Solved

Dynamic Creation of Objects

Posted on 2004-09-15
8
251 Views
Last Modified: 2010-04-05
I need to create DYNAMICALLY some objects within other objects. The pseudocode I want goes something like this:

// on click of a button

For iLoop := 1 to iNoOfPanelsToDo do
begin
  // Create a panel
  // give it a cyclic name ('panel001')
  // set its size and location on the form by Top := iLoop*20 etc.
  // Create a child panel on the above panel
  // give it a cyclic name ('innerpanel001')
  // set its size and location on the form
  // Create a button on the innerpanel
  // Attach procedure 'InnerButtonPressed' to the button's OnClick event
end;

I've stumbled through the Delphi Help but I cant seem to find anything like this in terms I've guessed to put in the search, yet I suspect it is something the more experienced Delphi people will know like the back of their hand. I did it before ages ago; all I can remember is the bit about accessing the dynamically-created components by name with FindComponent.

Sample code is best; I learn well from plagiarism; oops, I mean example.

Martin C  

0
Comment
Question by:MartinC
  • 4
  • 3
8 Comments
 
LVL 27

Accepted Solution

by:
kretzschmar earned 100 total points
ID: 12072454
var
  pi, po : TPanel;
  bt : TButton;
  i : integer;
begin
  for i := 1 to howmanyyouneed do
  begin
    po := TPanel.Create(self);
    with po do
    begin
       top := SomeOffset * i;
       left := whatUNeedHere;
       name := YourPrefix+inttostr(i); //usually name is not needed
       parent := self;
       //maybe more
       show; //maybe not needed
   end;
    pi := TPanel.Create(self);
    with pi do
    begin
       top := whatUNeedHere;
       left := whatUNeedHere;
       parent := po;
       //maybe more
       show; //maybe not needed
   end;
    bt := TButton.Create(self);
    with bt do
    begin
       top := whatUNeedHere;
       left := whatUNeedHere;
       parent := pi;
       onClick := YourPredefinedClickProc;
       //maybe more
       show; //maybe not needed
   end;
  end;
end;

just from head

meikl ;-)

0
 

Author Comment

by:MartinC
ID: 12122570
Meikl:

I got all that to work - thx! - except the line:

 onClick := YourPredefinedClickProc;

which says "[Error] uAssetFacet.pas(67): Incompatible types: 'method pointer and regular procedure'" ... I presume there is some way I am not defining the procedure ... I wrote it as:

procedure YourPredefinedClickProc;
begin
  beep;
  beep;
  beep;
end;

... and I have no idea where I am supposed to store its top line:

procedure YourPredefinedClickProc;

... which I cuurently have above the form's type declaration:

type
  TfrmAssetFacet = class(TForm)

... any idea where it should go?

 
0
 
LVL 27

Expert Comment

by:kretzschmar
ID: 12122801
well, glad to hear

about the error you get

redefine your proc to

procedure TFormClassName.YourPredefinedClickProc(Sender : TObject);
begin
  beep;
  beep;
  beep;
end;

you may notice TFormClassName
this means you should declare this procedure within your formtype like

type
  TfrmAssetFacet = class(TForm)
     .....
   private //could also public
     procedure YourPredefinedClickProc(Sender : TObject);
     ......
   end;

so that your proc becomes

procedure TfrmAssetFacet.YourPredefinedClickProc(Sender : TObject);
begin
  beep;
  beep;
  beep;
end;

hope you get it work

meikl ;-)
0
PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

 

Author Comment

by:MartinC
ID: 12134724
I tried that before ... I have the declaration like this:

type
  TfrmAssetFacet = class(TForm)
    procedure FormShow(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    procedure YourPredefinedClickProc;
  end;

... then in the code I have:

       onClick := YourPredefinedClickProc;

... and later I have:

procedure TfrmAssetFacet.YourPredefinedClickProc;
begin
  beep;
  beep;
  beep;
end;

... but the compiler says:

[Error] uAssetFacet.pas(68): Incompatible types: 'Parameter lists differ'

... any clues?
0
 
LVL 27

Expert Comment

by:kretzschmar
ID: 12134858
an easy one (you just not read my comment carfully ;-)

replace this
procedure TfrmAssetFacet.YourPredefinedClickProc;
begin
  beep;
  beep;
  beep;
end;

with
procedure TfrmAssetFacet.YourPredefinedClickProc(Sender : TObject);  //just add the sender
begin
  beep;
  beep;
  beep;
end;

hope now you get it work

meikl ;-)
0
 
LVL 11

Assisted Solution

by:ZhaawZ
ZhaawZ earned 20 total points
ID: 12136023
don't forget to add sender also in public declaration of procedure ;)

  public
    { Public declarations }
    procedure YourPredefinedClickProc(Sender : TObject);
0
 
LVL 27

Expert Comment

by:kretzschmar
ID: 12136086
good point, ZhaawZ, overlooked this
0
 

Author Comment

by:MartinC
ID: 12142728
Sorry, normally I am a good copier but I missed that one. I've increased the points a bit (60 to 100) and chucked a tidbit to ZhaawZ for his correction, which no doubt would have tripped me up too.

Martin
0

Featured Post

ScreenConnect 6.0 Free Trial

Explore all the enhancements in one game-changing release, ScreenConnect 6.0, based on partner feedback. New features include a redesigned UI, app configurations and chat acknowledgement to improve customer engagement!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
This Micro Tutorial will teach you how to censor certain areas of your screen. The example in this video will show a little boy's face being blurred. This will be demonstrated using Adobe Premiere Pro CS6.
This Micro Tutorial will give you a basic overview how to record your screen with Microsoft Expression Encoder. This program is still free and open for the public to download. This will be demonstrated using Microsoft Expression Encoder 4.

810 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question