Added VIEW_GROUP for grouping items to be displayed on a single layer.

common/CMakeLists.txt

@@ -152,6 +152,7 @@ set(COMMON_SRCS
 	${COMMON_SRCS}
 	view/view.cpp
 	view/view_item.cpp
+	view/view_group.cpp
 
 	system/fcontext.s
 	

common/drawpanel_gal.cpp

@@ -88,7 +88,6 @@ EDA_DRAW_PANEL_GAL::EDA_DRAW_PANEL_GAL( wxWindow* aParentWindow, wxWindowID aWin
     Connect( wxEVT_SIZE, wxSizeEventHandler( EDA_DRAW_PANEL_GAL::onSize ), NULL, this );
 
     /* Generic events for the Tool Dispatcher */
-
 	Connect( wxEVT_MOTION, wxEventHandler( EDA_DRAW_PANEL_GAL::onEvent ), NULL, this );
 	Connect( wxEVT_LEFT_UP, wxEventHandler( EDA_DRAW_PANEL_GAL::onEvent ), NULL, this );
 	Connect( wxEVT_LEFT_DOWN, wxEventHandler( EDA_DRAW_PANEL_GAL::onEvent ), NULL, this );
@@ -127,8 +126,8 @@ void EDA_DRAW_PANEL_GAL::onPaint( wxPaintEvent& WXUNUSED( aEvent ) )
 void EDA_DRAW_PANEL_GAL::onSize( wxSizeEvent& aEvent )
 {
     m_gal->ResizeScreen( aEvent.GetSize().x, aEvent.GetSize().y );
-    m_view->SetTargetDirty( KiGfx::TARGET_CACHED );
-    m_view->SetTargetDirty( KiGfx::TARGET_NONCACHED );
+    m_view->MarkTargetDirty( KiGfx::TARGET_CACHED );
+    m_view->MarkTargetDirty( KiGfx::TARGET_NONCACHED );
 }
 
 

common/view/view.cpp

@@ -28,6 +28,7 @@
 #include <layers_id_colors_and_visibility.h>
 
 #include <view/view.h>
+#include <view/view_group.h>
 #include <view/view_rtree.h>
 #include <gal/definitions.h>
 #include <gal/graphics_abstraction_layer.h>
@@ -48,7 +49,7 @@ VIEW::VIEW( bool aIsDynamic ) :
 {
     // Redraw everything at the beginning
     for( int i = 0; i < TARGETS_NUMBER; ++i )
-        SetTargetDirty( i );
+        MarkTargetDirty( i );
 }
 
 
@@ -111,53 +112,6 @@ void VIEW::Remove( VIEW_ITEM* aItem )
 }
 
 
-void VIEW::Draw( VIEW_ITEM* aItem, int aLayer ) const
-{
-    if( isCached( aLayer ) )
-    {
-        // Draw using cached information or create one
-        int group = aItem->getGroup( aLayer );
-
-        if( group >= 0 )
-        {
-            m_gal->DrawGroup( group );
-        }
-        else
-        {
-            group = m_gal->BeginGroup();
-            aItem->setGroup( aLayer, group );
-            if( !m_painter->Draw( aItem, aLayer ) )
-                aItem->ViewDraw( aLayer, m_gal, BOX2I() ); // Alternative drawing method
-            m_gal->EndGroup();
-        }
-    }
-    else
-    {
-        // Immediate mode
-        if( !m_painter->Draw( aItem, aLayer ) )
-            aItem->ViewDraw( aLayer, m_gal, BOX2I() );  // Alternative drawing method
-    }
-
-    // Draws a bright contour around the item
-    if( static_cast<const EDA_ITEM*>( aItem )->IsBrightened() )
-    {
-        m_painter->DrawBrightened( aItem );
-    }
-}
-
-
-void VIEW::Draw( VIEW_ITEM* aItem ) const
-{
-    int layers[VIEW_MAX_LAYERS], layers_count;
-    aItem->ViewGetLayers( layers, layers_count );
-
-    for( int i = 0; i < layers_count; ++i )
-    {
-        Draw( aItem, layers[i] );
-    }
-}
-
-
 void VIEW::SetRequired( int aLayerId, int aRequiredId, bool aRequired )
 {
     wxASSERT( (unsigned) aLayerId < m_layers.size() );
@@ -271,9 +225,9 @@ void VIEW::SetGAL( GAL* aGal )
     clearGroupCache();
 
