Track mouse with a dotted-line image of a control

#include <Controls.h> Control Manager

void DragControl( theControl, startPt, limitRect, slopRect, axis );

ControlHandle theControl ; handle of control to be dragged

Point startPt ; current mouse point, within theControl

Rect *limitRect ; area in which control may be moved

Rect *slopRect ; area in which gray outline is visible

short axis ; motion constraints; 0=none; 1=horiz; 2=vert

DragControl is needed only by applications that allow a user to move

controls manually. It drags a gray outline of the control, tracking the mouse,

and calls MoveControl to change its position and redraw it. Use

TrackControl for the more common operation of manipulating a dial (e.g.,

theControl is a handle leading to a variable-length ControlRecord structure. It

startPt is a point in local coordinates; normally a point in a control at the

current mouse position (i.e., a value obtained via WaitNextEvent

limitRect is the address of an 8-byte Rect structure, expressed in local

coordinates. It identifies the area in which the control may be moved.

slopRect is the address of a Rect in local coordinates. It should enclose

limitRect completely. If the mouse moves outside of this rectangle,

axis specifies any constraints you may wish to place on the dragging

motion. It may be one of the following constants defined in

noConstraint (0) May move in any direction

hAxisOnly (1) May move left and right only

vAxisOnly (2) May move up and down only

Notes: DragControl lets a user reposition individual controls within a window.

Since controls are normally stationary with respect to a window, this is

The startPt, limitRect, slopRect, and axis parameters are used in the same

way as in the Window Manager's DragGrayRgn function. You may tinker

with the global variables DragHook and DragPattern if you wish to customize