NAME

circles − TNT Selection and Reception service demo

DISCLAIMER

This program is furnished on an AS IS basis as a demonstration of TNT applications programming. 

SYNOPSIS

circles

DESCRIPTION

Circles is a complete application that demonstrates much of what’s involved in supporting making/manipulating selections within a canvas.  The application brings up two instances of a window containing a few circular subcanvases (which scale automatically with the parent window). 
 
OPEN LOOK specifies two basic mechanisms by which a graphical object may be (de)selected.  The first method involves pressing the SELECT button over the canvas behind the object to be selected, and then dragging a bounding-box to enclose the objects to be selected.  The second method involves clicking the SELECT button directly over the object to be selected. 
 
Objects may be added to or removed from the selection in a similar manner using the ADJUST button to toggle the selected state.  When used to draw a bounding box, each object within the box will individually toggle it’s state. 
 
Per OPEN LOOK , if you mouse down inside an existing selection and move the mouse, it drags the selection to a new location.  (Holding down the CONTROL key while you do this causes the selection to be copied instead of moved.)  You can drag between two different Circles windows; you can also use cut and paste. 
 
OPEN LOOK also allows an object to be selected and drug in a single operation by holding the SELECT button down over an object. 
 
To demonstrate the use of invalid dropsites, only portions of the background canvas not covered by a circle are valid dropsites.  (It is possible to drop a canvas where it will overlap another, but the center of the dropped canvas must be over the background.)
 
Comments throughout the code explain how each piece fits into the selection paradigm.

BUGS

Transient selections (quick-copy/move) are not supported. 
 
A circle is considered to be within a rubber-banded selection box if it’s center is within the box.

SEE ALSO

The Open Look Graphical User Interface Functional Specification. 

LEGAL STUFF

PostScript is a trademark of Adobe Systems, Inc. 
NeWS is a trademark of Sun Microsystems, Inc. 
OPEN LOOK is a trademark of AT&T. 

Sun Release 4.1  —  Last change: 12/22/89