unit TrMemo;
{$R-}
interface
uses
Windows, Messages, Controls, StdCtrls, Classes;
const
TMWM__SpecialInvalidate = WM_USER + ;
type
TTransparentMemo = class(TMemo)
private
procedure SpecialInvalidate(var Message:TMessage); message TMWM__SpecialInvalidate;
procedure WMHScroll(var Message: TWMHScroll); message WM_HSCROLL;
procedure WMVScroll(var Message: TWMVScroll); message WM_VSCROLL;
procedure WMSetText(var Message:TWMSetText); message WM_SETTEXT;
procedure CNCTLCOLOREDIT(var Message:TWMCTLCOLOREDIT); message CN_CTLCOLOREDIT;
procedure WMKeyDown(var Message: TWMKeyDown); message WM_KEYDOWN;
procedure WMEraseBkgnd(var Message: TWMEraseBkgnd); message WM_ERASEBKGND;
protected
procedure CreateParams(var Params: TCreateParams); override;
public
constructor Create(AOwner: TComponent); override;
end;
procedure Register;
implementation
{ TTransparentMemo }
procedure TTransparentMemo.WMHScroll(var Message: TWMHScroll);
begin
inherited;
PostMessage(Handle,TMWM__SpecialInvalidate,,);
end;
procedure TTransparentMemo.WMVScroll(var Message: TWMVScroll);
begin
SendMessage(Handle,TMWM__SpecialInvalidate,,);
inherited;
PostMessage(Handle,TMWM__SpecialInvalidate,,);
end;
procedure TTransparentMemo.CNCTLCOLOREDIT(var Message:TWMCTLCOLOREDIT);
begin
with Message do
begin
SetBkMode(ChildDC,TRANSPARENT);
Result:=GetStockObject(HOLLOW_BRUSH)
end
end;
procedure TTransparentMemo.WMSetText(var Message:TWMSetText);
begin
inherited;
if not (csDesigning in ComponentState) then
PostMessage(Handle,TMWM__SpecialInvalidate,,)
end;
procedure TTransparentMemo.SpecialInvalidate(var Message:TMessage);
var r:TRect;
begin
if Parent<>nil then
begin
r:=ClientRect;
r.TopLeft:=Parent.ScreenToClient(ClientToScreen(r.TopLeft));
r.BottomRight:=Parent.ScreenToClient(ClientToScreen(r.BottomRight));
InvalidateRect(Parent.Handle,@r,true);
RedrawWindow(Handle,nil,,RDW_FRAME+RDW_INVALIDATE)
end;
end;
procedure TTransparentMemo.WMKeyDown(var Message: TWMKeyDown);
begin
SendMessage(Handle,TMWM__SpecialInvalidate,,);
inherited;
PostMessage(Handle,TMWM__SpecialInvalidate,,);
end;
procedure TTransparentMemo.WMEraseBkgnd(var Message: TWMEraseBkgnd);
begin
Message.Result := ;
end;
constructor TTransparentMemo.Create(AOwner: TComponent);
begin
inherited;
ControlStyle := [csCaptureMouse, csDesignInteractive, csClickEvents,
csSetCaption, csOpaque, csDoubleClicks, csReplicatable, csNoStdEvents];
end;
procedure TTransparentMemo.CreateParams(var Params: TCreateParams);
begin
inherited CreateParams(Params);
with Params do
begin
ExStyle:=ExStyle or WS_EX_TRANSPARENT and not WS_EX_WINDOWEDGE
and not WS_EX_STATICEDGE and not WS_EX_DLGMODALFRAME and not WS_EX_CLIENTEDGE;
end;
end;
procedure Register;
begin
RegisterComponents('cool!', [tTransparentMemo]);
end;
end.