All: fix horizontal touchpad panning

Commit e10c01aaf didn't work when touchpad panning was enabled.

This commit changes it to only discard horizontal wheel events
when in "scroll mode" rather than "pan mode".

Based on a patch by Adrian Scripcă <benishor@gmail.com>.

Follow-up to fix: lp:1828080
https://bugs.launchpad.net/kicad/+bug/1828080

common/view/wx_view_controls.cpp

@@ -147,8 +147,6 @@ void WX_VIEW_CONTROLS::onMotion( wxMouseEvent& aEvent )
 
 void WX_VIEW_CONTROLS::onWheel( wxMouseEvent& aEvent )
 {
-    const double wheelPanSpeed = 0.001;
-
 #ifdef __WXGTK3__
     if( aEvent.GetTimestamp() == m_lastTimestamp )
     {
@@ -159,11 +157,8 @@ void WX_VIEW_CONTROLS::onWheel( wxMouseEvent& aEvent )
     m_lastTimestamp = aEvent.GetTimestamp();
 #endif
 
-    // Fix issue caused by modern mice that feature horizontal scrolling by only handling
-    // vertical axis, otherwise horizontal scrolling events end up interpreted as vertical
-    // scroll events and confuse the user.
-    if( aEvent.GetWheelAxis() > 0 )
-        return;
+    const double wheelPanSpeed = 0.001;
+    const int    axis = aEvent.GetWheelAxis();
 
     // mousewheelpan disabled:
     //      wheel + ctrl    -> horizontal scrolling;
@@ -180,7 +175,6 @@ void WX_VIEW_CONTROLS::onWheel( wxMouseEvent& aEvent )
         // Scrolling
         VECTOR2D scrollVec = m_view->ToWorld( m_view->GetScreenPixelSize(), false ) *
                              ( (double) aEvent.GetWheelRotation() * wheelPanSpeed );
-        int axis = aEvent.GetWheelAxis();
         double scrollX = 0.0;
         double scrollY = 0.0;
 
@@ -206,18 +200,24 @@ void WX_VIEW_CONTROLS::onWheel( wxMouseEvent& aEvent )
     }
     else
     {
-        int    rotation = aEvent.GetWheelRotation();
-        double zoomScale = m_zoomController->GetScaleForRotation( rotation );
-
-        if( IsCursorWarpingEnabled() )
-        {
-            CenterOnCursor();
-            m_view->SetScale( m_view->GetScale() * zoomScale );
-        }
-        else
+        // Restrict zoom handling to the vertical axis, otherwise horizontal
+        // scrolling events (e.g. touchpads and some mice) end up interpreted
+        // as vertical scroll events and confuse the user.
+        if( axis == wxMOUSE_WHEEL_VERTICAL )
         {
-            VECTOR2D anchor = m_view->ToWorld( VECTOR2D( aEvent.GetX(), aEvent.GetY() ) );
-            m_view->SetScale( m_view->GetScale() * zoomScale, anchor );
+            const int    rotation = aEvent.GetWheelRotation();
+            const double zoomScale = m_zoomController->GetScaleForRotation( rotation );
+
+            if( IsCursorWarpingEnabled() )
+            {
+                CenterOnCursor();
+                m_view->SetScale( m_view->GetScale() * zoomScale );
+            }
+            else
+            {
+                const VECTOR2D anchor = m_view->ToWorld( VECTOR2D( aEvent.GetX(), aEvent.GetY() ) );
+                m_view->SetScale( m_view->GetScale() * zoomScale, anchor );
+            }
         }
     }