more nanometer work, see comment at line 66 of pcbnew/classpcb.cpp

common/base_screen.cpp

@@ -98,16 +98,8 @@ double BASE_SCREEN::GetScalingFactor() const
 
 void BASE_SCREEN::SetScalingFactor( double aScale )
 {
-    double zoom = aScale;
-
     // Limit zoom to max and min allowed values:
-    if( zoom < m_ZoomList[0] )
-        zoom = m_ZoomList[0];
-
-    int idxmax = m_ZoomList.GetCount() - 1;
-
-    if( zoom > m_ZoomList[idxmax] )
-        zoom = m_ZoomList[idxmax];
+    double zoom = Clamp( GetMinAllowedZoom(), aScale, GetMaxAllowedZoom() );
 
     SetZoom( zoom );
 }
@@ -115,38 +107,30 @@ void BASE_SCREEN::SetScalingFactor( double aScale )
 
 bool BASE_SCREEN::SetFirstZoom()
 {
-    if( m_ZoomList.IsEmpty() )
-    {
-        if( m_Zoom != 1.0 )
-        {
-            SetZoom( 1.0 );
-            return true;
-        }
-    }
-    else if( m_Zoom != m_ZoomList[0] )
-    {
-        SetZoom( m_ZoomList[0] );
-        return true;
-    }
-
-    return false;
+    return SetZoom( GetMinAllowedZoom() );
 }
 
 
-double BASE_SCREEN::GetZoom() const
+bool BASE_SCREEN::SetLastZoom()
 {
-    return m_Zoom;
+    return SetZoom( GetMaxAllowedZoom() );
 }
 
 
-bool BASE_SCREEN::SetZoom( double coeff )
+bool BASE_SCREEN::SetZoom( double iu_per_du )
 {
-    if( coeff == m_Zoom )
+    if( iu_per_du == m_Zoom )
         return false;
 
-    wxLogDebug( "Zoom:%16g  1/Zoom:%16g", coeff, 1/coeff );
+    wxLogDebug( "Zoom:%16g  1/Zoom:%16g", iu_per_du, 1/iu_per_du );
 
-    m_Zoom = coeff;
+    if( iu_per_du < GetMinAllowedZoom() )
+        return false;
+
+    if( iu_per_du > GetMaxAllowedZoom() )
+        return false;
+
+    m_Zoom = iu_per_du;
 
     return true;
 }
@@ -154,10 +138,7 @@ bool BASE_SCREEN::SetZoom( double coeff )
 
 bool BASE_SCREEN::SetNextZoom()
 {
-    if( m_ZoomList.IsEmpty() || m_Zoom >= m_ZoomList.Last() )
-        return false;
-
-    for( unsigned i = 0; i < m_ZoomList.GetCount(); i++ )
+    for( unsigned i=0; i < m_ZoomList.size();  ++i )
     {
         if( m_Zoom < m_ZoomList[i] )
         {
@@ -172,10 +153,7 @@ bool BASE_SCREEN::SetNextZoom()
 
 bool BASE_SCREEN::SetPreviousZoom()
 {
-    if( m_ZoomList.IsEmpty() || m_Zoom <= m_ZoomList[0] )
-        return false;
-
-    for( unsigned i = m_ZoomList.GetCount(); i != 0; i-- )
+    for( unsigned i = m_ZoomList.size(); i != 0;  --i )
     {
         if( m_Zoom > m_ZoomList[i - 1] )
         {
@@ -188,15 +166,6 @@ bool BASE_SCREEN::SetPreviousZoom()
 }
 
 
-bool BASE_SCREEN::SetLastZoom()
-{
-    if( m_ZoomList.IsEmpty() || m_Zoom == m_ZoomList.Last() )
-        return false;
-
-    return SetZoom( m_ZoomList.Last() );
-}
-
-
 void BASE_SCREEN::SetGridList( GRIDS& gridlist )
 {
     if( !m_grids.empty() )