Share the text grid choices; add a preference, a status hint and a unit test

Drop 1:2.5: on a grid of 10 it steps by 4, which misses 10, so texts on
two elements 10 apart could never line up. Every remaining divisor is a
whole number, which tst_textgrid checks.

The divisor list and the snapping arithmetic move to the header-only
textgrid.h so the toolbar menu, the preferences page and the test share
them. The preferences page gets the same choice under Grille + Clavier;
QETApp::textGridChanged keeps every editor's toolbar button in step.
While element texts are dragged, the status bar names the text grid and
says to release Shift and hold Ctrl for free placement -- Ctrl+Shift
together is the pan shortcut.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01G2d2Zi8BfrYRPX88zhaoFG

sources/diagram.cpp

@@ -42,6 +42,7 @@
 #include "qetinformation.h"
 #include "qetproject.h"
 #include "diagramsortkeys.h"
+#include "textgrid.h"
 #include <QTextStream>
 #include <algorithm>
 #include <climits>
@@ -2686,32 +2687,25 @@ QPointF Diagram::snapToGrid(const QPointF &p)
 
 /**
 	@brief Diagram::snapToTextGrid
-	Return the nearest point of p on the text grid.
-	The text grid is the folio grid divided by the
-	"diagrameditor/text_grid_divisor" setting (1 = same as the folio grid,
-	0 = no grid). Because it divides the folio grid, texts snapped to it
-	still line up with every element and with each other.
-	Ctrl held, or a divisor of 0, rounds to the nearest pixel instead.
+	Return the nearest point of p on the text grid, see TextGrid.
+	Ctrl held rounds to the nearest pixel instead, as snapToGrid() does.
 	@param p point to find the nearest snapped point
 	@return
 */
 QPointF Diagram::snapToTextGrid(const QPointF &p)
 {
 	QSettings settings;
-	const qreal divisor = settings.value(
-				QStringLiteral("diagrameditor/text_grid_divisor"),
-				1).toReal();
+	const qreal divisor =
+		QApplication::keyboardModifiers().testFlag(Qt::ControlModifier)
+			? 0
+			: settings.value(TextGrid::settings_key, 1).toReal();
 
-	if (divisor <= 0
-		|| QApplication::keyboardModifiers().testFlag(Qt::ControlModifier))
-		return QPointF(qRound(p.x()), qRound(p.y()));
-
-	const qreal x_step = settings.value(QStringLiteral("diagrameditor/Xgrid"),
-										Diagram::xGrid).toInt() / divisor;
-	const qreal y_step = settings.value(QStringLiteral("diagrameditor/Ygrid"),
-										Diagram::yGrid).toInt() / divisor;
-	return QPointF(qRound(p.x() / x_step) * x_step,
-				   qRound(p.y() / y_step) * y_step);
+	return TextGrid::snap(p,
+						  settings.value(QStringLiteral("diagrameditor/Xgrid"),
+										 Diagram::xGrid).toInt(),
+						  settings.value(QStringLiteral("diagrameditor/Ygrid"),
+										 Diagram::yGrid).toInt(),
+						  divisor);
 }
 
 

sources/elementtextsmover.cpp

@@ -22,8 +22,11 @@
 #include "qetapp.h"
 #include "qetgraphicsitem/dynamicelementtextitem.h"
 #include "qetgraphicsitem/elementtextitemgroup.h"
+#include "qetdiagrameditor.h"
+#include "textgrid.h"
 
