How to move circle with mouse in delphi?

Question

How to move circle with mouse in delphi?

circle:Shape;

Answer 1

Be sure to convert the Mouse X,Y client coordinates that you get from MouseMove on your Control to the Parent's client using ClientToScreen and ScreenToClient.

The following procedure moves the center of a Control to the point (X,Y) in it's client coordinates:

procedure MoveControl(AControl: TControl; const X, Y: Integer);
var
  lPoint: TPoint;
begin
  lPoint := AControl.Parent.ScreenToClient(AControl.ClientToScreen(Point(X, Y)));
  AControl.Left := lPoint.X - AControl.Width div 2;
  AControl.Top := lPoint.Y - AControl.Height div 2;
end;

Now to move your TShape when when it is clicked, you have to provide the following MouseMove event handler:

procedure TForm1.ShapeToMoveMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
begin
  if ssLeft in Shift then // only move it when Left-click is down
    MoveControl(Sender as TControl, X, Y);
end;

And to test it, drop a button in your Form with this code:

procedure TForm1.ButtonTestClick(Sender: TObject);
begin
  with TShape.Create(nil) do
  begin
    Name := Format('ShapeToMove%d',[Self.ControlCount + 1]);
    Parent := Self; // Parent will free it
    Shape := stCircle;
    Width := 65;
    Height := 65;
    OnMouseMove := ShapeToMoveMouseMove;
  end;
end;

Now, that's a minimalist example, but it should get you started.
For fun, just hook other controls with this MouseMove event handler... :-)

Answer 2

If you go to my webpage, you can Find some samples (all with code included) thah can help you about this question. "Sample for visual work with figures and plans"; Use two components for manage, move, resize and save elements visually; One for selection, movement, resize,... (TSeleccOnRuntime) and other (TSaveComps) for save the state (position, size,...). alt text http://neftali-mirror.site11.com/images/imagen_ej_restaurante.png

Select Shapes Visually; Sample for explain two modes for select visually shapes and images.

Create, move and resive controls on Runtime (like IDE); Another sample of TSeleccOnRuntime component. Simulate and IDE.

alt text http://neftali-mirror.site11.com/images/image_ej_form_designer.png

And finally another sample for Create/destroy components in runtime and move with mouse; This sample is made without components. All code at the sample.

alt text http://neftali-mirror.site11.com/images/imagen_ej_mover_mouse.png

I hope that is usefull for you.
Regards

P.D: Excuse for my bad english.

Answer 3

Well, I don't have too much to go on, but having something move to follow the mouse generally works like this:

Have a "IsFollowingMouse" flag somewhere. Turn it on when you should be following the mouse. On the form's MouseMove event, do something like this:

procedure TMyForm.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
  if FIsFollowingMouse then
  begin
    myCircle.left := x + fShapeOffsetX;
    myCircle.top := y + fShapeOffsetY;
  end;
end;

The offsets are variables you use that gives the difference between the location of the mouse pointer and the top-left corner of the TShape.