hsvandrew

Just wondering if anyone has gotten printing to work from Delphi (FMX, FMXLINUX) with recent Delphi versions i.e. 12.3 and recent Linux builds i.e. Ubuntu 24.

For example, on both Ubuntu 24 & Amazon Linux 2023 I used Gnome settings UI to install a printer.

Under the lpq command the printer shows. Printing works in other Gnome apps i.e. Text Editor - the device is shown.

In Delphi (12.3), the printer list only contains an entry called '.pdf'

If I use a PrintDialog/PrintSetupDialog, the app crashes

When I use Lazarus, which is free, all of the above work perfectly.

I've used TNetHTTPRequest to setup a request with headers successfully like this:

NetHTTPRequest1.CustomHeaders['Content-Type'] = 'text/html';

Typical object setup is like this

  NetHTTPClient1 :=  TNetHTTPClient.create(nil);
  NetHTTPRequest1 := TNetHTTPRequest .create(nil);
  NetHTTPRequest1.Client := NetHTTPClient1;

Usage

NetHTTPRequest1.post( url , data , outcome );

Instructions for linux can be a bit tricky because there are slight differences between versions.

If the above doesn't work for you, like it didn't for me on Centos9 (October 2024),

install the yum packages as per the script above

Find your python 3 library using

sudo find / -name libpython3*.so*

For example, mine was /usr/lib64/libpython3.9.so.1.0

Run the symbolic link command (ln) as in the script, but using the correct path as you found using find.

You might find multiple libpython files. You want the one that looks similar to mine.

Hope this helps someone.

The Delphi VCL is not multi-threaded. The code that's running to create all those forms will block code like your animation from working.

Its rarely a good idea to actually 'create every form' on startup like this. I know that's how Delphi does it, but its less than ideal.

App startup will either be slow because

You have some code running in an initialization section somewhere, either in your code or the many libraries you may be using.

You have a database connection on a form, perhaps to a database that may not be connectable, and this is causing a delay until it times out when creating a form

Generally I would suggest these principles:

Create forms when they are first used rather than at startup or during an idle stage when the user won't notice

Move operations that aren't VCL/drawing related into threads, allowing the UI to still update whilst they run i.e. disk operations, database operations etc

If these things don't work, even though it will have other impacts, you could consider creating a launcher app that shows the splash screen whilst then launching the real app.

This will cause a few issues with taskbar/icons etc, but maybe a solution for a very slow startup that can't otherwise be coded around with the above 2 suggestions.

Delphi can sometimes encourage people to create enormous forms with thousands of components. This is the only reason I can think of in a modern computing environment other than an IO delay for any noticeable 'load time' during creation of forms on startup.

Hi Jim,

To handle parameters built into the URL rather than as query parameters you'll need to do the following:

Assign a partial path to the 'pathInfo' of your WebModule Action i.e.

/getname/*

Then, in your ActionHandler you'll want to access the path part of the URL, break it into an array split by / and then execute based on the parts that matter

var paths: TArray<string> = Request.PathInfo.split(['/']);

//Check array length etc

if sameText(paths[2],'add') then //Do add function

else if sameText(paths[2],'delete') then //Do add function

object.delete( paths[3] );

Hope that makes sense. I haven't tested this exact code so there might be slight syntax issues.

On 1/10/2024 at 11:16 PM, Brian Evans said:

More than just not ideal. Logging should have minimal impact which means introducing lock contention is counterproductive. The locks will change the runtime behaviour of the processes introducing coupling, uncertainly and variance. Performance issues will have admins turn off logging in production then when issues need to be investigated turning it back on means the processes behave differently frustrating attempts to reproduce those issues. 

 

Most go with one of:

1) One log file per process + read them into a combined view as needed. 

2) A logging process of some sort that other processes send log message to.   

I agree with you. I just have to create a solution within a team where someone higher than me doesn't get this 🙂

I don't know how much access to this server you have, but I would start by connecting to its console session either physically or via something like Anydesk and logging in there, then running your app to see how the base operating system settings are affecting your application. This will then determine if its ONLY via RDP or across the entire machine.

If you determine its only in RDP, review the settings in the remote desktop connection (MSTSC) app, by selecting LAN (10mbps or higher) and ensuring all are ticked ON

It is also possible for a system admin to disable some of these options server side via policy.

