Sketches, charts, and other diagrams visualize correlations in software development, break down complex operations into individual steps, or highlight controls in technical manuals for the reader. Artistic quality is not necessarily the aim in such business graphics. Quick results and easy handling of the drawing software are far more important.

In this article, we review four drawing programs that will benefit office users, scientists, programmers, and others. Our lab team tested how well suited the candidates were for quickly producing drawings without demanding requirements. The candidates were Inkscape [1], which also has some artistic ambitions; the drawing tools from the two large office suites, LibreOffice Draw [2] and Calligra Karbon [3]; and the simple Python program sK1 [4].

Inkscape

The first candidate is licensed under the GPLv2 and, according to the developers, specializes in two-dimensional vector graphics. Inkscape is available for Linux, Windows, and OS X; the testers looked at the current version 0.91 from January 2015.

Inkscape's jam-packed interface raises doubts as to whether feature overload could be a burden if you just need purpose-built, simple drawings. The toolbar on the left with its 20 tools is larger than that of the competitors. Rectangles, 3D objects, circles, ellipses, arcs, stars, polygons, and the selection tool are immediately recognizable. It also offers buttons for freehand lines (pencil) and straight and Bezier curves (stylus). The fountain pen symbol opens the calligraphy tool; it is not suitable for sketches and unfurls its full functionality only on graphics tablets.

Round, Edged, and Colored

When drawing rectangles, circles, ellipses, and arcs, the Control key limits the height and width ratio to integer values. Inkscape draws beveled or asymmetrically rounded edges with edged objects. Users can determine the radius using the mouse or enter the parameter in the two fields at the top. A round drag point, which reduces the full circle to an arc segment when you move it, also appears for circular objects once you release the mouse button. Inkscape will draw a piece of pie or an arc segment depending on whether the mouse is inside or outside the circle when dragged.

Users can then select the background color for an object using the color palette at the bottom; holding down the Shift key defines the contour. Double-clicking the color fields Fill and Stroke at bottom left below the palette opens the Fill and Stroke dialog for granular adjustments in the right pane. Users can adjust the thickness and shape of the border, the node markings, and beveled line ends; this is particularly practical for technical drawings. The fills include radial and linear gradients but also losslessly scaling line and dot patterns for an ink-drawn look.

Anyone who has already tried to draw a line freehand using the mouse knows that this rarely produces presentable results (Figure 1, top left). With the smoothing algorithms, the freehand tool achieves levels similar to pencil sketches (top right); genuinely professional results are possible using the Bezier curves that originated with CAD applications (see below).

Figure 1: The mouse is not really suitable as an alternative to a pen (top left). Smoothing algorithms (top right) and Bezier curves (below) in Inkscape deliver better results.

When working with the freehand tool, users enter the line thickness in the fields at the top. A value of 50 suffices to produce attractive results. Alternatively, you can choose a lower number and simplify the lines later by pressing Ctrl+L once or multiple times.

Fine Motor Skills

Bezier curves are created intuitively using the mouse in Inkscape. Individual clicks set control points, then pulling defines the direction and steepness of the curve. If there is no movement, straight lines are created. Each segment is usually attached to its predecessor's curve. The shift key makes it possible to draw corners. Inkscape is the only candidate in the test capable of drawing such corners or pointed nodes directly (i.e., without switching from the drawing to the node tool).

Like most functions, the tool requires a bit of familiarization. It takes a bit of practice to match the curves with the artist's ideas when dragging the control points and tangents. The shortcut Ctrl+L smooths the curves as needed.

None of the other test candidates provide as many functions for adjustments as Inkscape. Helpful guidelines appear in the virtual page when users click the ruler and then drag it into the drawing area. Double-clicking a line opens the Guideline dialog, which allows lines and corners to be placed and set very precisely. Although the software is not necessarily designed for technical drawings, the guidelines replace a ruler and compass to a certain extent (Figure 2).

Figure 2: Guidelines snap into place in Inkscape in several places. The palette in the right pane aligns the objects and distributes them equally.

The Snap Controls Bar, found under the View | Show/Hide menu, is responsible for magnetizing guidelines and contours or control points so that objects placed nearby snap to the grid. The Object snap functions also provide snapping to centers, rotation points, intersections, and many other geometric constructs with attraction. The function has 18 options altogether – too many for beginners, but they are all quite useful in practice.

Perhaps the easiest option for aligning objects is offered by the grid found under Object | Align and Distribute (Figure 2). The palette allows you to align objects on their left or right borders, on center points, or flush.