trunk/pages/faq.html

title: Skencil / Frequently Asked Questions

<h2>Table of Contents</h2>
  1 <a href="#FAQ1">About Skencil</a><br />
&nbsp;&nbsp;  1.1 <a href="#FAQ1.1">What is Skencil?</a><br />
&nbsp;&nbsp;  1.2 <a href="#FAQ1.2">Why would I want to use Skencil? I have GIMP!</a><br />
&nbsp;&nbsp;  1.3 <a href="#FAQWebpage">Where can I find out more about Skencil?</a><br />
&nbsp;&nbsp;  1.4 <a href="#FAQ1.4">Which Platforms does Skencil work on?</a><br />
  2 <a href="#FAQ2">Troubleshooting</a><br />
&nbsp;&nbsp;  2.1 <a href="#FAQ2.1">I get the error message &quot;ImportError: No module named Image&quot;</a><br />
&nbsp;&nbsp;  2.2 <a href="#FAQ2.2">The window resizes when I drag the mouse or change the selection</a><br />
  3 <a href="#FAQ3">Using Skencil</a><br />
&nbsp;&nbsp;  3.1 <a href="#FAQ3.1">How do I import a PostScript or EPS file?</a><br />
&nbsp;&nbsp;  3.2 <a href="#FAQ3.2">How do I export a drawing as EPS?</a><br />
&nbsp;&nbsp;  3.3 <a href="#FAQ3.3">How do I close a curve or polygon?</a><br />
&nbsp;&nbsp;  3.4 <a href="#FAQ3.4">How do I rotate an object by a precise angle?</a><br />
&nbsp;&nbsp;  3.5 <a href="#FAQ3.5">Is there a command line tool to convert sk-files to PostScript?</a><br />
  4 <a href="#FAQ4">Miscellaneous</a><br />
&nbsp;&nbsp;  4.1 <a href="#FAQFeatureRequest">Why doesn't Skencil have support for &lt;some cool feature&gt;?</a><br />
&nbsp;&nbsp;  4.2 <a href="#FAQ4.2">Which font formats are supported?</a><br />
&nbsp;&nbsp;  4.3 <a href="#FAQTrueTypeFonts">Why doesn't Skencil support TrueType fonts?</a><br />
&nbsp;&nbsp;  4.4 <a href="#FAQEncodings">Can I input text in ISO-Latin-2 or some other encoding?</a><br />
  5 <a href="#FAQ5">Microsoft Windows specific issues</a><br />
&nbsp;&nbsp;  5.1 <a href="#FAQWindowsImportError">I get &quot;ImportError: DLL load failed&quot; error message when trying to start
the program</a><br />
<h2><a name="FAQ1">1 About Skencil</a></h2>
<h3><a name="FAQ1.1">1.1 What is Skencil?</a></h3>
<p>

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.
</p>
<h3><a name="FAQ1.2">1.2 Why would I want to use Skencil? I have GIMP!</a></h3>

<p>Skencil is a <em>vector drawing program</em>. 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.</p>

<p>GIMP, on the other hand, is an <em>image manipulation program</em>.
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.</p>


<p>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.</p>
<h3><a name="FAQWebpage">1.3 Where can I find out more about Skencil?</a></h3>
<p>

The best place to go for information about Skencil is its web-page at
<a href="http://www.skencil.org/">http://www.skencil.org/</a>.
</p>
<h3><a name="FAQ1.4">1.4 Which Platforms does Skencil work on?</a></h3>

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

<ul><li>GNU/Linux on i386, Alpha, m68k, PowerPC and Sparc</li><li>FreeBSD</li><li>Solaris 2.5.1, 2.6, 2.7</li><li>IRIX64 6.4</li><li>AIX</li></ul>
<h2><a name="FAQ2">2 Troubleshooting</a></h2>
<h3><a name="FAQ2.1">2.1 I get the error message &quot;ImportError: No module named Image&quot;</a></h3>