     // every target has to be refreshed
-    SetTargetDirty( TARGET_CACHED );
-    SetTargetDirty( TARGET_NONCACHED );
-    SetTargetDirty( TARGET_OVERLAY );
+    MarkTargetDirty( TARGET_CACHED );
+    MarkTargetDirty( TARGET_NONCACHED );
+    MarkTargetDirty( TARGET_OVERLAY );
 
     // force the new GAL to display the current viewport.
     SetCenter( m_center );
@@ -336,8 +290,8 @@ void VIEW::SetScale( double aScale, const VECTOR2D& aAnchor )
     m_scale = aScale;
 
     // Redraw everything after the viewport has changed
-    SetTargetDirty( TARGET_CACHED );
-    SetTargetDirty( TARGET_NONCACHED );
+    MarkTargetDirty( TARGET_CACHED );
+    MarkTargetDirty( TARGET_NONCACHED );
 }
 
 
@@ -348,31 +302,50 @@ void VIEW::SetCenter( const VECTOR2D& aCenter )
     m_gal->ComputeWorldScreenMatrix();
 
     // Redraw everything after the viewport has changed
-    SetTargetDirty( TARGET_CACHED );
-    SetTargetDirty( TARGET_NONCACHED );
+    MarkTargetDirty( TARGET_CACHED );
+    MarkTargetDirty( TARGET_NONCACHED );
 }
 
 
-void VIEW::sortLayers()
+void VIEW::SetLayerOrder( int aLayer, int aRenderingOrder )
 {
-    int n = 0;
-
-    m_orderedLayers.resize( m_layers.size() );
+    m_layers[aLayer].renderingOrder = aRenderingOrder;
 
-    for( LayerMapIter i = m_layers.begin(); i != m_layers.end(); ++i )
-        m_orderedLayers[n++] = &i->second;
+    sortLayers();
+}
 
-    sort( m_orderedLayers.begin(), m_orderedLayers.end(), compareRenderingOrder );
 
-    SetTargetDirty( TARGET_CACHED );
+int VIEW::GetLayerOrder( int aLayer ) const
+{
+    return m_layers.at(aLayer).renderingOrder;
 }
 
 
-void VIEW::SetLayerOrder( int aLayer, int aRenderingOrder )
+void VIEW::SortLayers( int aLayers[], int& aCount ) const
 {
-    m_layers[aLayer].renderingOrder = aRenderingOrder;
+    int maxLay, maxOrd, maxIdx;
 
-    sortLayers();
+    for( int i = 0; i < aCount; ++i )
+    {
+        maxLay = aLayers[i];
+        maxOrd = GetLayerOrder( maxLay );
+        maxIdx = i;
+
+        // Look for the max element in the range (j..aCount)
+        for( int j = i; j < aCount; ++j )
+        {
+            if( maxOrd < GetLayerOrder( aLayers[j] ) )
+            {
+                maxLay = aLayers[j];
+                maxOrd = GetLayerOrder( maxLay );
+                maxIdx = j;
+            }
+        }
+
+        // Swap elements
+        aLayers[maxIdx] = aLayers[i];
+        aLayers[i] = maxLay;
+    }
 }
 
 
@@ -559,7 +532,7 @@ struct VIEW::drawItem
         if( !drawCondition )
             return;
 
-        view->Draw( aItem, currentLayer->id );
+        view->draw( aItem, currentLayer->id );
     }
 
     const VIEW_LAYER* currentLayer;
@@ -585,13 +558,73 @@ void VIEW::redrawRect( const BOX2I& aRect )
 }
 
