From 386ead30c5690b14a9ae38e870a4c6f8556f115f Mon Sep 17 00:00:00 2001
From: Seth Hillbrand <seth@kipro-pcb.com>
Date: Fri, 29 Jan 2021 10:13:31 -0800
Subject: [PATCH] All circle and arc tools to select all at first

Non-layer elements can be logical centers for the circle and arc tools.
We allow the non-layer to snap for the center points and revert to only
on-layer elements after

Fixes https://gitlab.com/kicad/code/kicad/issues/7327
---
 pcbnew/tools/drawing_tool.cpp    | 19 +++++++++++++++++--
 pcbnew/tools/pcb_grid_helper.cpp |  8 ++++----
 pcbnew/tools/pcb_grid_helper.h   | 10 +++++++++-
 3 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/pcbnew/tools/drawing_tool.cpp b/pcbnew/tools/drawing_tool.cpp
index 3cfd058987..fa2b17c826 100644
--- a/pcbnew/tools/drawing_tool.cpp
+++ b/pcbnew/tools/drawing_tool.cpp
@@ -1304,7 +1304,14 @@ bool DRAWING_TOOL::drawSegment( const std::string& aTool, PCB_SHAPE** aGraphic,
 
         grid.SetSnap( !evt->Modifier( MD_SHIFT ) );
         grid.SetUseGrid( getView()->GetGAL()->GetGridSnapping() && !evt->Modifier( MD_ALT ) );
-        cursorPos = grid.BestSnapAnchor( m_controls->GetMousePosition(), m_frame->GetActiveLayer() );
+
+        // The first point in a circle should be able to snap to items on all layers because it doesn't
+        // overlap the graphical line
+        if( !started && graphic && shape == S_CIRCLE )
+            cursorPos = grid.BestSnapAnchor( m_controls->GetMousePosition(), nullptr );
+        else
+            cursorPos = grid.BestSnapAnchor( m_controls->GetMousePosition(), m_frame->GetActiveLayer() );
+
         m_controls->ForceCursorPosition( true, cursorPos );
 
         // 45 degree angle constraint enabled with an option and toggled with Ctrl
@@ -1607,7 +1614,15 @@ bool DRAWING_TOOL::drawArc( const std::string& aTool, PCB_SHAPE** aGraphic, bool
 
         grid.SetSnap( !evt->Modifier( MD_SHIFT ) );
         grid.SetUseGrid( getView()->GetGAL()->GetGridSnapping() && !evt->Modifier( MD_ALT ) );
-        VECTOR2I cursorPos = grid.BestSnapAnchor( m_controls->GetMousePosition(), graphic );
+        VECTOR2I cursorPos;
+
+        // The first point in an arc should be able to snap to items on all layers because it doesn't
+        // overlap the graphical line
+        if( firstPoint )
+            cursorPos = grid.BestSnapAnchor( m_controls->GetMousePosition(), graphic );
+        else
+            cursorPos = grid.BestSnapAnchor( m_controls->GetMousePosition(), nullptr );
+
         m_controls->ForceCursorPosition( true, cursorPos );
 
         auto cleanup =
diff --git a/pcbnew/tools/pcb_grid_helper.cpp b/pcbnew/tools/pcb_grid_helper.cpp
index c1defea850..3274b2b399 100644
--- a/pcbnew/tools/pcb_grid_helper.cpp
+++ b/pcbnew/tools/pcb_grid_helper.cpp
@@ -189,15 +189,15 @@ VECTOR2I PCB_GRID_HELPER::BestDragOrigin( const VECTOR2I &aMousePos,
 }
 
 
-VECTOR2I PCB_GRID_HELPER::BestSnapAnchor( const VECTOR2I& aOrigin, BOARD_ITEM* aDraggedItem )
+VECTOR2I PCB_GRID_HELPER::BestSnapAnchor( const VECTOR2I& aOrigin, BOARD_ITEM* aReferenceItem )
 {
     LSET layers;
     std::vector<BOARD_ITEM*> item;
 
-    if( aDraggedItem )
+    if( aReferenceItem )
     {
-        layers = aDraggedItem->GetLayerSet();
-        item.push_back( aDraggedItem );
+        layers = aReferenceItem->GetLayerSet();
+        item.push_back( aReferenceItem );
     }
     else
         layers = LSET::AllLayersMask();
diff --git a/pcbnew/tools/pcb_grid_helper.h b/pcbnew/tools/pcb_grid_helper.h
index f06f6b0f3f..b5b34d7372 100644
--- a/pcbnew/tools/pcb_grid_helper.h
+++ b/pcbnew/tools/pcb_grid_helper.h
@@ -60,7 +60,15 @@ public:
 
     VECTOR2I AlignToArc ( const VECTOR2I& aPoint, const SHAPE_ARC& aSeg );
 
-    VECTOR2I BestSnapAnchor( const VECTOR2I& aOrigin, BOARD_ITEM* aDraggedItem );
+    /**
+     * Chooses the "best" snap anchor around the given point, optionally taking layers from
+     * the reference item.  The reference item will not be snapped to (it is being dragged or
+     * created) and we choose the layers that can be snapped based on the reference item layer
+     * @param aOrigin Point we want to snap from
+     * @param aReferenceItem Reference item for layer/type special casing
+     * @return snapped screen point
+     */
+    VECTOR2I BestSnapAnchor( const VECTOR2I& aOrigin, BOARD_ITEM* aReferenceItem );
     VECTOR2I BestSnapAnchor( const VECTOR2I& aOrigin, const LSET& aLayers,
                              const std::vector<BOARD_ITEM*>& aSkip = {} );