XmRedisplayWidget (3) - Linux Manuals

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

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);
}