xref: /petsc/src/sys/classes/draw/impls/image/drawimage.c (revision 4dfa11a44d5adf2389f1d3acbc8f3c1116dc6c3a)

#include <../src/sys/classes/draw/impls/image/drawimage.h> /*I  "petscdraw.h" I*/
#include <petsc/private/drawimpl.h>                        /*I  "petscdraw.h" I*/

#if defined(PETSC_USE_DEBUG)
#define PetscDrawValidColor(color) PetscCheck((color) >= 0 && (color) < 256, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Color value %" PetscInt_FMT " out of range [0..255]", (PetscInt)(color))
#else
#define PetscDrawValidColor(color) \
  do { \
  } while (0)
#endif

#define XTRANS(draw, img, x) ((int)(((img)->w - 1) * ((draw)->port_xl + ((((x) - (draw)->coor_xl) * ((draw)->port_xr - (draw)->port_xl)) / ((draw)->coor_xr - (draw)->coor_xl)))))
#define YTRANS(draw, img, y) (((img)->h - 1) - (int)(((img)->h - 1) * ((draw)->port_yl + ((((y) - (draw)->coor_yl) * ((draw)->port_yr - (draw)->port_yl)) / ((draw)->coor_yr - (draw)->coor_yl)))))

#define ITRANS(draw, img, i) ((draw)->coor_xl + (((PetscReal)(i)) * ((draw)->coor_xr - (draw)->coor_xl) / ((img)->w - 1) - (draw)->port_xl) / ((draw)->port_xr - (draw)->port_xl))
#define JTRANS(draw, img, j) ((draw)->coor_yl + (((PetscReal)(j)) / ((img)->h - 1) + (draw)->port_yl - 1) * ((draw)->coor_yr - (draw)->coor_yl) / ((draw)->port_yl - (draw)->port_yr))

static PetscErrorCode PetscDrawSetViewport_Image(PetscDraw draw, PetscReal xl, PetscReal yl, PetscReal xr, PetscReal yr) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  {
    int xmax = img->w - 1, ymax = img->h - 1;
    int xa = (int)(xl * xmax), ya = ymax - (int)(yr * ymax);
    int xb = (int)(xr * xmax), yb = ymax - (int)(yl * ymax);
    PetscImageSetClip(img, xa, ya, xb + 1 - xa, yb + 1 - ya);
  }
  PetscFunctionReturn(0);
}

/*
static PetscErrorCode PetscDrawSetCoordinates_Image(PetscDraw draw,PetscReal xl,PetscReal yl,PetscReal xr,PetscReal yr)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawSetCoordinates_Image NULL

static PetscErrorCode PetscDrawCoordinateToPixel_Image(PetscDraw draw, PetscReal x, PetscReal y, int *i, int *j) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  if (i) *i = XTRANS(draw, img, x);
  if (j) *j = YTRANS(draw, img, y);
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawPixelToCoordinate_Image(PetscDraw draw, int i, int j, PetscReal *x, PetscReal *y) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  if (x) *x = ITRANS(draw, img, i);
  if (y) *y = JTRANS(draw, img, j);
  PetscFunctionReturn(0);
}

/*
static PetscErrorCode PetscDrawPointSetSize_Image(PetscDraw draw,PetscReal width)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawPointSetSize_Image NULL

static PetscErrorCode PetscDrawPoint_Image(PetscDraw draw, PetscReal x, PetscReal y, int c) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  PetscDrawValidColor(c);
  {
    int j, xx = XTRANS(draw, img, x);
    int i, yy = YTRANS(draw, img, y);
    for (i = -1; i <= 1; i++)
      for (j = -1; j <= 1; j++) PetscImageDrawPixel(img, xx + j, yy + i, c);
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawPointPixel_Image(PetscDraw draw, int x, int y, int c) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  PetscDrawValidColor(c);
  { PetscImageDrawPixel(img, x, y, c); }
  PetscFunctionReturn(0);
}

