[FEATURE][processing] Add option to enable automatic snapping to grid

while designer models

If enabled, model component moving or resizing will be automatically
snapped to a grid

src/gui/processing/models/qgsmodeldesignerdialog.cpp

@@ -118,6 +118,7 @@ QgsModelDesignerDialog::QgsModelDesignerDialog( QWidget *parent, Qt::WindowFlags
   mainLayout->insertWidget( 0, mMessageBar );
 
   mView->setAcceptDrops( true );
+  QgsSettings settings;
 
   connect( mActionClose, &QAction::triggered, this, &QWidget::close );
   connect( mActionZoomIn, &QAction::triggered, this, &QgsModelDesignerDialog::zoomIn );
@@ -132,6 +133,14 @@ QgsModelDesignerDialog::QgsModelDesignerDialog( QWidget *parent, Qt::WindowFlags
   connect( mActionSaveAs, &QAction::triggered, this, [ = ] { saveModel( true ); } );
   connect( mActionDeleteComponents, &QAction::triggered, this, &QgsModelDesignerDialog::deleteSelected );
 
+  mActionSnappingEnabled->setChecked( settings.value( QStringLiteral( "/Processing/modelDesignerEnableSnap" ), true ).toBool() );
+  connect( mActionSnappingEnabled, &QAction::toggled, this, [ = ]( bool enabled )
+  {
+    mView->snapper()->setSnapToGrid( enabled );
+    QgsSettings().setValue( QStringLiteral( "/Processing/modelDesignerEnableSnap" ), enabled );
+  } );
+  mView->snapper()->setSnapToGrid( mActionSnappingEnabled->isChecked() );
+
   mUndoAction = mUndoStack->createUndoAction( this );
   mUndoAction->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionUndo.svg" ) ) );
   mUndoAction->setShortcuts( QKeySequence::Undo );
@@ -146,7 +155,7 @@ QgsModelDesignerDialog::QgsModelDesignerDialog( QWidget *parent, Qt::WindowFlags
   mToolbar->insertAction( mActionZoomIn, mRedoAction );
   mToolbar->insertSeparator( mActionZoomIn );
 
-  QgsSettings settings;
+
   QgsProcessingToolboxProxyModel::Filters filters = QgsProcessingToolboxProxyModel::FilterModeler;
   if ( settings.value( QStringLiteral( "Processing/Configuration/SHOW_ALGORITHMS_KNOWN_ISSUES" ), false ).toBool() )
   {

src/gui/processing/models/qgsmodelsnapper.cpp

@@ -21,7 +21,7 @@
 QgsModelSnapper::QgsModelSnapper()
 {
   QgsSettings s;
-  mTolerance = s.value( QStringLiteral( "LayoutDesigner/defaultSnapTolerancePixels" ), 5, QgsSettings::Gui ).toInt();
+  mTolerance = s.value( QStringLiteral( "/Processing/modelDesignerSnapTolerancePixels" ), 20 ).toInt();
 }
 
 void QgsModelSnapper::setSnapTolerance( const int snapTolerance )
@@ -34,19 +34,19 @@ void QgsModelSnapper::setSnapToGrid( bool enabled )
   mSnapToGrid = enabled;
 }
 
-QPointF QgsModelSnapper::snapPoint( QPointF point, double scaleFactor, bool &snapped ) const
+QPointF QgsModelSnapper::snapPoint( QPointF point, double scaleFactor, bool &snapped, bool snapHorizontal, bool snapVertical ) const
 {
   snapped = false;
 
   bool snappedXToGrid = false;
   bool snappedYToGrid = false;
   QPointF res = snapPointToGrid( point, scaleFactor, snappedXToGrid, snappedYToGrid );
-  if ( snappedXToGrid )
+  if ( snappedXToGrid && snapVertical )
   {
     snapped = true;
     point.setX( res.x() );
   }
-  if ( snappedYToGrid )
+  if ( snappedYToGrid && snapHorizontal )
   {
     snapped = true;
     point.setY( res.y() );
@@ -55,7 +55,7 @@ QPointF QgsModelSnapper::snapPoint( QPointF point, double scaleFactor, bool &sna
   return point;
 }
 