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

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

<p>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)</p>

<h3><a name="FAQ2.2">2.2 The window resizes when I drag the mouse or change the selection</a></h3>
<p>

The frequent resizes are caused by the changing texts in the status bar.
The best solution is to either use the &quot;--geometry&quot; command line option
to set the size of the main window or to put an entry like
&quot;sketch.geometry: 900x680&quot; into your .Xdefaults file.
</p>
<h2><a name="FAQ3">3 Using Skencil</a></h2>
<h3><a name="FAQ3.1">3.1 How do I import a PostScript or EPS file?</a></h3>


<p>That depends on what you want to do exactly.</p>

<p>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-&gt;Create-&gt;Load Image file or use the corresponding toolbar button
which is the rightmost one.</p>

<p>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.</p>

<p>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-&gt;Open or
File-&gt;Insert Document, to achieve this. It only works if the file is
actually an Illustrator file.</p>

<p> For other postscript files, have a look at <a href="http://www.geocities.com/SiliconValley/Network/1958/pstoedit/">pstoedit</a>. It uses ghostscript to interpret arbitrary postscript
files and can write several vector file formats, including Skencil's own
sk-format.</p>
<h3><a name="FAQ3.2">3.2 How do I export a drawing as EPS?</a></h3>
<p>

Just print into a file or use File-&gt;Save as PostScript in the menu.
Skencil always generates EPS files. You don't have to do anything
special.
</p>
<h3><a name="FAQ3.3">3.3 How do I close a curve or polygon?</a></h3>
<p>

In edit mode, select both end points and invoke the menu command
Curve-&gt;Close Nodes.
</p>
<h3><a name="FAQ3.4">3.4 How do I rotate an object by a precise angle?</a></h3>
<p>

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.
</p>
<h3><a name="FAQ3.5">3.5 Is there a command line tool to convert sk-files to PostScript?</a></h3>
<p>

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.
</p>
<h2><a name="FAQ4">4 Miscellaneous</a></h2>
<h3><a name="FAQFeatureRequest">4.1 Why doesn't Skencil have support for &lt;some cool feature&gt;?</a></h3>

<p>Depending on what the feature in question is, there are several possible
answers.</p>

<p>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.</p>

<p>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.</p>

<p>See also the FAQs about TrueType fonts (<a href="#FAQTrueTypeFonts">4.3</a>) and text encodings (<a href="#FAQEncodings">4.4</a>)</p>
<h3><a name="FAQ4.2">4.2 Which font formats are supported?</a></h3>
<p>

Currently, Skencil supports only Type 1 fonts.
</p>
<h3><a name="FAQTrueTypeFonts">4.3 Why doesn't Skencil support TrueType fonts?</a></h3>

<p>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.</p>

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

<p>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 <a href="addon.html">add-on page</a></p>
<h3><a name="FAQEncodings">4.4 Can I input text in ISO-Latin-2 or some other encoding?</a></h3>

<p>Unfortunately, no. At least not in the 0.6 stable releases.</p>

<p>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.</p>

<p>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.</p>

<p>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.</p>
<h2><a name="FAQ5">5 Microsoft Windows specific issues</a></h2>
<h3><a name="FAQWindowsImportError">5.1 I get &quot;ImportError: DLL load failed&quot; error message when trying to start
the program</a></h3>

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

<p>If the error message is e.g. &quot;The specified procedure could not be found&quot;,
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.</p>

<p>DLL problems can usually be solved be examining PyGTK's gobject.pyd using
<a href="http://www.dependencywalker.com">Dependency Walker</a>.</p>