/*
static PetscErrorCode PetscDrawLineSetWidth_Image(PetscDraw draw,PetscReal width)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawLineSetWidth_Image NULL

static PetscErrorCode PetscDrawLineGetWidth_Image(PetscDraw draw, PetscReal *width) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  {
    int lw = 1;
    *width = lw * (draw->coor_xr - draw->coor_xl) / (img->w * (draw->port_xr - draw->port_xl));
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawLine_Image(PetscDraw draw, PetscReal xl, PetscReal yl, PetscReal xr, PetscReal yr, int c) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  {
    int x_1 = XTRANS(draw, img, xl), x_2 = XTRANS(draw, img, xr);
    int y_1 = YTRANS(draw, img, yl), y_2 = YTRANS(draw, img, yr);
    PetscImageDrawLine(img, x_1, y_1, x_2, y_2, c);
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawArrow_Image(PetscDraw draw, PetscReal xl, PetscReal yl, PetscReal xr, PetscReal yr, int c) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  PetscDrawValidColor(c);
  {
    int x_1 = XTRANS(draw, img, xl), x_2 = XTRANS(draw, img, xr);
    int y_1 = YTRANS(draw, img, yl), y_2 = YTRANS(draw, img, yr);
    if (x_1 == x_2 && y_1 == y_2) PetscFunctionReturn(0);
    PetscImageDrawLine(img, x_1, y_1, x_2, y_2, c);
    if (x_1 == x_2 && PetscAbs(y_1 - y_2) > 7) {
      if (y_2 > y_1) {
        PetscImageDrawLine(img, x_2, y_2, x_2 - 3, y_2 - 3, c);
        PetscImageDrawLine(img, x_2, y_2, x_2 + 3, y_2 - 3, c);
      } else {
        PetscImageDrawLine(img, x_2, y_2, x_2 - 3, y_2 + 3, c);
        PetscImageDrawLine(img, x_2, y_2, x_2 + 3, y_2 + 3, c);
      }
    }
    if (y_1 == y_2 && PetscAbs(x_1 - x_2) > 7) {
      if (x_2 > x_1) {
        PetscImageDrawLine(img, x_2 - 3, y_2 - 3, x_2, y_2, c);
        PetscImageDrawLine(img, x_2 - 3, y_2 + 3, x_2, y_2, c);
      } else {
        PetscImageDrawLine(img, x_2, y_2, x_2 + 3, y_2 - 3, c);
        PetscImageDrawLine(img, x_2, y_2, x_2 + 3, y_2 + 3, c);
      }
    }
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawRectangle_Image(PetscDraw draw, PetscReal xl, PetscReal yl, PetscReal xr, PetscReal yr, int c1, int c2, int c3, int c4) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  PetscDrawValidColor(c1);
  PetscDrawValidColor(c2);
  PetscDrawValidColor(c3);
  PetscDrawValidColor(c4);
  {
    int x = XTRANS(draw, img, xl), w = XTRANS(draw, img, xr) + 1 - x;
    int y = YTRANS(draw, img, yr), h = YTRANS(draw, img, yl) + 1 - y;
    int c = (c1 + c2 + c3 + c4) / 4;
    PetscImageDrawRectangle(img, x, y, w, h, c);
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawEllipse_Image(PetscDraw draw, PetscReal x, PetscReal y, PetscReal a, PetscReal b, int c) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  PetscDrawValidColor(c);
  a = PetscAbsReal(a);
  b = PetscAbsReal(b);
  {
    int xc = XTRANS(draw, img, x), w = XTRANS(draw, img, x + a / 2) + 0 - xc;
    int yc = YTRANS(draw, img, y), h = YTRANS(draw, img, y - b / 2) + 0 - yc;
    if (PetscAbsReal(a - b) <= 0) w = h = PetscMin(w, h); /* workaround truncation errors */
    PetscImageDrawEllipse(img, xc, yc, w, h, c);
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawTriangle_Image(PetscDraw draw, PetscReal X_1, PetscReal Y_1, PetscReal X_2, PetscReal Y_2, PetscReal X_3, PetscReal Y_3, int c1, int c2, int c3) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  PetscDrawValidColor(c1);
  PetscDrawValidColor(c2);
  PetscDrawValidColor(c3);
  {
    int x_1 = XTRANS(draw, img, X_1), x_2 = XTRANS(draw, img, X_2), x_3 = XTRANS(draw, img, X_3);
    int y_1 = YTRANS(draw, img, Y_1), y_2 = YTRANS(draw, img, Y_2), y_3 = YTRANS(draw, img, Y_3);
    PetscImageDrawTriangle(img, x_1, y_1, c1, x_2, y_2, c2, x_3, y_3, c3);
  }
  PetscFunctionReturn(0);
}

