3.4.2 The Control Point Mode Buttons
The Control Point Mode Buttons are shown in
Figure
3.21. These consist of the New
Point, Add Point , Delete Point , and Edit Point buttons. These control the behavior, or mode,
of mouse clicks in the image window when you're using the Bezier
Path tool.
When using the Bezier Path tool with the New Point mode button
selected in the Paths dialog, there are two behaviors for a mouse click
in the image window. The first behavior is associated to working on
an open path. In this case, clicking in the image window creates a
new control point that is immediately connected to the last control
point on the path by a path segment. The last new control point on an
open path is displayed as a circle outline. All the other points on
the path are displayed as solid circles.
The second behavior of the New Point mode button is when there is no
open path. Then, a mouse click in the image window initializes a new
path.
When the Bezier path is in New Point mode, the mouse cursor appears in
the image window as an arrow with a filled circle below it. This
indicates that the next mouse click will create a new control point.
The Add Point mode button is for adding a point to a path segment
between two existing control points. This is useful when a path has
been created but doesn't have a sufficient number of points to
properly follow the desired shape. When the Add Point mode button is
active, the mouse cursor changes to an arrow with a plus symbol below
it whenever the cursor is close enough to a path segment to add a
point. If the mouse button is not released when the point is added,
the point can immediately be edited. In other words, if the mouse
button remains pressed the control handles will appear when you drag
the mouse, and the Shift and Control keys can be used to manipulate
the control point and the control handles. This is a handy feature
because a control point can be added to a path and then immediately
edited without having to return to the Paths menu.
The Delete Point mode button removes control points from a Bezier
path. This can be used to delete extraneous control points or those
that were added accidentally. When you use the Delete Point mode
button, the mouse cursor changes to an arrow with a minus symbol below
it whenever the cursor is close enough to a control point to delete it.
If the Shift key is pressed while using the Delete Point mode button,
the mouse click deletes the entire path.
Finally, the Edit Point mode button allows the control handles to be
manipulated and the control points to be moved, as described in
Section
3.1.1. That is, clicking and dragging on a
control point moves the point's control handles in unison.
Shift-clicking and dragging a control handle moves that handle
independently of the other one. Control-clicking and dragging the
mouse on a control point makes the control point move, following the
mouse. Finally, Alt-clicking and dragging the mouse on a control
point causes the entire path to follow the mouse. When you're using
the Edit Point mode button, the mouse cursor changes to an arrow with
the outline of a square below it whenever the mouse cursor is close
enough to a control point to edit it.
