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Window rendering error after calling CallWindowProc and DefWindowProc
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Author
Topic: Window rendering error after calling CallWindowProc and DefWindowProc (Read 2340 times)
Pixelmak
New member
Posts: 7
Window rendering error after calling CallWindowProc and DefWindowProc
«
on:
December 21, 2021, 11:10:47 am »
I am trying to get Windows messages via WndCallback in Windows 11. But, after receiving the message, the window is not rendered normally. What am I doing wrong? (Screen in Attachment)
Code: Pascal
[Select]
[+]
[-]
unit
Unit1
;
{$mode delphi}{$H+}
interface
uses
Classes
,
SysUtils
,
Forms
,
Controls
,
Graphics
,
Dialogs
,
StdCtrls
,
Windows
;
type
{ TForm1 }
TForm1
=
class
(
TForm
)
Button1
:
TButton
;
procedure
Button1Click
(
Sender
:
TObject
)
;
procedure
FormCreate
(
Sender
:
TObject
)
;
private
public
end
;
function
WndCallback
(
Ahwnd
:
HWND
;
uMsg
:
UINT
;
wParam
:
WParam
;
lParam
:
LParam
)
:
LRESULT
;
stdcall
;
var
Form1
:
TForm1
;
PrevWndProc
:
windows
.
WNDPROC
;
implementation
function
WndCallback
(
Ahwnd
:
HWND
;
uMsg
:
UINT
;
wParam
:
WParam
;
lParam
:
LParam
)
:
LRESULT
;
stdcall
;
begin
result
:
=
CallWindowProc
(
PrevWndProc
,
Ahwnd
,
uMsg
,
WParam
,
LParam
)
;
end
;
{$R *.lfm}
{ TForm1 }
procedure
TForm1
.
FormCreate
(
Sender
:
TObject
)
;
begin
PrevWndProc
:
=
Windows
.
WNDPROC
(
SetWindowLongPtr
(
Self
.
Handle
,
GWL_WNDPROC
,
PtrUInt
(
@
WndCallback
)
)
)
;
end
;
procedure
TForm1
.
Button1Click
(
Sender
:
TObject
)
;
begin
writeln
(
'Button clicked'
)
;
end
;
end
.
Logged
Pixelmak
New member
Posts: 7
Re: Window rendering error after calling CallWindowProc and DefWindowProc
«
Reply #1 on:
December 21, 2021, 11:14:27 am »
Oh, I'm sorry. This code works now. I don’t know for what reason this error occurred.
Perhaps the reason was that I used DefWindowProc instead of CallWindowProc
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Window rendering error after calling CallWindowProc and DefWindowProc
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