From 30a7876593122b5185222d7e4bbe441e7e0c7cff Mon Sep 17 00:00:00 2001
From: "james.k.crook@gmail.com"
 <james.k.crook@gmail.com@47890b92-0858-11df-a26f-8b716316a5bc>
Date: Fri, 4 May 2012 11:47:29 +0000
Subject: [PATCH] Ctrl-Wheel Zooming now behaves like zoom buttons, so we don't
 zoom into empty space.

---
 src/Menus.cpp      | 19 +++++++++++++++----
 src/Project.h      |  2 ++
 src/TrackPanel.cpp | 18 +++++++++---------
 3 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/src/Menus.cpp b/src/Menus.cpp
index 6ed69953e..08e009c9f 100644
--- a/src/Menus.cpp
+++ b/src/Menus.cpp
@@ -4757,10 +4757,15 @@ void AudacityProject::OnSelectAllTracks()
 //
 
 void AudacityProject::OnZoomIn()
+{
+   ZoomInByFactor( 2.0 );
+}
+
+void AudacityProject::ZoomInByFactor( double ZoomFactor )
 {
    // LLL: Handling positioning differently when audio is active
    if (gAudioIO->IsStreamActive(GetAudioIOToken()) != 0) {
-      Zoom(mViewInfo.zoom * 2.0);
+      Zoom(mViewInfo.zoom * ZoomFactor);
       mTrackPanel->ScrollIntoView(gAudioIO->GetStreamTime());
       mTrackPanel->Refresh(false);
       return;
@@ -4791,7 +4796,7 @@ void AudacityProject::OnZoomIn()
             (mViewInfo.h + mViewInfo.screen - mViewInfo.sel0) / 2;
          
       // Zoom in
-      Zoom(mViewInfo.zoom *= 2.0);
+      Zoom(mViewInfo.zoom *= ZoomFactor);
 
       // Recenter on selCenter
       TP_ScrollWindow(selCenter - mViewInfo.screen / 2);
@@ -4801,7 +4806,7 @@ void AudacityProject::OnZoomIn()
 
    double origLeft = mViewInfo.h;
    double origWidth = mViewInfo.screen;
-   Zoom(mViewInfo.zoom *= 2.0);
+   Zoom(mViewInfo.zoom *= ZoomFactor);
    
    double newh = origLeft + (origWidth - mViewInfo.screen) / 2;
    
@@ -4823,11 +4828,17 @@ void AudacityProject::OnZoomIn()
 
 void AudacityProject::OnZoomOut()
 {  
+   ZoomOutByFactor( 1 /2.0 );
+}
+
+
+void AudacityProject::ZoomOutByFactor( double ZoomFactor )
+{
    //Zoom() may change these, so record original values:
    double origLeft = mViewInfo.h;
    double origWidth = mViewInfo.screen;
 
-   Zoom(mViewInfo.zoom /= 2.0);
+   Zoom(mViewInfo.zoom *=ZoomFactor);
 
    double newh = origLeft + (origWidth - mViewInfo.screen) / 2;
    // newh = (newh > 0) ? newh : 0;
diff --git a/src/Project.h b/src/Project.h
index 706d3e235..09b293668 100644
--- a/src/Project.h
+++ b/src/Project.h
@@ -275,6 +275,8 @@ class AUDACITY_DLL_API AudacityProject:  public wxFrame,
 
    void HandleResize();
    void UpdateLayout();
+   void ZoomInByFactor( double ZoomFactor );
+   void ZoomOutByFactor( double ZoomFactor );
 
    // Other commands
    static TrackList *GetClipboardTracks();
diff --git a/src/TrackPanel.cpp b/src/TrackPanel.cpp
index d9aa600dd..f0d178af1 100644
--- a/src/TrackPanel.cpp
+++ b/src/TrackPanel.cpp
@@ -4659,16 +4659,16 @@ void TrackPanel::HandleWheelRotation(wxMouseEvent & event)
          50.0 * -steps / mViewInfo->zoom);
    } else if (event.CmdDown())
    {
-      // MM: Zoom in/out when used with Control key down
-      // MM: I don't understand what trackLeftEdge does
-      int trackLeftEdge = GetLeftOffset();
-      
-      double center_h = PositionToTime(event.m_x, trackLeftEdge);
-      mViewInfo->zoom = wxMin(mViewInfo->zoom * pow(2.0, steps), gMaxZoom);
+      // JKC: Now using AudacityProject zooming, which is smarter,
+      // it keeps selections on screen and centred if it can,
+      // also this ensures mousewheel and zoom buttons give same result.
+      double ZoomFactor = pow(2.0, steps);
+      AudacityProject *p = GetProject();
+      if( steps > 0 )
+         p->ZoomInByFactor( ZoomFactor );
+      else 
+         p->ZoomOutByFactor( ZoomFactor );
 
-      double new_center_h = PositionToTime(event.m_x, trackLeftEdge);
-      mViewInfo->h += (center_h - new_center_h);
-      
       MakeParentRedrawScrollbars();
       Refresh(false);
    } else