On approximately 12/9/2003 2:59 AM, came the following characters from
the keyboard of Stephen Pick:
Hi all.
When I do this:
Win32::GUI::Dialog()
I receive all my events like WM_LBUTTONDOWN (-onMouseDown) once, as
should happen.
When I do this:
while(1) {
Win32::GUI::DoEvents()
print "Loop!\n";
}
I get endless calls to my event handler so long as the mouse button is
down. I have NO idea why. Must be some kind of windows internal thing.
Certain Windows messages are "queued and combined" if you are not
looking, but the more often you look, the more often you get them.... I
could say if MouseDown is one of those, off hand.
I have noticed that a difference between Dialog() and DoEvents() is that
if used to process a dialog box containing a text box, that the former
responds normally, but the latter generally doubles the characters
received by the text box. One difference in my situation is that I was
calling DoEvents() from an event, and that might cause some sort of
reentrancy problem, but I couldn't understand what it would be if it is
such. I gave up and restructured my code to use Dialog() only.
Additionally, since the code for DoEvents() and Dialog() is practically
identical except that DoEvents uses PeekMessage and Dialog uses
GetMessage, I copied both into seperate files and took a look at them in
WinMerge. Interesting. Dialog does ENTER; SAVETMPS; before doing
GetMessage and FREETMPS; LEAVE; at the end of it's while() loop.
DoEvents() doesn't do this.
This is because Dialog is "long-running" and needs to be sure to do Perl
temporary variable management, and DoEvents returns to Perl more often,
so can let Perl do the temporary variable management. I think.
Also, DoEvents has the line "acc =
perlud->hAcc;", and Dialog() DOESNT have that. Dialog() does a
comparison on acc (acc != NULL) in the next few lines just like DoEvents
does, but this comparison will always yield false in Dialog().
I think that was one of the lines I "fixed" in making accelerator keys
work. If not, it should have been. What version of source are you
looking at?
So. I don't have a compiler here but this is weird. Surely these
functions should be identical but for the change from GetMessage to
PeekMessage. Moreover, if these functions should be identical then why
write the same code for both when a simple function that does either
PeekMessage or GetMessage depending on an argument would remove a lot of
redundant code, for example the new function checkEvents(hwnd,
peekmessage) would do the current Dialog() code with PeekMessage if
peekmessage was set to 1, otherwise it'd do GetMessage, and the Dialog()
and DoEvents() methods could be truncated to:
Well, the exit condition is different too, not just the call to
GetMessage vs PeekMessage. But that also could be based on the
"argument". I agree there is much redundant code there, also see DoModal.
DWORD
Dialog(hwnd=NULL)
HWND hwnd
CODE:
RETVAL = checkEvents(hwnd,0);
OUTPUT:
RETVAL
DWORD
DoEvents(hwnd=NULL)
HWND hwnd
CODE:
RETVAL = checkEvents(hwnd,1);
OUTPUT:
RETVAL
Steve
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--
Glenn -- http://nevcal.com/
===========================
Like almost everyone, I receive a lot of spam every day, much of it
offering to help me get out of debt or get rich quick. It's ridiculous.
-- Bill Gates
And here is why it is ridiculous:
The division that includes Windows posted an operating profit of $2.26
billion on revenue of $2.81 billion.
--from Reuters via
http://biz.yahoo.com/rc/031113/tech_microsoft_msn_1.html
So that's profit of over 400% of investment... with a bit more
investment in Windows technology, particularly in the area of
reliability, the profit percentage might go down, but so might the bugs
and security problems? Seems like it would be a reasonable tradeoff.
WalMart earnings are 3.4% of investment.
