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Home in the Vector graphic module

Vector graphic module



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:

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Last updated on June 24, 2015

Home in the Vector graphic module