unit Unit9;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ComCtrls;
type
TForm9 = class(TForm)
RichEdit1: TRichEdit;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
public
FRichWindowProc: TWndMethod;
procedure RichWindowProc(var message: TMessage);
end;
var
Form9: TForm9;
implementation
{$R *.dfm}
procedure TForm9.FormCreate(Sender: TObject);
begin
SetWindowLong(Handle, GWL_STYLE,
GetWindowLong(Handle, GWL_STYLE) and not WS_CLIPCHILDREN);
SetWindowLong(RichEdit1.Handle, GWL_EXSTYLE,
GetWindowLong(RichEdit1.Handle, GWL_EXSTYLE) or WS_EX_TRANSPARENT);
FRichWindowProc := RichEdit1.WindowProc;
RichEdit1.WindowProc := RichWindowProc;
end;
procedure TForm9.RichWindowProc(var message: TMessage);
var
Buffer: HDC;
Bitmap, OldBitmap: HBITMAP;
Origin: TPoint;
begin
if message.Msg <> WM_ERASEBKGND then
FRichWindowProc(message)
else
begin
message.Result := 1;
Buffer := CreateCompatibleDC(TWMEraseBkGnd(message).DC);
Bitmap := CreateCompatibleBitmap(TWMEraseBkGnd(message).DC,
RichEdit1.Width, RichEdit1.Height);
OldBitmap := SelectObject(Buffer, Bitmap);
Origin := ScreenToClient(RichEdit1.ClientOrigin);
MoveWindowOrg(Buffer, -Origin.X, -Origin.Y);
Perform(WM_ERASEBKGND, Buffer, 0);
Perform(WM_PAINT, Buffer, 0);
MoveWindowOrg(Buffer, Origin.X, Origin.Y);
BitBlt(TWMEraseBkGnd(message).DC, 0, 0, RichEdit1.Width,
RichEdit1.Height, Buffer, 0, 0, SRCCOPY);
SelectObject(Buffer, OldBitmap);
DeleteDC(Buffer);
DeleteObject(Bitmap);
end;
end;
procedure TForm9.FormDestroy(Sender: TObject);
begin
RichEdit1.WindowProc := FRichWindowProc;
end;
end.
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