http://www.techradar.com/pro/linux May 2019 LXF249 77
Vector graphics TuTorials
We’ve struggled to
think of anything
you might need for
drawing technical
and business
illustrations that
LibreOffice Draw
doesn’t provide.Although LibreOffice Draw doesn’t have some of the
more artistic features of the highly respected Inkscape
and Gravit vector graphics packages, for more down-to-
earth applications in science, engineering and business
it takes some beating. So, in common with just about all
vector graphics software, it’s ideal for drawing technical
illustrations, flow charts, organisational charts,
electronic circuit diagrams and the like. This being the
case, our first step-by-step guide (see over the page)
introduces you to the basic principles by describing how
to draw a diagram of a MOSFET, the type of transistor
that powers just about all our electronic gear.
Only connect
One reason for choosing to base this tutorial on
LibreOffice Draw is that it has some features that are
not universal among vector graphics software, but
which are particularly useful for the sort of uses you
might be interested in. An especially powerful feature
is something called connectors. Connectors look like
ordinary lines, and are used for connecting boxes and
similar shapes in flow diagrams, organisational charts
and the like – but with one important difference –
Connectors remain attached to the objects they join
together, even if you edit your diagram by moving those
objects around – the connecting lines re-route as
necessary. Because this is such a time-saver for many
types of technical and business charts, our second step-
by-step guide makes use of connectors.
Another handy feature, for those who require
mechanical drawings, is specific support for
dimensions. Of course, you can add dimensions
yourself in any drawing package, using text and
lines with arrow heads, but if you change the size
of something you’d have to amend the dimensional
information manually. With LibreOffice Draw’s
dedicated dimensioning facility, on the other hand,
once you’ve added a dimension, it will continue to
show the correct value, irrespective of any resizing.
There’s clearly a limit to the number of LibreOffice
Draw’s facilities that we can illustrate in step-by-step
guides, but this need not limit your voyage of discovery.
So let’s consider a few more things that you might like
to try out to help you get to grips with this powerful
package. You might want to work with bitmaps, for
instance. We suggest that you get to grips with this
useful feature by elaborating on the organisational
chart that we create in our second step-by-step guide.
In particular, since that exercise involves producing
a company organisational chart, a good next step would
be to add photos of each staff member. If you don’t
have any suitable head-and-shoulder shots at hand,
a quick Google image search will reveal no shortage
of sample images. Because they will be reproduced at
quite a small size, we suggest that you limit the file size
of your diagram by down-sampling the photos first, to
something like 300 pixels, using a photo editing
package such as GIMP.
More irregular shapes
So far, we’ve mostly talked about regular shapes such
as squares, rectangles, circles and straight lines, since
they’re pretty much all you need for so many types of
illustration. There are times, though, when you need
something not quite so regular – for example, the cloud
LibreOffice
Drawoffers
optionsfor
editingbitmaps.
as you’dexpect,
youcanadjust
brightness
andcontrast,
andthisbasic
functionalityis
enhancedwith
controlover
thethree
primarycolours
andgamma.shapes used to signify the internet in network diagrams- and fortunately LibreOffice Draw provides several
tools for drawing irregular objects. You’ll find these at
the Curve icon in the Drawing toolbar, and we’ll look at
the general concepts here.
First up is the Polygon, and there are several options
for this. The filled Polygon is much as you expect, and it
enables you to define any closed shape from a number
of straight-line segments. There is also a variant where
you are constrained to angles that are multiples of 45
degrees. Then there’s the plain (unfilled) Polygon, also
with the 45 degree option – but this is really a
misnomer. It would be more accurately called a
polyline, a line made up from several straight-line
segments but with no fill. Note that, having drawn a
polygon, it’s possible to move, delete or add nodes –
that is, the points between line segments which appear
as small squares.
Next is Curve, which is perhaps a bit confusing, since
all these tools are found under the broad heading of
Curve. Unlike the various types of Polygon, which are
composed of straight-line segments, a Curve – as the
name suggests – is made up of curved-line segments.
Space doesn’t permit us a full description of how to
draw a Curve or edit one and in any case, this is
something that’s best learned by trying it out. With a
Curve,inadditiontoeditingthe nodes you also have
GrOupinG
In the walkthrough on page 78, we create a line and a circle and then
make several copies of that combination for use elsewhere in the
diagram. If you’re doing this sort of thing, when you’re moving a
group of objects around it’s notoriously easy for them to become
separated because you’ve accidentally forgotten to select one of
them. It’s simple to prevent this, however.
The secret is to convert those objects into what LibreOffice Draw
considers to be a group. To do this, select the objects to be grouped
and then select Modify > Group. Once a combination of objects is
grouped in this way, it will be treated as a single object – as you’ll
discover if you try to select just one constituent part of the group.
As a group, therefore, it’s pretty much impossible to try to edit the
group and find that your editing operation applies to only part of it.
Grouping is reversible, which is good news if you subsequently
decide that you need to edit the individual parts of the group. As
you’ve probably guessed, having selected a group all you need to
do this is to use Modify > Ungroup.