Merge pull request #1350 from ispyisail/fix/1339-dxf

Fix DXF export of circles, arcs and right-side title blocks (#1339)

sources/bordertitleblock.cpp

@@ -708,13 +708,26 @@ void BorderTitleBlock::drawDxf(
 	// render the titleblock, using the TitleBlockTemplate object
 	if (display_titleblock_) {
 		Createdxf::layer = DxfExport::Layer::TitleBlock;
-		//qp -> translate(titleblock_rect_.topLeft());
-		QRectF rect = titleBlockRect();
+			//Laid out horizontally, then turned like the QPainter in
+			//draw(): a quarter turn counter-clockwise around its top
+			//left, which for a title block at the right is the bottom
+			//right of the diagram (issue #1339).
+		QRectF rect = titleBlockRectForQPainter();
+		QTransform dxf_transform;
+		if (m_edge != Qt::BottomEdge)
+		{
+			const QPointF pivot(rect.left() * Createdxf::xScale,
+					    Createdxf::sheetHeight
+					    - rect.top() * Createdxf::yScale);
+			dxf_transform.translate(pivot.x(), pivot.y());
+			dxf_transform.rotate(90);
+			dxf_transform.translate(-pivot.x(), -pivot.y());
+		}
 		m_titleblock_template_renderer -> renderDxf(rect,
 							    rect.width(),
 							    file_path,
-							    color);
-		//qp -> translate(-titleblock_rect_.topLeft());
+							    color,
+							    dxf_transform);
 	}
 
 	// Transform back to QET scale

sources/createdxf.cpp

@@ -22,6 +22,9 @@
 #include <QString>
 #include "dxfexport.h"
 
+#include <QtMath>
+#include <cmath>
+
 
 const double Createdxf::sheetWidth = 4000;
 const double Createdxf::sheetHeight = 2700;
@@ -504,6 +507,24 @@ int Createdxf::dxfColor(QPen pen) {
 	return Createdxf::dxfColor(pen.color());
 }
 
+/**
+	@brief Createdxf::drawArcEllipse
+	Draw an arc of an ellipse, or a whole ellipse, in DXF units.
+	@param x, y : top left of the ellipse's bounding rect (y is the top, the
+	DXF Y axis going up)
+	@param w, h : width and height of that rect
+	@param startAngle, spanAngle : in degrees, as QPainter::drawArc() takes
+	them: counter-clockwise from 3 o'clock
+	@param hotspot_x, hotspot_y, rotation_angle : the whole shape is turned
+	clockwise by rotation_angle degrees around the hotspot, as a rotated
+	symbol is
+	A circle, or an arc of one, is written as one exact CIRCLE or ARC. R10,
+	the version this file declares, has no ELLIPSE entity, so a true
+	ellipse is written as a polyline through points of the curve, one every
+	5 degrees. It used to be four ARCs fitted through a point between the
+	curve and its chord, which drew every circle as a flattened diamond
+	(issue #1339).
+*/
 void Createdxf::drawArcEllipse(
 		const QString &file_path,
 		qreal x,
@@ -517,138 +538,46 @@ void Createdxf::drawArcEllipse(
 		qreal rotation_angle,
 		const int &colorcode)
 {
-	// vector of parts of arc (stored as a pair of startAngle and spanAngle) for each quadrant.
-	QVector< QPair<qreal,qreal> > arc_parts_vector;
+	if (qFuzzyIsNull(spanAngle) || w <= 0 || h <= 0)
+		return;
 