 
+void VIEW::draw( VIEW_ITEM* aItem, int aLayer, bool aImmediate ) const
+{
+    if( isCached( aLayer ) && !aImmediate )
+    {
+        // Draw using cached information or create one
+        int group = aItem->getGroup( aLayer );
+
+        if( group >= 0 )
+        {
+            m_gal->DrawGroup( group );
+        }
+        else
+        {
+            group = m_gal->BeginGroup();
+            aItem->setGroup( aLayer, group );
+            if( !m_painter->Draw( aItem, aLayer ) )
+                aItem->ViewDraw( aLayer, m_gal, BOX2I() ); // Alternative drawing method
+            m_gal->EndGroup();
+        }
+    }
+    else
+    {
+        // Immediate mode
+        if( !m_painter->Draw( aItem, aLayer ) )
+            aItem->ViewDraw( aLayer, m_gal, BOX2I() );  // Alternative drawing method
+    }
+
+    // Draws a bright contour around the item
+    if( static_cast<const EDA_ITEM*>( aItem )->IsBrightened() )
+    {
+        m_painter->DrawBrightened( aItem );
+    }
+}
+
+
+void VIEW::draw( VIEW_ITEM* aItem, bool aImmediate ) const
+{
+    int layers[VIEW_MAX_LAYERS], layers_count;
+    aItem->ViewGetLayers( layers, layers_count );
+    SortLayers( layers, layers_count );
+
+    for( int i = 0; i < layers_count; ++i )
+    {
+        m_gal->SetLayerDepth( m_layers.at( i ).renderingOrder );
+        draw( aItem, layers[i], aImmediate );
+    }
+}
+
+
+void VIEW::draw( VIEW_GROUP* aGroup, bool aImmediate ) const
+{
+    std::set<VIEW_ITEM*>::const_iterator it;
+    for( it = aGroup->Begin(); it != aGroup->End(); ++it )
+    {
+        draw( *it, aImmediate );
+    }
+}
+
+
 bool VIEW::IsDirty() const
 {
-    BOOST_FOREACH( VIEW_LAYER* l, m_orderedLayers )
+    for( int i = 0; i < TARGETS_NUMBER; ++i )
     {
-        if( l->isDirty )
+        if( isTargetDirty( i ) )
             return true;
-    }   
+    }
+
     return false;
 }
 
@@ -675,18 +708,22 @@ void VIEW::Redraw()
         m_gal->ClearTarget( TARGET_NONCACHED );
         m_gal->ClearTarget( TARGET_CACHED );
 
-        SetTargetDirty( TARGET_NONCACHED );
-        SetTargetDirty( TARGET_CACHED );
+        MarkTargetDirty( TARGET_NONCACHED );
+        MarkTargetDirty( TARGET_CACHED );
 
         m_gal->DrawGrid();
     }
+
+    // Always refresh the overlay
+    MarkTargetDirty( TARGET_OVERLAY );
     m_gal->ClearTarget( TARGET_OVERLAY );
 
     redrawRect( rect );
 
     // All targets were redrawn, so nothing is dirty
-    SetTargetDirty( TARGET_CACHED, false );
-    SetTargetDirty( TARGET_NONCACHED, false );
+    clearTargetDirty( TARGET_CACHED );
+    clearTargetDirty( TARGET_NONCACHED );
+    clearTargetDirty( TARGET_OVERLAY );
 }
 
 
@@ -752,10 +789,26 @@ void VIEW::invalidateItem( VIEW_ITEM* aItem, int aUpdateFlags )
 
         // Mark those layers as dirty, so the VIEW will be refreshed
         m_layers[layers[i]].isDirty = true;
+        MarkTargetDirty( m_layers[layers[i]].target );   // TODO remove?
     }
 }
 
