Path: utzoo!mnetor!uunet!husc6!hao!ames!aurora!labrea!rocky!ali
From: ali@rocky.STANFORD.EDU (Ali Ozer)
Newsgroups: comp.sys.amiga
Subject: OpenScreen() problem
Message-ID: <883@rocky.STANFORD.EDU>
Date: 22 Dec 87 06:58:37 GMT
Distribution: na
Organization: Stanford University Computer Science Department
Lines: 49

[]
A chip-memory hog program of mine was losing 256 bytes whenever it failed to
open a hires, 4-bit plane, interlaced screen. I finally tracked the problem
to the OpenScreen() calls in the following routine. Seems like when
OpenScreen() fails in the following example, I lose 128 chip bytes. Because
OpenScreen() is called twice, I end up losing 256. Any ideas on why? Is there
a problem with OpenScreen(), or am I just being rather blind?
(Note: Taking out the font assignment line doesn't help, and neither does
running without morerows...)

Ali Ozer, ali@rocky.stanford.edu

---------buggy code----------

struct TextAttr NormalFontDesc = {(STRPTR)"topaz.font", 8, 0, 0};

struct Screen *OpenPictureScreen (borderpen, detailpen, depth)
int borderpen, detailpen, depth;
{
  struct NewScreen ns;
  struct NewWindow nw;

  setmem (&ns, sizeof(ns), 0);
  setmem (&nw, sizeof(nw), 0);

  ns.DefaultTitle  = (UBYTE *)PROGNAME;  /* Some #define'ed string */
  ns.Font = &NormalFontDesc;
  ns.Width  = nw.Width  = ((struct GfxBase *)GfxBase)->NormalDisplayColumns; 
  ns.Height = nw.Height = ((struct GfxBase *)GfxBase)->NormalDisplayRows * 2;
  ns.DetailPen = nw.DetailPen = detailpen; 
  ns.BlockPen  = nw.BlockPen  = borderpen;  
  ns.Depth  = depth;
  ns.Type   = nw.Type   = CUSTOMSCREEN;
  nw.Flags  = SMART_REFRESH | BORDERLESS | BACKDROP | RMBTRAP | ACTIVATE;
  nw.IDCMPFlags = MOUSEBUTTONS | MOUSEMOVE | GADGETUP;
  ns.ViewModes  = HIRES | LACE;
  if (nw.Screen = OpenScreen (&ns)) {
    if (OpenWindow (&nw)) return (nw.Screen);
    else CloseScreen (nw.Screen);
  } else {   /* Try with a smaller screen and see if we can open that. */
    ns.Width  = nw.Width  = 640;
    ns.Height = nw.Height = 400;
    if (nw.Screen = OpenScreen (&ns)) {
      if (OpenWindow (&nw)) return (nw.Screen);
      else CloseScreen (nw.Screen);
    }
  }
  return (NULL);
}