Skencil / Frequently Asked Questions

Table of Contents

1 About Skencil

1.1 What is Skencil?

Skencil is an interactive vector drawing program for GNU/Linux and other UNIX compatible systems. Skencil is implemented almost completely in Python, a very high-level, object oriented, interpreted language, with the rest written in C for speed.

1.2 Why would I want to use Skencil? I have GIMP!

Skencil is a vector drawing program. That means a Skencil drawing is made up of shapes like rectangles, ellipses and curves that can be filled and stroked. Each object is represented by the mathematical description of its shape, e.g. for a circle they're the coordinates of the center point and the length of the radius. Because of this, vector drawings can be scaled without quality loss and it's very easy to change parts of a drawing.

GIMP, on the other hand, is an image manipulation program. A GIMP image is made up of thousands of pixels and apart from layers has no inner structure. This representation has the advantage that you can easily have a lot of fine detail because each pixel can have a different color, but after you e.g. have drawn a line, all you have is pixels. You can't easily change the position or length or color of the line after you've drawn it. Furthermore, a raster image is always designed with one particular resolution in mind and scaling it often reduces its quality.

Both kinds of graphics programs have their strengths and weaknesses and for some purposes an image manipulation program is the appropriate tool while for others it's the vector drawing program and often you'll need both.

1.3 Where can I find out more about Skencil?

The best place to go for information about Skencil is its web-page at http://www.skencil.org/.

1.4 Which Platforms does Skencil work on?

The feedback I've got so far about other platforms indicates that Skencil runs on these platforms too:

• GNU/Linux on i386, Alpha, m68k, PowerPC and Sparc
• FreeBSD
• Solaris 2.5.1, 2.6, 2.7
• IRIX64 6.4
• AIX

2 Troubleshooting

2.1 I get the error message "ImportError: No module named Image"

This message usually means that the Python Imaging Library (PIL) is not installed on your system, so the solution is to install it.

URLs for the sources and rpms can be found on Skencil's web-page (see FAQ 1.3) and in the INSTALL file. Some Linux distributions already contain a suitable version of PIL although in some cases they're a bit buggy.

SuSE Linux 6.2, 6.3 and 6.4, for instance, have a PIL-package, but it's slightly broken. The file /usr/lib/python1.5/site-packages/PIL.pth is missing. To fix this, create that file with just the line 'PIL' in it (without the quotes). (the purpose and syntax of *.pth files is described in /usr/lib/python1.5/site.py)

2.2 The window resizes when I drag the mouse or change the selection

The frequent resizes are caused by the changing texts in the status bar. The best solution is to either use the "--geometry" command line option to set the size of the main window or to put an entry like "sketch.geometry: 900x680" into your .Xdefaults file.

3 Using Skencil

3.1 How do I import a PostScript or EPS file?

That depends on what you want to do exactly.

If you want to embed an EPS file as a whole into a Skencil drawing, just treat it like a raster image, i.e. use the menu command Edit->Create->Load Image file or use the corresponding toolbar button which is the rightmost one.

In this case, you get an EPS-object which Skencil displays with a preview image rendered by ghostscript. It behaves very much like a raster image, but when you output your drawing as a postscript file, the EPS' postscript code is copied to the output file.

If you want to import your postscript file because you want to edit its contents, to change fill colors for example, you can in some circumstances use the normal file loading commands, i.e. File->Open or File->Insert Document, to achieve this. It only works if the file is actually an Illustrator file.

For other postscript files, have a look at pstoedit. It uses ghostscript to interpret arbitrary postscript files and can write several vector file formats, including Skencil's own sk-format.

3.2 How do I export a drawing as EPS?

Just print into a file or use File->Save as PostScript in the menu. Skencil always generates EPS files. You don't have to do anything special.

3.3 How do I close a curve or polygon?

In edit mode, select both end points and invoke the menu command Curve->Close Nodes.

3.4 How do I rotate an object by a precise angle?

Skencil doesn't have a dialog for this yet, but if you want to rotate it by a multiple of 15 degrees, just hold control while rotating the object interactively.

3.5 Is there a command line tool to convert sk-files to PostScript?

Skencil comes with a script called sk2ps that does just that. It's automatically installed alongside Skencil and can even read all the file formats Skencil can read.

4 Miscellaneous

4.1 Why doesn't Skencil have support for <some cool feature>?

Depending on what the feature in question is, there are several possible answers.

The most common reason is simply that nobody has written it yet. There are many useful features that Skencil should have, but currently there's only one Programmer writing code and that severely limits what gets implemented and how fast.

Of course, not every feature is useful or fits well with the goals of the Skencil project. However, I hope to make Skencil flexible and extensible enough to accommodate such features with plugins and user scripts.

See also the FAQs about TrueType fonts (4.3) and text encodings (4.4)

4.2 Which font formats are supported?

Currently, Skencil supports only Type 1 fonts.

4.3 Why doesn't Skencil support TrueType fonts?

Well, font-handling under Linux/Unix/X is pretty complex. Applications have to do a lot of things themselves that should be provided by the 'system' (whatever that means). So it's simply a lot of work and I went the easy route and support only Type1 fonts because X can render them even without any special setup and printing them is no problem because it's the native PostScript font format.

Now, with FreeType and XFree 4.0, supporting TrueType fonts will become much easier and Skencil will support them one day.

You may also want to have a look at the CurveText extension or the JapaneseText extension which let you create bezier objects based on TrueType fonts. Both extensions are available through the add-on page

4.4 Can I input text in ISO-Latin-2 or some other encoding?

Unfortunately, no. At least not in the 0.6 stable releases.

Adding proper support for that would require a lot more work than I want to do for 0.6.x. It would require changes to the way events are handled, text objects would have to know about encodings and the post-script output code as well, and it would require changes to the file format.

That having been said, one of the goals of the current developer series, 0.7, is better text support including better support for encodings other than ISO-Latin-1. One of the first steps will probably be to switch to unicode internally.

When I added text support to Skencil, I simply chose the most simple way to handle encodings that would suffice for my needs and that's Latin-1 and some support for font-specific encodings for symbol fonts. I knew of course that this wouldn't be enough in the long run, especially with respect to non-latin scripts and multi-byte character sets, but having a simple implementation that works for many users is always better than to have no usable code because the project gets bogged down in a too complex design, IMO, especially in a Free Software project.

5 Microsoft Windows specific issues

5.1 I get "ImportError: DLL load failed" error message when trying to start the program

The error can be caused by missing DLL libraries or by wrong versions of some DLL libraries on your system.

If the error message is e.g. "The specified procedure could not be found", you propably have an old version of some GTK-related DLL in your system directory. On Windows, DLLs are searched from system directories before PATH directories. That's why a wrong version of a library can get loaded. To solve the problem, move the offending DLL form the system directory to a non-system directory on PATH.

DLL problems can usually be solved be examining PyGTK's gobject.pyd using Dependency Walker.