Prevent snapping to selected items when resizing

python/core/layout/qgslayoutsnapper.sip

@@ -83,7 +83,8 @@ class QgsLayoutSnapper: QgsLayoutSerializableObject
 %End
 
     QPointF snapPoint( QPointF point, double scaleFactor, bool &snapped /Out/, QGraphicsLineItem *horizontalSnapLine = 0,
-                       QGraphicsLineItem *verticalSnapLine = 0 ) const;
+                       QGraphicsLineItem *verticalSnapLine = 0,
+                       const QList< QgsLayoutItem * > *ignoreItems = 0 ) const;
 %Docstring
  Snaps a layout coordinate ``point``. If ``point`` was snapped, ``snapped`` will be set to true.
 
@@ -95,6 +96,8 @@ class QgsLayoutSnapper: QgsLayoutSerializableObject
 
  If the ``horizontalSnapLine`` and ``verticalSnapLine`` arguments are specified, then the snapper
  will automatically display and position these lines to indicate snapping positions to item bounds.
+
+ A list of items to ignore during the snapping can be specified via the ``ignoreItems`` list.
  :rtype: QPointF
 %End
 

src/core/layout/qgslayoutsnapper.cpp

@@ -49,7 +49,8 @@ void QgsLayoutSnapper::setSnapToItems( bool enabled )
   mSnapToItems = enabled;
 }
 
-QPointF QgsLayoutSnapper::snapPoint( QPointF point, double scaleFactor, bool &snapped, QGraphicsLineItem *horizontalSnapLine, QGraphicsLineItem *verticalSnapLine ) const
+QPointF QgsLayoutSnapper::snapPoint( QPointF point, double scaleFactor, bool &snapped, QGraphicsLineItem *horizontalSnapLine, QGraphicsLineItem *verticalSnapLine,
+                                     const QList< QgsLayoutItem * > *ignoreItems ) const
 {
   snapped = false;
 
@@ -77,7 +78,7 @@ QPointF QgsLayoutSnapper::snapPoint( QPointF point, double scaleFactor, bool &sn
   bool snappedYToItems = false;
   if ( !snappedXToGuides )
   {
-    newX = snapPointToItems( point.x(), Qt::Horizontal, scaleFactor, QList< QgsLayoutItem * >(), snappedXToItems, verticalSnapLine );
+    newX = snapPointToItems( point.x(), Qt::Horizontal, scaleFactor, ignoreItems ? *ignoreItems : QList< QgsLayoutItem * >(), snappedXToItems, verticalSnapLine );
     if ( snappedXToItems )
     {
       snapped = true;
@@ -86,7 +87,7 @@ QPointF QgsLayoutSnapper::snapPoint( QPointF point, double scaleFactor, bool &sn
   }
   if ( !snappedYToGuides )
   {
-    newY = snapPointToItems( point.y(), Qt::Vertical, scaleFactor, QList< QgsLayoutItem * >(), snappedYToItems, horizontalSnapLine );
+    newY = snapPointToItems( point.y(), Qt::Vertical, scaleFactor, ignoreItems ? *ignoreItems : QList< QgsLayoutItem * >(), snappedYToItems, horizontalSnapLine );
     if ( snappedYToItems )
     {
       snapped = true;

src/core/layout/qgslayoutsnapper.h

@@ -105,9 +105,12 @@ class CORE_EXPORT QgsLayoutSnapper: public QgsLayoutSerializableObject
      *
      * If the \a horizontalSnapLine and \a verticalSnapLine arguments are specified, then the snapper
      * will automatically display and position these lines to indicate snapping positions to item bounds.
+     *
+     * A list of items to ignore during the snapping can be specified via the \a ignoreItems list.
      */
     QPointF snapPoint( QPointF point, double scaleFactor, bool &snapped SIP_OUT, QGraphicsLineItem *horizontalSnapLine = nullptr,
-                       QGraphicsLineItem *verticalSnapLine = nullptr ) const;
+                       QGraphicsLineItem *verticalSnapLine = nullptr,
+                       const QList< QgsLayoutItem * > *ignoreItems = nullptr ) const;
 
     /**
      * Snaps a layout coordinate \a point to the grid. If \a point

src/gui/layout/qgslayoutmousehandles.cpp

@@ -24,6 +24,7 @@
 #include "qgslayoututils.h"
 #include "qgslayoutview.h"
 #include "qgslayoutviewtoolselect.h"
+#include "qgslayoutsnapper.h"
 #include <QGraphicsView>
 #include <QGraphicsSceneHoverEvent>
 #include <QPainter>
@@ -41,6 +42,13 @@ QgsLayoutMouseHandles::QgsLayoutMouseHandles( QgsLayout *layout, QgsLayoutView *
 
   //accept hover events, required for changing cursor to resize cursors
   setAcceptHoverEvents( true );
+
+  mHorizontalSnapLine.reset( mView->createSnapLine() );
+  mHorizontalSnapLine->hide();
+  layout->addItem( mHorizontalSnapLine.get() );
+  mVerticalSnapLine.reset( mView->createSnapLine() );
+  mVerticalSnapLine->hide();
+  layout->addItem( mVerticalSnapLine.get() );
 }
 
 void QgsLayoutMouseHandles::paint( QPainter *painter, const QStyleOptionGraphicsItem *itemStyle, QWidget *pWidget )
@@ -697,6 +705,58 @@ void QgsLayoutMouseHandles::resetStatusBar()
   }
 }
 
+QPointF QgsLayoutMouseHandles::snapPoint( QPointF originalPoint, QgsLayoutMouseHandles::SnapGuideMode mode )
+{
+  //align item
+  double alignX = 0;
+  double alignY = 0;
+
+  bool snapped = false;
+
+  const QList< QgsLayoutItem * > selectedItems = mLayout->selectedLayoutItems();
+
+  //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 = alignItem( alignX, alignY, point.x(), point.y() );
+      break;
+    case Point:
+      snappedPoint = mLayout->snapper().snapPoint( originalPoint, mView->transform().m11(), snapped, mHorizontalSnapLine.get(), mVerticalSnapLine.get(), &selectedItems );
+      break;
+  }
+#if 0
+  if ( !qgsDoubleNear( alignX, -1.0 ) )
+  {
+    QGraphicsLineItem *item = hAlignSnapItem();
+    int numPages = mComposition->numPages();
+    double yLineCoord = 300; //default in case there is no single page
+    if ( numPages > 0 )
+    {
+      yLineCoord = mComposition->paperHeight() * numPages + mComposition->spaceBetweenPages() * ( numPages - 1 );
+    }
+    item->setLine( QLineF( alignX, 0, alignX, yLineCoord ) );
+    item->show();
+  }
+  else
+  {
+    deleteHAlignSnapItem();
+  }
+  if ( !qgsDoubleNear( alignY, -1.0 ) )
+  {
+    QGraphicsLineItem *item = vAlignSnapItem();
+    item->setLine( QLineF( 0, alignY, mComposition->paperWidth(), alignY ) );
+    item->show();
+  }
+  else
+  {
+    deleteVAlignSnapItem();
+  }
+#endif
+  return snappedPoint;
+}
+
 void QgsLayoutMouseHandles::mousePressEvent( QGraphicsSceneMouseEvent *event )
 {
   //save current cursor position
@@ -797,9 +857,6 @@ void QgsLayoutMouseHandles::dragMouseMove( QPointF currentPosition, bool lockMov
 
   QPointF snappedLeftPoint;
 
-  //TODO
-  snappedLeftPoint = upperLeftPoint;
-#if 0
   //no snapping for rotated items for now
   if ( !preventSnap && qgsDoubleNear( rotation(), 0.0 ) )
   {
@@ -810,9 +867,11 @@ void QgsLayoutMouseHandles::dragMouseMove( QPointF currentPosition, bool lockMov
   {
     //no snapping
     snappedLeftPoint = upperLeftPoint;
+#if 0
     deleteAlignItems();
-  }
 #endif
+  }
+
   //calculate total shift for item from beginning of drag operation to current position
   double moveRectX = snappedLeftPoint.x() - mBeginHandlePos.x();
   double moveRectY = snappedLeftPoint.y() - mBeginHandlePos.y();
@@ -859,11 +918,8 @@ void QgsLayoutMouseHandles::resizeMouseMove( QPointF currentPosition, bool lockR
     //subtract cursor edge offset from begin mouse event and current cursor position, so that snapping occurs to edge of mouse handles
     //rather then cursor position
     beginMousePos = mapFromScene( QPointF( mBeginMouseEventPos.x() - mCursorOffset.width(), mBeginMouseEventPos.y() - mCursorOffset.height() ) );
-#if 0
     QPointF snappedPosition = snapPoint( QPointF( currentPosition.x() - mCursorOffset.width(), currentPosition.y() - mCursorOffset.height() ), QgsLayoutMouseHandles::Point );
     finalPosition = mapFromScene( snappedPosition );
-#endif
-    finalPosition = mapFromScene( currentPosition );
   }
   else
   {

src/gui/layout/qgslayoutmousehandles.h

@@ -22,6 +22,7 @@
 #include <QGraphicsRectItem>
 #include <QObject>
 #include <QPointer>
+#include <memory>
 
 #include "qgis_gui.h"
 
@@ -157,8 +158,8 @@ class GUI_EXPORT QgsLayoutMouseHandles: public QObject, public QGraphicsRectItem
     bool mIsResizing = false;
 
     //! Align snap lines
-    QGraphicsLineItem *mHAlignSnapItem = nullptr;
-    QGraphicsLineItem *mVAlignSnapItem = nullptr;
+    std::unique_ptr< QGraphicsLineItem > mHorizontalSnapLine;
+    std::unique_ptr< QGraphicsLineItem > mVerticalSnapLine;
 
     QSizeF mCursorOffset;
 
@@ -199,6 +200,10 @@ class GUI_EXPORT QgsLayoutMouseHandles: public QObject, public QGraphicsRectItem
 
     //resets the composer window status bar to the default message
     void resetStatusBar();
+
+    //! Snaps an item or point (depending on mode) originating at originalPoint to the grid or align rulers
+    QPointF snapPoint( QPointF originalPoint, SnapGuideMode mode );
+
 };
 
 ///@endcond PRIVATE

src/gui/layout/qgslayoutview.h

@@ -306,6 +306,7 @@ class GUI_EXPORT QgsLayoutView: public QGraphicsView
     int mCurrentPage = 0;
 
     friend class TestQgsLayoutView;
+    friend class QgsLayoutMouseHandles;
 
     QGraphicsLineItem *createSnapLine() const;
 };

tests/src/python/test_qgslayoutsnapper.py

@@ -314,6 +314,11 @@ def testSnapPoint(self):
         self.assertTrue(snapped)
         self.assertEqual(point, QPointF(0, 1.1))
 
+        # ... unless item is ignored!
+        point, snapped = s.snapPoint(QPointF(1, 1), 1, None, None, [item1])
+        self.assertTrue(snapped)
+        self.assertEqual(point, QPointF(0, 0))
+
     def testReadWriteXml(self):
         p = QgsProject()
         l = QgsLayout(p)