/*
static PetscErrorCode PetscDrawStringSetSize_Image(PetscDraw draw,PetscReal w,PetscReal h)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawStringSetSize_Image NULL

static PetscErrorCode PetscDrawStringGetSize_Image(PetscDraw draw, PetscReal *w, PetscReal *h) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  {
    int tw = PetscImageFontWidth;
    int th = PetscImageFontHeight;
    if (w) *w = tw * (draw->coor_xr - draw->coor_xl) / (img->w * (draw->port_xr - draw->port_xl));
    if (h) *h = th * (draw->coor_yr - draw->coor_yl) / (img->h * (draw->port_yr - draw->port_yl));
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawString_Image(PetscDraw draw, PetscReal x, PetscReal y, int c, const char text[]) {
  PetscImage img = (PetscImage)draw->data;
  PetscToken token;
  char      *subtext;
  PetscFunctionBegin;
  PetscDrawValidColor(c);
  {
    int xx = XTRANS(draw, img, x);
    int yy = YTRANS(draw, img, y);
    PetscCall(PetscTokenCreate(text, '\n', &token));
    PetscCall(PetscTokenFind(token, &subtext));
    while (subtext) {
      PetscImageDrawText(img, xx, yy, c, subtext);
      yy += PetscImageFontHeight;
      PetscCall(PetscTokenFind(token, &subtext));
    }
    PetscCall(PetscTokenDestroy(&token));
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawStringVertical_Image(PetscDraw draw, PetscReal x, PetscReal y, int c, const char text[]) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  PetscDrawValidColor(c);
  {
    char chr[2] = {0, 0};
    int  xx     = XTRANS(draw, img, x);
    int  yy     = YTRANS(draw, img, y);
    int  offset = PetscImageFontHeight;
    while ((chr[0] = *text++)) {
      PetscImageDrawText(img, xx, yy + offset, c, chr);
      yy += PetscImageFontHeight;
    }
  }
  PetscFunctionReturn(0);
}

/*
static PetscErrorCode PetscDrawStringBoxed_Image(PetscDraw draw,PetscReal sxl,PetscReal syl,int sc,int bc,const char text[],PetscReal *w,PetscReal *h)
{
  PetscFunctionBegin;
  if (w) *w = 0;
  if (h) *h = 0;
  PetscFunctionReturn(0);
*/
#define PetscDrawStringBoxed_Image NULL

/*
static PetscErrorCode PetscDrawFlush_Image(PetscDraw draw)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawFlush_Image NULL

static PetscErrorCode PetscDrawClear_Image(PetscDraw draw) {
  PetscImage img = (PetscImage)draw->data;
  PetscFunctionBegin;
  { PetscImageClear(img); }
  PetscFunctionReturn(0);
}

/*
static PetscErrorCode PetscDrawSetDoubleBuffer_Image(PetscDraw draw)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawSetDoubleBuffer_Image NULL

static PetscErrorCode PetscDrawGetPopup_Image(PetscDraw draw, PetscDraw *popup) {
  PetscBool flg = PETSC_FALSE;

  PetscFunctionBegin;
  PetscCall(PetscOptionsGetBool(((PetscObject)draw)->options, ((PetscObject)draw)->prefix, "-draw_popup", &flg, NULL));
  if (!flg) {
    *popup = NULL;
    PetscFunctionReturn(0);
  }
  PetscCall(PetscDrawCreate(PetscObjectComm((PetscObject)draw), NULL, NULL, 0, 0, 220, 220, popup));
  PetscCall(PetscDrawSetType(*popup, PETSC_DRAW_IMAGE));
  PetscCall(PetscObjectSetOptionsPrefix((PetscObject)*popup, "popup_"));
  PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)*popup, ((PetscObject)draw)->prefix));
  draw->popup = *popup;
  PetscFunctionReturn(0);
}

