From: mark@bhanu.lcs.mit.EDU (Mark Levison)
Subject: display postscript woes
Organization: The Internet
Date: Tue, 18 Aug 1992 20:14:02 GMT



    I am trying to use X Display Postscript on an SGI Indigo running IRIX 4.0.1
the X Server X11R4.  My problem I can create an display postscript context
set fonts, query string widths etc. but I cannot get my program to display
anything on the screen (I can do normal XDraw* stuff but postscript).
I have tried a variety of showpage and copypage commands. The program I
will append below is a simple variation on the one found in the
"The Display Postscript System 1.0" manual.  The XDrawLine is to
demonstrate that the graphics context and drawing are valid.
If you would rather just send a trivial working X Display Postscript
example and I will work from there.  Please reply to me directly and I will
summarize if there is intrest.

Mark Levison
mark@bhanu.andyne.on.ca

/*---------------------------Cut Here-----------------------*/

#include <X11/Intrinsic.h>
#include <X11/Shell.h>
#include <X11/MwmUtil.h>

#include <Xm/Xm.h>
#include <Xm/DrawingA.h>
#include <Xm/RowColumn.h>
#include <Xm/MainW.h>
#include <Xm/Text.h>

#include <stdlib.h>
#include <stdio.h>

#include "DPS/dpsXclient.h"
#include "DPS/dpsops.h"
#include "DPS/psops.h"

#define DRAW_WIDTH  512
#define DRAW_HEIGHT 100

DPSContext      ps_ctxt;
DPSContext      txtCtxt;

Display        *display;
XtAppContext    appc;
Widget          toplevel, main_window;
Widget          drawing_area;
GC              graphics;

static void expose(Widget, caddr_t, caddr_t);

static void
expose(Widget parent, caddr_t client_data, caddr_t call_data)
{
    printf("in expose callback\n");
    DPSshowpage(ps_ctxt);
    DPSsetrgbcolor(ps_ctxt, 0.5, 0.5, 0.5);
    DPSrectfill(ps_ctxt, 0.0, 0.0, 50.0, 50.0);
    DPSWaitContext(ps_ctxt);
    XDrawLine(display, XtWindow(drawing_area), graphics, 0, 0, 50, 50);
}

void main(argc,argv)
unsigned int    argc;
char        **argv;
{
    Drawable    window;
    XGCValues   values;
    short   ac;
    Arg     al[20];

    /* init toolkit */
    XtToolkitInitialize();
    appc = XtCreateApplicationContext();
    display = XtOpenDisplay (
                  appc,          /* application context = default */
                  NULL,        /* use DISPLAY from environment  */
                  NULL,        /* use last of argv[0] as name   */
                  NULL,
                  NULL,        /* no additional cmd line options*/
                  0,           /* ditto                         */
                  &argc,
                  argv);       /* use and delete std options    */

    if (display == NULL)       /* necessary !                   */
        XtErrorMsg (
            "NErrCannotOpen", NULL,    /* resource name         */
            NULL,                      /* resource class        */
            "cannot open display",     /* default message       */
            NULL, NULL);               /* parameters            */

    /* create application shell */
    ac = 0;
    XtSetArg(al[ac], XmNheight, 200); ac++;
    XtSetArg(al[ac], XmNwidth, 512); ac++;
    toplevel = XtAppCreateShell (
                   NULL,               /* use same program name */
                   NULL,               /* repeat class param    */
                   applicationShellWidgetClass,
                   display,
                   al, ac);           /* argument list         */

    /* create main window */
    ac = 0;
    XtSetArg(al[ac], XmNvisualPolicy, XmCONSTANT); ac++;
    XtSetArg(al[ac], XmNscrollBarDisplayPolicy, XmSTATIC); ac++;
    XtSetArg(al[ac], XmNscrollingPolicy, XmAUTOMATIC); ac++;
    main_window = XmCreateMainWindow(toplevel, "main", al, ac);

    ac = 0;
    XtSetArg(al[ac], XmNwidth, DRAW_WIDTH); ac++;
    XtSetArg(al[ac], XmNheight, DRAW_HEIGHT); ac++;
    drawing_area = XmCreateDrawingArea(main_window, " ", al, ac);

    XtAddCallback(drawing_area, XmNexposeCallback, expose, NULL);
    XmMainWindowSetAreas(main_window, NULL, NULL, NULL, NULL, drawing_area);
    /* start loop */

    XtManageChild(drawing_area);
    XtManageChild(main_window);
    XtRealizeWidget (toplevel);

    values.line_style = LineSolid;
    values.foreground = BlackPixel(XtDisplay(drawing_area), DefaultScreen(XtDisplay(drawing_area)));
    values.background = WhitePixel(XtDisplay(drawing_area), DefaultScreen(XtDisplay(drawing_area)));
    graphics = XCreateGC(XtDisplay(drawing_area),
        RootWindow(XtDisplay(drawing_area), DefaultScreen(XtDisplay(drawing_area))),
        GCLineStyle | GCForeground | GCBackground, &values);

    display = XtDisplay(drawing_area);
    window = XtWindow(drawing_area);

    if ((ps_ctxt = XDPSCreateSimpleContext(display, window, graphics, 0, 0,
        DPSDefaultTextBackstop, DPSDefaultErrorProc, NULL)) == NULL)
    {
      printf("XDPSCreateSimpleContext returned null");
      XtDestroyWidget(toplevel);
      return;
    }

    DPSSetContext(ps_ctxt);
    txtCtxt = DPSCreateTextContext(DPSDefaultTextBackstop, DPSDefaultErrorProc);
    DPSChainContext(ps_ctxt, txtCtxt);

    XtAppMainLoop (appc);
}
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