-	if (spanAngle > 0) {
-		qreal start = startAngle;
-		qreal span;
-		int i;
-		for ( i = startAngle; i < startAngle+spanAngle; i++ ) {
-			int absolute_theta = (i > 0) ? i : -i;
-			if (absolute_theta == 0 || absolute_theta == 90 ||
-				absolute_theta == 180 || absolute_theta == 270 ||
-				absolute_theta == 360) {
-				span = i - start;
-				QPair<qreal, qreal> newPart(start,span);
-				arc_parts_vector.push_back(newPart);
-				start = i;
-			}
-		}
-		if (start != i) {
-			span = i - start;
-			QPair<qreal, qreal> newPart(start,span);
-			arc_parts_vector.push_back(newPart);
-		}
-	} else {
-		qreal start = startAngle;
-		qreal span;
-		int i;
-		for ( i = startAngle; i > startAngle+spanAngle; i-- ) {
-			int absolute_theta = (i > 0) ? i : -i;
-			if (absolute_theta == 0 || absolute_theta == 90 ||
-				absolute_theta == 180 || absolute_theta == 270 ||
-				absolute_theta == 360) {
-				span = i - start;
-				QPair<qreal, qreal> newPart(start,span);
-				arc_parts_vector.push_back(newPart);
-				start = i;
-			}
-		}
-		if (start != i) {
-			span = i - start;
-			QPair<qreal, qreal> newPart(start,span);
-			arc_parts_vector.push_back(newPart);
+	const qreal a = w/2;
+	const qreal b = h/2;
+	const QPointF center = DxfExport::rotation_transformed(
+				x + a, y - b, hotspot_x, hotspot_y, rotation_angle);
+	const bool full_turn = qAbs(spanAngle) >= 360;
+
+	if (qAbs(a - b) <= 1e-6 * qMax(a, b))
+	{
+		if (full_turn) {
+			drawCircle(file_path, a, center.x(), center.y(), colorcode);
+			return;
 		}
+			//A DXF ARC always runs counter-clockwise from 50 to 51.
+		qreal start = startAngle - rotation_angle;
+		if (spanAngle < 0)
+			start += spanAngle;
+		start = std::fmod(start, 360.0);
+		if (start < 0)
+			start += 360;
+		drawArc(file_path, center.x(), center.y(), a,
+				start, start + qAbs(spanAngle), colorcode);
+		return;
 	}
 
-	for (int i = 0; i < arc_parts_vector.size(); i++) {
-
-		QPair<qreal,qreal> arc = arc_parts_vector[i];
-		if (arc.second == 0)
-			continue;
-		qreal arc_startAngle = arc.first * 3.142/180;
-		qreal arc_spanAngle = arc.second * 3.142/180;
-
-		qreal a = w/2;
-		qreal b = h/2;
-
-		qreal x1 = x + w/2 + a*cos(arc_startAngle);
-		qreal y1 = y - h/2 + b*sin(arc_startAngle);
-		qreal x2 = x + w/2 + a*cos(arc_startAngle + arc_spanAngle);
-		qreal y2 = y - h/2 + b*sin(arc_startAngle + arc_spanAngle);
-
-
-		qreal mid_ellipse_x = x + w/2 + a*cos(arc_startAngle + arc_spanAngle/2);
-		qreal mid_ellipse_y = y - h/2 + b*sin(arc_startAngle + arc_spanAngle/2);
-		qreal mid_line_x = (x1+x2)/2;
-		qreal mid_line_y = (y1+y2)/2;
-
-		qreal x3 = (mid_ellipse_x + mid_line_x)/2;
-		qreal y3 = (mid_ellipse_y + mid_line_y)/2;
-
-		// find circumcenter of points (x1,y1), (x3,y3) and (x2,y2)
-		qreal a1 = 2*x2 - 2*x1;
-		qreal b1 = 2*y2 - 2*y1;
-		qreal c1 = x1*x1 + y1*y1 - x2*x2 - y2*y2;
-
-		qreal a2 = 2*x3 - 2*x1;
-		qreal b2 = 2*y3 - 2*y1;
-		qreal c2 = x1*x1 + y1*y1 - x3*x3 - y3*y3;
-
-		qreal center_x = (b1*c2 - b2*c1) / (a1*b2 - a2*b1);
-		qreal center_y = (a1*c2 - a2*c1) / (b1*a2 - b2*a1);
-
-		qreal radius = sqrt( (x1-center_x)*(x1-center_x) + (y1-center_y)*(y1-center_y) );
-
-		if ( x1 > center_x && y1 > center_y )
-			arc_startAngle = asin( (y1 - center_y) / radius );
-		else if ( x1 > center_x && y1 < center_y )
-			arc_startAngle = 3.142*2 - asin( (center_y - y1) / radius );
-		else if ( x1 < center_x && y1 < center_y )
-			arc_startAngle = 3.142 + asin( (center_y - y1) / radius );
-		else
-			arc_startAngle = 3.142 - asin( (y1 - center_y) / radius );
-
-		qreal arc_endAngle;
-
-		if ( x2 > center_x && y2 > center_y )
-			arc_endAngle = asin( (y2 - center_y) / radius );
-		else if ( x2 > center_x && y2 < center_y )
-			arc_endAngle = 3.142*2 - asin( (center_y - y2) / radius );
-		else if ( x2 < center_x && y2 < center_y )
-			arc_endAngle = 3.142 + asin( (center_y - y2) / radius );
-		else
-			arc_endAngle = 3.142 - asin( (y2 - center_y) / radius );
-
-		if (arc_endAngle < arc_startAngle) {
-			qreal temp = arc_startAngle;
-			arc_startAngle = arc_endAngle;
-			arc_endAngle = temp;
-		}
-
-		QPointF transformed_point = DxfExport::rotation_transformed(
-					center_x,
-					center_y,
-					hotspot_x,
-					hotspot_y,
-					rotation_angle);
-		center_x = transformed_point.x();
-		center_y = transformed_point.y();
-		arc_endAngle *= 180/3.142;
-		arc_startAngle *= 180/3.142;
-		arc_endAngle -= rotation_angle;
-		arc_startAngle -= rotation_angle;
-
-		drawArc(
-					file_path,
-					center_x,
-					center_y,
-					radius,
-					arc_startAngle,
-					arc_endAngle,
-					colorcode);
+	const qreal span = full_turn ? 360 : spanAngle;
+	const int steps = qMax(2, qCeil(qAbs(span) / 5));
+	QPolygonF poly;
+	poly.reserve(steps + 1);
+	for (int i = 0 ; i <= steps ; ++i)
+	{
+		const qreal theta = qDegreesToRadians(startAngle + span * i / steps);
+		poly << DxfExport::rotation_transformed(
+					x + a + a*std::cos(theta),
+					y - b + b*std::sin(theta),
+					hotspot_x, hotspot_y, rotation_angle);
 	}
+	drawPolyline(file_path, poly, colorcode, true);
 }
 
