вот так можно
| Код |
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, ExtCtrls, jpeg;
type
TForm1 = class(TForm)
Image1: TImage;
procedure Image1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure Image1MouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
g_LButtonDown : boolean = false;
g_DownX, g_DownY : Integer;
implementation
{$R *.dfm}
procedure TForm1.Image1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if Button=mbLeft then
begin
g_LButtonDown:=true;
g_DownX:=X;
g_DownY:=Y;
end;
end;
procedure TForm1.Image1MouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if Button=mbLeft then
begin
g_LButtonDown:=false;
end;
end;
procedure TForm1.Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
var
offset : TPoint;
begin
if g_LButtonDown then
begin
Image1.Refresh;
{вот это все можно узнавать и устанавливать заранее}
offset.X:=Image1.Left;
offset.Y:=Image1.Top;
Form1.Canvas.Brush.Style:=bsClear;
Form1.Canvas.Pen.Style:=psDash;
Form1.Canvas.Pen.Color:=clBlue;
Form1.Canvas.Rectangle(g_DownX+offset.X,g_DownY+offset.Y,X+offset.X,Y+offset.Y);
end;
end;
end.
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