ControlDragging was: Re: [lazarus] CVS Changes

Alexander Reiter r.alex at
Thu Jun 15 15:37:22 EDT 2000

i think the problem is in TDesignerForm.MouseMove.
if you try this, you can move your control. well is not the
best solution, but it is a good starting point. take a look 
at this:

 Procedure TDesignerForm.MouseMove(Sender: TObject; Shift: TShiftState;
X, Y: Integer);
  dx, dy: Integer;
  //if TCOntrol(sender).dragging then
  if (FMoveCOntrol.Control = Sender) 
  then begin
    WriteLn(Format('[TDesignerForm.MouseMove] Start(%d, %d) Stop(%d,
%d)', [FMoveCOntrol.X, FMoveCOntrol.Y, X, Y]));
  not correct  --> //dx := X - FMoveCOntrol.X;
  not correct  --> //dy := Y - FMoveCOntrol.Y;
     dx := X - FMoveControl.Control.Left;
     dy := Y - FMoveControl.Control.Top;
    FMoveControl.Control.Left := FMoveControl.Control.Left + dX;
    FMoveControl.Control.Top  := FMoveControl.Control.Top + dY;


Marc Weustink wrote:
> At 13:30 14-06-2000 -0500, Shane Miller wrote:
> >Press the NEW FORM button.
> >Select the Button component and drop it onto the form.
> >Drag the button 2 pixels up.  It probably moved a little.  Now do it again.
> >It doesn't work.
> >If you look at the output (look at designerform.pp in mousedown and mouseup
> >to see what SHOULD be displayed)  you'll see that the TOP and LEFT seem to
> >be reported incorrectly.
> >If you MOVE the form then try it again it's reported correctly.
> >This also occurs when trying to place controls onto the form.  Sometimes
> >they appear correctly, sometimes not.
> >When they dont you can move the form and thn the  next one appears
> >correctly.
> >
> >Any ideas?
> Mouse.Cursorpos is given in screen coordinates, not in form coordinates.
> Onmousedown you store Cursorpos (or better, the given X and Y),
> onmouseUp you calc the difference with the new Cursorpos (or better, the
> given X and Y) THe difference is added to the Left and Top.
> I committed a solution which normally should work, however it doesn't due
> to a bug in the MouseMove and MouseUp handlers
> MouseMove / MouseUp should always give the mouseposition X and Y in the
> Sender coordinates.  It does as long as the up event occoured in the
> control itself. However if you are outside the control you get the X and Y
> in Form coordinates.
> Marc
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