 
+void VIEW::sortLayers()
+{
+    int n = 0;
+
+    m_orderedLayers.resize( m_layers.size() );
+
+    for( LayerMapIter i = m_layers.begin(); i != m_layers.end(); ++i )
+        m_orderedLayers[n++] = &i->second;
+
+    sort( m_orderedLayers.begin(), m_orderedLayers.end(), compareRenderingOrder );
+
+    MarkTargetDirty( TARGET_CACHED );
+}
+
+
 void VIEW::updateItemAppearance( VIEW_ITEM* aItem, int aLayer )
 {
     wxASSERT( (unsigned) aLayer < m_layers.size() );
@@ -811,15 +864,13 @@ void VIEW::RecacheAllItems( bool aImmediately )
     r.SetMaximum();
 
 #ifdef __WXDEBUG__
-    wxLogDebug( wxT( "RecacheAllItems::immediately: %u" ), aImmediately );
-
     prof_counter totalRealTime;
     prof_start( &totalRealTime, false );
 #endif /* __WXDEBUG__ */
 
     for( LayerMapIter i = m_layers.begin(); i != m_layers.end(); ++i )
     {
-        VIEW_LAYER* l = & ( ( *i ).second );
+        VIEW_LAYER* l = &( ( *i ).second );
 
         // Obviously, there is only one cached target that has to be recomputed
         if( isCached( l->id ) )
@@ -834,7 +885,8 @@ void VIEW::RecacheAllItems( bool aImmediately )
 #ifdef __WXDEBUG__
     prof_end( &totalRealTime );
 
-    wxLogDebug( wxT( "RecacheAllItems::%.1f ms" ), (double) totalRealTime.value / 1000.0 );
+    wxLogDebug( wxT( "RecacheAllItems::immediately: %u %.1f ms" ),
+                aImmediately, (double) totalRealTime.value / 1000.0 );
 #endif /* __WXDEBUG__ */
 }
 
@@ -843,6 +895,10 @@ bool VIEW::isTargetDirty( int aTarget ) const
 {
     wxASSERT( aTarget < TARGETS_NUMBER );
 
+    // Check the target status
+    if( m_dirtyTargets[aTarget] )
+        return true;
+
     // Check if any of layers belonging to the target is dirty
     BOOST_FOREACH( VIEW_LAYER* l, m_orderedLayers )
     {
@@ -850,6 +906,5 @@ bool VIEW::isTargetDirty( int aTarget ) const
             return true;
     }
 
-    // If no layer is dirty, just check the target status itself
-    return m_dirtyTargets[aTarget];
+    return false;
 }

