pcbnew: use centerpoint distribution in align tool for overlaping items

reimplement the centerpoint distribution and use it when the items to be
distributed overlap leaving no gap to use for spacing

Fixes: lp:1748763
* https://bugs.launchpad.net/kicad/+bug/1748763

pcbnew/tools/placement_tool.cpp

@@ -400,21 +400,42 @@ int ALIGN_DISTRIBUTE_TOOL::DistributeHorizontally( const TOOL_EVENT& aEvent )
 
     // find the last item by reverse sorting
     std::sort( itemsToDistribute.begin(), itemsToDistribute.end(), SortRightmostX );
-    const auto maxRight = itemsToDistribute.begin()->second.GetRight();
     const auto lastItem = itemsToDistribute.begin()->first;
 
+    const auto maxRight = itemsToDistribute.begin()->second.GetRight();
+
     // sort to get starting order
     std::sort( itemsToDistribute.begin(), itemsToDistribute.end(), SortLeftmostX );
-
-    auto totalGap = maxRight - itemsToDistribute.begin()->second.GetX();
+    const auto minX = itemsToDistribute.begin()->second.GetX();
+    auto totalGap = maxRight - minX;
+    int totalWidth = 0;
 
     for( auto& i : itemsToDistribute )
     {
-        totalGap -= i.second.GetWidth();
+        totalWidth += i.second.GetWidth();
     }
 
-    const auto itemGap = totalGap / ( itemsToDistribute.size() - 1 );
+    if( totalGap < totalWidth )
+    {
+        // the width of the items exceeds the gap (overlapping items) -> use center point spacing
+        doDistributeCentersHorizontally( itemsToDistribute );
+    }
+    else
+    {
+        totalGap -= totalWidth;
+        doDistributeGapsHorizontally( itemsToDistribute, lastItem, totalGap );
+    }
 
+    commit.Push( _( "Distribute horizontally" ) );
+
+    return 0;
+}
+
+
+void ALIGN_DISTRIBUTE_TOOL::doDistributeGapsHorizontally( ALIGNMENT_RECTS& itemsToDistribute,
+                                                          const BOARD_ITEM* lastItem, int totalGap ) const
+{
+    const auto itemGap = totalGap / ( itemsToDistribute.size() - 1 );
     auto targetX = itemsToDistribute.begin()->second.GetX();
 
     for( auto& i : itemsToDistribute )
@@ -427,10 +448,23 @@ int ALIGN_DISTRIBUTE_TOOL::DistributeHorizontally( const TOOL_EVENT& aEvent )
         i.first->Move( wxPoint( difference, 0 ) );
         targetX += ( i.second.GetWidth() + itemGap );
     }
+}
 
-    commit.Push( _( "Distribute horizontally" ) );
 
-    return 0;
+void ALIGN_DISTRIBUTE_TOOL::doDistributeCentersHorizontally( ALIGNMENT_RECTS &itemsToDistribute ) const
+{
+    std::sort( itemsToDistribute.begin(), itemsToDistribute.end(), SortCenterX );
+    const auto totalGap = ( itemsToDistribute.end()-1 )->second.GetCenter().x
+                          - itemsToDistribute.begin()->second.GetCenter().x;
+    const auto itemGap = totalGap / ( itemsToDistribute.size() - 1 );
+    auto targetX = itemsToDistribute.begin()->second.GetCenter().x;
+
+    for( auto& i : itemsToDistribute )
+        {
+            int difference = targetX - i.second.GetCenter().x;
+            i.first->Move( wxPoint( difference, 0 ) );
+            targetX += ( itemGap );
+        }
 }
 
 
@@ -453,17 +487,37 @@ int ALIGN_DISTRIBUTE_TOOL::DistributeVertically( const TOOL_EVENT& aEvent )
 
     // sort to get starting order
     std::sort( itemsToDistribute.begin(), itemsToDistribute.end(), SortTopmostY );
+    auto minY = itemsToDistribute.begin()->second.GetY();
 
-    // determine the distance between the bottommost and topmost Y coordinates
-    auto totalGap = maxBottom - itemsToDistribute.begin()->second.GetY();
+    auto totalGap = maxBottom - minY;
+    int totalHeight = 0;
 
     for( auto& i : itemsToDistribute )
     {
-        totalGap -= i.second.GetHeight();
+        totalHeight += i.second.GetHeight();
     }
 
