Creating forms dynamically

[dietmar]

Hi,

is there anywhere out here an example how to create forms "on the fly" during program runtime?
I think I will have to calculate the position where elements are setup...?

Dietmar

[minesadorada]

Hi,

is there anywhere out here an example how to create forms "on the fly" during program runtime?
I think I will have to calculate the position where elements are setup...?

Dietmar

Not only that, but be sure to set the created form's parent property.  That is the easiest mistake to make.

[Handoko]

Try these:

http://wiki.freepascal.org/Form_Tutorial#Create_a_Lazarus_designed_form_dynamically

https://stackoverflow.com/questions/16112924/how-to-create-a-form-programmatically-with-a-couple-components-on-it-in-delphi

[sam707]

http://lazarus-ccr.sourceforge.net/docs/lcl/forms/requirederivedformresource.html

if you plan to work with ONLY dynamic forms, you can set RequireDerivedFromResource to false, in your project main source file.

After what you would use Application.CreateForm in a classic way

Description of global variable RequireDerivedFromResource from wiki
"The form resource is the lfm file compiled into the executable of your application. For this flag it does not matter if it was compiled via an lrs file or via fpcres. The resource is automatically loaded by TForm and therfore any descendant when it is created via Create(Owner). If the resource is missing there is something wrong with either a resource or the unit which contains the faulty form. If the flag is false you will see a blank form and probably search a long time what is wrong. If you set this flag to true you get an exception. For creating forms without resources you have 3 options:
1) Create a TForm class (not a descendant)
2) Construct your form using the CreateNew() constructor.
3) It is also possible to disable the exception by setting the global variable RequireDerivedFormResource to False."

[Lasarus Menu bar ] >> [Project] >> [View  Project Source] will open the main project file in lazarus.
RequireDerivedFromResource should be one of the 1st instructions at the begin..end. block.

I do personnally prefer the CreateNew constructor. check it 

[howardpc]

Hi,

is there anywhere out here an example how to create forms "on the fly" during program runtime?
I think I will have to calculate the position where elements are setup...?

Dietmar

Not only that, but be sure to set the created form's parent property.  That is the easiest mistake to make.

I think minesadorada means remembering to set the various contained components' Parent properties to the dynamic form that displays them.
The form's Parent property itself should be nil.

[sam707]

@howardpc

any "constructive" comment apart from your keyboard color or the length of your pants?

LOVE YOU LOL

when I debugged delphi 5.5 years ago I was wondering why a MAIN form created in a DLL (BPL / Borland Package Library) was animating on minimize/restore, and DEF NOT a SAME main form created in the executable.
After nights and nights of disassembly spy (2 weeks), i discovered that the main form in the executable had Application's hidden window handle as Owner, so when Application terminated the form was destroyed (FIFO childcomponents way). under windows 95 it was disabling the OS animations.
As far as i can see, Lazarus can not create a MainForm from a package (concept did never happen because of multiplatform issues) BUT the MainForm do not follow OS animations, so I suppose/guess, that the Application.CreateForm from Lazarus is walking the same path as old delphi.
I'm not going to invistigate disassembler as I did, my old bones do prefer to rest at night

[sam707]

basic concept
in pascal GUI OOP
Parent is the one receiving notifications while Owner is the one destroying childcomponents

so Parent and Owner 'can' be the same component, but not always

[minesadorada]

Hi,

is there anywhere out here an example how to create forms "on the fly" during program runtime?
I think I will have to calculate the position where elements are setup...?

Dietmar

Not only that, but be sure to set the created form's parent property.  That is the easiest mistake to make.

I think minesadorada means remembering to set the various contained components' Parent properties to the dynamic form that displays them.
The form's Parent property itself should be nil.

Yes of course - forgive me folks for a senior moment   I was thinking of components.

[dietmar]

Hm,

that's what I tried:

Code: Pascal  [Select][+][-]

1.   frmSplash := TForm.Create(nil);
2.   frmSplash.Name := 'frmSplash';
3.   frmSplash.SetBounds(0, 0, 800, 600);
4.   frmSplash.BorderStyle := bsNone;
5.  

The compiler breaks in the last line, because it doesn't know "bsNone" like in the Lazarus GUI.
Where is that defined?

Thx,
Dietmar

[Handoko]

bsNone is in unit: Controls, so put Controls in your uses clause.

[dietmar]

Thanks!

Now, I am searching for "poScreenCenter" of a form.
Documentation says: "Source position: forms.pp line 59"
But I have Forms already in my uses statement.

... :/

Dietmar

[RAW]

Here is an easy example... 

[RAW]

frmSplash := TForm.Create(nil);
frmSplash.Name := 'frmSplash';
frmSplash.SetBounds(0, 0, 800, 600);
frmSplash.BorderStyle := bsNone;

If you want to make a splash screen and you are on Windows then this is what I would do:
A nice and cool Splash screen...

[RAW]

 

[RAW]