Dynamical creation of objects
lazarus / 43-Android

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peterbos · 2023-11-30 20:10

Hi,

How do I create an object dynamically? I tried this (and lots of
variations on it) but it doesn't show the CheckBox:

procedure TAndroidModule1.AndroidModule1Create(Sender: TObject);
begin
  ajCheckBox:=jCheckBox.Create(Self);
  ajCheckBox.Parent:=Self;
  ajCheckBox.PosRelativeToParent:=[];
  ajCheckBox.Anchor:=CheckBox1;
  ajCheckBox.Text:= 'Hello World!';
  ajCheckBox.PosRelativeToAnchor:=[raBelow];
  ajCheckBox.LayoutParamHeight:=lpWrapContent;
  ajCheckBox.LayoutParamWidth:=lpWrapContent;
  ajCheckBox.Init;
end;

On this forum I also found ajCheckBox.Init(gApp) but that does not
work because gApp is apparently not recognized.

Peter

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jmpessoa · 2023-12-02 03:54

Do like this:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i {hint:
Pascal files location: ...\AppCreateComponentAtRuntime\jni }unit
unit1; {$mode delphi} interface uses  {$IFDEF UNIX}{$IFDEF
UseCThreads}  cthreads,  {$ENDIF}{$ENDIF}  Classes, SysUtils,
AndroidWidget, Laz_And_Controls;  type   { TAndroidModule1 }  
TAndroidModule1 = class(jForm)    Button1: jButton;    TextView1:
jTextView;    procedure AndroidModule1Create(Sender: TObject);   
procedure AndroidModule1JNIPrompt(Sender: TObject);    procedure
Button1Click(Sender: TObject);  private    {private declarations}   
ButtonDynamic: jButton;  public    {public declarations}    procedure
ButtonDynamicClick(Sender: TObject);  end; var  AndroidModule1:
TAndroidModule1; implementation  {$R *.lfm}   { TAndroidModule1
} procedure TAndroidModule1.AndroidModule1Create(Sender:
TObject);begin   // put here only pure pascal code  (that is, don't
put here JNI api interface code...)end; //put here JNI api interface
code...//note that you will necessarily need a component of the same
type on the form....procedure
TAndroidModule1.AndroidModule1JNIPrompt(Sender: TObject);begin  if
ButtonDynamic = nil then  begin     //ShowMessage('"ButtonDynamic"
Created at Runtime...!');     ButtonDynamic:= jButton.Create(Self);
 //pascal side button     ButtonDynamic.Tag:= 2;   
 ButtonDynamic.Parent:= Self;     ButtonDynamic.Text:=
'ButtonDynamic';     ButtonDynamic.LayoutParamWidth:=
lpTwoThirdOfParent;     ButtonDynamic.Anchor:= Button1;   
 ButtonDynamic.PosRelativeToAnchor:= [raBelow];   
 ButtonDynamic.PosRelativeToParent:= [rpCenterHorizontal];   
 ButtonDynamic.OnClick:= ButtonDynamicClick;  //delphi mode...   
 ButtonDynamic.Init;    //init java side button  end;end; procedure
TAndroidModule1.Button1Click(Sender: TObject);begin 
ShowMessage('Hello from "Button1" ...');end; procedure
TAndroidModule1.ButtonDynamicClick(Sender: TObject);begin 
 ShowMessage('Hello from "ButtonDynamic" Created at
Runtime!')end; end.

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maxerist · 2023-12-10 10:17

Quote from: jmpessoa on December 02, 2023, 04:54:09 am
Do like this:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i ....   
 ButtonDynamic:= jButton.Create(Self);  //pascal side button..... 
I little observation about ownership. I suspect that there are cases
when it's better to pass Nil and free the control (component) by own
means. This is because jForm will call Init for every control owned
when you leave the app (running) and start the cached app again. For
me this was unconvinient when I used jBitmap and wanted to keep it
loaded. SO, when I created a jBitmap with jForm ownership, I got the
empty one after returning to the app (since Init clears the internal
bitmap). And when I passed Nil, everything was ok

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jmpessoa · 2023-12-10 22:19

QuoteAnd when I passed Nil, everything was ok...

Nice!