/*
static PetscErrorCode PetscDrawSetTitle_Image(PetscDraw draw,const char title[])
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawSetTitle_Image NULL

/*
static PetscErrorCode PetscDrawCheckResizedWindow_Image(PetscDraw draw)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawCheckResizedWindow_Image NULL

static PetscErrorCode PetscDrawResizeWindow_Image(PetscDraw draw, int w, int h) {
  PetscImage img = (PetscImage)draw->data;

  PetscFunctionBegin;
  if (w == img->w && h == img->h) PetscFunctionReturn(0);
  PetscCall(PetscFree(img->buffer));

  img->w = w;
  img->h = h;
  PetscCall(PetscCalloc1((size_t)(img->w * img->h), &img->buffer));
  PetscCall(PetscDrawSetViewport_Image(draw, draw->port_xl, draw->port_yl, draw->port_xr, draw->port_yr));
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawDestroy_Image(PetscDraw draw) {
  PetscImage img = (PetscImage)draw->data;

  PetscFunctionBegin;
  PetscCall(PetscDrawDestroy(&draw->popup));
  PetscCall(PetscFree(img->buffer));
  PetscCall(PetscFree(draw->data));
  PetscFunctionReturn(0);
}

/*
static PetscErrorCode PetscDrawView_Image(PetscDraw draw,PetscViewer viewer)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawView_Image NULL

/*
static PetscErrorCode PetscDrawGetMouseButton_Image(PetscDraw draw,PetscDrawButton *button,PetscReal *x_user,PetscReal *y_user,PetscReal *x_phys,PetscReal *y_phys)
{
  PetscFunctionBegin;
  *button = PETSC_BUTTON_NONE;
  if (x_user) *x_user = 0;
  if (y_user) *y_user = 0;
  if (x_phys) *x_phys = 0;
  if (y_phys) *y_phys = 0;
  PetscFunctionReturn(0);
}*/
#define PetscDrawGetMouseButton_Image NULL

/*
static PetscErrorCode PetscDrawPause_Image(PetscDraw draw)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawPause_Image NULL

/*
static PetscErrorCode PetscDrawBeginPage_Image(PetscDraw draw)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawBeginPage_Image NULL

/*
static PetscErrorCode PetscDrawEndPage_Image(PetscDraw draw)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawEndPage_Image NULL

static PetscErrorCode PetscDrawGetSingleton_Image(PetscDraw draw, PetscDraw *sdraw) {
  PetscImage pimg = (PetscImage)draw->data;
  PetscImage simg;

  PetscFunctionBegin;
  PetscCall(PetscDrawCreate(PETSC_COMM_SELF, NULL, NULL, 0, 0, draw->w, draw->h, sdraw));
  PetscCall(PetscDrawSetType(*sdraw, PETSC_DRAW_IMAGE));
  (*sdraw)->ops->resizewindow = NULL;
  simg                        = (PetscImage)(*sdraw)->data;
  PetscCall(PetscArraycpy(simg->buffer, pimg->buffer, pimg->w * pimg->h));
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawRestoreSingleton_Image(PetscDraw draw, PetscDraw *sdraw) {
  PetscImage pimg = (PetscImage)draw->data;
  PetscImage simg = (PetscImage)(*sdraw)->data;

  PetscFunctionBegin;
  PetscCall(PetscArraycpy(pimg->buffer, simg->buffer, pimg->w * pimg->h));
  PetscCall(PetscDrawDestroy(sdraw));
  PetscFunctionReturn(0);
}

/*
static PetscErrorCode PetscDrawSave_Image(PetscDraw draw)
{
  PetscFunctionBegin;
  PetscFunctionReturn(0);
}*/
#define PetscDrawSave_Image NULL

static PetscErrorCode PetscDrawGetImage_Image(PetscDraw draw, unsigned char palette[256][3], unsigned int *w, unsigned int *h, unsigned char *pixels[]) {
  PetscImage     img    = (PetscImage)draw->data;
  unsigned char *buffer = NULL;
  PetscMPIInt    rank, size;