1	jpaalasm	606	title: Skencil / Frequently Asked Questions
2
3			<h2>Table of Contents</h2>
4			1 <a href="#FAQ1">About Skencil</a><br />
5			1.1 <a href="#FAQ1.1">What is Skencil?</a><br />
6			1.2 <a href="#FAQ1.2">Why would I want to use Skencil? I have GIMP!</a><br />
7			1.3 <a href="#FAQWebpage">Where can I find out more about Skencil?</a><br />
8			1.4 <a href="#FAQ1.4">Which Platforms does Skencil work on?</a><br />
9			2 <a href="#FAQ2">Troubleshooting</a><br />
10			2.1 <a href="#FAQ2.1">I get the error message "ImportError: No module named Image"</a><br />
11			2.2 <a href="#FAQ2.2">The window resizes when I drag the mouse or change the selection</a><br />
12			3 <a href="#FAQ3">Using Skencil</a><br />
13			3.1 <a href="#FAQ3.1">How do I import a PostScript or EPS file?</a><br />
14			3.2 <a href="#FAQ3.2">How do I export a drawing as EPS?</a><br />
15			3.3 <a href="#FAQ3.3">How do I close a curve or polygon?</a><br />
16			3.4 <a href="#FAQ3.4">How do I rotate an object by a precise angle?</a><br />
17			3.5 <a href="#FAQ3.5">Is there a command line tool to convert sk-files to PostScript?</a><br />
18			4 <a href="#FAQ4">Miscellaneous</a><br />
19			4.1 <a href="#FAQFeatureRequest">Why doesn't Skencil have support for <some cool feature>?</a><br />
20			4.2 <a href="#FAQ4.2">Which font formats are supported?</a><br />
21			4.3 <a href="#FAQTrueTypeFonts">Why doesn't Skencil support TrueType fonts?</a><br />
22			4.4 <a href="#FAQEncodings">Can I input text in ISO-Latin-2 or some other encoding?</a><br />
23			5 <a href="#FAQ5">Microsoft Windows specific issues</a><br />
24			5.1 <a href="#FAQWindowsImportError">I get "ImportError: DLL load failed" error message when trying to start
25			the program</a><br />
26			<h2><a name="FAQ1">1 About Skencil</a></h2>
27			<h3><a name="FAQ1.1">1.1 What is Skencil?</a></h3>
28			<p>
29
30			Skencil is an interactive vector drawing program for GNU/Linux and other
31			UNIX compatible systems. Skencil is implemented almost completely in
32			Python, a very high-level, object oriented, interpreted language, with
33			the rest written in C for speed.
34			</p>
35			<h3><a name="FAQ1.2">1.2 Why would I want to use Skencil? I have GIMP!</a></h3>
36
37			<p>Skencil is a <em>vector drawing program</em>. That means a Skencil drawing
38			is made up of shapes like rectangles, ellipses and curves that can be
39			filled and stroked. Each object is represented by the mathematical
40			description of its shape, e.g. for a circle they're the coordinates of
41			the center point and the length of the radius. Because of this, vector
42			drawings can be scaled without quality loss and it's very easy to change
43			parts of a drawing.</p>
44
45			<p>GIMP, on the other hand, is an <em>image manipulation program</em>.
46			A GIMP image is made up of thousands of pixels and apart from layers has
47			no inner structure. This representation has the advantage that you can
48			easily have a lot of fine detail because each pixel can have a different
49			color, but after you e.g. have drawn a line, all you have is pixels. You
50			can't easily change the position or length or color of the line after
51			you've drawn it. Furthermore, a raster image is always designed with one
52			particular resolution in mind and scaling it often reduces its quality.</p>
53
54
55			<p>Both kinds of graphics programs have their strengths and weaknesses
56			and for some purposes an image manipulation program is the appropriate
57			tool while for others it's the vector drawing program and often you'll
58			need both.</p>
59			<h3><a name="FAQWebpage">1.3 Where can I find out more about Skencil?</a></h3>
60			<p>
61
62			The best place to go for information about Skencil is its web-page at
63			<a href="http://www.skencil.org/">http://www.skencil.org/</a>.
64			</p>
65			<h3><a name="FAQ1.4">1.4 Which Platforms does Skencil work on?</a></h3>
66
67			<p>
68			The feedback I've got so far about other platforms indicates that Skencil
69			runs on these platforms too:
70			</p>
71
72			<ul><li>GNU/Linux on i386, Alpha, m68k, PowerPC and Sparc</li><li>FreeBSD</li><li>Solaris 2.5.1, 2.6, 2.7</li><li>IRIX64 6.4</li><li>AIX</li></ul>