 
@@ -809,6 +738,31 @@ void Createdxf::drawTextAligned(
 		double xAlign,
 	double xScaleW,
 		int colour)
+{
+	drawTextAligned(fileName, text, x, y, height, rotation, oblique,
+					hAlign, vAlign, xAlign, y, xScaleW, colour);
+}
+
+/**
+	@brief Createdxf::drawTextAligned
+	As above, with the second alignment point given in full (@a xAlign,
+	@a yAlign) instead of on the same horizontal line as the insertion
+	point, which is what a rotated aligned text needs.
+*/
+void Createdxf::drawTextAligned(
+		const QString& fileName,
+		const QString& text,
+		double x,
+		double y,
+		double height,
+		double rotation,
+		double oblique,
+		int hAlign,
+		int vAlign,
+		double xAlign,
+		double yAlign,
+		double xScaleW,
+		int colour)
 {
 	if (!fileName.isEmpty()) {
 		QFile file(fileName);
@@ -869,7 +823,7 @@ void Createdxf::drawTextAligned(
 				To_Dxf << 11       << "\r\n"; // XYZ
 				To_Dxf << xAlign   << "\r\n"; // X in UCS (User Coordinate System)coordinates
 				To_Dxf << 21       << "\r\n";
-				To_Dxf << y        << "\r\n"; // Y in UCS (User Coordinate System)coordinates
+				To_Dxf << yAlign   << "\r\n"; // Y in UCS (User Coordinate System)coordinates
 				To_Dxf << 31       << "\r\n";
 				To_Dxf << 0.0      << "\r\n"; // Z in UCS (User Coordinate System)coordinates
 			}

sources/createdxf.h

@@ -141,6 +141,20 @@ class Createdxf
 				double xAlign,
 				double xScale,
 				int colour);
+		static void drawTextAligned(
+				const QString& fileName,
+				const QString& text,
+				double x,
+				double y,
+				double height,
+				double rotation,
+				double oblique,
+				int hAlign,
+				int vAlign,
+				double xAlign,
+				double yAlign,
+				double xScale,
+				int colour);
 
 	static void drawPolyline(
 		const QString &filepath,

sources/dxfexport.cpp

@@ -80,8 +80,13 @@ void DxfExport::write(Diagram *diagram, int width, int height,
 	width  -= 2*Diagram::margin;
 	height -= 2*Diagram::margin;
 
