From ac543ffc750d95023f1d58c41647402c9a3e1fc4 Mon Sep 17 00:00:00 2001
From: Hyunjin Song <tteu.ingog@gmail.com>
Date: Thu, 22 Mar 2018 12:39:17 +0900
Subject: [PATCH] Play correct note when dragging left side of virtual keyboard
 (#4265)

---
 src/gui/PianoView.cpp | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/src/gui/PianoView.cpp b/src/gui/PianoView.cpp
index 351806936..2a64e72dd 100644
--- a/src/gui/PianoView.cpp
+++ b/src/gui/PianoView.cpp
@@ -327,7 +327,9 @@ void PianoView::modelChanged()
  */
 int PianoView::getKeyFromMouse( const QPoint & _p ) const
 {
-	int key_num = (int)( (float) _p.x() / (float) PW_WHITE_KEY_WIDTH );
+	int offset = _p.x() % PW_WHITE_KEY_WIDTH;
+	if( offset < 0 ) offset += PW_WHITE_KEY_WIDTH;
+	int key_num = ( _p.x() - offset) / PW_WHITE_KEY_WIDTH;
 
 	for( int i = 0; i <= key_num; ++i )
 	{
@@ -336,6 +338,13 @@ int PianoView::getKeyFromMouse( const QPoint & _p ) const
 			++key_num;
 		}
 	}
+	for( int i = 0; i >= key_num; --i )
+	{
+		if ( Piano::isBlackKey( m_startKey+i ) )
+		{
+			--key_num;
+		}
+	}
 
 	key_num += m_startKey;
 
@@ -345,16 +354,14 @@ int PianoView::getKeyFromMouse( const QPoint & _p ) const
 		// then do extra checking whether the mouse-cursor is over
 		// a black key
 		if( key_num > 0 && Piano::isBlackKey( key_num-1 ) &&
-			_p.x() % PW_WHITE_KEY_WIDTH <=
-					( PW_WHITE_KEY_WIDTH / 2 ) -
-						( PW_BLACK_KEY_WIDTH / 2 ) )
+			offset <= ( PW_WHITE_KEY_WIDTH / 2 ) -
+					( PW_BLACK_KEY_WIDTH / 2 ) )
 		{
 			--key_num;
 		}
 		if( key_num < NumKeys - 1 && Piano::isBlackKey( key_num+1 ) &&
-			_p.x() % PW_WHITE_KEY_WIDTH >=
-				( PW_WHITE_KEY_WIDTH -
-				  		PW_BLACK_KEY_WIDTH / 2 ) )
+			offset >= ( PW_WHITE_KEY_WIDTH -
+					PW_BLACK_KEY_WIDTH / 2 ) )
 		{
 			++key_num;
 		}