73			<h2><a name="FAQ2">2 Troubleshooting</a></h2>
74			<h3><a name="FAQ2.1">2.1 I get the error message "ImportError: No module named Image"</a></h3>
75
76
77			<p>This message usually means that the Python Imaging Library (PIL) is not
78			installed on your system, so the solution is to install it.</p>
79
80			<p> URLs for the sources and rpms can be found on Skencil's web-page
81			(see FAQ <a href="#FAQWebpage">1.3</a>) and in the INSTALL file. Some Linux
82			distributions already contain a suitable version of PIL although in some
83			cases they're a bit buggy.</p>
84
85			<p>SuSE Linux 6.2, 6.3 and 6.4, for instance, have a PIL-package, but
86			it's slightly broken. The file /usr/lib/python1.5/site-packages/PIL.pth
87			is missing. To fix this, create that file with just the line 'PIL' in it
88			(without the quotes). (the purpose and syntax of *.pth files is
89			described in /usr/lib/python1.5/site.py)</p>
90
91			<h3><a name="FAQ2.2">2.2 The window resizes when I drag the mouse or change the selection</a></h3>
92			<p>
93
94			The frequent resizes are caused by the changing texts in the status bar.
95			The best solution is to either use the "--geometry" command line option
96			to set the size of the main window or to put an entry like
97			"sketch.geometry: 900x680" into your .Xdefaults file.
98			</p>
99			<h2><a name="FAQ3">3 Using Skencil</a></h2>
100			<h3><a name="FAQ3.1">3.1 How do I import a PostScript or EPS file?</a></h3>
101
102
103			<p>That depends on what you want to do exactly.</p>
104
105			<p>If you want to embed an EPS file as a whole into a Skencil drawing,
106			just treat it like a raster image, i.e. use the menu command
107			Edit->Create->Load Image file or use the corresponding toolbar button
108			which is the rightmost one.</p>
109
110			<p>In this case, you get an EPS-object which Skencil displays with a
111			preview image rendered by ghostscript. It behaves very much like a
112			raster image, but when you output your drawing as a postscript file, the
113			EPS' postscript code is copied to the output file.</p>
114
115			<p>If you want to import your postscript file because you want to edit
116			its contents, to change fill colors for example, you can in some
117			circumstances use the normal file loading commands, i.e. File->Open or
118			File->Insert Document, to achieve this. It only works if the file is
119			actually an Illustrator file.</p>
120
121			<p> For other postscript files, have a look at <a href="http://www.geocities.com/SiliconValley/Network/1958/pstoedit/">pstoedit</a>. It uses ghostscript to interpret arbitrary postscript
122			files and can write several vector file formats, including Skencil's own
123			sk-format.</p>
124			<h3><a name="FAQ3.2">3.2 How do I export a drawing as EPS?</a></h3>
125			<p>
126
127			Just print into a file or use File->Save as PostScript in the menu.
128			Skencil always generates EPS files. You don't have to do anything
129			special.
130			</p>
131			<h3><a name="FAQ3.3">3.3 How do I close a curve or polygon?</a></h3>
132			<p>
133
134			In edit mode, select both end points and invoke the menu command
135			Curve->Close Nodes.
136			</p>
137			<h3><a name="FAQ3.4">3.4 How do I rotate an object by a precise angle?</a></h3>
138			<p>
139
140			Skencil doesn't have a dialog for this yet, but if you want to rotate it
141			by a multiple of 15 degrees, just hold control while rotating the object
142			interactively.
143			</p>
144			<h3><a name="FAQ3.5">3.5 Is there a command line tool to convert sk-files to PostScript?</a></h3>
145			<p>
146
147			Skencil comes with a script called sk2ps that does just that. It's
148			automatically installed alongside Skencil and can even read all the file
149			formats Skencil can read.
150			</p>
151			<h2><a name="FAQ4">4 Miscellaneous</a></h2>
152			<h3><a name="FAQFeatureRequest">4.1 Why doesn't Skencil have support for <some cool feature>?</a></h3>
153
154			<p>Depending on what the feature in question is, there are several possible
155			answers.</p>
156
