Element files: anchor="alignment" puts a static text's x at its alignment (#1251)

A static text's x/y in an .elmt file are the baseline-left of the text.
A program writing an element (a pinout generator, dxf2elmt) then has to
measure the text with QET's font metrics to right-align or centre it.

With the opt-in anchor="alignment", x is the left edge, centre or right
edge selected by Halignment; y stays the baseline. The box is the text
without the document margin, as ElementPictureFactory draws it, so the
editor and the folio agree. Rotation pivots on x/y as before.

The element editor reads it and writes it back for the texts that had
it; it does not add it to other texts. Files without anchor draw and
save as before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/qttest/tst_statictextanchor.cpp

@@ -0,0 +1,84 @@
+/*
+	Copyright 2006-2026 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 <QtTest>
+#include <QProcess>
+#include <QTemporaryDir>
+
+/**
+	A static text with anchor="alignment" has its x at the edge or centre
+	its Halignment selects, instead of its left edge (#1251). The symbol in
+	fixtures/static_text_anchor.qet has the same text five times, all at
+	x = 0: left, right and centre anchored, right aligned without anchor,
+	and anchored without Halignment. --export-dxf writes where each is drawn.
+*/
+class tst_statictextanchor : public QObject
+{
+	Q_OBJECT
+
+private slots:
+	void anchoredX()
+	{
+		const QString project = QFINDTESTDATA("fixtures/static_text_anchor.qet");
+		QVERIFY2(!project.isEmpty(), "fixture project not found");
+		QTemporaryDir dir;
+		QVERIFY(dir.isValid());
+
+		QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
+		env.insert(QStringLiteral("QT_QPA_PLATFORM"), QStringLiteral("offscreen"));
+		QProcess proc;
+		proc.setProcessEnvironment(env);
+		proc.start(QStringLiteral(QET_TEST_BINARY_PATH), {QStringLiteral("--export-dxf"), project, dir.path()});
+		QVERIFY2(proc.waitForFinished(60000), "--export-dxf timed out");
+		QCOMPARE(proc.exitCode(), 0);
+
+		QFile file(dir.filePath(QStringLiteral("01_diagram.dxf")));
+		QVERIFY(file.open(QIODevice::ReadOnly | QIODevice::Text));
+		const QStringList values = QString::fromUtf8(file.readAll()).split(QLatin1Char('\n'));
+
+			//x (group code 10) of each TEXT entity of the symbol, in order
+		QList<qreal> xs;
+		for (int i = 0 ; i + 1 < values.size() ; i += 2) {
+			if (values.at(i).trimmed() != QLatin1String("0") || values.at(i + 1).trimmed() != QLatin1String("TEXT"))
+				continue;
+			qreal x = 0;
+			QString text;
+			for (int j = i + 2 ; j + 1 < values.size() && values.at(j).trimmed() != QLatin1String("0") ; j += 2) {
+				if (values.at(j).trimmed() == QLatin1String("10"))
+					x = values.at(j + 1).trimmed().toDouble();
+				else if (values.at(j).trimmed() == QLatin1String("1"))
+					text = values.at(j + 1).trimmed();
+			}
+			if (text == QLatin1String("GPIO21 PCM_DOUT"))
+				xs << x;
+		}
+		QCOMPARE(xs.size(), 5);
+
+		const qreal left = xs.at(0), right = xs.at(1), centre = xs.at(2);
+			//anchored on the right edge: drawn one text width to the left
+		QVERIFY2(left - right > 20, qPrintable(QStringLiteral("left %1 right %2").arg(left).arg(right)));
+			//anchored on the centre: half as far
+		QVERIFY(qAbs(2 * (left - centre) - (left - right)) < 0.01);
+			//without anchor, x stays the left edge whatever the alignment
+		QCOMPARE(xs.at(3), left);
+			//anchor without Halignment is the left edge too
+		QCOMPARE(xs.at(4), left);
+	}
+};
+
+QTEST_APPLESS_MAIN(tst_statictextanchor)
+#include "tst_statictextanchor.moc"