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<!-- -*- Mode: rst -*- -->
<a class="reference external image-reference" href="https://badge.fury.io/py/PyValentina"><object data="https://badge.fury.io/py/PyValentina.svg" type="image/svg+xml">https://badge.fury.io/py/PyValentina.svg</object></a>
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<a class="reference external image-reference" href="https://raw.githubusercontent.com/FabriceSalvaire/PyValentina/master/LICENSE.txt"><object data="https://img.shields.io/pypi/l/PyValentina.svg" type="image/svg+xml">https://img.shields.io/pypi/l/PyValentina.svg</object></a>
<!-- -*- Mode: rst -*- -->
<!-- |PyValentinaUrl|
|PyValentinaHomePage|_
|PyValentinaDoc|_
|PyValentina@github|_
|PyValentina@readthedocs|_
|PyValentina@readthedocs-badge|
|PyValentina@pypi|_ -->
<!-- .. _PyValentina@github: https://github.com/FabriceSalvaire/PyValentina -->
<!-- .. _PyValentina@readthedocs: http://pyvalentina.readthedocs.org -->
<!-- .. _PyValentina@pypi: https://pypi.python.org/pypi/PyValentina -->
<!-- coverage test -->
<!-- https://img.shields.io/pypi/status/Django.svg -->
<!-- https://img.shields.io/github/stars/badges/shields.svg?style=social&label=Star -->
<!-- End -->
<!-- -*- Mode: rst -*- -->
<!-- End -->
<div class="section" id="pyvalentina">
<h1>PyValentina</h1>
<p>The official PyValentina Home Page is located at <a class="reference external" href="http://fabricesalvaire.github.io/PyValentina">http://fabricesalvaire.github.io/PyValentina</a></p>
<p>The latest documentation build from the git repository is available at readthedocs.org <a class="reference external" href="http://pyvalentina.readthedocs.org/en/latest"><img alt="PyValentina@readthedocs-badge" src="https://readthedocs.org/projects/pyvalentina/badge/?version=latest" /></a></p>
<p>Written by <a class="reference external" href="http://fabrice-salvaire.pagesperso-orange.fr">Fabrice Salvaire</a>.</p>
<!-- -*- Mode: rst -*- -->
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</div>
<div class="section" id="introduction">
<h1>Introduction</h1>
<p>PyValentina is a python implementation of the <a class="reference external" href="http://valentina-project.org/">Valentina</a> Pattern
Drafting software, which only focus to the core engine and not to the graphical user interface.</p>
<p>A pattern in flat pattern design is build from geometrical operations which can be turned to a
computer program and is thus a field of applications of Computer Aided Design. It corresponds more
precisely to parametric modelling with dedicated features to fashion modelling and manufacturing.</p>
<div class="section" id="what-is-the-requirements-of-a-pattern-drafting-software">
<h2>What is the requirements of a pattern drafting software ?</h2>
<p>The core functionality of a CAD system for pattern drafting consists of these two software components :</p>
<ul class="simple">
<li>an _open_ file format to store and exchange the pattern,</li>
<li>a geometrical engine to compute the pattern, e.g. to generate the layout of each fabric's piece of a clothe.</li>
</ul>
<p>The XML language is a natural candidate to define an open file format to store and exchange the
pattern. Valentina uses XML to sore measurements in <em>.vit</em> files and patterns in <em>.val</em> files.</p>
<p>Another solution to define and store a pattern is to use a programming language, it can be a
dedicated language or any programming language associated to a dedicated API. Many graphical
languages was invented for specific usages, e.g. PostScript for printer, Metafont and MetaPost for
publishing, G-code for machining etc.</p>
<p>Usually the geometrical operations of a pattern are simple in comparison to the requirements of a
mechanical or electronic CAD software. In first hand it is only 2D and the number of operations
should be handled smoothly by a computer of these days, whereas it is still challenging for other
domains. A pattern drafting software only need a good geometrical engine to be designed
efficiently.</p>
<p>Finally, a pattern drafting software requires an efficient graphical user interface so as to be used
