> Kirk

> On Tue, 16 Feb 1999 13:43:30 -0700, Mike Mormando <m...@mormando.com> wrote:

> >I've got an app that  I where people assign relationships between
> >objects.  These objects currently reside in different panels, and they
> >want to draw lines between the objects.  I'm able to accomplish this by
> >converting everything to screen coordinates, and using a canvas to draw
> >to the screen dc.  Everything works fine until part of the form is
> >either hidden, or I resize it, the lines are redrawn right where I want
> >them to be.  Once I do either of the things above though, the lines are
> >redrawn directly on the desktop.
> >Any able to enlighten me?
> >TIA
> >Mike

> David Boudreau wrote:

> > Are the Panels directly adjacent, or is there some of the form showing
> > between them?  The Paint that happens when uncovering or resizing will
> > probably paint the form, then the panels.  If the drawing of the connector
> > is part of the Form's Paint handler, as it ought to be, then it might be
> > being drawn and then overdrawn by the panels.  Or is it possible that you
> > are just drawing the connector once and not each time the Paint event fires?

> Davie Reed wrote:

> > Maybe you could put a paintbox ON the panel and then draw on the paintbox?
> > Davie

> > David Boudreau wrote:

> > > Are the Panels directly adjacent, or is there some of the form showing
> > > between them?  The Paint that happens when uncovering or resizing will
> > > probably paint the form, then the panels.  If the drawing of the connector
> > > is part of the Form's Paint handler, as it ought to be, then it might be
> > > being drawn and then overdrawn by the panels.  Or is it possible that you
> > > are just drawing the connector once and not each time the Paint event fires?

>The following code may help you.
>  TForm1 = class(TForm)
>    procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
>      Shift: TShiftState; X, Y: Integer);
>    procedure FormShow(Sender: TObject);
>    procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X,
>      Y: Integer);
>    procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
>      Shift: TShiftState; X, Y: Integer);
>  private
>    { Private declarations }
>    MD: Boolean;
>    DP: TPoint;
>  public
>    { Public declarations }
>    Procedure BoundMouse(const isLimit: Boolean);
>    Procedure OverDraw(const isOver: Boolean);
>  end;

>......
>procedure TForm1.FormShow(Sender: TObject);
>begin
>  MD:= False;
>end;

>Procedure TForm1.BoundMouse(const isLimit: Boolean);
>Var
>  MRect: TRect;
>Begin
>  If isLimit then
>  Begin
>    MRect.TopLeft:= ClientToScreen(Point(0,0));
>    MRect.BottomRight:= ClientToScreen(Point(ClientRect.Right,
>ClientRect.Bottom));
>    ClipCursor(@MRect);
>  End Else
>    ClipCursor(nil);
>End;

>Procedure TForm1.OverDraw(const isOver: Boolean);
>Var
>  Style: Longint;
>Begin
>  Style:= GetWindowLong(Handle, GWl_Style);
>  If isOver then
>    Style:= Style and (not WS_ClipChildren)
>  Else
>    Style:= Style or WS_ClipChildren;

>  SetWindowLong(Handle, GWl_Style, Style);
>End;

>procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
>  Shift: TShiftState; X, Y: Integer);
>begin
>  DP:= Point(X, Y);

>  MD:= True;
>  BoundMouse(MD);
>  OverDraw(MD);
>  Canvas.Pen.Width:= 2;
>{2}  Canvas.Pen.Mode:= pmNotXor;
>  Canvas.Pen.Color:= RGB(Random(256), Random(256), Random(256));{2}

>{1  Canvas.Pen.Mode:= pmXor;//pmNotXor;
>  Canvas.Pen.Color:= RGB(Random(256), Random(256), Random(256));
>  Canvas.Brush.Style:= bsClear;{1}

>  Canvas.Rectangle(X-50, Y-50, X+50, Y+50);
>end;

>procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
>  Y: Integer);
>begin
>  If MD then
>  Begin
>    Canvas.Rectangle(DP.X-50, DP.Y-50, DP.X+50, DP.Y+50);
>    DP:= Point(X, Y);
>    Canvas.Rectangle(DP.X-50, DP.Y-50, DP.X+50, DP.Y+50);
>  End;
>end;

>procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
>  Shift: TShiftState; X, Y: Integer);
>begin
>  Canvas.Rectangle(DP.X-50, DP.Y-50, DP.X+50, DP.Y+50);
>  MD:= False;
>  BoundMouse(MD);
>  OverDraw(MD);
>end;

> Mike Mormando ???g??31 <7aqjm6$o...@forums.borland.com>...
> >I've tried your code, and it seems to work fine, until it comes time to
> >repaint, it looks like the form repaints, then the panels repaint on top
of
> >my lines, obscuring them.
> >Any other ideas?