ephraim@Think.COM (Ephraim Vishniac) (02/27/90)
How is the screen restored after a call to _SysError?
Before you say, "There is no 'after' _SysError," please note that the
disk-swap alert is displayed by _SysError. A little creeping around
with Macsbug informs me that there's a low-mem global called DSWndUpdate,
but I haven't puzzled out how it's used or what it does.
The reason I'm asking about this is that I'd like to be able to display an
alert at just about any time (much like the disk-swap alert, and for
similar reasons) and then clean up nicely. Right now, I'm waiting for the
next call to _GetOSEvent and using _PaintBehind to get the alert rect
redrawn. This works, but it's not as smooth as whatever the disk-swap code
does.
Ephraim Vishniac ephraim@think.com ThinkingCorp@applelink.apple.com
Thinking Machines Corporation / 245 First Street / Cambridge, MA 02142
One of the flaws in the anarchic bopper society was
the ease with which such crazed rumors could spread.amanda@mermaid.intercon.com (Amanda Walker) (02/27/90)
In article <34252@news.Think.COM>, ephraim@Think.COM (Ephraim Vishniac) writes: > Right now, I'm waiting for the > next call to _GetOSEvent and using _PaintBehind to get the alert rect > redrawn. This works, but it's not as smooth as whatever the disk-swap code > does. If you know how big your alert is going to be, you could reserve a bitmap/pixmap and just save the stuff behind the alert before you put it up, and restore it on your way out... I believe there was once some code floating around sumex that did this, called "quickalert" or some such. -- Amanda Walker InterCon Systems Corporation "Many of the truths we cling to depend greatly upon our own point of view." --Obi-Wan Kenobi in "Return of the Jedi"
lsr@Apple.COM (Larry Rosenstein) (03/01/90)
In article <34252@news.Think.COM> ephraim@Think.COM (Ephraim Vishniac) writes: > How is the screen restored after a call to _SysError? There's a low memory global called DSAlertRect. In GetMouse, if the high bit of DSWndUpdate is 1, then the system refreshes the rectangle stored in DSAlertRect. Since this doesn't seem to be documented, use at your own risk. Larry Rosenstein, Apple Computer, Inc. Object Specialist Internet: lsr@Apple.com UUCP: {nsc, sun}!apple!lsr AppleLink: Rosenstein1
ephraim@think.com (Ephraim Vishniac) (03/01/90)
In article <6959@internal.Apple.COM> lsr@Apple.COM (Larry Rosenstein) writes: >In article <34252@news.Think.COM> ephraim@Think.COM (Ephraim Vishniac) >writes: >> How is the screen restored after a call to _SysError? >There's a low memory global called DSAlertRect. In GetMouse, if the high >bit of DSWndUpdate is 1, then the system refreshes the rectangle stored in >DSAlertRect. GetMouse doesn't do this on my Mac II (6.02, Multifinder off). I disassembled it and found that the only subroutine call was to a journaling routine which exits immedidately if journaling is off. Also, DSWndUpdate seems to be $FF most of the time (i.e., the high bit is always set). >Since this doesn't seem to be documented, use at your own risk. Not documented? Not so! Please refer to "Low Memory in Alphabetical Order" dated 12 Apr 85. (You did keep every scrap of paper from the Macintosh Software Supplements, right?) DSWndUpdate is at least as well documented as the famous MrMacHook. Notice the line that reads: DSWndUpdate .EQU $15D ;01 GNE not to paintBehind DS AlertRect? [byte] This suggests that it's GetNextEvent, not GetMouse, and painting will occur when the bit is cleared, not set. I haven't actually tried this out yet - it took me a while to find the right documentation. -- Ephraim Vishniac ephraim@think.com ThinkingCorp@applelink.apple.com Thinking Machines Corporation / 245 First Street / Cambridge, MA 02142 One of the flaws in the anarchic bopper society was the ease with which such crazed rumors could spread.
wdh@well.sf.ca.us (Bill Hofmann) (03/02/90)
In article <34252@news.Think.COM> ephraim@Think.COM (Ephraim Vishniac) writes: >How is the screen restored after a call to _SysError? > >The reason I'm asking about this is that I'd like to be able to display an >alert at just about any time (much like the disk-swap alert, and for >similar reasons) and then clean up nicely. Right now, I'm waiting for the >next call to _GetOSEvent and using _PaintBehind to get the alert rect >redrawn. This works, but it's not as smooth as whatever the disk-swap code >does. The Debugger is much handier for obscure trivia like this. Its listing for DSWndUpdate is "GetNextEvent not to paintBehind DS AlertRect", and looking at the code for EventAvail and GetNextEvent, it does something like this: BSET #7,DsWndUpdate BNE.S out ...GetPort(curPort) SetPort(WMgrPort) SUBQ #4,a7 _FrontWindow SUBQ #4,a7 _NewRgn MOVEA.L (a7),a3 PEA DsAlertRect ; $3f8 PUSH.L a3 _PaintBehind PUSH.L a3 _DisposRgn ...SetPort(curPort) So to force a cleanup, just BCLR #7,DsWndUpdate, being sure DsAlertRect is properly set up. But how about using the Notification Manager? That'll let you put up an alert in front of everything, in a much less hackish way. -Bill Hofmann PS: How're things?