common/view/view_group.cpp

+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2013 CERN
+ * @author Maciej Suminski <maciej.suminski@cern.ch>
+ *
+ * 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.
+ *
+ * This program 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 this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ *
+ */
+
+/**
+ * @file view_group.cpp
+ * @brief VIEW_GROUP extends VIEW_ITEM by possibility of grouping items into a single object.
+ * VIEW_GROUP does not take over ownership of the held items. The main purpose of this class is
+ * to group items and draw them on a single layer (in particular the overlay).
+ */
+
+#include <set>
+#include <algorithm>
+#include <view/view_group.h>
+#include <view/view.h>
+#include <painter.h>
+#include <gal/graphics_abstraction_layer.h>
+#include <boost/foreach.hpp>
+#include <layers_id_colors_and_visibility.h>
+
+using namespace KiGfx;
+
+VIEW_GROUP::VIEW_GROUP( VIEW* aView ) :
+        m_layer( ITEM_GAL_LAYER( GP_OVERLAY ) )
+{
+    m_view = aView;
+}
+
+
+VIEW_GROUP::~VIEW_GROUP()
+{
+}
+
+
+void VIEW_GROUP::Add( VIEW_ITEM* aItem )
+{
+    m_items.insert( aItem );
+    updateBbox();
+}
+
+
+void VIEW_GROUP::Remove( VIEW_ITEM* aItem )
+{
+    m_items.erase( aItem );
+    updateBbox();
+}
+
+
+void VIEW_GROUP::Clear()
+{
+    m_items.clear();
+    updateBbox();
+}
+
+
+unsigned int VIEW_GROUP::GetSize() const
+{
+    return m_items.size();
+}
+
+
+const BOX2I VIEW_GROUP::ViewBBox() const
+{
+    BOX2I box;
+
+    // Merge all bounding boxes, so the returned one contains all stored items
+    BOOST_FOREACH( VIEW_ITEM* item, m_items )
+    {
+        box.Merge( item->ViewBBox() );
+    }
+
+    return box;
+}
+
+
+void VIEW_GROUP::ViewDraw( int aLayer, GAL* aGal, const BOX2I& aVisibleArea ) const
+{
+    PAINTER* painter = m_view->GetPainter();
+
+    // Draw all items immediately (without caching)
+    BOOST_FOREACH( VIEW_ITEM* item, m_items )
+    {
+        int layers[VIEW::VIEW_MAX_LAYERS], layers_count;
+        item->ViewGetLayers( layers, layers_count );
+        m_view->SortLayers( layers, layers_count );
+
+        for( int i = 0; i < layers_count; i++ )
+        {
+            aGal->SetLayerDepth( m_view->GetLayerOrder( layers[i] ) );
+
+            if( !painter->Draw( item, layers[i] ) )
+                item->ViewDraw( layers[i], aGal, aVisibleArea );  // Alternative drawing method
+        }
+
+        /// m_view->Draw( item, true );
+    }
+}
+
+
+void VIEW_GROUP::ViewGetLayers( int aLayers[], int& aCount ) const
+{
+    aLayers[0] = m_layer;
+    aCount = 1;
+}
+
+
+void VIEW_GROUP::ViewUpdate( int aUpdateFlags, bool aForceImmediateRedraw )
+{
+    BOOST_FOREACH( VIEW_ITEM* item, m_items )
+    {
+        item->ViewUpdate( aUpdateFlags, aForceImmediateRedraw );
+    }
+}
+
+
+void VIEW_GROUP::updateBbox()
+{
+    // Save the used VIEW, as it used nulled during Remove()
+    VIEW* view = m_view;
+
+    // Reinsert the group, so the bounding box can be updated
+    view->Remove( this );
+    view->Add( this );
+}

include/view/view.h

@@ -37,6 +37,7 @@ namespace KiGfx
 class PAINTER;
 class GAL;
 class VIEW_ITEM;
+class VIEW_GROUP;
 class VIEW_RTREE;
 
 /**
@@ -95,19 +96,6 @@ public:
      */
     int     Query( const BOX2I& aRect, std::vector<LayerItemPair>& aResult );
 
-    /**
-     * Function Draw()
-     * Draws an item, but on a specified layers. It has to be marked that some of drawing settings
-     * are based on the layer on which an item is drawn.
-     */
-    void   Draw( VIEW_ITEM* aItem, int aLayer ) const;
-
-    /**
-     * Function Draw()
-     * Draws an item on all layers that the item uses.
-     */
-    void   Draw( VIEW_ITEM* aItem ) const;
-
     /**
      * Function SetRequired()
      * Marks the aRequiredId layer as required for the aLayerId layer. In order to display the
@@ -296,13 +284,30 @@ public:
 
     /**
      * Function SetLayerOrder()
-     * Sets rendering order of a particular layer.
+     * Sets rendering order of a particular layer. Lower values are rendered first.
      * @param aLayer: the layer
      * @param aRenderingOrder: arbitrary number denoting the rendering order.
-     * Lower values are rendered first.
      */
     void    SetLayerOrder( int aLayer, int aRenderingOrder );
 
