Add comments. Gerbview: in legacy mode, do not display D_Code id text when it is too small to be readable.

gerbview/class_gbr_layout.cpp

@@ -430,10 +430,18 @@ void GBR_LAYOUT::DrawItemsDCodeID( EDA_DRAW_PANEL* aPanel, wxDC* aDC,
                 width /= 2;
             }
 
-            DrawGraphicText( aPanel->GetClipBox(), aDC, pos, aDrawColor, Line,
-                             orient, wxSize( width, width ),
-                             GR_TEXT_HJUSTIFY_CENTER, GR_TEXT_VJUSTIFY_CENTER,
-                             0, false, false );
+            // Avoid to draw text, if it is too small (size in pixel < 5 pixels)
+            // to be readable:
+            int size_pixel = aDC->LogicalToDeviceXRel( width );
+            const int threshold = 5;
+
+            if( size_pixel >= threshold )
+            {
+                DrawGraphicText( aPanel->GetClipBox(), aDC, pos, aDrawColor, Line,
+                                 orient, wxSize( width, width ),
+                                 GR_TEXT_HJUSTIFY_CENTER, GR_TEXT_VJUSTIFY_CENTER,
+                                 0, false, false );
+            }
         }
     }
 }

gerbview/class_gerber_draw_item.cpp

@@ -281,7 +281,9 @@ const EDA_RECT GERBER_DRAW_ITEM::GetBoundingBox() const
     }
     case GBR_SPOT_MACRO:
     {
+        // Update the shape drawings and the bounding box coordiantes:
         code->GetMacro()->GetApertureMacroShape( this, m_Start );
+        // now the bounding box is valid:
         bbox = code->GetMacro()->GetBoundingBox();
         break;
     }
@@ -781,7 +783,10 @@ const BOX2I GERBER_DRAW_ITEM::ViewBBox() const
 
 unsigned int GERBER_DRAW_ITEM::ViewGetLOD( int aLayer, KIGFX::VIEW* aView ) const
 {
-    // DCodes will be shown only if zoom is appropriate
+    // DCodes will be shown only if zoom is appropriate:
+    // Returns the level of detail of the item.
+    // A level of detail (LOD) is the minimal VIEW scale that
+    // is sufficient for an item to be shown on a given layer.
     if( IsDCodeLayer( aLayer ) )
     {
         int size = 0;
@@ -800,7 +805,10 @@ unsigned int GERBER_DRAW_ITEM::ViewGetLOD( int aLayer, KIGFX::VIEW* aView ) cons
             size = m_Size.x;
         }
 
-        return ( 100000000 / ( size + 1 ) );
+        // the level of details is chosen experimentally, to show
+        // only a readable text:
+        const int level = Millimeter2iu( 1000 );
+        return ( level / ( size + 1 ) );
     }
 
     // Other layers are shown without any conditions

include/view/view_item.h

@@ -128,8 +128,13 @@ public:
 
     /**
      * Function ViewGetLOD()
-     * Returns the level of detail of the item. A level of detail is the minimal VIEW scale that
+     * Returns the level of detail (LOD) of the item.
+     * A level of detail is the minimal VIEW scale that
      * is sufficient for an item to be shown on a given layer.
+     * @param aLayer: current drawing layer
+     * @param aView: pointer to the VIEW device we are drawing on
+     * @return the level of detail. 0 always show the item, because the
+     * actual zoom level (or VIEW scale) is always > 0
      */
     virtual unsigned int ViewGetLOD( int aLayer, VIEW* aView ) const
     {