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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘Delphi 8’ Category

“Don’t access VCL from a background thread” – how to demo that?

Posted by jpluimers on 2018/07/11

When accessing the VCL from multiple threads at the same time: adopted from ...\DEMOS\THREADS\THRDDEMO.DPR

When accessing the VCL from multiple threads at the same time: adopted from …\DEMOS\THREADS\THRDDEMO.DPR

Great question a while ago:

[WayBack] “Don’t access VCL from a background thread” – how to demo that? – Primož Gabrijelčič – Google+

For me, the ultimate way why not to access the VCL from a background thread is the precursor of the official threads demo that ships from Delphi 2 to Delphi XE6 in ...DEMOS\THREADS\THRDDEMO.DPR. where you’d think the thread isolation would be in ...DEMOS\THREADS\ThSort.pas but actually is in ...DEMOS\THREADS\SortThds.pas.

The first public showing of that demo did not include main thread protection. It originates from a session at the the 1995 Borland Developers Conference where Ray Konopka showed the below code from Bob Ainsbury.

That session reminded why this joke [WayBack] Via the EKON20 sessions… – Jeroen Wiert Pluimers – Google+ was so funny:  “When Ray Konopka enters the room you have a Raize condition.“.

The question above also made me find back this reference to BorCon95 in San Diego:

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Posted in Delphi, Delphi 10 Seattle, Delphi 10.1 Berlin (BigBen), Delphi 10.2 Tokyo (Godzilla), Delphi 2, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi 3, Delphi 4, Delphi 5, Delphi 6, Delphi 7, Delphi 8, Delphi x64, Delphi XE, Delphi XE2, Delphi XE3, Delphi XE4, Delphi XE5, Delphi XE6, Delphi XE7, Delphi XE8, Development, Software Development | 2 Comments »

Delphi history – on the FINITEFLOAT compiler option that has no one-character shortcut

Posted by jpluimers on 2016/12/14

Back in the .NET days, Delphi had an FINITEFLOAT compile option that came without a single-character shortcut.

It was about the handling of infinite float and other special float values in cases like overflow and underflow (including +Inf, -Inf and  NaN).

At first – in the Delphi 8 (Octane) era of which few people want to be reminded off – it was the undocumented counterpart of the 8087 exception mask in x86 mode. Hallvard Vassbotn wrote an article about it and Chee Wee Chua documented it before it got documented in Delphi 2009 (that coincidentally dropped .NET support in the compiler – go figure):

Whereas the native Delphi compilers had exceptions turned on, Microsoft compilers (including .NET) had them turned off, hence the compiler option.

Like most new Delphi features in this century, FINITEFLOAT didn’t come without quirks. Often these are fleshed out in 2-3 product releases, but this one wasn’t:

The FINITEFLOAT compile option didn’t have a single-character shortcut. This made it impossible to use the {$IFOPT ...} construct as IFOPT only works for single-character compiler options.

Which means you get questions like Why doesn’t {$ifopt FINITEFLOAT ON} compile? – Stack Overflow (I actually got into writing this article because I found a {$DEFINE FINFINITEFLOAT_ENABLED} in some pretty old code) and compiler enhancement requests like [WayBack] QualityCentral – Please enhance the IFOPT directive for long switch names. It’s easier to read (which will likely never bee fixed).

For completeness some more information about exception masks in the native compiler:

  1. In the past you could only set the exception mask as part of the full control word using Set8087CW, nowadays you can use SetExceptionMask.
  2. Next to a precision mask, there are five exception masks you can set, see for instance this table from the Simply FPU Chap.1 Control Word section:

PM (bit 5) or Precision Mask
UM (bit 4) or Underflow Mask
OM (bit 3) or Overflow Mask
ZM (bit 2) or Zero divide Mask
DM (bit 1) or Denormalized operand Mask
IM (bit 0) or Invalid operation Mask

–jeroen

Posted in 8087, Algorithms, Delphi, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 8, Development, Floating point handling, History, QC, Software Development | 1 Comment »

Workaround for Printing from Delphi (or the Delphi IDE): three strikes and you get “Printer is not currently printing.” – yes I mentioned “Delphi 8!”

Posted by jpluimers on 2016/08/31

Recently when printing the 3rd time and up, you get this error in many Delphi programs and the Delphi IDE:

Printer is not currently printing.

Printer is not currently printing.

In the past this only occurred when you used a TPrinter and forgot to call BeginDoc.

But now it always occurs after reusing the same TPrinter instance for the 3rd time and up. Since the Delphi Galileo based IDEs (8 and higher; likely older ones as well: the source code printing hasn’t changed in a long time). The error actually occurs twice: after starting a source code print job, but also after cancelling the same failed source code print job.

The second error stroke me as odd, so I went searching for “printer is not currently printing” “IDE” leading to this stack overflow question: c++builder – Why is TPrinter (XE7) suddenly having problems today? – Stack Overflow [WayBack].

The pattern there is using the Printer() function which has been the way the (un)official code examples have shown for ages (Delphi 2007 Printers.Printer Function [WayBack]; earlier examples like Delphi 7 [WayBack] usually in PDF files).

