPI process in the communicator.

  All MPI ranks in the communicator must call `PetscDrawLGDraw()` to display the updated graph.

.seealso: `PetscDrawLGDestroy()`, `PetscDrawLGAddPoint()`, `PetscDrawLGAddCommonPoint()`, `PetscDrawLGAddPoints()`, `PetscDrawLGDraw()`, `PetscDrawLGSave()`,
          `PetscDrawLGView()`, `PetscDrawLGReset()`, `PetscDrawLGSetDimension()`, `PetscDrawLGGetDimension()`, `PetscDrawLGSetLegend()`, `PetscDrawLGGetAxis()`,
          `PetscDrawLGGetDraw()`, `PetscDrawLGSetUseMarkers()`, `PetscDrawLGSetLimits()`, `PetscDrawLGSetColors()`, `PetscDrawLGSetOptionsPrefix()`, `PetscDrawLGSetFromOptions()`
@*/
PetscErrorCode PetscDrawLGCreate(PetscDraw draw, PetscInt dim, PetscDrawLG *outlg)
{
  PetscDrawLG lg;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(draw, PETSC_DRAW_CLASSID, 1);
  PetscValidLogicalCollectiveInt(draw, dim, 2);
  PetscAssertPointer(outlg, 3);

  PetscCall(PetscHeaderCreate(lg, PETSC_DRAWLG_CLASSID, "DrawLG", "Line Graph", "Draw", PetscObjectComm((PetscObject)draw), PetscDrawLGDestroy, NULL));
  PetscCall(PetscDrawLGSetOptionsPrefix(lg, ((PetscObject)draw)->prefix));

  PetscCall(PetscObjectReference((PetscObject)draw));
  lg->win = draw;

  lg->view    = NULL;
  lg->destroy = NULL;
  lg->nopts   = 0;
  lg->xmin    = 1.e20;
  lg->ymin    = 1.e20;
  lg->xmax    = -1.e20;
  lg->ymax    = -1.e20;
  PetscCall(PetscCIntCast(dim, &lg->dim));
  PetscCall(PetscMalloc2(dim * PETSC_DRAW_LG_CHUNK_SIZE, &lg->x, dim * PETSC_DRAW_LG_CHUNK_SIZE, &lg->y));

  lg->len         = lg->dim * PETSC_DRAW_LG_CHUNK_SIZE;
  lg->loc         = 0;
  lg->use_markers = PETSC_FALSE;

  PetscCall(PetscDrawAxisCreate(draw, &lg->axis));

  *outlg = lg;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGSetColors - Sets the color of each line graph drawn

  Logically Collective

  Input Parameters:
+ lg     - the line graph context.
- colors - the colors, an array of length the value set with `PetscDrawLGSetDimension()`

  Level: intermediate

.seealso: `PetscDrawLG`, `PetscDrawLGCreate()`, `PetscDrawLGSetDimension()`, `PetscDrawLGGetDimension()`
@*/
PetscErrorCode PetscDrawLGSetColors(PetscDrawLG lg, const int colors[])
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  if (lg->dim) PetscAssertPointer(colors, 2);

  PetscCall(PetscFree(lg->colors));
  PetscCall(PetscMalloc1(lg->dim, &lg->colors));
  PetscCall(PetscArraycpy(lg->colors, colors, lg->dim));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
  PetscDrawLGSetLegend - sets the names of each curve plotted

  Logically Collective

  Input Parameters:
+ lg    - the line graph context.
- names - the names for each curve

  Level: intermediate

  Note:
  Call `PetscDrawLGGetAxis()` and then change properties of the `PetscDrawAxis` for detailed control of the plot

.seealso: `PetscDrawLGGetAxis()`, `PetscDrawAxis`, `PetscDrawAxisSetColors()`, `PetscDrawAxisSetLabels()`, `PetscDrawAxisSetHoldLimits()`
@*/
PetscErrorCode PetscDrawLGSetLegend(PetscDrawLG lg, const char *const names[])
{
  PetscInt i;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  if (names) PetscAssertPointer(names, 2);

  if (lg->legend) {
    for (i = 0; i < lg->dim; i++) PetscCall(PetscFree(lg->legend[i]));
    PetscCall(PetscFree(lg->legend));
  }
  if (names) {
    PetscCall(PetscMalloc1(lg->dim, &lg->legend));
    for (i = 0; i < lg->dim; i++) PetscCall(PetscStrallocpy(names[i], &lg->legend[i]));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGGetDimension - Get the number of curves that are to be drawn.

  Not Collective

  Input Parameter:
. lg - the line graph context.

  Output Parameter:
. dim - the number of curves.

