MDI Application problem

[PeterX]

MDIsimulator06.zip

works better than before, but I still have trouble
finding the right place in the source code
for storing / reloading "OldPosition" ..

[PeterX]

Changes from minimized to normal to (simulated) maximized and back. This works now.

[PeterX]

I am waiting since about 2016 for a working MDI in LCL (win32).
With a - very very old - large project in my hands, born under Delphi 5, twenty years ago.
But until today I never had the knowledge of how to implement MDI, or how to simulate it.

Just a remark: MDI applications are deprecated (by microsoft) for the past 20 years ..

I still do not understand why people make such general statements like that.
Indeed I would never recommend starting a new Project based on MDI today.

=> https://docs.microsoft.com/en-us/windows/win32/winmsg/multiple-document-interface
The official Microsoft Website does indeed no more recommend MDI, yes.
"Many new and intermediate users find it difficult to learn to use MDI applications.
Therefore, you should consider other models for your user interface."

But Microsoft would terminate all the apps out there that still use MDI
if they would wipe out native MDI support in Windows.

Microsoft explains us - statement from date 05/31/2018:
"However, you can use MDI for applications which do not easily fit into an existing model."
https://docs.microsoft.com/en-us/windows/win32/winmsg/multiple-document-interface


Microsoft has never improved MDI anymore (I think ..) over the last years
because it's a "dead" user interface.
But Microsoft has never stopped supporting MDI in Windows OS.

MDI applications ... never worked well with Lazarus.

I can agree with that.

But, as even old Delphi 5 compiled MDI applications do still work (more or less ..),
this is a Lazarus LCL win32 widgetset issue, not a Microsoft issue.


So I hope, my "MDIsimulator" helps out a little bit here, keeping some old MDI projects alive.
Or the existing win32 MDI code in Trunk is committed for a upcoming Lazarus Release Version one day ..

( Hint:  in  "MDIsimulator" Forms do not set Mainform to fsMDIForm / ChildForm to fsMDIChild - this is not real MDI ! )

[PeterX]

The trunk has working MDI for windows.

I tried this today .. works !

[jamie]

Years ago with smaller res screens the MDI didn't always work well for users but since many now have far more screen res you can now build MDI apps with lots of childs in the parent and still have room..

[PeterX]

            

Everybody wants this back:

[jamie]

Lets not get carried away! 

[bpranoto]

Wow cool,

Will it work on other platform? It will be great if you publish your work. Thanks

[PeterX]

Wow cool,

Will it work on other platform? It will be great if you publish your work. Thanks

I already attached my example "MDIsimulator" as sourcecode in earlier posts here.
But "MDIsimulator" is only a playground for trying to simulate MDI behavior under Windows.
I don't know how far this maybe works on other platforms. Please download and try.


I did not do any work inside Lazarus LCL sources.
So I'm sorry, I cannot publish anything else.

The Multi Document Interface thing inside Lazarus that I was talking about
in my latest posts, is the win32 widgetset. Windows only.
And currently exists in Trunk only (developer version), not in the current 2.0.12 Lazarus.
=>
https://wiki.lazarus.freepascal.org/Getting_Lazarus#Getting_Lazarus_from_Subversion_server


For MDI You could try qt5 widgetset - which is said to be working under Windows, Linux and MacOS.
But I know nothing about that widgetset ..
=>
https://wiki.lazarus.freepascal.org/Qt5_Interface

[bpranoto]

I already attached my example "MDIsimulator" as sourcecode in earlier posts here.
But "MDIsimulator" is only a playground for trying to simulate MDI behavior under Windows.
I don't know how far this maybe works on other platforms. Please download and try.

It doesn't compile in Linux. After commenting out Windows uses clause, I got this:

Code: Pascal  [Select][+][-]

1. Compile Project, Target: exeOutput/MDIsimulator: Exit code 1, Errors: 6
2. subunit.pas(46,37) Error: Identifier not found "TWMSysCommand"
3. subunit.pas(46,61) Error: Identifier not found "WM_SYSCOMMAND"
4. subunit.pas(46,74) Error: Illegal expression after message directive
5. subunit.pas(47,48) Error: Identifier not found "TWMWindowPosChanging"
6. subunit.pas(47,79) Error: Identifier not found "WM_WINDOWPOSCHANGING"
7. subunit.pas(47,99) Error: Illegal expression after message directive
8.  

For MDI You could try qt5 widgetset - which is said to be working under Windows, Linux and MacOS.

Yes, I have played with it some times ago. The MDI works well. The thing was I couldn't use qt5 widget set because it doesn't support Raw printing which I needed that time.

[PeterX]

As TChildForm.WMSysCommand() does nothing for You,
in Your OS, You can delete this function.


WMWindowPosChanging() does something and cannot be dropped ..

I found something that might help here =>
Topic: Porting Win32 code to Apple Mac
https://forum.lazarus.freepascal.org/index.php?topic=37959.0


[Edit]
Looks like this now:

Code: Pascal  [Select][+][-]

1.     procedure WMWindowPosChanging(var Message: TLMWindowPosChanging); message LM_WINDOWPOSCHANGING;

[PeterX]

Found something while playing around with the Example code today ..

https://forum.lazarus.freepascal.org/index.php/topic,54771.msg407060/topicseen.html#new

[PeterX]

I kept on working on this thing,
and some bugs are solved.

- wrong "Old Size" stored on ChildWin Create
- from Minimized directly to Maximized lead to wrong stored Size
- uses real wsMaximized property now

But there's still missing a lot ..