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>

sources/editor/graphicspart/parttext.cpp

@@ -164,6 +164,10 @@ void PartText::fromXml(const QDomElement &xml_element) {
 	setPos(xml_element.attribute("x").toDouble(),
 			xml_element.attribute("y").toDouble());
 	QGraphicsObject::setRotation(QET::correctAngle(xml_element.attribute("rotation", QString::number(0)).toDouble()));
+
+	m_anchor_to_alignment = xml_element.attribute("anchor") == QLatin1String("alignment");
+	if (m_anchor_to_alignment)
+		setPos(pos() - anchorOffset());
 }
 
 /**
@@ -175,8 +179,10 @@ const QDomElement PartText::toXml(QDomDocument &xml_document) const
 {
 	QDomElement xml_element = xml_document.createElement(xmlName());
 
-	qreal x   = (qRound(pos().x() * 100.0) / 100.0);
-	qreal y   = (qRound(pos().y() * 100.0) / 100.0);
+	const QPointF anchor = m_anchor_to_alignment ? pos() + anchorOffset()
+												 : pos();
+	qreal x   = (qRound(anchor.x() * 100.0) / 100.0);
+	qreal y   = (qRound(anchor.y() * 100.0) / 100.0);
 	qreal rot = (qRound(rotation() * 10.0) /  10.0);
 	xml_element.setAttribute("x", QString::number(x));
 	xml_element.setAttribute("y", QString::number(y));
@@ -197,6 +203,8 @@ const QDomElement PartText::toXml(QDomDocument &xml_document) const
 		xml_element.setAttribute("Valignment", me.valueToKey(Qt::AlignBottom));
 	else if (m_alignment & Qt::AlignVCenter)
 		xml_element.setAttribute("Valignment", me.valueToKey(Qt::AlignVCenter));
+	if (m_anchor_to_alignment)
+		xml_element.setAttribute("anchor", "alignment");
 
 	return(xml_element);
 }
@@ -444,6 +452,25 @@ void PartText::finishAlignment()
 	setPos(pos() - (pa - p));
 }
 
+/**
+	@brief PartText::anchorOffset
+	@return the vector from the baseline-left of the text to the point
+	written as x/y with anchor="alignment" (#1251): the left edge, centre or
+	right edge of the text, without the document margin, on the baseline.
+	Same width as ElementPictureFactory::parseText, which draws without
+	a margin.
+*/
+QPointF PartText::anchorOffset() const
+{
+	qreal width = document()->idealWidth() - 2 * document()->documentMargin();
+	qreal dx = 0;
+	if (m_alignment & Qt::AlignRight)
+		dx = width;
+	else if (m_alignment & Qt::AlignHCenter)
+		dx = width / 2;
+	return QTransform().rotate(rotation()).map(QPointF(dx, 0));
+}
+
 void PartText::setFont(const QFont &font) {
 	if (font != this -> font()) {
 		prepareAlignment();

sources/editor/graphicspart/parttext.h

@@ -109,6 +109,7 @@ class PartText : public QGraphicsTextItem, public CustomElementPart {
 		void applyLineAlignment();
 		void prepareAlignment();
 		void finishAlignment();
+		QPointF anchorOffset() const;
 		QString previous_text;
 		qreal real_font_size_;
 		QPointF saved_point_;
@@ -117,5 +118,8 @@ class PartText : public QGraphicsTextItem, public CustomElementPart {
 		QPointF m_origin_pos;
 		Qt::Alignment m_alignment = (Qt::AlignTop | Qt::AlignLeft);
 		QRectF m_alignment_rect;
+			/// x/y in the .elmt are the aligned point, not the
+			/// baseline-left (anchor="alignment", #1251)
+		bool m_anchor_to_alignment = false;
 };
 #endif

sources/factory/elementpicturefactory.cpp

@@ -704,10 +704,11 @@ void ElementPictureFactory::parseText(const QDomElement &dom, QPainter &painter,
 		//adjusts the offset by the margin of the text document
 	text_document.setDocumentMargin(0.0);
 
-		//Optional line alignment of multi-line texts (the anchor behaviour
-		//of the alignment is handled in the element editor; the saved x/y
-		//always stay the baseline-left of the text block). The document
-		//only honors the text option once a text width is set.
+		//Optional line alignment of multi-line texts. The document only
+		//honors the text option once a text width is set.
+		//x/y are the baseline-left of the text block, unless
+		//anchor="alignment": x is then the left edge, centre or right edge
+		//selected by Halignment, and y stays the baseline (#1251).
 	if (dom.hasAttribute("Halignment")) {
 		const QMetaEnum me = QMetaEnum::fromType<Qt::Alignment>();
 		const Qt::Alignment h_alignment = Qt::Alignment(
@@ -717,12 +718,18 @@ void ElementPictureFactory::parseText(const QDomElement &dom, QPainter &painter,
 			option.setAlignment(h_alignment & Qt::AlignHorizontal_Mask);
 			text_document.setDefaultTextOption(option);
 			text_document.setTextWidth(text_document.idealWidth());
+			if (dom.attribute("anchor") == QLatin1String("alignment"))
+				qpainter_offset.rx() -= h_alignment & Qt::AlignRight
+						? text_document.idealWidth()
+						: text_document.idealWidth() / 2;
 		}
 	}
 
 	QTransform text_transform;
 	text_transform.translate(dom.attribute("x").toDouble(), dom.attribute("y").toDouble());
 	text_transform.rotate(dom.attribute("rotation", "0").toDouble());
+		//baseline-left of the text block, for the dxf export below
+	const QPointF baseline_left = text_transform.map(QPointF(qpainter_offset.x(), 0));
 	text_transform.translate(qpainter_offset.x(), qpainter_offset.y());
 
 	if (!m_build_texts_undo.isIdentity())
@@ -748,7 +755,7 @@ void ElementPictureFactory::parseText(const QDomElement &dom, QPainter &painter,
 	QGraphicsSimpleTextItem *qgsti = new QGraphicsSimpleTextItem();
 	qgsti->setText(dom.attribute("text"));
 	qgsti->setFont(font_);
-	qgsti->setPos(dom.attribute("x").toDouble(), dom.attribute("y").toDouble());
+	qgsti->setPos(baseline_left);
 	qgsti->setRotation(dom.attribute("rotation", "0").toDouble());
 	prim.m_texts << qgsti;