  Level: intermediate

.seealso: `PetscDrawLGC`, `PetscDrawLGCreate()`, `PetscDrawLGSetDimension()`
@*/
PetscErrorCode PetscDrawLGGetDimension(PetscDrawLG lg, PetscInt *dim)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  PetscAssertPointer(dim, 2);
  *dim = lg->dim;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGSetDimension - Change the number of curves that are to be drawn.

  Logically Collective

  Input Parameters:
+ lg  - the line graph context.
- dim - the number of curves.

  Level: intermediate

.seealso: `PetscDrawLGCreate()`, `PetscDrawLGGetDimension()`
@*/
PetscErrorCode PetscDrawLGSetDimension(PetscDrawLG lg, PetscInt dim)
{
  PetscInt i;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  PetscValidLogicalCollectiveInt(lg, dim, 2);
  if (lg->dim == dim) PetscFunctionReturn(PETSC_SUCCESS);

  PetscCall(PetscFree2(lg->x, lg->y));
  if (lg->legend) {
    for (i = 0; i < lg->dim; i++) PetscCall(PetscFree(lg->legend[i]));
    PetscCall(PetscFree(lg->legend));
  }
  PetscCall(PetscFree(lg->colors));
  PetscCall(PetscCIntCast(dim, &lg->dim));
  PetscCall(PetscMalloc2(dim * PETSC_DRAW_LG_CHUNK_SIZE, &lg->x, dim * PETSC_DRAW_LG_CHUNK_SIZE, &lg->y));
  lg->len = lg->dim * PETSC_DRAW_LG_CHUNK_SIZE;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
  PetscDrawLGGetData - Get the data being plotted.

  Not Collective

  Input Parameter:
. lg - the line graph context

  Output Parameters:
+ dim - the number of curves
. n   - the number of points on each line
. x   - The x-value of each point, x[p * dim + c]
- y   - The y-value of each point, y[p * dim + c]

  Level: intermediate

.seealso: `PetscDrawLGC`, `PetscDrawLGCreate()`, `PetscDrawLGGetDimension()`
@*/
PetscErrorCode PetscDrawLGGetData(PetscDrawLG lg, PetscInt *dim, PetscInt *n, const PetscReal *x[], const PetscReal *y[])
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  if (dim) {
    PetscAssertPointer(dim, 2);
    *dim = lg->dim;
  }
  if (n) {
    PetscAssertPointer(n, 3);
    *n = lg->nopts;
  }
  if (x) {
    PetscAssertPointer(x, 4);
    *x = lg->x;
  }
  if (y) {
    PetscAssertPointer(y, 5);
    *y = lg->y;
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGSetLimits - Sets the axis limits for a line graph. If more
  points are added after this call, the limits will be adjusted to
  include those additional points.

  Logically Collective

  Input Parameters:
+ lg    - the line graph context
. x_min - the horizontal lower limit
. x_max - the horizontal upper limit
. y_min - the vertical lower limit
- y_max - the vertical upper limit

  Level: intermediate

.seealso: `PetscDrawLGCreate()`, `PetscDrawLG`, `PetscDrawAxis`
@*/
PetscErrorCode PetscDrawLGSetLimits(PetscDrawLG lg, PetscReal x_min, PetscReal x_max, PetscReal y_min, PetscReal y_max)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);

  (lg)->xmin = x_min;
  (lg)->xmax = x_max;
  (lg)->ymin = y_min;
  (lg)->ymax = y_max;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGReset - Clears line graph to allow for reuse with new data.

  Logically Collective

  Input Parameter:
. lg - the line graph context.

  Level: intermediate

.seealso: `PetscDrawLG`, `PetscDrawLGCreate()`
@*/
PetscErrorCode PetscDrawLGReset(PetscDrawLG lg)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  lg->xmin  = 1.e20;
  lg->ymin  = 1.e20;
  lg->xmax  = -1.e20;
  lg->ymax  = -1.e20;
  lg->loc   = 0;
  lg->nopts = 0;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGDestroy - Frees all space taken up by line graph data structure.

