Take text height into account as well as thickness for knockout margin.

Also centralizes calculation so all clients will get the same answer.

Fixes https://gitlab.com/kicad/code/kicad/issues/11636

3d-viewer/3d_canvas/create_3Dgraphic_brd_items.cpp

@@ -91,7 +91,8 @@ void BOARD_ADAPTER::addText( const EDA_TEXT* aText, CONTAINER_2D_BASE* aContaine
         font->Draw( &callback_gal, aText->GetShownText(), aText->GetDrawPos(), attrs );
 
         SHAPE_POLY_SET finalPoly;
-        int            margin = attrs.m_StrokeWidth * 1.5;
+        int            margin = attrs.m_StrokeWidth * 1.5 +
+                                    GetKnockoutTextMargin( attrs.m_Size, attrs.m_StrokeWidth );
 
         aText->TransformBoundingBoxWithClearanceToPolygon( &finalPoly, margin );
         finalPoly.BooleanSubtract( knockouts, SHAPE_POLY_SET::PM_FAST );

include/gr_text.h

@@ -79,6 +79,19 @@ int GetPenSizeForBold( const wxSize& aTextSize );
 int GetPenSizeForNormal( int aTextSize );
 int GetPenSizeForNormal( const wxSize& aTextSize );
 
+
+/**
+ * Returns the margin for knockout text.
+ *
+ * Note that this is not a perfect calculation as fonts (especially outline fonts) vary greatly
+ * in how well ascender and descender heights are enforced.
+ */
+inline int GetKnockoutTextMargin( const VECTOR2I& aSize, int aThickness )
+{
+    return std::max( aThickness, KiROUND( aSize.y / 4.0 ) );
+}
+
+
 /**
  * The full X size is GraphicTextWidth + the thickness of graphic lines.
  *

pcbnew/pcb_painter.cpp

@@ -1681,7 +1681,8 @@ void PCB_PAINTER::draw( const PCB_TEXT* aText, int aLayer )
         font->Draw( &callback_gal, resolvedText, aText->GetDrawPos(), attrs );
 
         SHAPE_POLY_SET finalPoly;
-        int            margin = attrs.m_StrokeWidth * 2.5;
+        int            margin = attrs.m_StrokeWidth * 1.5
+                                    + GetKnockoutTextMargin( attrs.m_Size, attrs.m_StrokeWidth );
 
         aText->TransformBoundingBoxWithClearanceToPolygon( &finalPoly, margin );
         finalPoly.BooleanSubtract( knockouts, SHAPE_POLY_SET::PM_FAST );
@@ -1835,7 +1836,8 @@ void PCB_PAINTER::draw( const FP_TEXT* aText, int aLayer )
         font->Draw( &callback_gal, resolvedText, aText->GetDrawPos(), attrs );
 
         SHAPE_POLY_SET finalPoly;
-        int            margin = attrs.m_StrokeWidth * 1.5;
+        int            margin = attrs.m_StrokeWidth * 1.5
+                                    + GetKnockoutTextMargin( attrs.m_Size, attrs.m_StrokeWidth );
 
         aText->TransformBoundingBoxWithClearanceToPolygon( &finalPoly, margin );
         finalPoly.BooleanSubtract( knockouts, SHAPE_POLY_SET::PM_FAST );

pcbnew/plot_brditems_plotter.cpp

@@ -825,7 +825,8 @@ void BRDITEMS_PLOTTER::PlotPcbText( const EDA_TEXT* aText, PCB_LAYER_ID aLayer,
         font->Draw( &callback_gal, shownText, aText->GetDrawPos(), attrs );
 
         SHAPE_POLY_SET finalPoly;
-        int            margin = attrs.m_StrokeWidth * 1.5;
+        int            margin = attrs.m_StrokeWidth * 1.5
+                                    + GetKnockoutTextMargin( attrs.m_Size, attrs.m_StrokeWidth );
 
         aText->TransformBoundingBoxWithClearanceToPolygon( &finalPoly, margin );
         finalPoly.BooleanSubtract( knockouts, SHAPE_POLY_SET::PM_FAST );

pcbnew/zone_filler.cpp

@@ -521,33 +521,20 @@ void ZONE_FILLER::addHoleKnockout( PAD* aPad, int aGap, SHAPE_POLY_SET& aHoles )
 void ZONE_FILLER::addKnockout( BOARD_ITEM* aItem, PCB_LAYER_ID aLayer, int aGap,
                                bool aIgnoreLineWidth, SHAPE_POLY_SET& aHoles )
 {
-    // Text has a complicated relationship with its boudingBox due to ascenders, descenders,
+    EDA_TEXT* text = nullptr;
-    // diacriticals, etc.  Some things want a fairly tight bounding box, and some things don't.
+
-    // Since there's no uniformly "correct" answer, we pad the bounding box here to limit
-    // shorting as much as possible.  (Note, however, that it will be caught by DRC either way,
-    // as it's not reliant on the bounding box.)
     switch( aItem->Type() )
     {
-    case PCB_TEXT_T:
+    case PCB_TEXT_T:       text = static_cast<PCB_TEXT*>( aItem );    break;
-        aGap += static_cast<PCB_TEXT*>( aItem )->GetTextThickness();
+    case PCB_TEXTBOX_T:    text = static_cast<PCB_TEXTBOX*>( aItem ); break;
-        break;
+    case PCB_FP_TEXT_T:    text = static_cast<FP_TEXT*>( aItem );     break;
-
+    case PCB_FP_TEXTBOX_T: text = static_cast<FP_TEXTBOX*>( aItem );  break;
-    case PCB_TEXTBOX_T:
+    default:                                                          break;
-        aGap += static_cast<PCB_TEXTBOX*>( aItem )->GetTextThickness();
-        break;
-
-    case PCB_FP_TEXT_T:
-        aGap += static_cast<FP_TEXT*>( aItem )->GetTextThickness();
-        break;
-
-    case PCB_FP_TEXTBOX_T:
-        aGap += static_cast<FP_TEXTBOX*>( aItem )->GetTextThickness();
-        break;
-
-    default:
-        break;
     }
 
+    if( text )
+        aGap += GetKnockoutTextMargin( text->GetTextSize(), text->GetTextThickness() );
+
     switch( aItem->Type() )
     {
     case PCB_SHAPE_T:
@@ -561,17 +548,13 @@ void ZONE_FILLER::addKnockout( BOARD_ITEM* aItem, PCB_LAYER_ID aLayer, int aGap,
         break;
 
     case PCB_FP_TEXT_T:
-    {
-        FP_TEXT* text = static_cast<FP_TEXT*>( aItem );
-
         if( text->IsVisible() )
         {
-            text->TransformShapeWithClearanceToPolygon( aHoles, aLayer, aGap, m_maxError,
+            aItem->TransformShapeWithClearanceToPolygon( aHoles, aLayer, aGap, m_maxError,
-                                                        ERROR_OUTSIDE, aIgnoreLineWidth );
+                                                         ERROR_OUTSIDE, aIgnoreLineWidth );
         }
 
         break;
-    }
 
     default:
         break;