-    const auto itemGap = totalGap / ( itemsToDistribute.size() - 1 );
+    if( totalGap < totalHeight )
+    {
+        // the width of the items exceeds the gap (overlapping items) -> use center point spacing
+        doDistributeCentersVertically( itemsToDistribute );
+    }
+    else
+    {
+        totalGap -= totalHeight;
+        doDistributeGapsVertically( itemsToDistribute, lastItem, totalGap );
+    }
 
+    commit.Push( _( "Distribute vertically" ) );
+
+    return 0;
+}
+
+
+void ALIGN_DISTRIBUTE_TOOL::doDistributeGapsVertically( ALIGNMENT_RECTS& itemsToDistribute,
+                                                        const BOARD_ITEM* lastItem, int totalGap ) const
+{
+    const auto itemGap = totalGap / ( itemsToDistribute.size() - 1 );
     auto targetY = itemsToDistribute.begin()->second.GetY();
 
     for( auto& i : itemsToDistribute )
@@ -476,10 +530,23 @@ int ALIGN_DISTRIBUTE_TOOL::DistributeVertically( const TOOL_EVENT& aEvent )
         i.first->Move( wxPoint( 0, difference ) );
         targetY += ( i.second.GetHeight() + itemGap );
     }
+}
 
-    commit.Push( _( "Distribute vertically" ) );
 
-    return 0;
+void ALIGN_DISTRIBUTE_TOOL::doDistributeCentersVertically( ALIGNMENT_RECTS& itemsToDistribute ) const
+{
+    std::sort( itemsToDistribute.begin(), itemsToDistribute.end(), SortCenterY );
+    const auto totalGap = ( itemsToDistribute.end()-1 )->second.GetCenter().y
+                          - itemsToDistribute.begin()->second.GetCenter().y;
+    const auto itemGap = totalGap / ( itemsToDistribute.size() - 1 );
+    auto targetY = itemsToDistribute.begin()->second.GetCenter().y;
+
+    for( auto& i : itemsToDistribute )
+    {
+        int difference = targetY - i.second.GetCenter().y;
+        i.first->Move( wxPoint( 0, difference ) );
+        targetY += ( itemGap );
+    }
 }
 
 

pcbnew/tools/placement_tool.h

@@ -118,6 +118,42 @@ private:
     SELECTION_TOOL* m_selectionTool;
 
     CONTEXT_MENU* m_placementMenu;
+
+    /**
+     * Distributes selected items using an even spacing between the centers of their bounding boxes
+     *
+     * NOTE: Using the centers of bounding box of items can give unsatisfactory visual results since
+     * items of differing widths will be placed with different gaps. Is only used if items overlap
+     */
+    void doDistributeCentersHorizontally( ALIGNMENT_RECTS &itemsToDistribute ) const;
+
+    /**
+     * Distributes selected items using an even spacing between the centers of their bounding boxes
+     *
+     * NOTE: Using the centers of bounding box of items can give unsatisfactory visual results since
+     * items of differing widths will be placed with different gaps. Is only used if items overlap
+     */
+    void doDistributeCentersVertically( ALIGNMENT_RECTS &itemsToDistribute ) const;
+
+    /**
+     * Distributes selected items using an even spacing between their bounding boxes
+     *
+     * NOTE: Using the edges of bounding box of items is only possible if there is enough space
+     * between them. If this is not the case, use the center spacing method
+     */
+    void doDistributeGapsHorizontally( ALIGNMENT_RECTS &itemsToDistribute,
+                                       const BOARD_ITEM *lastItem,
+                                       int totalGap ) const;
+
+    /**
+     * Distributes selected items using an even spacing between their bounding boxes
+     *
+     * NOTE: Using the edges of bounding box of items is only possible if there is enough space
+     * between them. If this is not the case, use the center spacing method
+     */
+    void doDistributeGapsVertically( ALIGNMENT_RECTS &itemsToDistribute,
+                                     const BOARD_ITEM *lastItem,
+                                     int totalGap ) const;
 };
 
 #endif /* ALIGN_DISTRIBUTE_TOOL_H_ */