I'm just wondering how others have created system wide locks to manage sharing a resource such as a single log file with multiple processes (I know, not ideal)

Two examples are as follows:

{$IFDEF useSemaphore}
procedure systemWideLock( name: string; proc: TProc; timeout: integer = 0 );
var
hSem: THandle;
nameWS: array[0..255] of WideChar;
begin
  StringToWideChar(name,nameWS,254);
  hSem := CreateSemaphore(nil,1,1,nameWS);
  try
    WaitForSingleObject(hSem,INFINITE);
    proc();
  except
  end;
  ReleaseSemaphore(hSem,1,nil);
end;
{$ENDIF}

{$IFDEF useFile}
procedure systemWideLock( name: string; proc: TProc; timeout: integer = 0 );
var
fs: TFileStream;
locked: boolean;
begin

  locked := false;
  while not locked do
  begin
    try
      fs := TFileStream.create('C:\temp\File.lock',fmCreate);
      locked := true;
    except
    end;
    sleep(random(3)); // can be removed
  end;

  try
    proc();
  except
  end;
  FreeAndNil(fs);
end;
{$ENDIF}

The challenge with the Semaphore, whilst being a much faster mechanism, is that, if for some reason code execution gets stuck between lock and unlock (let's say a dialog appears in a silent process or the process gets into an endless loop), end tasking the application will not release the semaphore, resulting in the need to reboot Windows.

The file approach seems to work better in that a file lock releases when the process terminates (apparently timing might vary but it happened ok in my testing), and you can argue if the sleep should be removed or the time changed, but either way its orders of magnitude slower.

Are there any other lock types that could be used that release upon process termination?

On 11/12/2023 at 3:37 AM, dummzeuch said:

I'm not sure it is a joke. Even today there are so many people with superstitions around, that releasing a version containing the number 13 might actually cost them some customers. I even have the impression this part of the population is growing rather than shrinking.

Or maybe, after the failures that have been 10.4,11 and 12, 13 could buck the trend and the show superstition for what it is and be amazing... Like do people really think the gods don't know you're staying on the forth floor even if the humans didn't number it 4?

First impressions of the installer: someone from 1990 tried to replicate the modern Visual Studio installer and failed. Looks ugly and embarrassing. Proportions are wrong, padding is wrong, looks amateur.

Let's see if Code Insight finally works as we haven't been able to upgrade since 10.3.3....

Just in-case it helps someone, I've spent hours trying to work out why my TEdgeBrowser (chromium) was blank in one app, whilst working fine in the simple demo app.

Turns out CoInitializeEx(nil,COINIT_MULTITHREADED); will stop TEdgeBrowser from working.

This adjustment replaces CEF4Delphi, where this method was called and all worked ok.

Of course you also need the WebView2Loader.dll in the same folder as your application and to have installed Chromium Edge.

For the future benefit of anyone having a similar problem, here is the solution and possible keywords for resolution.

The code/freeware/project I was using was uTLibVLC
FDllHandle was declared as an integer. I suspect the clue to help me realise there was a problem was that LoadLibrary for the libvlc.dll resulted in a negative integer whereas the other DLL's had positive handles i.e. integer overflow

Changing FDllHandle    : integer; to FDllHandle    : HMODULE; fixed the problem.

Does anyone have VLC player (the 64bit DLL) working in Delphi?
I load the 64bit DLL like this
DLL := ‘C:\Program Files\VideoLAN\VLC\libvlc.dll’;
FDllHandle := LoadLibrary(PChar(ExtractFilePath(DLL)+‘libvlccore.dll’));
FDllHandle := LoadLibrary(PChar(DLL));

But all the GetAProcAddress functions fail, even though I can see the exports in the DLL.

I don't know if its just Delphi developers that are negative on ChatGPT but it does seem fairly unreasonable.

Firstly, our IDE struggles to put begin's and ends and other basic structures in place at present, yet a newish product in its early versions can be given an english statement about what you require and knock out code in multiple languages. 

For example you can ask it to write a class about a patient going to hospital or ask it to show a delphi example of how a function in curl might be coded.

Sure, not every output of code is perfect in every day but seriously, show me the previous system that was even close to this amazing and giant step in computing.

This breakthrough is as least as important as the internet and iPhone were to changing the world.

If you watch this video and don't see how much this is going to impact business systems, something is wrong with you.

Thank you @Achim Kalwa I hadn't installed that part of the excellent work by Andreas Hausladen (I use the other critical bits).

Still amazes me that these key failures never get actually fixed. Even the alpha sort option doesn't actually work properly.

Is there an option (or plugin) to get class completion to work in a way where all new procedures & functions will appear at the bottom of the unit or in the same order as its declared, rather than in some kind of alpha sorted location?

The help topic https://docwiki.embarcadero.com/RADStudio/Sydney/en/Using_Class_Completion says "If your declarations and implementations are sorted alphabetically, class completion maintains their sorted order. Otherwise, new routines are placed at the end of the implementation section of the unit, and new declarations are placed in private sections at the beginning of the class declaration."

But I don't really know what this means in practice and I can't find any logical settings to control the behaviour...

