Make compress/expand preserve timing data by also adjusting BPM changes between start and end marker. The adjusting part is at TimingData::ScaleRegion.

src/ScreenEdit.cpp

@@ -3455,7 +3455,7 @@ void ScreenEdit::HandleAreaMenuChoice( AreaMenuChoice c, const vector<int> &iAns
 				else
 					NoteDataUtil::DeleteRows( m_NoteDataEdit, m_NoteFieldEdit.m_iBeginMarker, -iDeltaRows );
 
-				m_pSong->m_Timing.ScaleRegion( fScale, m_NoteFieldEdit.m_iBeginMarker, m_NoteFieldEdit.m_iEndMarker );
+				m_pSong->m_Timing.ScaleRegion( fScale, m_NoteFieldEdit.m_iBeginMarker, m_NoteFieldEdit.m_iEndMarker, true );
 
 				HandleAreaMenuChoice( paste_at_begin_marker );
 
@@ -3479,12 +3479,6 @@ void ScreenEdit::HandleAreaMenuChoice( AreaMenuChoice c, const vector<int> &iAns
 				}
 
 				m_NoteFieldEdit.m_iEndMarker = iNewClipboardEndRow;
-
-				float fPriorBPM = m_pSong->GetBPMAtBeat( NoteRowToBeat(iNewClipboardEndRow + 1) );
-				float fOldBPM = m_pSong->GetBPMAtBeat( NoteRowToBeat(m_NoteFieldEdit.m_iBeginMarker) );
-				float fNewBPM = fOldBPM * fScale;
-				m_pSong->m_Timing.SetBPMAtRow( m_NoteFieldEdit.m_iBeginMarker, fNewBPM );
-				m_pSong->m_Timing.SetBPMAtRow( iNewClipboardEndRow, fPriorBPM );
 			}
 			break;
 		case play:

src/TimingData.cpp

@@ -611,12 +611,12 @@ float TimingData::GetElapsedTimeFromBeatNoOffset( float fBeat ) const
 	return fElapsedTime;
 }
 
-void TimingData::ScaleRegion( float fScale, int iStartIndex, int iEndIndex )
+void TimingData::ScaleRegion( float fScale, int iStartIndex, int iEndIndex, bool bAdjustBPM )
 {
 	ASSERT( fScale > 0 );
 	ASSERT( iStartIndex >= 0 );
 	ASSERT( iStartIndex < iEndIndex );
-
+	
 	for ( unsigned i = 0; i < m_BPMSegments.size(); i++ )
 	{
 		const int iSegStart = m_BPMSegments[i].m_iStartRow;
@@ -638,6 +638,31 @@ void TimingData::ScaleRegion( float fScale, int iStartIndex, int iEndIndex )
 		else
 			m_StopSegments[i].m_iStartRow = lrintf((iSegStartRow - iStartIndex) * fScale) + iStartIndex;
 	}
+	
+	// adjust BPM changes to preserve timing
+	if( bAdjustBPM )
+	{
+		int iNewEndIndex = lrintf( (iEndIndex - iStartIndex) * fScale ) + iStartIndex;
+		float fEndBPMBeforeScaling = GetBPMAtRow(iNewEndIndex);
+		
+		// adjust BPM changes "between" iStartIndex and iNewEndIndex
+		for ( unsigned i = 0; i < m_BPMSegments.size(); i++ )
+		{
+			const int iSegStart = m_BPMSegments[i].m_iStartRow;
+			if( iSegStart <= iStartIndex )
+				continue;
+			else if( iSegStart >= iNewEndIndex )
+				continue;
+			else
+				m_BPMSegments[i].m_fBPS *= fScale;
+		}
+		
+		// set BPM at iStartIndex and iNewEndIndex.
+		SetBPMAtRow( iStartIndex, GetBPMAtRow(iStartIndex) * fScale );
+		SetBPMAtRow( iNewEndIndex, fEndBPMBeforeScaling );
+		
+	}
+	
 }
 
 void TimingData::InsertRows( int iStartRow, int iRowsToAdd )

src/TimingData.h

@@ -1073,7 +1073,7 @@ public:
 	 */
 	bool operator!=( const TimingData &other ) { return !operator==(other); }
 
-	void ScaleRegion( float fScale = 1, int iStartRow = 0, int iEndRow = MAX_NOTE_ROW );
+	void ScaleRegion( float fScale = 1, int iStartRow = 0, int iEndRow = MAX_NOTE_ROW, bool bAdjustBPM = false );
 	void InsertRows( int iStartRow, int iRowsToAdd );
 	void DeleteRows( int iStartRow, int iRowsToDelete );