bionic (3) XmRedisplayWidget.3.gz

NAME

       XmRedisplayWidget — Synchronously activates the expose method of a widget to draw its content

SYNOPSIS

       #include <Xm/Xm.h>
       voidXmRedisplayWidget(
       Widgetwidget);

DESCRIPTION

       This  function  is  a  convenience  routine that hides the details of the Xt internals to the application
       programmer by calling the expose method of the given widget with a well formed Expose  event  and  Region
       corresponding  to the total area of the widget. If the widget doesn't have an Expose method, the function
       does nothing.

       This is primarily used in the context of X Printing if the programming model chosen by the application is
       synchronous;  that  is,  it  doesn't  rely  of X Print events for the driving of page layout but wants to
       completely control the sequence of rendering requests.

       XmRedisplayWidget doesn't clear the widget window prior to calling  the  expose  method,  since  this  is
       handled by calls to XpStartPage .

       widget    The widget to redisplay.

RETURN VALUE

       None.

ERRORS/WARNINGS

       Not applicable

EXAMPLES

       In the following, a simple application wants to print the content of a multi-page text widget (similar to
       dtpad).

       PrintOKCallback(print_dialog...)
       /*-------------*/
       {
           pshell = XmPrintSetup (print_dialog, pbs->print_screen,
                                          "Print", NULL, 0);

           XpStartJob(XtDisplay(pshell), XPSpool);

           /**** here I realize the shell, get its size, create my widget
            hierarchy: a bulletin board, and then a text widget,
            that I stuff with the video text widget buffer */

           /* get the total number of pages to print */
           XtVaGetValues(ptext, XmNrows, &prows,
                                XmNtotalLines, n_lines, NULL);
           n_pages = n_lines / prows;

           /***** now print the pages in a loop */

           for (cur_page=0; cur_page != n_pages; cur_page++) {

                      XpStartPage(XtDisplay(pshell), XtWindow(pshell), False);
                      XmRedisplayWidget(ptext);  /* do the drawing */
                      XpEndPage(XtDisplay(pshell));

               XmTextScroll(ptext, prows);  /* get ready for next page */
           }

           /***** I'm done */
           XpEndJob(XtDisplay(pshell));

       }

       Of course, one could change the above code to include it in a fork() branch so that the main  program  is
       not  blocked  while printing is going on. Another way to achieve a "print-in-the-background" effect is to
       use an Xt workproc. Using the same sample application, that gives us:

       Boolean
       PrintOnePageWP(XtPointer npages) /* workproc */
       /*-------------*/
       {
           static int cur_page = 0;
           cur_page++;

           XpStartPage(XtDisplay(pshell), XtWindow(pshell), False);
           XmRedisplayWidget(ptext);  /* do the drawing */
           XpEndPage(XtDisplay(pshell));

           XmTextScroll(ptext, prows);  /*  get ready for next page */

           if (cur_page == n_pages) { /***** I'm done */
               XpEndJob(XtDisplay(pshell));

               XtDestroyWidget(pshell);
               XtCloseDisplay(XtDisplay(pshell));
           }

           return (cur_page == n_pages);
       }

       PrintOKCallback(...)
       /*-------------*/
       {
           pshell = XmPrintSetup (widget, pbs->print_screen,
                                          "Print", NULL, 0);

           XpStartJob(XtDisplay(pshell), XPSpool);

           /**** here I get the size of the shell, create my widget
                 hierarchy: a bulletin board, and then a text widget,
                         that I stuff with the video text widget buffer */

           /* get the total number of pages to print */
           /* ... same code as above example */

           /***** print the pages in the background */
           XtAppAddWorkProc(app_context, PrintOnePageWP, n_pages);
       }

SEE ALSO

       XmPrintSetup(3), XmPrintShell(3)

                                                                                            XmRedisplayWidget(3)