{*******************************************************************************
*
* Hintergrundfarbe eines MDI-Formulars setzen ohne die Farbe der darauf
* liegenden Objekte wie TGroupBox oder TPageControl zu verändern.
*
* Setting the Background color of a MDI Form without changing the color
* of overlayed objects like TGroupBox or TPageControl.
*
******************************************************************************}
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs;
type
TForm1 = class(TForm)
private
FClientInstance: TFarProc;
FPrevClientProc: TFarProc;
BkBrush: HBRUSH;
procedure ClientWndProc(var Message: TMessage);
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
end;
implementation
{$R *.dfm}
constructor TForm1.Create(AOwner: TComponent);
begin
inherited;
BkBrush := CreateSolidBrush(clGray);
FClientInstance := Classes.MakeObjectInstance(ClientWndProc);
FPrevClientProc := Pointer(GetWindowLong(ClientHandle, GWL_WNDPROC));
SetWindowLong(ClientHandle, GWL_WNDPROC, Longint(FClientInstance));
end;
destructor TForm1.Destroy;
begin
DeleteObject(BkBrush);
inherited;
end;
procedure TForm1.ClientWndProc(var Message: TMessage);
var
DC: HDC;
BrushOld: HBRUSH;
begin
with Message do
begin
case Msg of
WM_ERASEBKGND:
begin
DC := TWMEraseBkGnd(Message).DC;
BrushOld := SelectObject(DC, BkBrush);
FillRect(DC, ClientRect, BkBrush);
SelectObject(DC, BrushOld);
Result := 1;
end;
else
Result := CallWindowProc(FPrevClientProc, ClientHandle, Msg, wParam, lParam);
end;
end;
end;
end.
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