-	Createdxf::xScale = Createdxf::sheetWidth  / double(width);
-	Createdxf::yScale = Createdxf::sheetHeight / double(height);
+		//One scale for both axes, the largest that fits the sheet: two
+		//scales stretched the drawing and turned every circle into an oval
+		//(issue #1339).
+	const double scale = qMin(Createdxf::sheetWidth  / double(width),
+							  Createdxf::sheetHeight / double(height));
+	Createdxf::xScale = scale;
+	Createdxf::yScale = scale;
 
 	Createdxf::dxfBegin(file_path, Layer::all());
 

sources/titleblocktemplate.cpp

@@ -1646,12 +1646,16 @@ void TitleBlockTemplate::render(QPainter &painter,
 	Width of the titleblock to render
 	@param file_path :
 	@param color :
+	@param dxf_transform :
+	Applied to every DXF point after the title block is laid out, as the
+	QPainter is rotated for a title block at the right of the folio
 */
 void TitleBlockTemplate::renderDxf(QRectF &title_block_rect,
 				   const DiagramContext &diagram_context,
 				   int titleblock_width,
 				   QString &file_path,
-				   int color) const
+				   int color,
+				   const QTransform &dxf_transform) const
 {
 	QList<int> widths = columnsWidth(titleblock_width);
 
@@ -1663,12 +1667,13 @@ void TitleBlockTemplate::renderDxf(QRectF &title_block_rect,
 			*Createdxf::yScale;
 	double recWidth  = title_block_rect.width()  * Createdxf::xScale;
 	double recHeight = title_block_rect.height() * Createdxf::yScale;
-	Createdxf::drawRectangle(file_path,
-				 xCoord,
-				 yCoord,
-				 recWidth,
-				 recHeight,
-				 color);
+	Createdxf::drawPolyline(file_path,
+				dxf_transform.map(QPolygonF(QRectF(xCoord,
+								  yCoord,
+								  recWidth,
+								  recHeight))),
+				color,
+				true);
 
 	// run through each individual cell
 	for (int j = 0 ; j < rows_heights_.count() ; ++ j) {
@@ -1702,7 +1707,10 @@ void TitleBlockTemplate::renderDxf(QRectF &title_block_rect,
 			y = yCoord + recHeight - h - y*Createdxf::yScale;
 			w *= Createdxf::xScale;
 
-			Createdxf::drawRectangle(file_path, x, y, w, h, color);
+			Createdxf::drawPolyline(file_path,
+						dxf_transform.map(QPolygonF(QRectF(x, y, w, h))),
+						color,
+						true);
 			if (cells_[i][j] -> type() == TitleBlockCell::TextCell)
 			{
 				QString final_text =
@@ -1715,7 +1723,8 @@ void TitleBlockTemplate::renderDxf(QRectF &title_block_rect,
 						  y,
 						  w,
 						  h,
-						  color);
+						  color,
+						  dxf_transform);
 			}
 		}
 	}
@@ -1967,6 +1976,7 @@ void TitleBlockTemplate::renderTextCell(QPainter &painter,
 	@param w
 	@param h
 	@param color
+	@param dxf_transform : see renderDxf()
 */
 void TitleBlockTemplate::renderTextCellDxf(
 		QString &file_path,
@@ -1976,7 +1986,8 @@ void TitleBlockTemplate::renderTextCellDxf(
 		qreal y,
 		qreal w,
 		qreal h,
-		int color) const
+		int color,
+		const QTransform &dxf_transform) const
 {
 	if (text.isEmpty()) return;
 	QFont text_font = TitleBlockTemplate::fontForCell(cell);
@@ -2038,6 +2049,8 @@ void TitleBlockTemplate::renderTextCellDxf(
 	const QStringList lines = text.split(QRegularExpression(QStringLiteral("\r\n|\r|\n")));
 	const qreal line_spacing = textHeight * Createdxf::yScale * 1.6;
 	const int last = lines.size() - 1;
+	const qreal rotation = qRadiansToDegrees(
+				qAtan2(dxf_transform.m12(), dxf_transform.m11()));
 	for (int i = 0 ; i < lines.size() ; ++i)
 	{
 		const QString &line = lines.at(i);
@@ -2064,17 +2077,21 @@ void TitleBlockTemplate::renderTextCellDxf(
 		}
 