+    /**
+     * Function GetLayerOrder()
+     * Returns rendering order of a particular layer. Lower values are rendered first.
+     * @param aLayer: the layer
+     * @return Rendering order of a particular layer.
+     */
+    int     GetLayerOrder( int aLayer ) const;
+
+    /**
+     * Function SortLayers()
+     * Changes the order of given layer ids, so after sorting the order corresponds to layers
+     * rendering order (descending, ie. order in which layers should be drawn - from the bottom to
+     * the top).
+     * @param aLayers stores id of layers to be sorted.
+     * @param aCount stores the number of layers.
+     */
+    void    SortLayers( int aLayers[], int& aCount ) const;
+
     /**
      * Function UpdateLayerColor()
      * Applies the new coloring scheme held by RENDER_SETTINGS in case that it has changed.
@@ -390,22 +395,20 @@ public:
      * Returns true if any of the VIEW layers needs to be refreshened.
      * @return True in case if any of layers is marked as dirty.
      */
-    bool IsDirty() const;
+    bool    IsDirty() const;
 
     /**
-     * Function SetTargetDirty()
+     * Function MarkTargetDirty()
      * Sets or clears target 'dirty' flag.
      * @param aTarget is the target to set.
-     * @param aState says if the flag should be set or cleared.
      */
-    inline void SetTargetDirty( int aTarget, bool aState = true )
+    inline void MarkTargetDirty( int aTarget )
     {
         wxASSERT( aTarget < TARGETS_NUMBER );
 
-        m_dirtyTargets[aTarget] = aState;
+        m_dirtyTargets[aTarget] = true;
     }
 
-
     static const int VIEW_MAX_LAYERS = 128;      ///* maximum number of layers that may be shown
 
 private:
@@ -438,12 +441,49 @@ private:
     struct updateItemsColor;
     struct changeItemsDepth;
 
-    ///* Whether to use rendering order modifier or not
-    bool m_enableOrderModifier;
-
     ///* Redraws contents within rect aRect
     void redrawRect( const BOX2I& aRect );
 
+    inline void clearTargetDirty( int aTarget )
+    {
+        wxASSERT( aTarget < TARGETS_NUMBER );
+
+        m_dirtyTargets[aTarget] = false;
+    }
+
+    /**
+     * Function draw()
+     * Draws an item, but on a specified layers. It has to be marked that some of drawing settings
+     * are based on the layer on which an item is drawn.
+     *
+     * @param aItem is the item to be drawn.
+     * @param aLayer is the layer which should be drawn.
+     * @param aImmediate dictates the way of drawing - it allows to force immediate drawing mode
+     * for cached items.
+     */
+    void    draw( VIEW_ITEM* aItem, int aLayer, bool aImmediate = false ) const;
+
+    /**
+     * Function draw()
+     * Draws an item on all layers that the item uses.
+     *
+     * @param aItem is the item to be drawn.
+     * @param aImmediate dictates the way of drawing - it allows to force immediate drawing mode
+     * for cached items.
+     */
+    void    draw( VIEW_ITEM* aItem, bool aImmediate = false ) const;
+
+    /**
+     * Function draw()
+     * Draws a group of items on all layers that those items use.
+     *
+     * @param aItem is the group to be drawn.
+     * @param aImmediate dictates the way of drawing - it allows to force immediate drawing mode
+     * for cached items.
+     */
+    void    draw( VIEW_GROUP* aGroup, bool aImmediate = false ) const;
+
+
     ///* Manages dirty flags & redraw queueing when updating an item. Called internally
     ///  via VIEW_ITEM::ViewUpdate()
     void invalidateItem( VIEW_ITEM* aItem, int aUpdateFlags );
@@ -484,10 +524,13 @@ private:
      */
     bool isTargetDirty( int aTarget ) const;
 
+    ///* Whether to use rendering order modifier or not
+    bool m_enableOrderModifier;
+
     /// Contains set of possible displayed layers and its properties
     LayerMap    m_layers;
 
-    /// Sorted list of pointers to members of m_layers.
+    /// Sorted list of pointers to members of m_layers
     LayerOrder  m_orderedLayers;
 
