The coordinates of a control can be specified or retrieved in various ways

The following description applies to members of TControl and TWinControl.

Every control has an origin (Top, Left) and extent (Width, Height). The origin is relative to its Parent control (client coordinates) or, for floating controls (forms) with Parent=Nil, relative to the screen.

The BoundsRect describes the TopLeft and BottomRight coordinates of the control, relative to its Parent.

The BoundsRectForNewParent holds the new coordinates, to be used when the Parent of the control is changed later.

The ClientRect describes the internal (client) area of a container control (TWinControl), excluding borders. Its Top and Left are always zero. In a TScrollingWinControl...

BaseBounds holds the designed Bounds, to be used e.g. when a scale factor is set later.

GetControlOrigin returns the origin in screen coordinates. These values are not always in sync with the True screen position, managed by the widgetset.

ScreenToClient returns the client coordinates of an point given in the screen coordinates, i.e. the coordinates relative to the control's client origin.

ClientToScreen returns the screen coordinates for an point in client coordinates.