 		// x offset value below currently set heuristically based on appearance...
+		const QPointF insert = dxf_transform.map(
+					QPointF(x - 2*Createdxf::xScale, y1 + offset));
+		const QPointF align = dxf_transform.map(QPointF(x2, y1 + offset));
 		Createdxf::drawTextAligned(
 					file_path,
 					line,
-					x - 2*Createdxf::xScale,
-					y1 + offset,
+					insert.x(),
+					insert.y(),
 					textHeight*Createdxf::yScale,
-					0,
+					rotation,
 					0,
 					hAlign,
 					vAlign,
-					x2,
+					align.x(),
+					align.y(),
 					ratio,
 					color);
 	}

sources/titleblocktemplate.h

@@ -176,7 +176,8 @@ class TitleBlockTemplate : public QObject {
 			const DiagramContext &,
 			int,
 			QString &,
-			int) const;
+			int,
+			const QTransform & = QTransform()) const;
 	void renderCell(QPainter &,
 			const TitleBlockCell &,
 			const DiagramContext &,
@@ -245,7 +246,8 @@ class TitleBlockTemplate : public QObject {
 			qreal,
 			qreal,
 			qreal,
-			int) const;
+			int,
+			const QTransform &) const;
 	
 	// attributes
 	private:

sources/titleblocktemplaterenderer.cpp

@@ -91,15 +91,18 @@ void TitleBlockTemplateRenderer::render(QPainter *provided_painter,
 	@param titleblock_width
 	@param file_path
 	@param color
+	@param dxf_transform : see TitleBlockTemplate::renderDxf()
 */
 void TitleBlockTemplateRenderer::renderDxf(QRectF &title_block_rect,
 					   int titleblock_width,
 					   QString &file_path,
-					   int color) {
+					   int color,
+					   const QTransform &dxf_transform) {
 	if (!m_titleblock_template) return;
 	m_titleblock_template -> renderDxf(title_block_rect,
 					   m_context,
 					   titleblock_width,
-					   file_path, color);
+					   file_path, color,
+					   dxf_transform);
 }
 

sources/titleblocktemplaterenderer.h

@@ -18,6 +18,7 @@
 #ifndef TITLEBLOCK_TEMPLATE_RENDERER_H
 #define TITLEBLOCK_TEMPLATE_RENDERER_H
 #include <QPicture>
+#include <QTransform>
 #include "diagramcontext.h"
 
 class TitleBlockTemplate;
@@ -40,7 +41,8 @@ class TitleBlockTemplateRenderer : public QObject
 		
 		int height() const;
 		void render(QPainter *, int);
-		void renderDxf(QRectF &, int, QString &, int);
+		void renderDxf(QRectF &, int, QString &, int,
+			       const QTransform & = QTransform());
 	
 	private:
 		const TitleBlockTemplate *m_titleblock_template;

tests/qttest/CMakeLists.txt

@@ -478,6 +478,17 @@ target_link_libraries(tst_dxfwrappedtext PRIVATE Qt::Test)
 target_compile_definitions(tst_dxfwrappedtext PRIVATE
   "QET_TEST_BINARY_PATH=\"$<TARGET_FILE:qelectrotech>\"")
 
+# --export-dxf on a folio with its title block at the right (issue #1339):
+# a circle and an arc stay one CIRCLE and one ARC, the title block is turned.
+add_executable(
+  tst_dxfcurves
+  tst_dxfcurves.cpp)
+add_test(NAME tst_dxfcurves COMMAND tst_dxfcurves)
+add_dependencies(tst_dxfcurves qelectrotech)
+target_link_libraries(tst_dxfcurves PRIVATE Qt::Test)
+target_compile_definitions(tst_dxfcurves PRIVATE
+  "QET_TEST_BINARY_PATH=\"$<TARGET_FILE:qelectrotech>\"")
+
 # --export-pdf puts an A3 folio on an A3 page whichever way it is turned:
 # QPageSize matches standard sheets upright only, so a wide folio is matched
 # upright and turned. fixtures/pdf_page_a3.qet has one folio each way.

