Add import dxf feature

Use dxf2elmt to import dxf.
See https://github.com/antonioaja/dxf2elmt

sources/dxf/dxftoelmt.cpp

@@ -0,0 +1,102 @@
+/*
+	Copyright 2006-2022 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "dxftoelmt.h"
+#include "../ui/thirdpartybinaryinstalldialog.h"
+
+#include <QFile>
+#include <QProcess>
+#include <QMessageBox>
+#include <QDir>
+
+/**
+ * @brief dxftoElmt
+ * Return the dxf at @a file_path converted to elmt.
+ * The returned value is a QByteArray, instead of a
+ * QDomDocument or QString, to let user do what they want with that.
+ * @param file_path
+ * @return
+ */
+QByteArray dxfToElmt(const QString &file_path)
+{
+	if (!dxf2ElmtIsPresent(false)) {
+		return QByteArray();
+	}
+
+	QProcess process_;
+	const QString program{dxf2ElmtBinaryPath()};
+	const QStringList arguments{file_path, QStringLiteral("-v")};
+
+	process_.start(program, arguments);
+	process_.waitForFinished();
+
+	const auto byte_array{process_.readAll()};
+	process_.close();
+	return byte_array;
+}
+
+QString dxf2ElmtDirPath()
+{
+#if defined(Q_OS_WIN32) || defined(Q_OS_WIN64)
+	return (QDir::homePath() + QStringLiteral("/Application Data/qet/binary"));
+#elif defined(Q_OS_MAC)
+	return (QDir::homePath() + QStringLiteral("/.qet/binary"));
+#else
+	return (QDir::homePath() + QStringLiteral("/.qet/binary"));
+#endif
+}
+
+/**
+ * @brief dxf2ElmtBinaryPath
+ * @return the path to the dxf2elmt program
+ */
+QString dxf2ElmtBinaryPath()
+{
+#if defined(Q_OS_WIN32) || defined(Q_OS_WIN64)
+	return dxf2ElmtDirPath() + QStringLiteral("/dxf2elmt.exe");
+#elif defined(Q_OS_MAC)
+	return dxf2ElmtDirPath() + QStringLiteral("/dxf2elmt.app");
+#else
+	return dxf2ElmtDirPath() + QStringLiteral("/dxf2elmt");
+#endif
+}
+
+/**
+ * @brief dxf2ElmtIsPresent
+ * Return true if dxf2elmt is present in the system
+ * @param install_dialog
+ * True to display a dialog with the explanations
+ * of how to install the dxf2elmt program
+ * if not present in the system.
+ * @return
+ */
+bool dxf2ElmtIsPresent(bool install_dialog, QWidget *parent)
+{
+	const bool exist{QFile::exists(dxf2ElmtBinaryPath())};
+	if (!exist && install_dialog)
+	{
+		auto string_{QStringLiteral("L'import dxf nécessite le logiciel dxf2elmt. \n"
+									"Veuillez télécharger celui-ci en suivant le lien ci dessous et le dézipper dans le dossier d'installation")};
+
+		ThirdPartyBinaryInstallDialog dialog_(string_,
+											  QStringLiteral("https://github.com/antonioaja/dxf2elmt/releases"),
+											  dxf2ElmtDirPath(),
+											  parent);
+		dialog_.exec();
+	}
+	return exist;
+}