From cd145258392eeb277248cc8ddde0d32bdcdcf674 Mon Sep 17 00:00:00 2001
From: Jon Evans <jon@craftyjon.com>
Date: Tue, 27 Feb 2018 22:17:42 -0500
Subject: [PATCH] GerbView: More accurate selection of arc shapes

---
 gerbview/gerber_draw_item.cpp | 37 ++++++++++++++++++++++++++++++++++-
 include/trigo.h               | 10 ++++++++++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/gerbview/gerber_draw_item.cpp b/gerbview/gerber_draw_item.cpp
index d6df6d55b0..18c8ba8504 100644
--- a/gerbview/gerber_draw_item.cpp
+++ b/gerbview/gerber_draw_item.cpp
@@ -769,9 +769,44 @@ bool GERBER_DRAW_ITEM::HitTest( const wxPoint& aRefPos ) const
         return poly.Contains( VECTOR2I( ref_pos ), 0 );
 
     case GBR_SPOT_RECT:
-    case GBR_ARC:
         return GetBoundingBox().Contains( aRefPos );
 
+    case GBR_ARC:
+        {
+            double radius = GetLineLength( m_Start, m_ArcCentre );
+            VECTOR2D test_radius = VECTOR2D( ref_pos ) - VECTOR2D( m_ArcCentre );
+
+            // Are we within m_Size.x of the radius?
+            bool radius_hit = ( std::fabs( test_radius.EuclideanNorm() - radius) < m_Size.x );
+
+            if( radius_hit )
+            {
+                // Now check that we are within the arc angle
+
+                VECTOR2D start = VECTOR2D( m_Start ) - VECTOR2D( m_ArcCentre );
+                VECTOR2D end = VECTOR2D( m_End ) - VECTOR2D( m_ArcCentre );
+
+                double start_angle = NormalizeAngleRadiansPos( start.Angle() );
+                double end_angle = NormalizeAngleRadiansPos( end.Angle() );
+
+                if( m_Start == m_End )
+                {
+                    start_angle = 0;
+                    end_angle = 2 * M_PI;
+                }
+                else if( end_angle < start_angle )
+                {
+                    end_angle += 2 * M_PI;
+                }
+
+                double test_angle = NormalizeAngleRadiansPos( test_radius.Angle() );
+
+                return ( test_angle > start_angle && test_angle < end_angle );
+            }
+
+            return false;
+        }
+
     case GBR_SPOT_MACRO:
         // Aperture macro polygons are already in absolute coordinates
         auto p = GetDcodeDescr()->GetMacro()->GetApertureMacroShape( this, m_Start );
diff --git a/include/trigo.h b/include/trigo.h
index 5cb93f93b2..f8da175bf7 100644
--- a/include/trigo.h
+++ b/include/trigo.h
@@ -261,6 +261,16 @@ inline void NORMALIZE_ANGLE_DEGREES_POS( double& Angle )
     Angle = NormalizeAngleDegreesPos( Angle );
 }
 
+
+inline double NormalizeAngleRadiansPos( double Angle )
+{
+    while( Angle < 0 )
+        Angle += (2 * M_PI );
+    while( Angle >= ( 2 * M_PI ) )
+        Angle -= ( 2 * M_PI );
+    return Angle;
+}
+
 /// Add two angles (keeping the result normalized). T2 is here
 // because most of the time it's an int (and templates don't promote in
 // that way)