From 5af8d2d0a8e84c1bd75d32dc9bfb94b1c3ebc0da Mon Sep 17 00:00:00 2001
From: Seth Hillbrand <hillbrand@ucdavis.edu>
Date: Mon, 18 Feb 2019 09:39:10 -0800
Subject: [PATCH] cairo: Fix rotated oval pads

Fixes: lp:1816428
* https://bugs.launchpad.net/kicad/+bug/1816428
---
 common/gal/cairo/cairo_gal.cpp | 30 ++++++++++++++++++++----------
 include/gal/cairo/cairo_gal.h  |  1 +
 include/gal/definitions.h      | 11 +++++++++--
 3 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/common/gal/cairo/cairo_gal.cpp b/common/gal/cairo/cairo_gal.cpp
index 56683df328..8acdf53321 100644
--- a/common/gal/cairo/cairo_gal.cpp
+++ b/common/gal/cairo/cairo_gal.cpp
@@ -110,6 +110,14 @@ const VECTOR2D CAIRO_GAL_BASE::xform( const VECTOR2D& aP )
 }
 
 
+const double CAIRO_GAL_BASE::angle_xform( const double aAngle )
+{
+    double world_angle = -std::atan2( currentWorld2Screen.xy, currentWorld2Screen.xx );
+
+    return std::fmod( aAngle + world_angle, 2.0 * M_PI );
+}
+
+
 const double CAIRO_GAL_BASE::xform( double x )
 {
     double dx = currentWorld2Screen.xx * x;
@@ -256,7 +264,9 @@ void CAIRO_GAL_BASE::DrawArc( const VECTOR2D& aCenterPoint, double aRadius, doub
     auto startPointS = roundp( xform ( startPoint ) );
     auto endPointS = roundp( xform ( endPoint ) );
 
-    SWAP( aStartAngle, >, aEndAngle );
+    auto startAngleS = angle_xform( aStartAngle );
+    auto endAngleS = angle_xform( aEndAngle );
+    SWAP( startAngleS, >, endAngleS );
 
     if( isFillEnabled )     // Draw the filled area of the shape, before drawing the outline itself
     {
@@ -265,7 +275,7 @@ void CAIRO_GAL_BASE::DrawArc( const VECTOR2D& aCenterPoint, double aRadius, doub
 
         cairo_set_line_width( currentContext, 1.0 );
         cairo_new_sub_path( currentContext );
-        cairo_arc( currentContext, c.x, c.y, r, aStartAngle, aEndAngle );
+        cairo_arc( currentContext, c.x, c.y, r, startAngleS, endAngleS );
 
         cairo_move_to( currentContext, c.x, c.y );
         cairo_line_to( currentContext, startPointS.x, startPointS.y );
@@ -277,7 +287,7 @@ void CAIRO_GAL_BASE::DrawArc( const VECTOR2D& aCenterPoint, double aRadius, doub
 
     cairo_set_line_width( currentContext, lineWidthInPixels );
     cairo_new_sub_path( currentContext );
-    cairo_arc( currentContext, c.x, c.y, r, aStartAngle, aEndAngle );
+    cairo_arc( currentContext, c.x, c.y, r, startAngleS, endAngleS );
     flushPath();
 
     isElementAdded = true;
@@ -290,13 +300,15 @@ void CAIRO_GAL_BASE::DrawRectangle( const VECTOR2D& aStartPoint, const VECTOR2D&
     syncLineWidth();
 
     const auto p0 = roundp( xform( aStartPoint ) );
-    const auto p1 = roundp( xform( aEndPoint ) );
+    const auto p1 = roundp( xform( VECTOR2D( aEndPoint.x, aStartPoint.y ) ) );
+    const auto p2 = roundp( xform( aEndPoint ) );
+    const auto p3 = roundp( xform( VECTOR2D( aStartPoint.x, aEndPoint.y ) ) );
 
     // The path is composed from 4 segments
     cairo_move_to( currentContext, p0.x, p0.y );
-    cairo_line_to( currentContext, p1.x, p0.y );
     cairo_line_to( currentContext, p1.x, p1.y );
-    cairo_line_to( currentContext, p0.x, p1.y );
+    cairo_line_to( currentContext, p2.x, p2.y );
+    cairo_line_to( currentContext, p3.x, p3.y );
     cairo_close_path( currentContext );
     flushPath();
 
@@ -1452,11 +1464,9 @@ void CAIRO_GAL_BASE::DrawGrid()
     int gridEndY = KiROUND( ( worldEndPoint.y - gridOrigin.y ) / gridSize.y );
 
     // Ensure start coordinate > end coordinate
-    if( gridStartX > gridEndX )
-        std::swap( gridStartX, gridEndX );
 
-    if( gridStartY > gridEndY )
-        std::swap( gridStartY, gridEndY );
+    SWAP( gridStartX, >, gridStartX );
+    SWAP( gridStartY, >, gridEndY );
 
     // Ensure the grid fills the screen
     --gridStartX; ++gridEndX;
diff --git a/include/gal/cairo/cairo_gal.h b/include/gal/cairo/cairo_gal.h
index e39aebe4aa..dd43dda286 100644
--- a/include/gal/cairo/cairo_gal.h
+++ b/include/gal/cairo/cairo_gal.h
@@ -218,6 +218,7 @@ protected:
     const double xform( double x );
     const VECTOR2D xform( double x, double y );
     const VECTOR2D xform( const VECTOR2D& aP );
+    const double angle_xform( const double aAngle );
 
     /// @copydoc GAL::BeginDrawing()
     virtual void beginDrawing() override;
diff --git a/include/gal/definitions.h b/include/gal/definitions.h
index 4ee1d6f077..456d5f6c29 100644
--- a/include/gal/definitions.h
+++ b/include/gal/definitions.h
@@ -28,8 +28,15 @@
 #define DEFINITIONS_H_
 
 /// Swap the variables if a condition is met.
-#define SWAP( varA, condition, varB ) if( varA condition varB ) { double tmp = varA; varA = varB; \
-                                                                  varB = tmp; }
+#define SWAP( varA, condition, varB )   \
+    assert( typeid( varA ).hash_code() == typeid( varB ).hash_code() ); \
+    \
+    if( varA condition varB )           \
+    {                                   \
+        decltype( varA ) tmp = varA;    \
+        varA = varB;                    \
+        varB = tmp;                     \
+    }
 
 namespace KIGFX
 {