by fashion designers and not only by computer scientists. This software component is more challenging in
therms of software engineering, i.e. in therms of design and cost.</p>
</div>
<div class="section" id="why-python-is-a-good-language-for-this-library">
<h2>Why Python is a good language for this library ?</h2>
<p>The Python language has a large audience in engineering, due to its canonical syntax and richness of
its ecosystem (scientific libraries).</p>
<p>Python is a high level language and thus more productive.</p>
<p>Python is used as scripting language to extend many software, in particular the famous open source
3D creation suite <a class="reference external" href="https://www.blender.org">Blender</a>, the parametric 3D modeller <a class="reference external" href="http://freecadweb.org">FreeCad</a> as well as the SVG editor <a class="reference external" href="https://inkscape.org/">Inkscape</a>. Moreover
the 3D human model generator <a class="reference external" href="http://www.makehuman.org">MakeHuman</a> is written in Python.</p>
<p>Python can be easily extended by C libraries using <a class="reference external" href="http://cffi.readthedocs.io/en/latest">CFFI</a>
and C++ libraries using <a class="reference external" href="http://www.swig.org">SWIG</a>.</p>
<p>Python as other dynamic languages is able to evaluate code on the fly which provide an expression
evaluator for free. And this feature is even more pertinent in our case because of the canonical
nature of the syntax of Python which is natural to somebody initiated to a basic mathematical
language level.</p>
</div>
<div class="section" id="what-is-the-purpose-of-this-library">
<h2>What is the purpose of this library ?</h2>
<p>This library could serve several purposes :</p>
<ul class="simple">
<li>help to experiment core features for pattern drafting,</li>
<li>plug Valentina to software featuring a Python plugin mechanism like Blender, FreeCad etc.</li>
</ul>
</div>
<div class="section" id="could-we-implement-a-full-software-using-python">
<h2>Could we implement a full software using Python ?</h2>
<p>The answer is <em>yes we can!</em> since <a class="reference external" href="https://www.qt.io">Qt</a> has as a nice binding so called <a class="reference external" href="https://riverbankcomputing.com/software/pyqt/intro">PyQt</a> (if we consider Qt is superior to GTK and
WxWidgets).</p>
<p>But up to now Python as of course some drawbacks!</p>
<p>Its main drawback is due to the fact the standard interpreter cannot execute more than one <em>Python
bytecode</em> thread in true parallelism (multi-core), this limitation so called Global Interpreter Lock
is required for implementation simplicity. Consequently we can do multi-threading, even on
multi-core in some cases, but less easily than in Java or Cxx11.</p>
<p>Despite a GUI implemented in PyQt is almost of the time more faster than the human perception on a
computer of these days. It can be sometime difficult to overcome some latency arising from the
software stack. Thus yes we can do it, but it could requires some tricks to achieve the performance
of a C++ application.</p>
</div>
<div class="section" id="how-to-generate-drawings-in-standard-format-like-pdf-or-svg">
<h2>How to generate drawings in standard format like PDF or SVG ?</h2>
<p>SVG is not difficult to generate from Python since it is based on XML. However the PDF format is
more challenging, for efficiency reason PDF is a binary format and is thus much more complicated
than PostScript which a true programming language.</p>
<p>There is several possibilities to generate PDF.</p>
<p>The most disturbing one is to use the <a class="reference external" href="https://en.wikipedia.org/wiki/LaTeX">LaTeX</a> publishing
system in combination with the <a class="reference external" href="http://www.texample.net/tikz/examples">PGF</a> package which provide
an amazing graphical language on top of LaTeX. This solution could terrify people, but it do the
job and very well as well as for text and graphics. However user must install a LaTeX environment