Example:

TFoo = class(Tobject)

public

//Containers

procedure Zoo;

//Animals

procedure Cat;

procedure Dog;

end;

I want the same order to be preserved when creating the implementation.

In my opinion hot reload is probably the most significant improvement to development since the Delphi IDE made VB look ancient.

Developers are very expensive, and there are never enough hours in the day. 

For some reason developers spend all day making productivity tools for others, but seem to still work with spades instead of bulldozers.

I can see this feature being worth at least $5000USD/year/developer which is a game changer.

The fact the Delphi community doesn't see how important this is, well, it says a lot. 

In my view, this is how the future Delphi products should be designed.

https://www.canva.com/design/DAEr0Sff_lA/42dTO0oDSOAcvWEN0oDA6g/view?utm_content=DAEr0Sff_lA&utm_campaign=designshare&utm_medium=link&utm_source=sharebutton&fbclid=IwAR0vPdkL1g_ckz9rwLzsLEM2Z-kJrB5WnS_lKHTL37F7QzL5QHAm1XxJqYo#8

I really hope that we could have a discussion about this as a community. Review the presentation. Compliment any good ideas. Ask questions. Question things constructively. Discuss different ways.

@Cristian Peța From what I can see ICU is available (IsICUAvailable returns true)

As many Delphi developers we have a knowledge base of all the quirks on Windows. I feel this is going to be a learning experience to discover the quirks of Linux.

This to me is a dangerous issue that needs to be understood because it could have all sorts of unintended and very hard to track down bugs, especially when the problem disappears as soon as you run it on Windows or Linux console.

I suspect the same problem will be affecting many string handling functions and probably other functions as well.

On 12/21/2018 at 2:48 AM, Yaron said:

But how do you apply it to use with Delphi which in the docs says that the PAserver needs to be in a local network?

 

Is there some help/docs on Delphi integration with such services for iOS development?

You simply need the hosting provider to allow you to VPN to the cloud network running the Mac.

However, if you want to make a good iOS app you'll need to do your testing on a real device: you just can't get the 'feel' of an app without touching it.

If you want to develop cheaply for iOS you would be using Xcode + HTML + JS or similar. As you've already paid a huge amount of money for Delphi, a Mac should be somewhat affordable.

This issue has now been updated to show the offending function. Under the operating environment above, the result of this code is -1

Does anyone know why this might happen?

procedure TWebModule1.WebModule1DefaultHandlerAction(Sender: TObject;
  Request: TWebRequest; Response: TWebResponse; var Handled: Boolean);
begin
  response.contentType := 'text/plain';
  response.content := 'AnsiCompareText(''PARAMname'',''paramNAME'') ) = ' + inttostr(AnsiCompareText('PARAMname','paramNAME'));
end;

On 1/15/2019 at 5:52 PM, Andrea Magni said:

 

There's no entry for my MARS REST library (https://github.com/andrea-magni/MARS) in your poll...

I am happily doing web backend development since years, using DataSnap at first. Using MARS since it exists 😉

 

Apologies @Andrea Magni I wasn't able to edit the survey once it collected results and I wasn't aware of the MARS REST Library

On 1/6/2019 at 12:28 AM, Uwe Raabe said:

Given that file access is almost sequential (remember how hard drives work), I assume that the OS will serialize those parallel tasks in the end anyway. But perhaps I am just missing something.

I'm not sure that I agree with this comment. Any memory based storage i.e. SSD, Memory Sticks etc can perform multiple operations at the same time. There is no head to move and multiple parts can be written or changed at the same time.

So yes, using a thread would be very helpful. You should create a queue (pool) that receives files to delete, and another process that scans directories. This way you won't need to wait before the directory scan is done to start removing things. You may even want to consider the low level features Everything by Voidtools uses to get the directory structures/file structures faster than FindFirst.

We are having a problem with a devart control which may in the end be something funny they did wrong but the behaviour seems strange and more like a low level issue.

Basically, the standard SQL Query control contains a simple SQL statement i.e. 

thisQuery.SQL.text := 'select * from emp where job = :PARAMname';
thisQuery.ParamByName('paramNAME').asString := 'new';
thisQuery.open;

On Windows VCL, console etc and on Linux as a console app this works as expected (param is case insensitive as expected)

When the exact same code is compiled into a generic brand new Delphi Apache Module and ran on the exact same machine as the console test app, the query fails unless the param is the same case in the SQL statement as it is in the ParamByName function.

This seems strange to me.

Does anyone know of any kind of Linux operating system quirk where the host application could override a function in such a way that you might expect this type of behaviour?
 

Returns a blank string, yes logged 

https://quality.embarcadero.com/browse/RSP-17838