  Collective

  Input Parameter:
. lg - the line graph context

  Level: intermediate

.seealso: `PetscDrawLG`, `PetscDrawLGCreate()`
@*/
PetscErrorCode PetscDrawLGDestroy(PetscDrawLG *lg)
{
  PetscInt i;

  PetscFunctionBegin;
  if (!*lg) PetscFunctionReturn(PETSC_SUCCESS);
  PetscValidHeaderSpecific(*lg, PETSC_DRAWLG_CLASSID, 1);
  if (--((PetscObject)*lg)->refct > 0) {
    *lg = NULL;
    PetscFunctionReturn(PETSC_SUCCESS);
  }

  if ((*lg)->legend) {
    for (i = 0; i < (*lg)->dim; i++) PetscCall(PetscFree((*lg)->legend[i]));
    PetscCall(PetscFree((*lg)->legend));
  }
  PetscCall(PetscFree((*lg)->colors));
  PetscCall(PetscFree2((*lg)->x, (*lg)->y));
  PetscCall(PetscDrawAxisDestroy(&(*lg)->axis));
  PetscCall(PetscDrawDestroy(&(*lg)->win));
  PetscCall(PetscHeaderDestroy(lg));
  PetscFunctionReturn(PETSC_SUCCESS);
}
/*@
  PetscDrawLGSetUseMarkers - Causes the line graph object to draw a marker for each data-point.

  Logically Collective

  Input Parameters:
+ lg  - the linegraph context
- flg - should mark each data point

  Options Database Key:
. -lg_use_markers  <true,false> - true means it draws a marker for each point

  Level: intermediate

.seealso: `PetscDrawLG`, `PetscDrawLGCreate()`
@*/
PetscErrorCode PetscDrawLGSetUseMarkers(PetscDrawLG lg, PetscBool flg)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  PetscValidLogicalCollectiveBool(lg, flg, 2);
  lg->use_markers = flg;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGDraw - Redraws a line graph.

  Collective

  Input Parameter:
. lg - the line graph context

  Level: intermediate

.seealso: `PetscDrawLG`, `PetscDrawSPDraw()`, `PetscDrawLGSPDraw()`, `PetscDrawLGReset()`
@*/
PetscErrorCode PetscDrawLGDraw(PetscDrawLG lg)
{
  PetscReal   xmin, xmax, ymin, ymax;
  PetscMPIInt rank;
  PetscDraw   draw;
  PetscBool   isnull;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  PetscCall(PetscDrawIsNull(lg->win, &isnull));
  if (isnull) PetscFunctionReturn(PETSC_SUCCESS);
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)lg), &rank));

  draw = lg->win;
  PetscCall(PetscDrawCheckResizedWindow(draw));
  PetscCall(PetscDrawClear(draw));

  xmin = lg->xmin;
  xmax = lg->xmax;
  ymin = lg->ymin;
  ymax = lg->ymax;
  // Try not to freak out the axis
  if (ymax - ymin < PETSC_SMALL) {
    ymin -= 0.1 * ymax;
    ymax += 0.1 * ymax;
  }
  PetscCall(PetscDrawAxisSetLimits(lg->axis, xmin, xmax, ymin, ymax));
  PetscCall(PetscDrawAxisDraw(lg->axis));

  PetscDrawCollectiveBegin(draw);
  if (rank == 0) {
    int i, j, dim = lg->dim, nopts = lg->nopts, cl;
    for (i = 0; i < dim; i++) {
      for (j = 1; j < nopts; j++) {
        cl = lg->colors ? lg->colors[i] : ((PETSC_DRAW_BLACK + i) % PETSC_DRAW_MAXCOLOR);
        PetscCall(PetscDrawLine(draw, lg->x[(j - 1) * dim + i], lg->y[(j - 1) * dim + i], lg->x[j * dim + i], lg->y[j * dim + i], cl));
        if (lg->use_markers) PetscCall(PetscDrawMarker(draw, lg->x[j * dim + i], lg->y[j * dim + i], cl));
      }
    }
  }
  if (rank == 0 && lg->legend) {
    PetscBool right = PETSC_FALSE;
    int       i, dim = lg->dim, cl;
    PetscReal xl, yl, xr, yr, tw, th;
    size_t    slen, len = 0;

    PetscCall(PetscDrawAxisGetLimits(lg->axis, &xl, &xr, &yl, &yr));
    PetscCall(PetscDrawStringGetSize(draw, &tw, &th));
    for (i = 0; i < dim; i++) {
      PetscCall(PetscStrlen(lg->legend[i], &slen));
      len = PetscMax(len, slen);
    }
    if (right) {
      xr = xr - 1.5 * tw;
      xl = xr - ((PetscReal)len + 7) * tw;
    } else {
      xl = xl + 1.5 * tw;
      xr = xl + ((PetscReal)len + 7) * tw;
    }
    yr = yr - 1.0 * th;
    yl = yr - (dim + 1) * th;
    PetscCall(PetscDrawLine(draw, xl, yl, xr, yl, PETSC_DRAW_BLACK));
    PetscCall(PetscDrawLine(draw, xr, yl, xr, yr, PETSC_DRAW_BLACK));
    PetscCall(PetscDrawLine(draw, xr, yr, xl, yr, PETSC_DRAW_BLACK));
    PetscCall(PetscDrawLine(draw, xl, yr, xl, yl, PETSC_DRAW_BLACK));
    for (i = 0; i < dim; i++) {
      cl = lg->colors ? lg->colors[i] : (PETSC_DRAW_BLACK + i);
      PetscCall(PetscDrawLine(draw, xl + 1 * tw, yr - (i + 1) * th, xl + 5 * tw, yr - (i + 1) * th, cl));
      PetscCall(PetscDrawString(draw, xl + 6 * tw, yr - (i + 1.5) * th, PETSC_DRAW_BLACK, lg->legend[i]));
    }
  }
  PetscDrawCollectiveEnd(draw);