 #include <QObject>
+#include <QSettings>
 
 /**
 	@brief ElementTextsMover::ElementTextsMover
@@ -80,6 +83,19 @@ int ElementTextsMover::beginMovement(Diagram *diagram, QGraphicsItem *driver_ite
 		return -1;
 	
 	m_movement_running = true;
+
+	m_status_bar.clear();
+	if (!diagram->views().isEmpty())
+		if (const auto qde = QETApp::diagramEditorAncestorOf(diagram->views().at(0)))
+			m_status_bar = qde->statusBar();
+	if (m_status_bar)
+	{
+		const qreal divisor = QSettings().value(TextGrid::settings_key, 1).toReal();
+		m_status_bar->showMessage(divisor > 0
+			? QObject::tr("Grille des textes %1. Relâcher Maj et maintenir Ctrl pour placer librement.")
+				  .arg(TextGrid::ratioLabel(divisor))
+			: QObject::tr("Grille des textes désactivée."));
+	}
 	
 	return m_items_hash.size();
 }
@@ -112,6 +128,9 @@ void ElementTextsMover::continueMovement(QGraphicsSceneMouseEvent *event)
 void ElementTextsMover::endMovement()
 {	
 		//No movement or no items to move
+	if (m_status_bar)
+		m_status_bar->clearMessage();
+
 	if(!m_movement_running || m_items_hash.isEmpty())
 		return;
 			

sources/elementtextsmover.h

@@ -21,6 +21,8 @@
 #include <QSet>
 #include <QPointF>
 #include <QHash>
+#include <QPointer>
+#include <QStatusBar>
 
 class QGraphicsItem;
 class DiagramTextItem;
@@ -55,6 +57,7 @@ class ElementTextsMover
 		QHash <DiagramTextItem *, QPointF> m_texts_hash;
 		QHash <QGraphicsItemGroup *, QPointF> m_grps_hash;
 		QHash <QGraphicsItem *, QPointF> m_items_hash;
+		QPointer<QStatusBar> m_status_bar;
 		int m_text_count = 0,
 			m_group_count = 0;
 };

sources/qetapp.cpp

@@ -2231,6 +2231,7 @@ void QETApp::configureQET()
 	// affiche le dialogue puis evite de le lier a un quelconque widget parent
 	cd.exec();
 	cd.setParent(nullptr, cd.windowFlags());
+	emit textGridChanged();
 
 #ifdef QET_SPACEMOUSE_SUPPORT
 	if (m_space_mouse_listener) {

sources/qetapp.h

@@ -260,6 +260,10 @@ class QETApp : public QObject
 		
 		static QString m_interface_language;
 	
+	signals:
+			/// The text grid setting changed, see TextGrid.
+		void textGridChanged();
+
 	public slots:
 		void systray(QSystemTrayIcon::ActivationReason);
 		void reduceEveryEditor();

sources/qetdiagrameditor.cpp

@@ -49,6 +49,7 @@
 #include "qeticons.h"
 #include "qetmessagebox.h"
 #include "recentfiles.h"
+#include "textgrid.h"
 #include "shortcutmanager.h"
 #include "ui/bomexportdialog.h"
 #include "ui/conductorcolortoolbutton.h"
@@ -493,29 +494,21 @@ void QETDiagramEditor::setUpActions()
 	m_text_grid_button->setToolTip(tr("Grille d'accrochage des textes déplacés à la souris.\n"
 									  "Maintenir Ctrl pendant le déplacement pour placer librement."));
 	auto text_grid_group = new QActionGroup(this);
-	const qreal current_divisor = settings.value("diagrameditor/text_grid_divisor", 1).toReal();
-	const QList<QPair<QString, qreal>> text_grids {
-		{tr("Désactivée"), 0},
-		{QStringLiteral("1:1"), 1},
-		{QStringLiteral("1:2"), 2},
-		{QStringLiteral("1:2.5"), 2.5},
-		{QStringLiteral("1:5"), 5},
-		{QStringLiteral("1:10"), 10}};
-	for (const auto &grid : text_grids)
+	for (const qreal divisor : TextGrid::divisors)
 	{
-		QAction *action = m_text_grid_menu->addAction(grid.first);
+		QAction *action = m_text_grid_menu->addAction(
+					divisor > 0 ? TextGrid::ratioLabel(divisor) : tr("Désactivée"));
 		action->setCheckable(true);
-		action->setData(grid.second);
+		action->setData(divisor);
 		text_grid_group->addAction(action);
-		if (qFuzzyCompare(grid.second + 1, current_divisor + 1)) {
-			action->setChecked(true);
-			m_text_grid_button->setText(tr("Textes %1").arg(grid.first));
-		}
 	}
-	connect(text_grid_group, &QActionGroup::triggered, this, [this](QAction *action) {
-		QSettings().setValue("diagrameditor/text_grid_divisor", action->data());
-		m_text_grid_button->setText(tr("Textes %1").arg(action->text()));
+	connect(text_grid_group, &QActionGroup::triggered, this, [](QAction *action) {
+		QSettings().setValue(TextGrid::settings_key, action->data());
+		emit QETApp::instance()->textGridChanged();
 	});
+	connect(QETApp::instance(), &QETApp::textGridChanged,
+			this, &QETDiagramEditor::updateTextGridButton);
+	updateTextGridButton();
 