  PetscFunctionBegin;
  if (w) *w = (unsigned int)img->w;
  if (h) *h = (unsigned int)img->h;
  if (pixels) *pixels = NULL;
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)draw), &rank));
  if (rank == 0) {
    PetscCall(PetscMemcpy(palette, img->palette, sizeof(img->palette)));
    PetscCall(PetscMalloc1((size_t)(img->w * img->h), &buffer));
    if (pixels) *pixels = buffer;
  }
  PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)draw), &size));
  if (size == 1) {
    PetscCall(PetscArraycpy(buffer, img->buffer, img->w * img->h));
  } else {
    PetscCallMPI(MPI_Reduce(img->buffer, buffer, img->w * img->h, MPI_UNSIGNED_CHAR, MPI_MAX, 0, PetscObjectComm((PetscObject)draw)));
  }
  PetscFunctionReturn(0);
}

static struct _PetscDrawOps DvOps = {PetscDrawSetDoubleBuffer_Image, PetscDrawFlush_Image, PetscDrawLine_Image, PetscDrawLineSetWidth_Image, PetscDrawLineGetWidth_Image, PetscDrawPoint_Image, PetscDrawPointSetSize_Image, PetscDrawString_Image, PetscDrawStringVertical_Image, PetscDrawStringSetSize_Image, PetscDrawStringGetSize_Image, PetscDrawSetViewport_Image, PetscDrawClear_Image, PetscDrawRectangle_Image, PetscDrawTriangle_Image, PetscDrawEllipse_Image, PetscDrawGetMouseButton_Image, PetscDrawPause_Image, PetscDrawBeginPage_Image, PetscDrawEndPage_Image, PetscDrawGetPopup_Image, PetscDrawSetTitle_Image, PetscDrawCheckResizedWindow_Image, PetscDrawResizeWindow_Image, PetscDrawDestroy_Image, PetscDrawView_Image, PetscDrawGetSingleton_Image, PetscDrawRestoreSingleton_Image, PetscDrawSave_Image, PetscDrawGetImage_Image, PetscDrawSetCoordinates_Image, PetscDrawArrow_Image, PetscDrawCoordinateToPixel_Image, PetscDrawPixelToCoordinate_Image, PetscDrawPointPixel_Image, PetscDrawStringBoxed_Image};

static const unsigned char BasicColors[PETSC_DRAW_BASIC_COLORS][3] = {
  {255, 255, 255}, /* white */
  {0,   0,   0  }, /* black */
  {255, 0,   0  }, /* red */
  {0,   255, 0  }, /* green */
  {0,   255, 255}, /* cyan */
  {0,   0,   255}, /* blue */
  {255, 0,   255}, /* magenta */
  {127, 255, 212}, /* aquamarine */
  {34,  139, 34 }, /* forestgreen */
  {255, 165, 0  }, /* orange */
  {238, 130, 238}, /* violet */
  {165, 42,  42 }, /* brown */
  {255, 192, 203}, /* pink */
  {255, 127, 80 }, /* coral */
  {190, 190, 190}, /* gray */
  {255, 255, 0  }, /* yellow */
  {255, 215, 0  }, /* gold */
  {255, 182, 193}, /* lightpink */
  {72,  209, 204}, /* mediumturquoise */
  {240, 230, 140}, /* khaki */
  {105, 105, 105}, /* dimgray */
  {54,  205, 50 }, /* yellowgreen */
  {135, 206, 235}, /* skyblue */
  {0,   100, 0  }, /* darkgreen */
  {0,   0,   128}, /* navyblue */
  {244, 164, 96 }, /* sandybrown */
  {95,  158, 160}, /* cadetblue */
  {176, 224, 230}, /* powderblue */
  {255, 20,  147}, /* deeppink */
  {216, 191, 216}, /* thistle */
  {50,  205, 50 }, /* limegreen */
  {255, 240, 245}, /* lavenderblush */
  {221, 160, 221}, /* plum */
};