-QRectF QgsModelSnapper::snapRect( const QRectF &rect, double scaleFactor, bool &snapped ) const
+QRectF QgsModelSnapper::snapRect( const QRectF &rect, double scaleFactor, bool &snapped, bool snapHorizontal, bool snapVertical ) const
 {
   snapped = false;
   QRectF snappedRect = rect;
@@ -70,12 +70,12 @@ QRectF QgsModelSnapper::snapRect( const QRectF &rect, double scaleFactor, bool &
   QList< QPointF > points;
   points << rect.topLeft() << rect.topRight() << rect.bottomLeft() << rect.bottomRight();
   QPointF res = snapPointsToGrid( points, scaleFactor, snappedXToGrid, snappedYToGrid );
-  if ( snappedXToGrid )
+  if ( snappedXToGrid && snapVertical )
   {
     snapped = true;
     snappedRect.translate( res.x(), 0 );
   }
-  if ( snappedYToGrid )
+  if ( snappedYToGrid && snapHorizontal )
   {
     snapped = true;
     snappedRect.translate( 0, res.y() );
@@ -111,7 +111,7 @@ QPointF QgsModelSnapper::snapPointsToGrid( const QList<QPointF> &points, double
   for ( QPointF point : points )
   {
     //snap x coordinate
-    double gridRes = 10; //mLayout->convertToLayoutUnits( grid.resolution() );
+    double gridRes = 30; //mLayout->convertToLayoutUnits( grid.resolution() );
     int xRatio = static_cast< int >( ( point.x() ) / gridRes + 0.5 ); //NOLINT
     int yRatio = static_cast< int >( ( point.y() ) / gridRes + 0.5 ); //NOLINT
 

src/gui/processing/models/qgsmodelsnapper.h

@@ -80,7 +80,7 @@ class GUI_EXPORT QgsModelSnapper
 
      * \see snapRect()
      */
-    QPointF snapPoint( QPointF point, double scaleFactor, bool &snapped SIP_OUT ) const;
+    QPointF snapPoint( QPointF point, double scaleFactor, bool &snapped SIP_OUT, bool snapHorizontal = true, bool snapVertical = true ) const;
 
     /**
      * Snaps a layout coordinate \a rect. If \a rect was snapped, \a snapped will be set to TRUE.
@@ -101,7 +101,7 @@ class GUI_EXPORT QgsModelSnapper
      *
      * \see snapPoint()
      */
-    QRectF snapRect( const QRectF &rect, double scaleFactor, bool &snapped SIP_OUT ) const;
+    QRectF snapRect( const QRectF &rect, double scaleFactor, bool &snapped SIP_OUT, bool snapHorizontal = true, bool snapVertical = true ) const;
 
     /**
      * Snaps a layout coordinate \a point to the grid. If \a point

src/gui/processing/models/qgsmodelviewmousehandles.cpp

@@ -160,5 +160,24 @@ void QgsModelViewMouseHandles::endMacroCommand()
   mView->endMacroCommand();
 }
 
+QPointF QgsModelViewMouseHandles::snapPoint( QPointF originalPoint, QgsGraphicsViewMouseHandles::SnapGuideMode mode, bool snapHorizontal, bool snapVertical )
+{
+  bool snapped = false;
+
+  //depending on the mode, we either snap just the single point, or all the bounds of the selection
+  QPointF snappedPoint;
+  switch ( mode )
+  {
+    case Item:
+      snappedPoint = mView->snapper()->snapRect( rect().translated( originalPoint ), mView->transform().m11(), snapped, snapHorizontal, snapVertical ).topLeft();
+      break;
+    case Point:
+      snappedPoint = mView->snapper()->snapPoint( originalPoint, mView->transform().m11(), snapped, snapHorizontal, snapVertical );
+      break;
+  }
+
+  return snapped ? snappedPoint : originalPoint;
+}
+
 
 ///@endcond PRIVATE

src/gui/processing/models/qgsmodelviewmousehandles.h

@@ -65,6 +65,7 @@ class GUI_EXPORT QgsModelViewMouseHandles: public QgsGraphicsViewMouseHandles
     QRectF previewSetItemRect( QGraphicsItem *item, QRectF rect ) override;
     void startMacroCommand( const QString &text ) override;
     void endMacroCommand() override;
+    QPointF snapPoint( QPointF originalPoint, SnapGuideMode mode, bool snapHorizontal = true, bool snapVertical = true ) override;
 
   public slots:
 

src/ui/processing/qgsmodeldesignerdialogbase.ui

@@ -80,6 +80,8 @@
     <addaction name="mActionZoomToItems"/>
     <addaction name="separator"/>
     <addaction name="mActionShowComments"/>
+    <addaction name="separator"/>
+    <addaction name="mActionSnappingEnabled"/>
    </widget>
    <widget class="QMenu" name="mMenuEdit">
     <property name="title">
@@ -610,6 +612,14 @@
     <string>Del</string>
    </property>
   </action>
+  <action name="mActionSnappingEnabled">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>Enable Snapping</string>
+   </property>
+  </action>
  </widget>
  <customwidgets>
   <customwidget>