The Wiert Corner – irregular stream of stuff

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

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Archive for the ‘Delphi’ Category

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Delphi annoyance: in debug mode, no breakpoints are being adhered to, no blue bullets

Posted by jpluimers on 2019/04/16

For all Delphi Galileo versions (the BDS based Delphi versions: 8 until now), I have bumped into this annoyance:

Over time, while working on an application, running it in DEBUG mode in the debugger, wil not fire any breakpoints and all blue bullets (meaning the lines have code generated) are gone.

There are no warnings or (error) dialogs leading to this situation.

The only remedy is to quit Delphi, start it again, then do a full rebuild of the application.

Of course this happens more often with large applications than with small ones.

Is there anyone who has a reliable method to:

  • signal this before it happens
  • workaround it in a better way

–jeroen

Posted in Delphi, Development, Software Development | 1 Comment »

delphi – IfThen(Assigned(Widget), Widget.Description, ‘No Widget’) doesn’t crash. Should it? – Stack Overflow

Posted by jpluimers on 2019/04/16

Very interesting question [WayBack] delphi – IfThen(Assigned(Widget), Widget.Description, ‘No Widget’) doesn’t crash. Should it? – Stack Overflow.

Three important things here:

  • depending on inlining and kind of arguments, function calls can evaluate their arguments one or multiple times
  • lacking formal language specification, you never know if a method will be inlined or not
  • function calls should not have side effects

Via another interesting discussion at [WayBack] Inline functions are not guaranteed to evaluate their arguments exactly once… – David Heffernan – Google+

–jeroen

Posted in Delphi, Development, Software Development | Leave a Comment »

including enumerations and JPEG compression examples for wPDF 4 Manual: Compression related properties

Posted by jpluimers on 2019/04/11

Since I was tracking down an issue having to to with generating DIB in a compressed PDF: [Archive.is] wPDF 4 Manual: Compression related properties

Property CompressStreamMethod

By modifying this property you can let the PDF engine compress (deflate) text. By using compression the file will be reasonable smaller. On the other had compression will create binary data rather than ASCII data. While “deflate” produces the smallest files, “run-length” compression is compatible even to very old PDF reader programs.

Property JPEGQuality

wPDF can compress bitmaps using JPEG. This will work only for true color bitmaps (24 bits/pixel) and if you have set the desired quality in this property.

Property EncodeStreamMethod

If data in the PDF file is binary it can be encoded to be ASCII again. Binary data can be either compressed text or graphics. You can select HEX encoding or ASCII95 which is more effective then HEX.

Property ConvertJPEGData

Note: Only applies to TWPDFExport.

If this property is true JPEG data found in the TWPRichText editor will not be embedded as JPEG data. Instead the bitmap will be compressed using deflate or run length compression. It is necessary to set this property to TRUE if the PDF files must be compatible to older PDF reader programs which are incapable to read JPEG data.

Note that EncodeStreamMethod does not do compression, but it does belong here because the encodings result in different PDF sizes.

The settings are not documented in more detail, so here are the enumerations explaining them in a bit more depth:

–jeroen

Posted in ASCII95, Delphi, Development, Encoding, HEX encoding, Software Development | Leave a Comment »

Some notes on Testinsight Issues

Posted by jpluimers on 2019/04/10

So I won’t forget:

Note to self:

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Posted in Delphi, Development, Software Development, TestInsight | Leave a Comment »

ILockable/TLockable/Lockable. Similar to IManaged in Spring4D, but provides a Locked interface.

Posted by jpluimers on 2019/04/10

Had to use this to start solving threading issues in a project I inherited a while ago in a temporary way before doing a huge refactoring. Will likely need it in the future as well: ILockable/TLockable/Lockable. Similar to IManaged in Spring4D, but provides a Locked interface..

ILockable/TLockable/Lockable. Similar to IManaged(now IShared) in Spring4D, but provides a Locked interface.

Note this is very inefficient, but can be practical as a shotgun approach to start solving the mess when you inherit a project that has the “I know, I’ll use threads!” approach in it.

Replace the resource typed TNeedsLock that needs protection with a ILockable<TNeedsLock>, then route all references via a call to the Locked()() call to it.

If you need a simpler approach, then use [WayBack] Interfaced monitor lock — Bitbucket by Stefan Glienke.

–jeroen

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Posted in Conference Topics, Conferences, Delphi, Development, Event, Multi-Threading / Concurrency, Software Development | Leave a Comment »

Detecting the Delphi edition that is installed

Posted by jpluimers on 2019/04/09

Via [WayBack] In what ways can you detect which edition of Delphi in installed from the installed files? I’m trying to distinguish between Standard, Professional, E… – Jeroen Wiert Pluimers – Google+

Different Delphi editions have different msbuild support files. For instance IDL is only available in Enterprise/Architect/Ultimate (which use the exact same binaries anyway).

IDL is old, see

So I updated my [WayBack] jeroenp / wiert.me / Run-Dependend-rsvars-From-Path.bat — Bitbucket (which besides running rsvars.bat, can start the various Delphi IDE personalities, or run msbuild with various configurations) with [WayBack] jeroenp / wiert.me / commit / 2c55fa1bf786 — Bitbucket:

Support 10.1 Berlin and 10.2 Berlin in Run-Dependend-rsvars-From-Path.bat, as well as Professional/Starter editions.