tests/qttest/fixtures/dxf_curves.qet

@@ -0,0 +1,56 @@
+<project title="DXF curves and title block" uuid="{6c1a7d2e-9b54-4d2f-8f68-3f0d0f0a7b10}" version="0.200.1">
+    <properties>
+        <property name="saveddate" show="1">10/2/26</property>
+        <property name="saveddate-eu" show="1">02-10-2026</property>
+        <property name="saveddate-us" show="1">2026-10-02</property>
+        <property name="savedfilename" show="1">dxf_curves</property>
+        <property name="savedtime" show="1">18:39</property>
+    </properties>
+    <usage enabled="true" time_spent="0"/>
+    <newdiagrams>
+        <border cols="17" colsize="60" displaycols="true" displayrows="true" rows="8" rowsize="80"/>
+        <inset author="" auto_page_num="" date="null" displayAt="bottom" filename="" folio="" indexrev="" locmach="" plant="" title="" version=""/>
+        <conductors bicolor="false" bus="" cable="" color2="#000000" condsize="1" conductor_color="" conductor_section="" dash-size="1" displaytext="1" formula="" function="" horizontal-alignment="AlignBottom" horizrotatetext="0" num="_" numsize="7" onetextperfolio="0" tension_protocol="" text_color="#000000" type="multi" vertical-alignment="AlignRight" vertirotatetext="270"/>
+        <report label="%f-%l%c"/>
+        <xrefs>
+            <xref delayprefix="" displayhas="cross" master_label="%f-%l%c" offset="0" powerprefix="" showallconfiguredslaves="false" showpowerctc="true" showterminalname="true" slave_label="(%f-%l%c)" slave_offset="0" snapto="label" switchprefix="" type="coil" xrefpos="AlignBottom"/>
+            <xref delayprefix="" displayhas="cross" master_label="%f-%l%c" offset="0" powerprefix="" showallconfiguredslaves="false" showpowerctc="true" showterminalname="true" slave_label="(%f-%l%c)" slave_offset="0" snapto="label" switchprefix="" type="commutator" xrefpos="AlignBottom"/>
+            <xref delayprefix="" displayhas="cross" master_label="%f-%l%c" offset="0" powerprefix="" showallconfiguredslaves="false" showpowerctc="true" showterminalname="true" slave_label="(%f-%l%c)" slave_offset="0" snapto="label" switchprefix="" type="plc" xrefpos="AlignBottom"/>
+            <xref delayprefix="" displayhas="cross" master_label="%f-%l%c" offset="0" powerprefix="" showallconfiguredslaves="false" showpowerctc="true" showterminalname="true" slave_label="(%f-%l%c)" slave_offset="0" snapto="label" switchprefix="" type="protection" xrefpos="AlignBottom"/>
+        </xrefs>
+        <conductors_autonums auto_break_conductors="false" current_autonum="" freeze_new_conductors="false"/>
+        <folio_autonums/>
+        <element_autonums current_autonum="" freeze_new_elements="false"/>
+        <guides/>
+    </newdiagrams>
+    <diagram author="" auto_page_num="" cols="17" colsize="60" date="null" displayAt="right" displaycols="true" displayrows="true" filename="" folio="" freezeNewConductor="false" freezeNewElement="false" height="660" indexrev="" locmach="" order="1" plant="" rows="8" rowsize="80" title="" uuid="{6c1a7d2e-9b54-4d2f-8f68-3f0d0f0a7a01}" version="0.200.1-dev">
+        <defaultconductor bicolor="false" bus="" cable="" color2="#000000" condsize="1" conductor_color="" conductor_section="" dash-size="1" displaytext="1" formula="" function="" horizontal-alignment="AlignBottom" horizrotatetext="0" num="_" numsize="7" onetextperfolio="0" tension_protocol="" text_color="#000000" type="multi" vertical-alignment="AlignRight" vertirotatetext="270"/>
+        <elements>
+            <element freezeLabel="false" is_movable="1" orientation="0" prefix="" type="embed://import/curves.elmt" uuid="{6c1a7d2e-9b54-4d2f-8f68-3f0d0f0a7a02}" x="300" y="300" z="10">
+                <terminals/>
+                <inputs/>
+                <dynamic_texts/>
+                <texts_groups/>
+            </element>
+        </elements>
+    </diagram>
+    <collection>
+        <category name="import">
+            <names>
+                <name lang="en">Imported elements</name>
+            </names>
+            <element name="curves.elmt">
+                <definition height="80" hotspot_x="10" hotspot_y="10" link_type="simple" type="element" version="0.100.0" width="120">
+                    <uuid uuid="{6c1a7d2e-9b54-4d2f-8f68-3f0d0f0a7a05}"/>
+                    <names>
+                        <name lang="en">Circle and arc</name>
+                    </names>
+                    <description>
+                        <ellipse antialias="true" style="line-style:normal;line-weight:normal;filling:none;color:black" x="0" y="0" width="20" height="20"/>
+                        <arc antialias="true" style="line-style:normal;line-weight:normal;filling:none;color:black" x="40" y="0" width="20" height="20" start="30" angle="120"/>
+                    </description>
+                </definition>
+            </element>
+        </category>
+    </collection>
+</project>