 	// Draw or not the custom guides
 	m_draw_guides = new QAction ( QIcon::fromTheme("guides"), tr("Afficher les guides"), this);
@@ -3262,3 +3255,23 @@ void QETDiagramEditor::slot_runScript() {
 	QetScripting::runOnProject(script_path, project, currentDiagramView());
 }
 #endif
+
+/**
+	@brief QETDiagramEditor::updateTextGridButton
+	Show the current text grid on its toolbar button and check it in its menu.
+*/
+void QETDiagramEditor::updateTextGridButton()
+{
+	const qreal divisor = QSettings().value(TextGrid::settings_key, 1).toReal();
+	for (QAction *action : m_text_grid_menu->actions())
+	{
+		if (qFuzzyCompare(action->data().toReal() + 1, divisor + 1))
+		{
+			action->setChecked(true);
+			m_text_grid_button->setText(tr("Textes %1").arg(action->text()));
+			return;
+		}
+	}
+		//A divisor the menu does not offer, set by hand in the config file
+	m_text_grid_button->setText(tr("Textes %1").arg(TextGrid::ratioLabel(divisor)));
+}

sources/qetdiagrameditor.h

@@ -166,6 +166,7 @@ class QETDiagramEditor : public QETMainWindow
 		void subWindowActivated(QMdiSubWindow *subWindows);
 
 	private slots:
+		void updateTextGridButton();
 		void selectionChanged();
 
 	public:

sources/textgrid.h

@@ -0,0 +1,62 @@
+/*
+	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/>.
+*/
+#ifndef TEXTGRID_H
+#define TEXTGRID_H
+
+#include <QList>
+#include <QPointF>
+#include <QString>
+#include <QtMath>
+
+/**
+	The text grid: the step texts snap to when dragged with the mouse,
+	a fraction of the folio grid. A divisor of 1 is the folio grid itself,
+	0 means no grid. Because every step divides the folio grid, a text
+	snapped to it still lines up with every element and with the texts
+	of other elements.
+*/
+namespace TextGrid
+{
+		/// The choices offered in the menu and the preferences, 0 first.
+	inline const QList<qreal> divisors{0, 1, 2, 5, 10};
+
+		/// QSettings key holding the divisor.
+	inline const QString settings_key{QStringLiteral("diagrameditor/text_grid_divisor")};
+
+		/// "1:5" for 5. Not meaningful for 0.
+	inline QString ratioLabel(qreal divisor) {
+		return QStringLiteral("1:") + QString::number(divisor);
+	}
+
+	/**
+		@return p snapped to a grid of x_grid / divisor by y_grid / divisor,
+		or rounded to the nearest pixel when divisor is 0 or less.
+	*/
+	inline QPointF snap(const QPointF &p, int x_grid, int y_grid, qreal divisor)
+	{
+		if (divisor <= 0 || x_grid <= 0 || y_grid <= 0)
+			return QPointF(qRound(p.x()), qRound(p.y()));
+
+		const qreal x_step = x_grid / divisor;
+		const qreal y_step = y_grid / divisor;
+		return QPointF(qRound(p.x() / x_step) * x_step,
+					   qRound(p.y() / y_step) * y_step);
+	}
+}
+
+#endif // TEXTGRID_H