Like in the Delphi 7 “5-32 Developer’s Guide” page example:

procedure TForm1.Button1Click(Sender: TObject); 
var
  r: TRect;
  i: Integer;
begin
  with Printer do
  begin
    r := Rect(200,200,(Pagewidth - 200),(PageHeight - 200)); 
    BeginDoc;
    Canvas.Brush.Style := bsClear;
    for i := 0 to Memo1.Lines.Count do
      Canvas.TextOut(200,200 + (i * Canvas.TextHeight(Memo1.Lines.Strings[i])),
    Memo1.Lines.Strings[i]); 
    Canvas.Brush.Color := clBlack;
    Canvas.FrameRect(r);
    EndDoc; 
  end;
end;

(Yes, that’s back in the D7 days when examples were still using with and not using try/finally statements for resource cleanup).

Actual cause and permanent fix

The printing problems are caused by various recent Windows updates part of MS16-098:

Though MS16-098: Security update for Windows kernel-mode drivers: August 9, 2016 mentions the issue without a fix, KB3177725 in MS16-098: Description of the security update for Windows kernel-mode drivers: August 9, 2016 mentions both the issue and a permanent fix:

After you apply this security update and you print multiple documents in succession, the first two documents may print successfully. However, the third and subsequent documents may not print.

To resolve this issue, install update 3187022. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

3187022 Print functionality is broken after any of the MS16-098 security updates are installed

This article describes printing issues that occur after any of the security updates that are described in Microsoft Security Bulletin MS16-098 are installed in Windows. You can fix these issues by installing the update that is described in this article. Before you install this update, check out the Prerequisites section.

This update applies to the following operating systems:

  • Windows Server 2012 R2
  • Windows 8.1
  • Windows RT 8.1
  • Windows Server 2012
  • Windows Server 2008 R2 Service Pack 1 (SP1)
  • Windows 7 SP1
  • Windows Server 2008 Service Pack 2 (SP2)
  • Windows Vista SP2

No solution for Windows 10 yet…

Until you install the fix: workarounds

For your own code (Thanks Remy Lebau for your answer), add this code for your BeginDoc call:

MyPrinter.Copies := MyPrinter.Copies;

You might want to keep including this in your code as you’re never sure when the end-users apply which Windows update.

For the Delphi IDE either:

  1. Press the “Setup…” button in the “Print Selection” dialog when printing source code, then “OK” in the “Print Setup” dialog:
    Print Selection dialog

    Print Selection dialog

    “Print Setup” dialog.

  2. Uninstall the security updated marked in blue (Security Update for Microsoft Windows (KB3177725):

    Security Update for Microsoft Windows (KB3177725)

    Security Update for Microsoft Windows (KB3177725)

–jeroen

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Posted in Delphi, Delphi 10 Seattle, Delphi 10.1 Berlin (BigBen), Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi 8, Delphi XE, Delphi XE2, Delphi XE3, Delphi XE4, Delphi XE5, Delphi XE6, Delphi XE7, Delphi XE8, Development, Software Development | 2 Comments »

Canonical overview on Writing to the Windows Event Log using Delphi – Stack Overflow

Posted by jpluimers on 2016/07/26

A while ago, StackOverflow user Kobus Smit did some brilliant editorial work that – due to current state of StackOverflow – sort of fired backwards: his question got marked as duplicate before he could post his excellent answer. After that answer was posted, the oh-so pride SO-demi gods never took any energy to revisit to see which answers were best.

His simple question:

How can my Delphi app easily write to the Windows Event Log?What is the difference between TEventLogger and ReportEvent? How do I use the ReportEvent function?

Which somehow should be encompassed by this Delphi 5 question (apparently that 15+ year old Delphi version is still considered current by the SO demi-gods).

The answer summarises and extends existing answers spread out over StackOverflow and adds an EventLog git repository wrapping the ReportEvent and RegisterEventSource (which somehow is always a pain: Delphi services for instance often forget that).

Lesson learned when doing editorial work:

  1. prepare both the answer and question in markdown off-line
  2. ensure you mention in the question that the answer is meant as collection of “best of” answers found elsewhere
  3. post the question and answer in rapid succession
  4. cross your fingers for the StackOverflow demi-gods being in a good mood

–jeroen

via: Writing to the Windows Event Log using Delphi – Stack Overflow

Posted in Delphi, Delphi 10 Seattle, Delphi 10.1 Berlin (BigBen), Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi 5, Delphi 6, Delphi 7, Delphi 8, Delphi XE, Delphi XE2, Delphi XE3, Delphi XE4, Delphi XE5, Delphi XE6, Delphi XE7, Delphi XE8, Development, Software Development | 1 Comment »

Happy birthday Delphi, have some wine

Posted by jpluimers on 2016/02/14

Now that you’re 21, have a glass of wine and watch this great presentation by Warren Postma which he made for last years birthday:

–jeroen

Posted in Delphi, Delphi 1, Delphi 2, Delphi 2005, Delphi 2006, Delphi 2007, Delphi 2009, Delphi 2010, Delphi 3, Delphi 4, Delphi 5, Delphi 6, Delphi 7, Delphi 8, Delphi x64, Delphi XE, Delphi XE2, Delphi XE3, Delphi XE4, Delphi XE5, Delphi XE6, Delphi XE7, Delphi XE8, Development, Software Development | Leave a Comment »

 
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