157			<p>The most common reason is simply that nobody has written it yet.
158			There are many useful features that Skencil should have, but currently
159			there's only one Programmer writing code and that severely limits what
160			gets implemented and how fast.</p>
161
162			<p>Of course, not every feature is useful or fits well with the goals
163			of the Skencil project. However, I hope to make Skencil flexible and
164			extensible enough to accommodate such features with plugins and user
165			scripts.</p>
166
167			<p>See also the FAQs about TrueType fonts (<a href="#FAQTrueTypeFonts">4.3</a>) and text encodings (<a href="#FAQEncodings">4.4</a>)</p>
168			<h3><a name="FAQ4.2">4.2 Which font formats are supported?</a></h3>
169			<p>
170
171			Currently, Skencil supports only Type 1 fonts.
172			</p>
173			<h3><a name="FAQTrueTypeFonts">4.3 Why doesn't Skencil support TrueType fonts?</a></h3>
174
175			<p>Well, font-handling under Linux/Unix/X is pretty complex. Applications
176			have to do a lot of things themselves that should be provided by the
177			'system' (whatever that means). So it's simply a lot of work and I went
178			the easy route and support only Type1 fonts because X can render them
179			even without any special setup and printing them is no problem because
180			it's the native PostScript font format.</p>
181
182			<p> Now, with FreeType and XFree 4.0, supporting TrueType fonts will
183			become much easier and Skencil will support them one day.</p>
184
185			<p>You may also want to have a look at the CurveText extension or the
186			JapaneseText extension which let you create bezier objects based on
187			TrueType fonts. Both extensions are available through the <a href="addon.html">add-on page</a></p>
188			<h3><a name="FAQEncodings">4.4 Can I input text in ISO-Latin-2 or some other encoding?</a></h3>
189
190			<p>Unfortunately, no. At least not in the 0.6 stable releases.</p>
191
192			<p>Adding proper support for that would require a lot more work than I
193			want to do for 0.6.x. It would require changes to the way events are
194			handled, text objects would have to know about encodings and the
195			post-script output code as well, and it would require changes to the
196			file format.</p>
197
198			<p>That having been said, one of the goals of the current developer
199			series, 0.7, is better text support including better support for
200			encodings other than ISO-Latin-1. One of the first steps will probably
201			be to switch to unicode internally.</p>
202
203			<p>When I added text support to Skencil, I simply chose the most simple
204			way to handle encodings that would suffice for my needs and that's
205			Latin-1 and some support for font-specific encodings for symbol fonts. I
206			knew of course that this wouldn't be enough in the long run, especially
207			with respect to non-latin scripts and multi-byte character sets, but
208			having a simple implementation that works for many users is always
209			better than to have no usable code because the project gets bogged down
210			in a too complex design, IMO, especially in a Free Software project.</p>
211			<h2><a name="FAQ5">5 Microsoft Windows specific issues</a></h2>
212			<h3><a name="FAQWindowsImportError">5.1 I get "ImportError: DLL load failed" error message when trying to start
213			the program</a></h3>
214
215			<p>The error can be caused by missing DLL libraries or by wrong versions of
216			some DLL libraries on your system.</p>
217
218			<p>If the error message is e.g. "The specified procedure could not be found",
219			you propably have an old version of some GTK-related DLL in your system
220			directory. On Windows, DLLs are searched from system directories before PATH
221			directories. That's why a wrong version of a library can get loaded. To solve
222			the problem, move the offending DLL form the system directory to a non-system
223			directory on PATH.</p>
224
225			<p>DLL problems can usually be solved be examining PyGTK's gobject.pyd using
226			<a href="http://www.dependencywalker.com">Dependency Walker</a>.</p>
227
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