kicad-developers team mailing list archive

[Cirilo Bernardo <cirilo.bernardo@xxxxxxxxx>]

In the DXF importer a default line width of 0.1 is used when no line width
is specified in the file. That's all fine when the file specifies mm as the
unit of length but we have a conversion problem if we use any other unit.
Historically this is due to KiCad assuming that DXF files were all in some
specific unit (I can't recall now if it was inch or mm). When I worked on
the DXF importer to use the unit specified in the file (only defaulting to mm
if no unit was specified) I missed this issue with line width conversions.

To demonstrate the bug: create a DXF outline in a unit other than mm -
I recommend using inches since that demonstrates the problem nicely
while leaving the outline recognizable.  Do not assign a line width to
the glyphs, otherwise kicad will correctly process the assigned width.
Since kicad assigns a default line width of 0.1, the resulting line widths
will be 25.4mm/inch * 0.1 = 2.54mm wide.

Re: STABLE RELEASE: A similar fix will be required for the stable
release; I don't know if this patch will apply since the file has been
touched a number of times since the stable branch. Fortunately
there are not many lines that need to be changed and they all
follow the same formula. This bug was originally reported for the
stable branch (4.0.6) here:

https://forum.kicad.info/t/importing-dxf-to-pcb-new-creating-illegible-blobs/6548

[OT] Incidentally, on one occasion a user was complaining about his DXF
import going wrong. The problem in that case was that no unit length was
specified in the DXF file so KiCad assumed mm when the design was done
with inches. Is this issue (a) not worth worrying about, or (b) should be
fixed by adding a "default DXF unit length (if none specified)" drop-down
box in the DXF import dialog?

- Cirilo

From 8b97ac8ecc55659bcf132b09511058c9795d28be Mon Sep 17 00:00:00 2001
From: Cirilo Bernardo <cirilo.bernardo@xxxxxxxxx>
Date: Fri, 26 May 2017 01:44:46 +0000
Subject: [PATCH] Fixed line width bug for non-mm DXF units

---
 pcbnew/import_dxf/dxf2brd_items.cpp | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/pcbnew/import_dxf/dxf2brd_items.cpp b/pcbnew/import_dxf/dxf2brd_items.cpp
index dfd8272c9..0bba71106 100644
--- a/pcbnew/import_dxf/dxf2brd_items.cpp
+++ b/pcbnew/import_dxf/dxf2brd_items.cpp
@@ -120,7 +120,8 @@ void DXF2BRD_CONVERTER::addLine( const DRW_Line& aData )
     segm->SetStart( start );
     wxPoint end( mapX( aData.secPoint.x ), mapY( aData.secPoint.y ) );
     segm->SetEnd( end );
-    segm->SetWidth( mapDim( aData.thickness == 0 ? m_defaultThickness : aData.thickness ) );
+    segm->SetWidth( mapDim( aData.thickness == 0 ? m_defaultThickness / m_DXF2mm
+                            : aData.thickness ) );
     m_newItemsList.push_back( segm );
 }
 
@@ -153,7 +154,7 @@ void DXF2BRD_CONVERTER::addPolyline(const DRW_Polyline& aData )
         segm->SetStart( segment_startpoint );
         wxPoint segment_endpoint( mapX( vertex->basePoint.x ), mapY( vertex->basePoint.y ) );
         segm->SetEnd( segment_endpoint );
-        segm->SetWidth( mapDim( aData.thickness == 0 ? m_defaultThickness
+        segm->SetWidth( mapDim( aData.thickness == 0 ? m_defaultThickness / m_DXF2mm
                                 : aData.thickness ) );
         m_newItemsList.push_back( segm );
         segment_startpoint = segment_endpoint;
@@ -169,7 +170,7 @@ void DXF2BRD_CONVERTER::addPolyline(const DRW_Polyline& aData )
         closing_segm->SetLayer( ToLAYER_ID( m_brdLayer ) );
         closing_segm->SetStart( segment_startpoint );
         closing_segm->SetEnd( polyline_startpoint );
-        closing_segm->SetWidth( mapDim( aData.thickness == 0 ? m_defaultThickness
+        closing_segm->SetWidth( mapDim( aData.thickness == 0 ? m_defaultThickness / m_DXF2mm
                                 : aData.thickness ) );
         m_newItemsList.push_back( closing_segm );
     }
@@ -186,7 +187,7 @@ void DXF2BRD_CONVERTER::addLWPolyline(const DRW_LWPolyline& aData )
     wxRealPoint seg_start;
     wxRealPoint poly_start;
     double bulge = 0.0;
-    int lineWidth = mapDim( aData.thickness == 0 ? m_defaultThickness
+    int lineWidth = mapDim( aData.thickness == 0 ? m_defaultThickness / m_DXF2mm
                             : aData.thickness );
 
     for( unsigned ii = 0; ii < aData.vertlist.size(); ii++ )
@@ -235,7 +236,8 @@ void DXF2BRD_CONVERTER::addCircle( const DRW_Circle& aData )
     segm->SetCenter( center );
     wxPoint circle_start( mapX( aData.basePoint.x + aData.radious ), mapY( aData.basePoint.y ) );
     segm->SetArcStart( circle_start );
-    segm->SetWidth( mapDim( aData.thickness == 0 ? m_defaultThickness : aData.thickness ) );
+    segm->SetWidth( mapDim( aData.thickness == 0 ? m_defaultThickness / m_DXF2mm
+                            : aData.thickness ) );
     m_newItemsList.push_back( segm );
 }
 
@@ -274,7 +276,8 @@ void DXF2BRD_CONVERTER::addArc( const DRW_Arc& data )
 
     segm->SetAngle( angle );
 
-    segm->SetWidth( mapDim( data.thickness == 0 ? m_defaultThickness : data.thickness ) );
+    segm->SetWidth( mapDim( data.thickness == 0 ? m_defaultThickness / m_DXF2mm
+                            : data.thickness ) );
     m_newItemsList.push_back( segm );
 }
 
@@ -384,7 +387,8 @@ void DXF2BRD_CONVERTER::addText( const DRW_Text& aData )
     // The 0.8 factor gives a better height/width ratio with our font
     textItem->SetTextWidth( mapDim( aData.height * 0.8 ) );
     textItem->SetTextHeight( mapDim( aData.height ) );
-    textItem->SetThickness( mapDim( aData.thickness == 0 ? m_defaultThickness : aData.thickness ) );
+    textItem->SetThickness( mapDim( aData.thickness == 0 ? m_defaultThickness / m_DXF2mm
+                                    : aData.thickness ) );
     textItem->SetText( text );
 
     m_newItemsList.push_back( static_cast< BOARD_ITEM* >( brdItem ) );
@@ -446,7 +450,8 @@ void DXF2BRD_CONVERTER::addMText( const DRW_MText& aData )
     // The 0.8 factor gives a better height/width ratio with our font
     textItem->SetTextWidth( mapDim( aData.height * 0.8 ) );
     textItem->SetTextHeight( mapDim( aData.height ) );
-    textItem->SetThickness( mapDim( aData.thickness == 0 ? m_defaultThickness : aData.thickness ) );
+    textItem->SetThickness( mapDim( aData.thickness == 0 ? m_defaultThickness / m_DXF2mm
+                                    : aData.thickness ) );
     textItem->SetText( text );
 
     // Initialize text justifications:
-- 
2.11.0