Terminal sections: show the AWG equivalent in the section lists

The section combo boxes of the terminal strip editor and of the
element editor now show the nearest AWG / kcmil size next to the
section in mm2, for example "2.5 mm² (AWG 14)".

The correspondence is approximate (the two systems don't have the
same steps) and is stored in TerminalCatalog::awgForSection().
The stored value is unchanged (terminal_section, in mm2).

sources/TerminalStrip/terminalcatalog.h

@@ -18,6 +18,8 @@
 #ifndef TERMINALCATALOG_H
 #define TERMINALCATALOG_H
 
+#include <QLocale>
+#include <QString>
 #include <QVector>
 
 /**
@@ -41,6 +43,51 @@ namespace TerminalCatalog
 		return sections_;
 	}
 
+	/**
+	 * @brief awgForSection
+	 * @param mm2 : a section in mm2
+	 * @return the nearest AWG / kcmil size, as text ("14", "1/0", "250 kcmil"),
+	 * or an empty string if the section has no usual equivalent.
+	 * The correspondence is approximate (the usual table of the manufacturers),
+	 * the two systems don't have the same steps.
+	 */
+	inline QString awgForSection(double mm2)
+	{
+		struct Awg { double mm2; const char *awg; };
+		static const Awg table_[] {
+			{0.5,  "20"},      {0.75, "18"},      {1,   "17"},
+			{1.5,  "16"},      {2.5,  "14"},      {4,   "12"},
+			{6,    "10"},      {10,   "8"},       {16,  "6"},
+			{25,   "4"},       {35,   "2"},       {50,  "1/0"},
+			{70,   "2/0"},     {95,   "3/0"},     {120, "250 kcmil"},
+			{150,  "300 kcmil"}, {185, "350 kcmil"}, {240, "500 kcmil"},
+			{300,  "600 kcmil"}
+		};
+		for (const auto &entry : table_) {
+			if (qAbs(entry.mm2 - mm2) < 0.0001) {
+				return QString::fromLatin1(entry.awg);
+			}
+		}
+		return QString();
+	}
+
+	/**
+	 * @brief sectionText
+	 * @param mm2 : a section in mm2
+	 * @param unit_text : the text of the section with its unit, for example "2,5 mm²"
+	 * @return @a unit_text followed by the AWG size if there is one : "2,5 mm² (AWG 14)"
+	 */
+	inline QString sectionText(double mm2, const QString &unit_text)
+	{
+		const auto awg_ = awgForSection(mm2);
+		if (awg_.isEmpty()) {
+			return unit_text;
+		}
+		return awg_.contains(QLatin1String("kcmil"))
+				? unit_text + QStringLiteral(" (%1)").arg(awg_)
+				: unit_text + QStringLiteral(" (AWG %1)").arg(awg_);
+	}
+
 	inline const QVector<WidthEntry> &widthEntries()
 	{
 		static const QVector<WidthEntry> entries_ {

sources/TerminalStrip/ui/terminalstripmodel.cpp

@@ -956,7 +956,7 @@ QWidget *TerminalStripModelDelegate::createEditor(QWidget *parent, const QStyleO
 		qcb->addItem(tr("None (default)"), 0.0);
 			//Usual sections, in mm2
 		for (const auto section_ : TerminalCatalog::sections()) {
-			qcb->addItem(tr("%1 mm²").arg(QLocale().toString(section_, 'g', 6)), section_);
+			qcb->addItem(TerminalCatalog::sectionText(section_, tr("%1 mm²").arg(QLocale().toString(section_, 'g', 6))), section_);
 		}
 
 		return qcb;
@@ -1048,7 +1048,7 @@ void TerminalStripModelDelegate::setEditorData(QWidget *editor, const QModelInde
 			if (pos_ < 0)
 			{
 					//The section is not in the list (typed or pasted), keep it in the list
-				qcb->addItem(tr("%1 mm²").arg(QLocale().toString(section_, 'g', 6)), section_);
+				qcb->addItem(TerminalCatalog::sectionText(section_, tr("%1 mm²").arg(QLocale().toString(section_, 'g', 6))), section_);
 				pos_ = qcb->count() - 1;
 			}
 			qcb->setCurrentIndex(pos_);

sources/editor/ui/elementpropertieseditorwidget.cpp

@@ -440,7 +440,9 @@ void ElementPropertiesEditorWidget::populateTerminalSizeCombos(double section, d
 	ui->m_terminal_section_cb->clear();
 	ui->m_terminal_section_cb->addItem(tr("None (default)"), 0.0);
 	for (const auto section_ : TerminalCatalog::sections()) {
-		ui->m_terminal_section_cb->addItem(tr("%1 mm²").arg(QLocale().toString(section_, 'g', 6)), section_);
+		ui->m_terminal_section_cb->addItem(
+			TerminalCatalog::sectionText(section_, tr("%1 mm²").arg(QLocale().toString(section_, 'g', 6))),
+			section_);
 	}
 	setComboValue(ui->m_terminal_section_cb, section, tr(" mm²"));