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Adding event to a runtime component
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Author
Topic: Adding event to a runtime component (Read 1225 times)
justnewbie
Sr. Member
Posts: 292
Adding event to a runtime component
«
on:
March 02, 2021, 05:01:31 pm »
Guys, can you fix my code? Couldn't give an OnMouseUp event to it, doesn't compile.
Code: Pascal
[Select]
[+]
[-]
unit
Unit1
;
{$mode objfpc}{$H+}
interface
uses
Classes
,
SysUtils
,
Forms
,
Controls
,
Graphics
,
Dialogs
,
StdCtrls
,
ExtCtrls
,
LCLIntf
;
type
{ TForm1 }
TForm1
=
class
(
TForm
)
Button1
:
TButton
;
ColorDialog1
:
TColorDialog
;
procedure
Button1Click
(
Sender
:
TObject
)
;
procedure
ShapeMouseUp
(
Sender
:
TObject
;
Button
:
TMouseButton
;
Shift
:
TShiftState
;
X
,
Y
:
Integer
)
;
private
public
end
;
var
Form1
:
TForm1
;
implementation
{$R *.lfm}
{ TForm1 }
procedure
TForm1
.
Button1Click
(
Sender
:
TObject
)
;
// Make empty palette
var
shape
:
TShape
;
begin
shape
:
=
TShape
.
Create
(
Self
)
;
shape
.
Parent
:
=
Form1
;
shape
.
Left
:
=
100
;
shape
.
Top
:
=
100
;
shape
.
Width
:
=
20
;
shape
.
Height
:
=
20
;
shape
.
Pen
.
Width
:
=
1
;
shape
.
Pen
.
Color
:
=
clBlack
;
shape
.
Brush
.
Color
:
=
clDefault
;
shape
.
Visible
:
=
True
;
shape
.
Enabled
:
=
True
;
shape
.
OnMouseUp
:
=
ShapeMouseUp
;
end
;
procedure
TForm1
.
ShapeMouseUp
(
Sender
:
TObject
;
Button
:
TMouseButton
;
Shift
:
TShiftState
;
X
,
Y
:
Integer
)
;
begin
if
ColorDialog1
.
Execute
then
(
Sender as TShape
)
.
Brush
.
Color
:
=
ColorDialog1
.
Color
;
end
;
end
.
Logged
howardpc
Hero Member
Posts: 4144
Re: Adding event to a runtime component
«
Reply #1 on:
March 02, 2021, 05:10:32 pm »
You need an "@" for objfpc mode
Code: Pascal
[Select]
[+]
[-]
shape
.
OnMouseUp
:
=
@
ShapeMouseUp
;
Logged
justnewbie
Sr. Member
Posts: 292
Re: Adding event to a runtime component
«
Reply #2 on:
March 02, 2021, 05:17:34 pm »
Quote from: howardpc on March 02, 2021, 05:10:32 pm
You need an "@" for objfpc mode
Code: Pascal
[Select]
[+]
[-]
shape
.
OnMouseUp
:
=
@
ShapeMouseUp
;
Great, it works! Thank you!
BTW, why the @ needed here? For the OnClick it doesn't need.
Logged
Handoko
Hero Member
Posts: 5153
My goal: build my own game engine using Lazarus
Re: Adding event to a runtime component
«
Reply #3 on:
March 02, 2021, 05:58:27 pm »
Which OnClick did you mean?
If you want to pass a procedure as a variable then you need a @ symbol. It is not needed in Delphi Mode or if you use TypeAddressOn compiler switch.
Why do we need it? Because the syntax defines it so. That actually is a good thing, it can prevent programmers to do some stupid things.
Lazarus/FPC/Pascal is verbose and strict. Luckily all the rules can be found if you check the documentation:
https://wiki.lazarus.freepascal.org/@
https://www.freepascal.org/docs-html/user/usersu88.html#x132-1390007.3.3
https://www.freepascal.org/docs-html/prog/progsu76.html
«
Last Edit: March 02, 2021, 06:10:16 pm by Handoko
»
Logged
justnewbie
Sr. Member
Posts: 292
Re: Adding event to a runtime component
«
Reply #4 on:
March 02, 2021, 09:59:09 pm »
Thank you, Handoko!
Logged
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Tomas Hajny
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Adding event to a runtime component
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