/* w1mpi.c  test X Windows parallel with MPI  */
#include "mpi.h"
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

static int myid;
static Display *dpy;
static Window window1;
static GC gc;
static Screen *screen;

static void doInitialize(void);          /* function prototypes used below */
static void doCreateWindows(void);
static void doCreateGraphicsContext(void);
static void doExpose(XEvent *eventP);
static void doHandleEvents(void);

int main(int argc, char *argv[])
{
  int proc, numprocs;
  int master = 0;
  double esec = 0.0;

  MPI_Init(&argc,&argv);
  MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
  MPI_Comm_rank(MPI_COMM_WORLD,&myid);

  if(myid == 0)
  {
    printf("w1mpi.c  numprocs=%d \n", numprocs);
  }
  /* all */
  doInitialize();
  doHandleEvents();

  if(myid == 0)
  {
    esec = MPI_Wtime();
    printf("w1mpi.c took %g seconds \n", esec);
  }
  MPI_Finalize();
  return 0; 
} /* end main of w1mpi.c */
 
/***************** doInitialize **************************/
static void doInitialize(void)
{
    char msg[100];

    dpy = XOpenDisplay(0); 
    if (!dpy){
        printf("Display not opened!\n");
        exit(1);
    }
    screen = XDefaultScreenOfDisplay(dpy);
    doCreateWindows();
    doCreateGraphicsContext();
    sprintf(msg, "Process %d window", myid);
    XStoreName(dpy, window1, msg);
    XMapWindow(dpy, window1);
} 

/******* doCreateWindows *********/
static void doCreateWindows(void)
{   
  int window1X = 300;
  int window1Y = 200;
  int window1W = 250;
  int window1H = 100;
  XSetWindowAttributes xswa;
                   
  /* Create the window1 window */
  xswa.event_mask = ExposureMask | ButtonPressMask;
  xswa.background_pixel = XWhitePixelOfScreen(screen);

  window1 = XCreateWindow(dpy,
                          XRootWindowOfScreen(screen),
                          window1X, 
                          window1Y,
                          window1W,
                          window1H,
                          0,
                          XDefaultDepthOfScreen(screen),
                          InputOutput,
                          XDefaultVisualOfScreen(screen),
                          CWEventMask | CWBackPixel,
                          &xswa);
}

/******** Create the graphics context *********/    
static void doCreateGraphicsContext(void)
{                                                
  XGCValues xgcv;
    
  /* Create graphics context. */
  xgcv.background = XWhitePixelOfScreen(screen);
  xgcv.foreground = XBlackPixelOfScreen(screen);
  gc = XCreateGC(dpy, window1, GCForeground | GCBackground, &xgcv);   
}


/****************** doHandleEvents ***********************/
static void doHandleEvents(void)
{
  XEvent event;

  for ( ; ; )
  {
    XNextEvent(dpy, &event);
    switch (event.type)
    { 
      case Expose:
        doExpose(&event);
        break;
      case ButtonPress:
        XDestroyWindow(dpy, window1);
        XFlush(dpy);
        return; /* shut down */
    }
  }                                           
}

/***** draw and write the message in the window *****/
static void doExpose(XEvent *eventP)
{
  static char message[] = {"Click here to exit"}; 

  /* If this is an expose event on our window1 window,
     then write the text and rectangle. */

  if (eventP->xexpose.window != window1) return;
  XClearWindow(dpy, window1);
  XDrawImageString(dpy, window1, gc, 50, 25, message, strlen(message));
  XDrawRectangle(dpy, window1, gc, 50, 50, 100, 25);
  XFlush(dpy);
}