tests/qttest/tst_dxfcurves.cpp

@@ -0,0 +1,95 @@
+/*
+	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>
+
+/**
+	--export-dxf on a folio whose title block is at the right (issue #1339):
+	a symbol's circle is one CIRCLE and its arc one ARC with the symbol's own
+	angles, which needs the same scale on both axes; the title block is
+	turned a quarter, as it is on screen.
+*/
+class tst_dxfcurves : public QObject
+{
+	Q_OBJECT
+
+		/// The entities on @a layer, each as its group codes and values.
+	static QList<QMultiHash<int, QString>> entities(const QStringList &values,
+													const QString &type,
+													const QString &layer)
+	{
+		QList<QMultiHash<int, QString>> found;
+		for (int i = 0 ; i + 1 < values.size() ; i += 2)
+		{
+			if (values.at(i).trimmed() != QLatin1String("0")
+				|| values.at(i + 1).trimmed() != type)
+				continue;
+			QMultiHash<int, QString> entity;
+			for (int j = i + 2 ; j + 1 < values.size()
+				 && values.at(j).trimmed() != QLatin1String("0") ; j += 2)
+				entity.insert(values.at(j).trimmed().toInt(), values.at(j + 1).trimmed());
+			if (entity.value(8) == layer)
+				found << entity;
+		}
+		return found;
+	}
+
+private slots:
+	void curvesAndTitleBlock()
+	{
+		const QString project = QFINDTESTDATA("fixtures/dxf_curves.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'));
+		const QString symbols = QStringLiteral("QET_SYMBOLS");
+
+			//The 20 px circle: one CIRCLE, nothing approximated
+		const auto circles = entities(values, QStringLiteral("CIRCLE"), symbols);
+		QCOMPARE(circles.size(), 1);
+		QVERIFY(entities(values, QStringLiteral("POLYLINE"), symbols).isEmpty());
+
+			//The arc from 30 to 150 degrees, same radius as the circle
+		const auto arcs = entities(values, QStringLiteral("ARC"), symbols);
+		QCOMPARE(arcs.size(), 1);
+		QCOMPARE(arcs.first().value(50).toDouble(), 30.0);
+		QCOMPARE(arcs.first().value(51).toDouble(), 150.0);
+		QCOMPARE(arcs.first().value(40).toDouble(), circles.first().value(40).toDouble());
+
+			//Every title block text turned a quarter, as drawn on screen
+		const auto texts = entities(values, QStringLiteral("TEXT"), QStringLiteral("QET_TITLEBLOCK"));
+		QVERIFY(!texts.isEmpty());
+		for (const auto &text : texts)
+			QCOMPARE(text.value(50).toDouble(), 90.0);
+	}
+};
+
+QTEST_APPLESS_MAIN(tst_dxfcurves)
+#include "tst_dxfcurves.moc"