sources/ui/configpage/generalconfigurationpage.cpp

@@ -23,6 +23,7 @@
 #include "../../utils/qetsettings.h"
 #include "../../utils/qetutils.h"
 #include "../../qetmessagebox.h"
+#include "../../textgrid.h"
 #include "../nokde/kcolorbutton.h"
 #include <QFileDialog>
 #include <QFontDialog>
@@ -68,6 +69,15 @@ GeneralConfigurationPage::GeneralConfigurationPage(QWidget *parent) :
 	ui->guides_startup_cb->setChecked(settings.value("diagrameditor/guides_display_startup", false).toBool());
 	ui->DiagramEditor_xGrid_sb->setValue(settings.value("diagrameditor/Xgrid", 10).toInt());
 	ui->DiagramEditor_yGrid_sb->setValue(settings.value("diagrameditor/Ygrid", 10).toInt());
+	for (const qreal divisor : TextGrid::divisors)
+		ui->DiagramEditor_textGrid_cb->addItem(
+					divisor > 0 ? TextGrid::ratioLabel(divisor) : tr("Désactivée"),
+					divisor);
+	int text_grid_index = ui->DiagramEditor_textGrid_cb->findData(
+				settings.value(TextGrid::settings_key, 1).toReal());
+	if (text_grid_index < 0)
+		text_grid_index = ui->DiagramEditor_textGrid_cb->findData(qreal(1));
+	ui->DiagramEditor_textGrid_cb->setCurrentIndex(text_grid_index);
 	ui->DiagramEditor_xKeyGrid_sb->setValue(settings.value("diagrameditor/key_Xgrid", 10).toInt());
 	ui->DiagramEditor_yKeyGrid_sb->setValue(settings.value("diagrameditor/key_Ygrid", 10).toInt());
 	ui->DiagramEditor_xKeyGridFine_sb->setValue(settings.value("diagrameditor/key_fine_Xgrid", 1).toInt());
@@ -287,6 +297,7 @@ void GeneralConfigurationPage::applyConf()
 		//Grid step and key navigation
 	settings.setValue("diagrameditor/Xgrid", ui->DiagramEditor_xGrid_sb->value());
 	settings.setValue("diagrameditor/Ygrid", ui->DiagramEditor_yGrid_sb->value());
+	settings.setValue(TextGrid::settings_key, ui->DiagramEditor_textGrid_cb->currentData());
 	settings.setValue("diagrameditor/key_Xgrid", ui->DiagramEditor_xKeyGrid_sb->value());
 	settings.setValue("diagrameditor/key_Ygrid", ui->DiagramEditor_yKeyGrid_sb->value());
 	settings.setValue("diagrameditor/key_fine_Xgrid", ui->DiagramEditor_xKeyGridFine_sb->value());

sources/ui/configpage/generalconfigurationpage.ui

@@ -784,6 +784,26 @@ Vous pouvez spécifier ici la valeur par défaut de ce champ pour les éléments
             </property>
            </spacer>
           </item>
+          <item row="3" column="0">
+           <widget class="QLabel" name="Label_Diagram_textGrid">
+            <property name="text">
+             <string>Grille des textes déplacés à la souris</string>
+            </property>
+            <property name="toolTip">
+             <string>Fraction de la grille des folios. Maintenir Ctrl pendant le déplacement pour placer librement.</string>
+            </property>
+           </widget>
+          </item>
+          <item row="3" column="2">
+           <widget class="QComboBox" name="DiagramEditor_textGrid_cb">
+            <property name="minimumSize">
+             <size>
+              <width>80</width>
+              <height>0</height>
+             </size>
+            </property>
+           </widget>
+          </item>
          </layout>
         </widget>
        </item>