Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!kent
From: kent@swrinde.nde.swri.edu (Kent D. Polk)
Newsgroups: comp.sys.amiga.tech
Subject: Refreshing a window with gadtools gadgets
Keywords: gadtools library
Message-ID: <248@swrinde.nde.swri.edu>
Date: 13 Dec 90 03:44:15 GMT
Organization: Southwest Research Institute, San Antonio, Texas
Lines: 113

I have a window which may have 'variable' sets of gadtools gadgets. It determines
how to set things up based on a message that very seldom gets sent to it.

Done this way:

-------- On program startup (abbreviated version)

   if (!(GfxBase=(struct GfxBase *) OpenLibrary("graphics.library", 36L))) {
...
   if (!(IntuitionBase = (struct IntuitionBase *)
     OpenLibrary("intuition.library", 36L))) {
...
   if (!(GadToolsBase = OpenLibrary("gadtools.library", 36L))) {
...
   if (!(mysc = LockPubScreen(NULL))) {
...


-------- On each rethink message:

   if (reinit) closeinit(); /* closeinit can only be called after the first time */

   if (!(vi = GetVisualInfo(mysc, TAG_DONE))) {
...
   if (!CreateAllGadgets(&glist, vi, topborder, num)) {
...
   /***  Create the Gadget Window ***/
   if (!(mywin = OpenWindowTags(NULL,
...
   /* Add gadgets, refresh them, and call the toolkit refresh */
   AddGList(mywin, glist, ((UWORD) -1), ((UWORD) -1), NULL);
   RefreshGList(glist, mywin, NULL, ((UWORD) -1));
   GT_RefreshWindow(mywin, NULL);


-----------------------------

When this refresh or 'rethink' message gets sent to my program after
the first time, closeinit gets called, which frees the visualinfo, the
Gadgets & closes the window as seen in closeinit() below. Now, the
window & gadgets get created correctly, but cputrap gives me a rash of
invalid memory accesses to FFFFFFFF, typically.

I assume I am incorrectly freeing or reallocating resources.  What
would be the correct method of doing this?

======================================================================
Associated info:

struct GfxBase *GfxBase             = NULL;
struct IntuitionBase *IntuitionBase = NULL;
struct Library *GadToolsBase        = NULL;
struct Screen *mysc                 = NULL;
struct Gadget *glist                = NULL;
struct Window *mywin                = NULL;
void *vi                            = NULL;

/******************************/
closeinit()
{
   if (mywin) CloseWindow(mywin);
   if (vi) FreeVisualInfo(vi);
   if (glist) FreeGadgets(glist);
}

/******************************/
struct Gadget *CreateAllGadgets(
   struct Gadget **glistptr, void *vi, UWORD topborder, UWORD num)
{
   int i, j;
   struct NewGadget ng;
   struct Gadget *gad = NULL;

   gad = CreateContext(glistptr);

   ng.ng_VisualInfo  = vi;
   ng.ng_LeftEdge    = 70;
   ng.ng_Height      = 11;
   ng.ng_Width       = 45;
   ng.ng_Flags       = PLACETEXT_LEFT;

   for (j=0;j<num;j++) {
      ng.ng_TopEdge = topborder + w_HEIGHT*j + 5*j;
      ng.ng_GadgetText  = GadLabels[0];
      ng.ng_GadgetID    = j * MAXCHANNELS;
      gad = CreateGadget(CYCLE_KIND, gad, &ng,
         GTCY_Labels, ChanLabels,
         GTCY_Active, OFF,
         TAG_DONE);

      for (i=1;i<NUMGADS-1;i++)
         if (gad) {
            ng.ng_TopEdge     = ng.ng_TopEdge + topoffset;
            ng.ng_GadgetText  = GadLabels[i];
            ng.ng_GadgetID    = j * MAXCHANNELS + i;
            gad = CreateGadget(SLIDER_KIND, gad, &ng,
               GTSL_Min, SliderMin[i],
               GTSL_Max, SliderMax[i],
               GTSL_Level, SliderLevel[i],
               TAG_DONE);
         }

/* ... some more stuff like this */

   }
   return (gad);
}

Thanks Much,
====================================================================
Kent Polk - Southwest Research Institute - kent@swrinde.nde.swri.edu
        "Well... can't you get a Novell card for your Cray ?"
====================================================================