The basics:
Once you have
clicked on an object within the canvas, the object will change a bit to
show you that it is selected. If a one-dimensional object is
selected (like a line or circle), the object will be outlined in purple
to show its selected state. If a point is selecte, again it will
be outlined in purple. If an area is selected, its color will
turn a lighter shade and an image of the icon for this program will
appear. This is illustrated in the diagram below. In
every case of a selection,
a message will appear in the Message Area under the Canvas telling you
which object is currently selected.
To
select objects that are visually behind other objects (for example a
segment
that is behind another segment) click on the object repeatedly until
the
desired selection is made.
The
Selection
Box: This
allows
you to select a group of objects quickly and easily. Click
anywhere
on the canvas. One corner of the selection box will be set at
that
point. As you drag you will see a red rectangle which extends
from
wherever you originally clicked to wherever the cursor is currently
at.
When you release the mouse anything within the box will be selected.
Multiple Selection: To select multiple items, just click
on the items in sequence using the select tool. All of the items
will remain selected until you click in
an open space
on the canvas (at which point all selections will become
unselected). You can unselect specific
items by clicking on them
again.
The Shift
Key:
The shift key also allows you to
select
more than one object at a time. When
holding the shift key down, you can click on any number of items and
they
will all remain selected until you release the Shift key and click
anywhere
on the canvas (at which point all selections will become unselected).
While
the Shift is down, you can unselect specific items by clicking on them
again.
The
Control
Key: Holding down the Control key
and the Shift key simultaneously, while selecting, will cause Geometry
Explorer to select a region of the Canvas without changing any existing
selections. This is useful when one wants to save a copy of the current
state of the Canvas as an image. For example, suppose you have a
construction where a line is currently selected, but the endpoints are
not. If we click and drag a selection box around the line, all points
inside will be selected. If we hold the shift and control keys down
while creating the selection box, no changes to selections will be
made, and we can save the image exactly as it appears in the Canvas, as
is illustrated here:
Dragging Objects: In order to move an object across the canvas it is necessary to click on the object and drag it until it is in the desired position. If you would like to move two objects in unison just press the Shift key while you select the objects and hold it down while you drag them.