From 65c88ba2c3fdbf57e7cd8fe3b2c59aea4c65c71e Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Tue, 7 Jan 2020 19:35:45 +0000
Subject: [PATCH] Reduce the auto-panning margin and implement acceleration.

---
 common/view/view_controls.cpp    |  4 +++-
 common/view/wx_view_controls.cpp |  7 +++++--
 include/view/view_controls.h     | 13 +++++++++++++
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/common/view/view_controls.cpp b/common/view/view_controls.cpp
index 5a022ba007..bce53e3ecb 100644
--- a/common/view/view_controls.cpp
+++ b/common/view/view_controls.cpp
@@ -63,8 +63,9 @@ void VC_SETTINGS::Reset()
     m_grabMouse = false;
     m_autoPanEnabled = false;
     m_autoPanSettingEnabled = false;
-    m_autoPanMargin = 0.1f;
+    m_autoPanMargin = 0.02f;
     m_autoPanSpeed = 0.15f;
+    m_autoPanAcceleration = 1.5f;
     m_warpCursor = false;
     m_enableMousewheelPan = false;
     m_panWithRightButton = false;
@@ -82,5 +83,6 @@ void VIEW_CONTROLS::ApplySettings( const VC_SETTINGS& aSettings )
     SetAutoPan( aSettings.m_autoPanEnabled );
     SetAutoPanMargin( aSettings.m_autoPanMargin );
     SetAutoPanSpeed( aSettings.m_autoPanSpeed );
+    SetAutoPanAcceleration( aSettings.m_autoPanAcceleration );
     ForceCursorPosition( aSettings.m_forceCursorPosition, aSettings.m_forcedPosition );
 }
diff --git a/common/view/wx_view_controls.cpp b/common/view/wx_view_controls.cpp
index 7d7a690302..5e13c0e44f 100644
--- a/common/view/wx_view_controls.cpp
+++ b/common/view/wx_view_controls.cpp
@@ -363,11 +363,13 @@ void WX_VIEW_CONTROLS::onTimer( wxTimerEvent& aEvent )
 
         VECTOR2D dir( m_panDirection );
 
-        if( dir.EuclideanNorm() > borderSize )
+        if( dir.EuclideanNorm() > borderSize / 2 )
+            dir = dir.Resize( pow( borderSize, m_settings.m_autoPanAcceleration ) );
+        else if( dir.EuclideanNorm() > borderSize )
             dir = dir.Resize( borderSize );
 
         dir = m_view->ToWorld( dir, false );
-        m_view->SetCenter( m_view->GetCenter() + dir * m_settings.m_autoPanSpeed );
+        m_view->SetCenter( m_view->GetCenter() + dir );
 
         refreshMouse();
     }
@@ -591,6 +593,7 @@ bool WX_VIEW_CONTROLS::handleAutoPanning( const wxMouseEvent& aEvent )
     // Compute areas where autopanning is active
     int borderStart = std::min( m_settings.m_autoPanMargin * m_view->GetScreenPixelSize().x,
                                    m_settings.m_autoPanMargin * m_view->GetScreenPixelSize().y );
+    borderStart = std::max( borderStart, 2 );
     int borderEndX = m_view->GetScreenPixelSize().x - borderStart;
     int borderEndY = m_view->GetScreenPixelSize().y - borderStart;
 
diff --git a/include/view/view_controls.h b/include/view/view_controls.h
index 2844b99c90..1e16ae6cf9 100644
--- a/include/view/view_controls.h
+++ b/include/view/view_controls.h
@@ -81,6 +81,9 @@ struct VC_SETTINGS
     ///> How fast is panning when in auto mode
     float m_autoPanSpeed;
 
+    ///> How fast does panning accelerate when approaching the window boundary
+    float m_autoPanAcceleration;
+
     ///> If the cursor is allowed to be warped
     bool m_warpCursor;
 
@@ -181,6 +184,16 @@ public:
         m_settings.m_autoPanSpeed = aSpeed;
     }
 
+    /**
+     * Function SetAutoPanSpeed()
+     * Sets speed of autopanning.
+     * @param aSpeed is a new speed for autopanning.
+     */
+    virtual void SetAutoPanAcceleration( float aAcceleration )
+    {
+        m_settings.m_autoPanAcceleration = aAcceleration;
+    }
+
     /**
      * Function SetAutoPanMArgin()
      * Sets margin for autopanning (ie. the area when autopanning becomes active).