Thanks to Andrea Magni – Google+, Querying was simple: look for the value of the Edition entry under inside the *\X\BDS\Y.0 where Y is the BDS version, X is Borland, CodeGear or Embarcadero (depending on the BDS version) and * is the base key HKEY_CURRENT_USER\Software, HKEY_LOCAL_MACHINE\SOFTWARE , HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node.

–jeroen

Posted in Delphi, Development, Software Development | Leave a Comment »

When generics and VCL controls bite you: memory overwrites when you show the control usually ending up in access violations

Posted by jpluimers on 2019/04/09

Recently I got bitten by the 2013 reported http://qc.embarcadero.com/wc/qcmain.aspx?d=112101 (too bad the site is gone and the WayBack machine doesn’t have it archived) as a result of [WayBack] delphi – Why do I get access violations when a control’s class name is very, very long? – Stack Overflow.

It got reentered as [RSP-18399] Buffer overflow in TWinControl.CreateParams() – Embarcadero Technologies but since that requires logon, it’s not search machine indexed so it’s very hard to find unless you know where to look.

So I spent a quite some time to find out what was wrong:

Since Delphi 1, the [WayBack] Controls.TCreateParams Record has a 64-byte WinClassName field that’s blindingly copied by the TWinControl.CreateParams without range checking.

The structure is used by the [WayBack] TWinControl.CreateWnd Method to call the Windows API [WayBack] RegisterClass function that takes a [WayBack] WNDCLASS structure with a lpszClassName field that supports up to 256 characters and it fails when it’s longer.

That overwrite cause spurious other errors depending on the memory that gets overwritten. It took almost a day to figure out the cause of the error was this field, then an hour or to track that down to the long class names created by generic code.

To my surprise, I found back [WayBack] This issue caused coworkers and me quite a few hours wasted:Long story short – refactor some forms/frames to class names longer than 64 chars and boom… – Stefan Glienke – Google+.

As of Delphi 8 (yes, that version that a lot of people want to forget, but did bring a few good things), the structure was defined as below, and the code intialising also got improved:

Params.WinClassName := ClassName;
...
Params.WinClassName := Format('%s.%d', [Params.WinClassName, AppDomain.CurrentDomain.GetHashCode]);

So there it’s a string that – if it is too long – will get rejected by the Windows API anyway just like the native Delphi VCL implementation should have done 20+ years ago.

The sad part for FMX users: that structure and code got blindingly copied to the FMX.Controls.Win unit.

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Posted in Delphi, Development, Software Development | Leave a Comment »

Detecting if a debugger is present is different from detecting if an IDE is present.

Posted by jpluimers on 2019/04/04

I have seen this happen in various environments: people wanting to detect if their debugger is present, but trying to detect their IDE, or vice versa.

Similar reasoning is for detecting for being running on a console, or your project having been built to run on a console.

People use these decisions, for instance to determine if their application should behave as a service, or as a regular process.

Ways to determine the various permutation points:

  • Running inside a debugger: use the [WayBack] IsDebuggerPresent function (which can be true, even if Delphi DebugHook stays zero).
  • Check for the IDE: tricky; as IDEs have different behaviour over time. For Delphi, check for any TAppBuilder Window class with the [WayBack] FindWindow function.
  • Compiled for console: for Delphi check IsConsole, for .NET I could not find good information.
  • Running on a console: check if you can allocate a handle to stdout
  • Running as a service: check the hosting assembly or hosting process

Related links:

–jeroen

Posted in .NET, Delphi, Development, Software Development, Windows Development | Leave a Comment »

Firemonkey/Isometric at master · tothpaul/Firemonkey

Posted by jpluimers on 2019/04/04

This shows you how to do 2.5D isometric projection in Delphi using Firemonkey: [WayBack] Firemonkey/Isometric at master · tothpaul/Firemonkey.

[WayBack] Isometric projection – Wikipedia.

Via: [WayBack] I wonder what the best approach would be to use FireMonkey to develop an isometric 2.5D game in the “classic” way… – Fl Ko – Google+

–jeroen

Posted in Delphi, Development, FireMonkey, Software Development | Leave a Comment »

Delphi: do NOT use duplicate GUIDs on interfaces

Posted by jpluimers on 2019/04/04

One of the things when fixing bugs in an old codebase is wading through technical debt.

A quick win is to get rid of duplicate GUIDs when interface portions have been copy-paste re-used:

  1. interfaces with the same GUID are treated the same with as casts even if they are different.
  2. the compiler does not warn about duplicate GUID values**

These searches help big time: it shows the duplicate GUIDs if they have been indented all the same way. Good enough for most situations.

grep -Sh "\[\'{" *.pas | sort

grep -rh "\[\'{" *.pas | sort

It depends which flavour of grep you use (gnu or regular) to specify recursion.

Note that findstr doesn’t cut it as it always shows the filename: [WayBack] List files recursively showing only full path and file size from Windows Command Prompt – Super User

** this compiles without warning:

program NoWarningOnDuplicateInterfaceGUID;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils;

type
  IInterface1 = interface
    ['{ECF26C39-CBFF-488E-A3AB-2629726F1005}']
  end;

  IInterface2 = interface
    ['{ECF26C39-CBFF-488E-A3AB-2629726F1005}']
  end;

var
  Subject: IInterface;
begin
  try
    (Subject as IInterface1)._Release;
    (Subject as IInterface2)._release;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.

–jeroen

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Posted in Delphi, Development, Software Development | Leave a Comment »

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