     /// Stores set of layers that are displayed on the top

include/view/view_group.h

+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2013 CERN
+ * @author Maciej Suminski <maciej.suminski@cern.ch>
+ *
+ * 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.
+ *
+ * This program 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 this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ *
+ */
+
+/**
+ * @file view_group.h
+ * @brief VIEW_GROUP extends VIEW_ITEM by possibility of grouping items into a single object.
+ * VIEW_GROUP does not take over ownership of the held items. The main purpose of this class is
+ * to group items and draw them on a single layer (in particular the overlay).
+ */
+
+#ifndef VIEW_GROUP_H_
+#define VIEW_GROUP_H_
+
+#include <view/view_item.h>
+#include <deque>
+
+namespace KiGfx
+{
+
+class VIEW_GROUP : public VIEW_ITEM
+{
+public:
+    VIEW_GROUP( VIEW* aView );
+    virtual ~VIEW_GROUP();
+
+    /**
+     * Function Add()
+     * Adds an item to the group.
+     *
+     * @param aItem is the item to be added.
+     */
+    virtual void Add( VIEW_ITEM* aItem );
+
+    /**
+     * Function Remove()
+     * Removes an item from the group.
+     *
+     * @param aItem is the item to be removed.
+     */
+    virtual void Remove( VIEW_ITEM* aItem );
+
+    /**
+     * Function Clear()
+     * Removes all the stored items from the group.
+     */
+    virtual void Clear();
+
+    /**
+     * Function Begin()
+     * Returns iterator to beginning.
+     */
+    inline std::set<VIEW_ITEM*>::const_iterator Begin() const
+    {
+        return m_items.begin();
+    }
+
+    /**
+     * Function End()
+     * Returns iterator to end.
+     */
+    inline std::set<VIEW_ITEM*>::const_iterator End() const
+    {
+        return m_items.end();
+    }
+
+    /**
+     * Function GetSize()
+     * Returns the number of stored items.
+     *
+     * @return Number of stored items.
+     */
+    virtual unsigned int GetSize() const;
+
+    /**
+     * Function ViewBBox()
+     * Returns the bounding box for all stored items covering all its layers.
+     *
+     * @return The current bounding box
+     */
+    virtual const BOX2I ViewBBox() const;
+
+    /**
+     * Function ViewDraw()
+     * Draws all the stored items in the group on the given layer.
+     *
+     * @param aLayer is the layer which should be drawn.
+     * @param aGal is the GAL that should be used for drawing.
+     * @param aVisibleArea is limiting the drawing area.
+     */
+    virtual void ViewDraw( int aLayer, GAL* aGal, const BOX2I& aVisibleArea ) const;
+
+    /**
+     * Function ViewGetLayers()
+     * Returns all the layers used by the stored items.
+     *
+     * @param aLayers[] is the output layer index array.
+     * @param aCount is the number of layer indices in aLayers[].
+     */
+    virtual void ViewGetLayers( int aLayers[], int& aCount ) const;
+
+    /// @copydoc VIEW_ITEM::ViewUpdate()
+    virtual void ViewUpdate( int aUpdateFlags, bool aForceImmediateRedraw );
+
+    /**
+     * Function SetLayer()
+     * Sets layer used to draw the group.
+     *
+     * @param aLayer is the layer used for drawing.
+     */
+    inline virtual void SetLayer( int aLayer )
+    {
+        m_layer = aLayer;
+    }
+
+protected:
+    /// These functions cannot be used with VIEW_GROUP as they are intended only to work with
+    /// singular VIEW_ITEMs (there is only one-to-one relation between item/layer combination and
+    /// its group).
+    int getGroup( int aLayer ) const { return -1; };
+    std::vector<int> getAllGroups() const { return std::vector<int>(); };
+    void setGroup( int aLayer, int aGroup ) {};
+    void deleteGroups() {};
+    bool storesGroups() const { return false; };
+
+    /// Layer on which the group is drawn
+    int m_layer;
+
+private:
+    void updateBbox();
+
+    /// Container for storing VIEW_ITEMs
+    std::set<VIEW_ITEM*> m_items;
+};
+} // namespace KiGfx
+
+#endif // VIEW_GROUP_H_