#36 Mouse co-ordinates in Fortran

[B Thomas]

Is there a way to obtain the co-ordinates of mouse clicks and distinguish between different mouse buttons in Fortran ? Kindly do consider this feature. This will make PLplot a complete replacement of the PGplot for Fortran.

[GregJung]

Cursor input is not a big aspect of the plplot drivers; a left-button-down and character input events are the extent of what wingcc, xwin.c (the windows and x-windows driver routines) care about.

To get the control you want you can do direct Xlib calls as shown from {GDL-sourceforge}/gdlxstream.cpp:

//simple GetGin that reproduces IDL's own.
//However, trapping controlC should be done inside, to clean properly.

bool GDLXStream::GetGin(PLGraphicsIn *gin, int mode) {

  enum CursorOpt {
    NOWAIT = 0,
    WAIT, //1
    CHANGE, //2
    DOWN, //3
    UP //4
  };
  XwDev *dev = (XwDev *) pls->dev;
  XwDisplay *xwd = (XwDisplay *) dev->xwd;
  Window root, child;
  int root_x, root_y, oldx, oldy;
  unsigned int ostate;
  XQueryPointer(xwd->display, dev->window, &root, &child,
          &root_x, &root_y, &oldx, &oldy, &ostate);
  gin->pX = oldx;
  gin->pY = dev->height - oldy;
  gin->state = ostate;
  gin->dX = (PLFLT) gin->pX / (dev->width - 1);
  gin->dY = (PLFLT) gin->pY / (dev->height - 1);
  gin->string[0] = '\0';
  gin->keysym = 0x20;
  gin->button = 0;
  if (ostate & Button1Mask) gin->button = 1;
  if (ostate & Button2Mask) gin->button = 2;
  if (ostate & Button3Mask) gin->button = 3;
  if (ostate & Button4Mask) gin->button = 4;
  if (ostate & Button5Mask) gin->button = 5; //IDL does not support buttons 4-5 but we may?
  //return if NOWAIT
  setFocus(false);  // first try to get out of focus.
  if (mode == NOWAIT) return true;

  unsigned long event_mask = (PointerMotionMask|ButtonMotionMask);
  switch (mode) {
    case WAIT:
      if (gin->button > 0) return true; //else wait below for a down...
    case DOWN:
      event_mask |= ButtonPressMask;
      break;
    case UP:
    case CHANGE:
      event_mask |= (ButtonPressMask | ButtonReleaseMask);
  }

  XEvent event;
  XRaiseWindow(xwd->display, dev->window);
  XSelectInput(xwd->display, dev->window, event_mask);
  XSync(xwd->display, true);  //useful?
  while (1) {
    XWindowEvent(xwd->display, dev->window, event_mask, &event);

    switch (event.type) {
        int nchars;
        KeySym mykey;
      case ButtonRelease:
        gin->pX = event.xbutton.x;
        gin->pY = event.xbutton.y;
        gin->state = event.xbutton.state;
        gin->button = event.xbutton.button;
        gin->string[0] = '\0';
        gin->keysym = 0x20;
        if (mode==UP || mode==CHANGE) goto end;
        break;
      case ButtonPress:
        gin->pX = event.xbutton.x;
        gin->pY = event.xbutton.y;
        gin->state = event.xbutton.state;
        gin->button = event.xbutton.button;
        gin->string[0] = '\0';
        gin->keysym = 0x20;
        if (mode==WAIT || mode==DOWN || mode==CHANGE) goto end;
        break;
      case MotionNotify:
        if (mode==CHANGE) {
          gin->pX = event.xmotion.x;
          gin->pY = event.xmotion.y;
          gin->state = event.xmotion.state;
          gin->string[0] = '\0';
          gin->keysym = 0x20;
          goto end;
        }
        break;
      default:
        break;
    }
  }
end:
  gin->pY = dev->height - gin->pY;
  gin->dX = (PLFLT) gin->pX / (dev->width - 1);
  gin->dY = (PLFLT) gin->pY / (dev->height - 1);
  return true;
}

A windows method is also to be found in the same code base, at gdlwinstream.cpp.

[Alan W. Irwin]

Closed (too old).