Window rendering error after calling CallWindowProc and DefWindowProc
lazarus / 67-Windows

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Pixelmak · 2021-12-21 10:10

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][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i 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.

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Pixelmak · 2021-12-21 10:14

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