A-component-to-prevent-your-form-to-be-placed-out-of-visible-area


            Title: A component to prevent your form to be placed out of visible area.
Question: Just put this component on your form and set as active and your form will not be moved out of screen visible area.
Answer:
Unit ScreenSnap;
Interface
Uses
 Windows, Messages, SysUtils, Classes,
 Graphics, Controls, Forms, Dialogs,
 ShellAPI;
Type
 TNoOutScreen =
 Class( TComponent )
 Private
 OldWndProc : Pointer;
 NewWndProc : Pointer;
 FDistance : Integer;
 Procedure NewWndMethod( Var Msg : TMessage );
 Public
 Constructor Create( AOwner : TComponent ); OverRide;
 Destructor Destroy; OverRide;
 Published
 Property Distance : Integer Read FDistance Write FDistance Default 30;
 End;
 Procedure Register;
Implementation
Constructor TNoOutScreen.Create( AOwner : TComponent );
Begin
 Inherited;
 If ( Not( csDesigning In ComponentState ) ) Then Begin
 NewWndProc := MakeObjectInstance( NewWndMethod );
 OldWndProc := Pointer( SetWindowLong( TForm( Owner ).Handle, gwl_WndProc, LongInt( NewWndProc ) ) );
 End Else Begin
 NewWndProc := NIL;
 OldWndProc := NIL;
 End;
 FDistance := 30;
End;
Destructor TNoOutScreen.Destroy;
Begin
 If ( Assigned( NewWndProc ) ) Then FreeObjectInstance( NewWndProc );
 Inherited;
End;
Procedure TNoOutScreen.NewWndMethod( Var Msg : TMessage );
Var
 Pabd : APPBARDATA;
 ScreenWidth : Integer;
 ScreenHeight : Integer;
 ScreenRect : TRect;
 TaskBarRect : TRect;
Begin
 If ( Msg.Msg = WM_EXITSIZEMOVE ) Then Begin
 Pabd.cbSize := SizeOf( APPBARDATA );
 SHAppBarMessage( ABM_GETTASKBARPOS, Pabd );
 ScreenWidth := GetSystemMetrics( SM_CXSCREEN );
 ScreenHeight := GetSystemMetrics( SM_CYSCREEN );
 ScreenRect := Rect( 0, 0, ScreenWidth, ScreenHeight );
 TaskBarRect := Pabd.rc;
 If ( ( TaskBarRect.Left = -2 ) And ( TaskBarRect.Bottom = ( ScreenHeight + 2 ) ) And ( TaskBarRect.Right = ( ScreenWidth + 2 ) ) ) Then
 ScreenRect.Bottom := TaskBarRect.Top
 Else If ( ( TaskBarRect.Top = -2 ) And ( TaskBarRect.Left = -2 ) And ( TaskBarRect.Right = ( ScreenWidth + 2 ) ) ) Then
 ScreenRect.Top := TaskBarRect.Bottom
 Else If ( ( TaskBarRect.Left = -2 ) And ( TaskBarRect.Top = -2 ) And ( TaskBarRect.Bottom = ( ScreenHeight + 2 ) ) ) Then
 ScreenRect.Left := TaskBarRect.Right
 Else If ( ( TaskBarRect.Right = ( ScreenWidth + 2 ) ) And ( TaskBarRect.Top = -2 ) And ( TaskBarRect.Bottom = ( ScreenHeight + 2 ) ) ) Then
 ScreenRect.Right := TaskBarRect.Left;
 If ( TForm( Owner ).Left If ( TForm( Owner ).Top If ( ( TForm( Owner ).Left + TForm( Owner ).Width ) ( ScreenRect.Right - FDistance ) ) Then TForm( Owner ).Left := ScreenRect.Right - TForm( Owner ).Width;
 If ( ( TForm( Owner ).Top + TForm( Owner ).Height ) ( ScreenRect.Bottom - FDistance ) ) Then TForm( Owner ).Top := ScreenRect.Bottom - TForm( Owner ).Height;
 End;
 Msg.Result := CallWindowProc( OldWndProc, TForm( Owner ).Handle, Msg.Msg, Msg.WParam, Msg.LParam );
End;
Procedure Register;
Begin
 RegisterComponents( 'Christian', [ TNoOutScreen ] );
End;
End.
Forms Delphi
