Mega Code Archive
Moving Controls over the form
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Title: Moving Controls over the form
Question: How is it possiple to move an control over the form ?
Answer:
It's very simple - so don't try to write hundreds of lines to solve this problem
just take a look at this small source-snip
all what we need to do is to override the dynamic MouseDown method of the TControl-BaseClass and fire an WM_SysCommand event with the magicKey $F012.
best regards
Boris Benjamin Wittfoth
{-----------------------------------------------------------------------------
hEaDRoOm Development
29.10.2002
Unit Name: HREdit
Author: Benjamin Benjamin Wittfoth
Purpose:
History:
-----------------------------------------------------------------------------}
unit HREdit;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls;
type
THREdit = class(TEdit)
private
fDragable:Boolean;
protected
procedure MouseDown(Button: TMouseButton;Shift: TShiftState; X, Y: Integer);override;
public
Constructor Create(AOwner:TComponent);override;
Destructor Destroy;override;
published
property Dragable:Boolean read fDragable write fDragable;
end;
procedure Register;
implementation
procedure Register;
begin
RegisterComponents('HEADROOM DEVELOPMENT', [THREdit]);
end;
{ THREdit }
constructor THREdit.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
end;
destructor THREdit.Destroy;
begin
inherited;
end;
procedure THREdit.MouseDown(Button: TMouseButton; Shift: TShiftState; X,
Y: Integer);
const
SC_DragMove = $F012; // important key !!
begin
inherited;
if assigned(onMouseDown)then
OnMouseDown(self,Button,Shift,x,y);
if fDragable then
begin
ReleaseCapture;
(self as TControl).perform(WM_SysCommand, SC_DragMove, 0); // this is the key !
end;
end;
end.
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