  PetscCall(PetscDrawFlush(draw));
  PetscCall(PetscDrawPause(draw));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGSave - Saves a drawn image

  Collective

  Input Parameter:
. lg - The line graph context

  Level: intermediate

.seealso: `PetscDrawLG`, `PetscDrawSave()`, `PetscDrawLGCreate()`, `PetscDrawLGGetDraw()`, `PetscDrawSetSave()`
@*/
PetscErrorCode PetscDrawLGSave(PetscDrawLG lg)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  PetscCall(PetscDrawSave(lg->win));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGView - Prints a line graph.

  Collective

  Input Parameters:
+ lg     - the line graph context
- viewer - the viewer to view it with

  Level: beginner

.seealso: `PetscDrawLG`, `PetscDrawLGCreate()`
@*/
PetscErrorCode PetscDrawLGView(PetscDrawLG lg, PetscViewer viewer)
{
  PetscReal xmin = lg->xmin, xmax = lg->xmax, ymin = lg->ymin, ymax = lg->ymax;
  PetscInt  i, j, dim = lg->dim, nopts = lg->nopts;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);

  if (nopts < 1) PetscFunctionReturn(PETSC_SUCCESS);
  if (xmin > xmax || ymin > ymax) PetscFunctionReturn(PETSC_SUCCESS);

  if (!viewer) PetscCall(PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)lg), &viewer));
  PetscCall(PetscObjectPrintClassNamePrefixType((PetscObject)lg, viewer));
  for (i = 0; i < dim; i++) {
    PetscCall(PetscViewerASCIIPrintf(viewer, "Line %" PetscInt_FMT ">\n", i));
    for (j = 0; j < nopts; j++) PetscCall(PetscViewerASCIIPrintf(viewer, "  X: %g Y: %g\n", (double)lg->x[j * dim + i], (double)lg->y[j * dim + i]));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGSetOptionsPrefix - Sets the prefix used for searching for all
  `PetscDrawLG` options in the database.

  Logically Collective

  Input Parameters:
+ lg     - the line graph context
- prefix - the prefix to prepend to all option names

  Level: advanced

.seealso: `PetscDrawLG`, `PetscDrawLGSetFromOptions()`, `PetscDrawLGCreate()`
@*/
PetscErrorCode PetscDrawLGSetOptionsPrefix(PetscDrawLG lg, const char prefix[])
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);
  PetscCall(PetscObjectSetOptionsPrefix((PetscObject)lg, prefix));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
  PetscDrawLGSetFromOptions - Sets options related to the line graph object

  Collective

  Input Parameters:
. lg - the line graph context

  Options Database Key:
. -lg_use_markers  <true,false> - true means it draws a marker for each point

  Level: intermediate

.seealso: `PetscDrawLG`, `PetscDrawLGDestroy()`, `PetscDrawLGCreate()`
@*/
PetscErrorCode PetscDrawLGSetFromOptions(PetscDrawLG lg)
{
  PetscBool           usemarkers, set;
  PetscDrawMarkerType markertype;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(lg, PETSC_DRAWLG_CLASSID, 1);

  PetscCall(PetscDrawGetMarkerType(lg->win, &markertype));
  PetscCall(PetscOptionsGetEnum(((PetscObject)lg)->options, ((PetscObject)lg)->prefix, "-lg_marker_type", PetscDrawMarkerTypes, (PetscEnum *)&markertype, &set));
  if (set) {
    PetscCall(PetscDrawLGSetUseMarkers(lg, PETSC_TRUE));
    PetscCall(PetscDrawSetMarkerType(lg->win, markertype));
  }
  usemarkers = lg->use_markers;
  PetscCall(PetscOptionsGetBool(((PetscObject)lg)->options, ((PetscObject)lg)->prefix, "-lg_use_markers", &usemarkers, &set));
  if (set) PetscCall(PetscDrawLGSetUseMarkers(lg, usemarkers));
  PetscFunctionReturn(PETSC_SUCCESS);
}