Follow the line – the Vector graphic module
In the object editor of the Vector graphic module you can use the
frame functions Resize object proportionally
, Move only
horizontally
, Move only vertically
and Draw out from the
centre
.
The basic properties of vector graphics were explained earlier in
the chapter Fundamentals
. The Vector graphic module allows you
to edit vector graphic frames. In Calamus, vector graphics consist
basically of only two elements: So-called Paths
and Other
objects
. The "Other objects" can be a raster graphic incorporated
in the vector graphic, for instance, or something similar; in other
words objects that have little in common with vector graphics. For
this reason they can not be edited in the Vector graphic editor.
Paths, on the other hand, consist of combinations of lines and Bézier
curves and can be created and altered freely. With these basic
functions you can really create every kind of vector graphic. Calamus
even contains functions for recalculating vector graphics from
external programs that contain other elements. Thus, for example,
circles and arcs are converted to Bézier curves for modifying in the
Vector graphic module.
A vector graphic frame usually contains several (path) objects, each of which consists of one or more paths. A path is made up of lines and Bézier curves joined together. The object as a whole is assigned a line type and a fill pattern. This means in practice that all elements of the path have the same line type, and surround the same fill pattern. You may be familiar with simple vector graphic objects from working with the Raster area module. Each object has an outline (that is the path), a fill colour, a fill pattern and a line type. All these raster areas are present in the Vector graphic module too, and can be modified here.
Having dealt with objects, let's get to the paths. As mentioned, a
path consists of several points joined together by lines or Bézier
curves. It should be clear what lines are, but Bézier curves may
require further explanation: Bézier curves are like curved lines,
except that they have two external points in addition to the start and
end points. These extra points, called control points
,
determine the shape of the curve. The Bézier curve clings at either
endpoint to an imaginary line connecting the endpoint to the control
point. The distance between the control point and endpoint determines
the amount of bowing
of the curve. Here are some examples with
the control points visible that are clearer than words:
A path may consist of a combination of joined lines and Bézier curves. This creates either closed or open paths, as shown in the following examples:
The starting point of each path appears as a solid square, further points appear as small empty boxes, and control points of Bézier curves appear as small crosses. If an object is made up of more than one path, you only have to count the solid squares to see how many paths are involved.
As explained in the Raster area module, each object as a whole has a fill colour, a fill pattern, a line shape and a line colour. The important point is that the whole object must have the same colour, the same fill pattern and the same line attributes. If you want more than one fill pattern, colour or line type in your raster graphic, you will have to create separate objects.
From this it follows that it would appear not to be possible to
create objects with "holes" in them. Normally such objects are created
by placing a white-filled path on top of an object with a different
fill pattern. But as objects may only have a common fill pattern for
all paths, holes
in it would seem to be impossible. This
apparent dilemma can be solved thanks to the fact that the direction
of a path has a deciding influence on the filling of an object. The
following basic rule apples: Areas that lie inside two
opposing paths will not be filled. So if two objects
with the same fill pattern are drawn on top of each other with the
paths created in opposite directions, the area where they overlap will
be left blank. This may sound somewhat complicated again, but the
illustration should make everything clear:
