Port item alignment to layouts

python/core/core_auto.sip

@@ -157,6 +157,7 @@
 %Include composer/qgscomposermultiframecommand.sip
 %Include composer/qgscomposertexttable.sip
 %Include composer/qgspaperitem.sip
+%Include layout/qgslayoutaligner.sip
 %Include layout/qgslayoutcontext.sip
 %Include layout/qgslayoutgridsettings.sip
 %Include layout/qgslayoutmeasurement.sip

python/core/layout/qgslayoutaligner.sip

@@ -0,0 +1,52 @@
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/layout/qgslayoutaligner.h                                   *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
+
+
+
+class QgsLayoutAligner
+{
+%Docstring
+ Handles aligning and distributing sets of layout items.
+
+ QgsLayoutAligner contains methods for automatically aligning and distributing
+ sets of layout items, e.g. aligning a group of items to top or left sides.
+
+.. versionadded:: 3.0
+%End
+
+%TypeHeaderCode
+#include "qgslayoutaligner.h"
+%End
+  public:
+
+    enum Alignment
+    {
+      Left,
+      HCenter,
+      Right,
+      Top,
+      VCenter,
+      Bottom,
+    };
+
+    static void alignItems( QgsLayout *layout, const QList< QgsLayoutItem * > &items, Alignment alignment );
+%Docstring
+ Aligns a set of ``items`` from a ``layout`` in place.
+
+ The ``alignment`` argument specifies the method to use when aligning the items.
+%End
+
+};
+
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/layout/qgslayoutaligner.h                                   *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/

python/gui/layout/qgslayoutview.sip

@@ -127,6 +127,11 @@ class QgsLayoutView: QGraphicsView
  :rtype: list of int
 %End
 
+    void alignSelectedItems( QgsLayoutAligner::Alignment alignment );
+%Docstring
+ Aligns all selected items using the specified ``alignment``.
+%End
+
   public slots:
 
     void zoomFull();

src/app/layout/qgslayoutdesignerdialog.cpp

@@ -179,6 +179,20 @@ QgsLayoutDesignerDialog::QgsLayoutDesignerDialog( QWidget *parent, Qt::WindowFla
   orderingToolButton->setDefaultAction( mActionRaiseItems );
   mActionsToolbar->addWidget( orderingToolButton );
 
+  QToolButton *alignToolButton = new QToolButton( this );
+  alignToolButton->setPopupMode( QToolButton::InstantPopup );
+  alignToolButton->setAutoRaise( true );
+  alignToolButton->setToolButtonStyle( Qt::ToolButtonIconOnly );
+
+  alignToolButton->addAction( mActionAlignLeft );
+  alignToolButton->addAction( mActionAlignHCenter );
+  alignToolButton->addAction( mActionAlignRight );
+  alignToolButton->addAction( mActionAlignTop );
+  alignToolButton->addAction( mActionAlignVCenter );
+  alignToolButton->addAction( mActionAlignBottom );
+  alignToolButton->setDefaultAction( mActionAlignLeft );
+  mActionsToolbar->addWidget( alignToolButton );
+
   mAddItemTool = new QgsLayoutViewToolAddItem( mView );
   mPanTool = new QgsLayoutViewToolPan( mView );
   mPanTool->setAction( mActionPan );
@@ -213,6 +227,30 @@ QgsLayoutDesignerDialog::QgsLayoutDesignerDialog( QWidget *parent, Qt::WindowFla
   connect( mActionLowerItems, &QAction::triggered, this, &QgsLayoutDesignerDialog::lowerSelectedItems );
   connect( mActionMoveItemsToTop, &QAction::triggered, this, &QgsLayoutDesignerDialog::moveSelectedItemsToTop );
   connect( mActionMoveItemsToBottom, &QAction::triggered, this, &QgsLayoutDesignerDialog::moveSelectedItemsToBottom );
+  connect( mActionAlignLeft, &QAction::triggered, this, [ = ]
+  {
+    mView->alignSelectedItems( QgsLayoutAligner::Left );
+  } );
+  connect( mActionAlignHCenter, &QAction::triggered, this, [ = ]
+  {
+    mView->alignSelectedItems( QgsLayoutAligner::HCenter );
+  } );
+  connect( mActionAlignRight, &QAction::triggered, this, [ = ]
+  {
+    mView->alignSelectedItems( QgsLayoutAligner::Right );
+  } );
+  connect( mActionAlignTop, &QAction::triggered, this, [ = ]
+  {
+    mView->alignSelectedItems( QgsLayoutAligner::Top );
+  } );
+  connect( mActionAlignVCenter, &QAction::triggered, this, [ = ]
+  {
+    mView->alignSelectedItems( QgsLayoutAligner::VCenter );
+  } );
+  connect( mActionAlignBottom, &QAction::triggered, this, [ = ]
+  {
+    mView->alignSelectedItems( QgsLayoutAligner::Bottom );
+  } );
 
   connect( mActionAddPages, &QAction::triggered, this, &QgsLayoutDesignerDialog::addPages );
 

src/core/CMakeLists.txt

@@ -359,6 +359,7 @@ SET(QGIS_CORE_SRCS
   dxf/qgsdxfpallabeling.cpp
 
   layout/qgslayout.cpp
+  layout/qgslayoutaligner.cpp
   layout/qgslayoutcontext.cpp
   layout/qgslayoutgridsettings.cpp
   layout/qgslayoutguidecollection.cpp
@@ -965,6 +966,7 @@ SET(QGIS_CORE_HDRS
   composer/qgscomposertexttable.h
   composer/qgspaperitem.h
 
+  layout/qgslayoutaligner.h
   layout/qgslayoutcontext.h
   layout/qgslayoutgridsettings.h
   layout/qgslayoutitemundocommand.h

src/core/layout/qgslayoutaligner.cpp

@@ -0,0 +1,131 @@
+/***************************************************************************
+                             qgslayoutaligner.cpp
+                             --------------------
+    begin                : October 2017
+    copyright            : (C) 2017 by Nyall Dawson
+    email                : nyall dot dawson at gmail dot com
+ ***************************************************************************/
+/***************************************************************************
+ *                                                                         *
+ *   This program 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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgslayoutaligner.h"
+#include "qgslayoutitem.h"
+#include "qgslayout.h"
+
+void QgsLayoutAligner::alignItems( QgsLayout *layout, const QList<QgsLayoutItem *> &items, QgsLayoutAligner::Alignment alignment )
+{
+  if ( !layout || items.size() < 2 )
+  {
+    return;
+  }
+
+  QRectF itemBBox = boundingRectOfItems( items );
+  if ( !itemBBox.isValid() )
+  {
+    return;
+  }
+
+  double refCoord = 0;
+  switch ( alignment )
+  {
+    case Left:
+      refCoord = itemBBox.left();
+      break;
+    case HCenter:
+      refCoord = itemBBox.center().x();
+      break;
+    case Right:
+      refCoord = itemBBox.right();
+      break;
+    case Top:
+      refCoord = itemBBox.top();
+      break;
+    case VCenter:
+      refCoord = itemBBox.center().y();
+      break;
+    case Bottom:
+      refCoord = itemBBox.bottom();
+      break;
+  }
+
+  layout->undoStack()->beginMacro( QObject::tr( "Aligned items bottom" ) );
+  for ( QgsLayoutItem *item : items )
+  {
+    layout->undoStack()->beginCommand( item, QString() );
+
+    QPointF shifted = item->pos();
+    switch ( alignment )
+    {
+      case Left:
+        shifted.setX( refCoord );
+        break;
+      case HCenter:
+        shifted.setX( refCoord - item->rect().width() / 2.0 );
+        break;
+      case Right:
+        shifted.setX( refCoord - item->rect().width() );
+        break;
+      case Top:
+        shifted.setY( refCoord );
+        break;
+      case VCenter:
+        shifted.setY( refCoord - item->rect().height() / 2.0 );
+        break;
+      case Bottom:
+        shifted.setY( refCoord - item->rect().height() );
+        break;
+    }
+
+    // need to keep item units
+    QgsLayoutPoint newPos = layout->convertFromLayoutUnits( shifted, item->positionWithUnits().units() );
+    item->attemptMove( newPos );
+
+    layout->undoStack()->endCommand();
+  }
+  layout->undoStack()->endMacro();
+}
+
+QRectF QgsLayoutAligner::boundingRectOfItems( const QList<QgsLayoutItem *> &items )
+{
+  if ( items.empty() )
+  {
+    return QRectF();
+  }
+
+  auto it = items.constBegin();
+  //set the box to the first item
+  QgsLayoutItem *currentItem = *it;
+  it++;
+  double minX = currentItem->pos().x();
+  double minY = currentItem->pos().y();
+  double maxX = minX + currentItem->rect().width();
+  double maxY = minY + currentItem->rect().height();
+
+  double currentMinX, currentMinY, currentMaxX, currentMaxY;
+
+  for ( ; it != items.constEnd(); ++it )
+  {
+    currentItem = *it;
+    currentMinX = currentItem->pos().x();
+    currentMinY = currentItem->pos().y();
+    currentMaxX = currentMinX + currentItem->rect().width();
+    currentMaxY = currentMinY + currentItem->rect().height();
+
+    if ( currentMinX < minX )
+      minX = currentMinX;
+    if ( currentMaxX > maxX )
+      maxX = currentMaxX;
+    if ( currentMinY < minY )
+      minY = currentMinY;
+    if ( currentMaxY > maxY )
+      maxY = currentMaxY;
+  }
+
+  return QRectF( QPointF( minX, minY ), QPointF( maxX, maxY ) );
+}

src/core/layout/qgslayoutaligner.h

@@ -0,0 +1,71 @@
+/***************************************************************************
+                             qgslayoutaligner.h
+                             ------------------
+    begin                : October 2017
+    copyright            : (C) 2017 by Nyall Dawson
+    email                : nyall dot dawson at gmail dot com
+ ***************************************************************************/
+/***************************************************************************
+ *                                                                         *
+ *   This program 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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+#ifndef QGSLAYOUTALIGNER_H
+#define QGSLAYOUTALIGNER_H
+
+#include "qgis_core.h"
+#include <QList>
+#include <QRectF>
+
+class QgsLayoutItem;
+class QgsLayout;
+
+/**
+ * \ingroup core
+ * \class QgsLayoutAligner
+ * \brief Handles aligning and distributing sets of layout items.
+ *
+ * QgsLayoutAligner contains methods for automatically aligning and distributing
+ * sets of layout items, e.g. aligning a group of items to top or left sides.
+ *
+ * \since QGIS 3.0
+ */
+class CORE_EXPORT QgsLayoutAligner
+{
+
+  public:
+
+    //! Alignment options
+    enum Alignment
+    {
+      Left, //!< Align left edges
+      HCenter, //!< Align horizontal centers
+      Right, //!< Align right edges
+      Top, //!< Align top edges
+      VCenter, //!< Align vertical centers
+      Bottom, //!< Align bottom edges
+    };
+
+    /**
+     * Aligns a set of \a items from a \a layout in place.
+     *
+     * The \a alignment argument specifies the method to use when aligning the items.
+     */
+    static void alignItems( QgsLayout *layout, const QList< QgsLayoutItem * > &items, Alignment alignment );
+
+  private:
+
+    /**
+     * Returns the bounding rectangle of the selected items in
+     * scene coordinates.
+    */
+    static QRectF boundingRectOfItems( const QList< QgsLayoutItem * > &items );
+
+
+
+};
+
+#endif //QGSLAYOUTALIGNER_H

src/gui/layout/qgslayoutview.cpp

@@ -230,6 +230,12 @@ QList<int> QgsLayoutView::visiblePageNumbers() const
   return currentLayout()->pageCollection()->visiblePageNumbers( visibleRect );
 }
 
+void QgsLayoutView::alignSelectedItems( QgsLayoutAligner::Alignment alignment )
+{
+  const QList<QgsLayoutItem *> selectedItems = currentLayout()->selectedLayoutItems();
+  QgsLayoutAligner::alignItems( currentLayout(), selectedItems, alignment );
+}
+
 void QgsLayoutView::zoomFull()
 {
   fitInView( scene()->sceneRect(), Qt::KeepAspectRatio );

src/gui/layout/qgslayoutview.h

@@ -21,6 +21,7 @@
 #include "qgsprevieweffect.h" // for QgsPreviewEffect::PreviewMode
 #include "qgis_gui.h"
 #include "qgslayoutitempage.h"
+#include "qgslayoutaligner.h"
 #include <QPointer>
 #include <QGraphicsView>
 #include <QGraphicsRectItem>
@@ -157,6 +158,11 @@ class GUI_EXPORT QgsLayoutView: public QGraphicsView
      */
     QList< int > visiblePageNumbers() const;
 
+    /**
+     * Aligns all selected items using the specified \a alignment.
+     */
+    void alignSelectedItems( QgsLayoutAligner::Alignment alignment );
+
   public slots:
 
     /**