/*MC
   PETSC_DRAW_IMAGE - PETSc graphics device that uses a raster buffer

   Options Database Keys:
.  -draw_size w,h - size of image in pixels

   Level: beginner

.seealso: `PetscDrawOpenImage()`, `PetscDrawSetFromOptions()`
M*/
PETSC_EXTERN PetscErrorCode PetscDrawCreate_Image(PetscDraw);

PETSC_EXTERN PetscErrorCode PetscDrawCreate_Image(PetscDraw draw) {
  PetscImage img;
  int        w = draw->w, h = draw->h;
  PetscInt   size[2], nsize = 2;
  PetscBool  set;

  PetscFunctionBegin;
  draw->pause   = 0;
  draw->coor_xl = 0;
  draw->coor_xr = 1;
  draw->coor_yl = 0;
  draw->coor_yr = 1;
  draw->port_xl = 0;
  draw->port_xr = 1;
  draw->port_yl = 0;
  draw->port_yr = 1;

  size[0] = w;
  if (size[0] < 1) size[0] = 300;
  size[1] = h;
  if (size[1] < 1) size[1] = size[0];
  PetscCall(PetscOptionsGetIntArray(((PetscObject)draw)->options, ((PetscObject)draw)->prefix, "-draw_size", size, &nsize, &set));
  if (set && nsize == 1) size[1] = size[0];
  if (size[0] < 1) size[0] = 300;
  if (size[1] < 1) size[1] = size[0];
  draw->w = w = size[0];
  draw->x     = 0;
  draw->h = h = size[1];
  draw->x     = 0;

  PetscCall(PetscNew(&img));
  PetscCall(PetscMemcpy(draw->ops, &DvOps, sizeof(DvOps)));
  draw->data = (void *)img;

  img->w = w;
  img->h = h;
  PetscCall(PetscCalloc1((size_t)(img->w * img->h), &img->buffer));
  PetscImageSetClip(img, 0, 0, img->w, img->h);
  {
    int           i, k, ncolors = 256 - PETSC_DRAW_BASIC_COLORS;
    unsigned char R[256 - PETSC_DRAW_BASIC_COLORS];
    unsigned char G[256 - PETSC_DRAW_BASIC_COLORS];
    unsigned char B[256 - PETSC_DRAW_BASIC_COLORS];
    PetscCall(PetscDrawUtilitySetCmap(NULL, ncolors, R, G, B));
    for (k = 0; k < PETSC_DRAW_BASIC_COLORS; k++) {
      img->palette[k][0] = BasicColors[k][0];
      img->palette[k][1] = BasicColors[k][1];
      img->palette[k][2] = BasicColors[k][2];
    }
    for (i = 0; i < ncolors; i++, k++) {
      img->palette[k][0] = R[i];
      img->palette[k][1] = G[i];
      img->palette[k][2] = B[i];
    }
  }

  if (!draw->savefilename) PetscCall(PetscDrawSetSave(draw, draw->title));
  PetscFunctionReturn(0);
}

/*@C
   PetscDrawOpenImage - Opens an image for use with the `PetscDraw` routines.

   Collective

   Input Parameters:
+  comm - the communicator that will share image
-  filename - optional name of the file where the image will be stored
-  w, h - the image width and height in pixels

   Output Parameters:
.  draw - the drawing context.

   Level: beginner

.seealso: `PetscDraw`, `PETSC_DRAW_IMAGE`, `PETSC_DRAW_X`, `PetscDrawSetSave()`, `PetscDrawSetFromOptions()`, `PetscDrawCreate()`, `PetscDrawDestroy()`
@*/
PetscErrorCode PetscDrawOpenImage(MPI_Comm comm, const char filename[], int w, int h, PetscDraw *draw) {
  PetscFunctionBegin;
  PetscCall(PetscDrawCreate(comm, NULL, NULL, 0, 0, w, h, draw));
  PetscCall(PetscDrawSetType(*draw, PETSC_DRAW_IMAGE));
  PetscCall(PetscDrawSetSave(*draw, filename));
  PetscFunctionReturn(0);
}