from their Linux distribution or using <a class="reference external" href="https://www.tug.org/texlive">TexLive</a>.</p>
<p>A more conventional solution requires a library able to generate PDF from standard graphical
operations. Some libraries able to that are :</p>
<ul class="simple">
<li>Qt using QPainter API, Valentina solution, see <a class="reference external" href="https://wiki.qt.io/Handling_PDF">https://wiki.qt.io/Handling_PDF</a></li>
<li><a class="reference external" href="https://www.cairographics.org/manual/cairo-PDF-Surfaces.html">Cairo</a></li>
<li><a class="reference external" href="http://www.reportlab.com/opensource">ReportLab</a> open-source PDF Toolkit (more commercial and less known)</li>
<li><a class="reference external" href="http://matplotlib.org">Matplotlib</a> (but more oriented to plot)</li>
<li>and ???</li>
</ul>
<!-- -*- Mode: rst -*- -->
</div>
</div>
<div class="section" id="features">
<h1>Features</h1>
<p>The features of PyValentina are :</p>
<ul class="simple">
<li>read <em>.val</em> and <em>.vit</em> file</li>
<li><a class="reference external" href="http://beltoforion.de/article.php?a=muparser">QMuParser</a> expressions are translated to Python and evaluated on the fly</li>
<li>compute the detail of a pattern</li>
<li>export the detail to latex/pgf</li>
</ul>
<p>Missing features:</p>
<ul class="simple">
<li>write <em>.val</em> and <em>.vit</em> file</li>
<li>full operation support</li>
<ul class="simple">
<li>export to tiled A4 PDF</li>
<li>Python API to define pattern</li>
</ul>
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</div>
<div class="section" id="installation">
<span id="installation-page"></span><h1>Installation</h1>
<p>The installation of PyValentina by itself is quite simple. However it will be easier to get the
dependencies on a Linux desktop.</p>
<div class="section" id="dependencies">
<h2>Dependencies</h2>
<p>PyValentina requires the following dependencies:</p>
<blockquote>
<ul class="simple">
<li><a class="reference external" href="http://python.org">Python</a> 3</li>
<li><a class="reference external" href="http://www.numpy.org">Numpy</a></li>
</ul>
</blockquote>
<p>Also it is recommanded to have these Python modules:</p>
<blockquote>
<ul class="simple">
<li>pip</li>
<li>virtualenv</li>
</ul>
</blockquote>
<p>For development, you will need in addition:</p>
<blockquote>
<ul class="simple">
<li><a class="reference external" href="http://sphinx-doc.org">Sphinx</a></li>
</ul>
</blockquote>
</div>
<div class="section" id="installation-from-pypi-repository">
<h2>Installation from PyPi Repository</h2>
<p>PyValentina is made available on the <a class="reference external" href="https://pypi.python.org/pypi">PyPI</a> repository at <a class="reference external" href="https://pypi.python.org/pypi/PyValentina">https://pypi.python.org/pypi/PyValentina</a></p>
<p>Run this command to install the last release:</p>
<pre class="code sh literal-block">
pip install PyValentina
</pre>
</div>
<div class="section" id="installation-from-source">
<h2>Installation from Source</h2>
<p>The PyValentina source code is hosted at <a class="reference external" href="https://github.com/FabriceSalvaire/PyValentina">https://github.com/FabriceSalvaire/PyValentina</a></p>
<p>To clone the Git repository, run this command in a terminal:</p>
<pre class="code sh literal-block">
git clone git@github.com:FabriceSalvaire/PyValentina.git
</pre>
<p>Then to build and install PyValentina run these commands:</p>
<pre class="code sh literal-block">
python setup.py build
python setup.py install
</pre>
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<div class="section" id="bibliography">
<span id="bibliography-page"></span><h1>Bibliography</h1>
<ul class="simple">
<li><a class="reference external" href="http://www.cgal.org/">CGAL Computational Geometry Algorithms Library</a></li>
<li><a class="reference external" href="https://www.geometrictools.com/index.html">David Eberly Geometric Tools web site</a></li>
</ul>
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