SIGSEGV on cloning pattern

[StinaIsNormallyDistributed]

When ctrl-clicking to drag-clone any pattern (beat, pianoroll or automation), lmms segfaults without further error.

lmms 1.2.0-rc7.42
qt5 5.12.0-3

[Cangle50]

Looks a little like what was reported in #4738 .

@megahertz commented

Fixed in Arch Linux in qt5-base 5.12.0-2

Looks like qt5 5.12.0-3 has broken it again.

[dvzrv]

@StinaIsNormallyDistributed seems this is happening on exit:

QPixmap::grabWidget is deprecated, use QWidget::grab() instead
[1]    1168 segmentation fault (core dumped)  lmms

[dvzrv]

Looking at the QPixmap documentation, this is obsolete since 5.12 and needs to be changed within lmms in these files.
However, this should not lead to a crash (at least not intentionally).
FWIW, it's the same problem with 5.12.0-2.

[dvzrv]

This seems to trickle down to Qcursor:

Thread 1 "lmms" received signal SIGSEGV, Segmentation fault.
QCursor::shape (this=this@entry=0x0) at kernel/qcursor.cpp:539
539     kernel/qcursor.cpp: No such file or directory.

Don't have much time for a debug build, but might do that in the coming days

[ghost]

While dragging a leaveEvent in TrackContentObjectView is triggered that calls QApplication::restoreOverrideCursor(), that is what is causing the crash.

It won't crash with this patch:

include/Track.h

--- a/include/Track.h
+++ b/include/Track.h
@@ -311,6 +311,7 @@
 	bool m_gradient;
 
  	bool m_needsUpdate;
+ 	bool m_isDragging;
 	inline void setInitialMousePos( QPoint pos )
 	{
 		m_initialMousePos = pos;

src/core/Track.cpp

--- a/src/core/Track.cpp
+++ b/src/core/Track.cpp
@@ -275,7 +275,8 @@
 	m_textShadowColor( 0, 0, 0 ),
 	m_BBPatternBackground( 0, 0, 0 ),
 	m_gradient( true ),
-	m_needsUpdate( true )
+	m_needsUpdate( true ),
+	m_isDragging( false )
 {
 	if( s_textFloat == NULL )
 	{
@@ -598,9 +599,12 @@
  */
 void TrackContentObjectView::leaveEvent( QEvent * e )
 {
-	while( QApplication::overrideCursor() != NULL )
-	{
-		QApplication::restoreOverrideCursor();
+	if ( ! m_isDragging )
+	{
+		while( QApplication::overrideCursor() != NULL )
+		{
+			QApplication::restoreOverrideCursor();
+		}
 	}
 	if( e != NULL )
 	{
@@ -868,6 +872,8 @@
 			// Write the TCOs to the DataFile for copying
 			DataFile dataFile = createTCODataFiles( tcoViews );
 
+			m_isDragging = true;
+
 			// TODO -- thumbnail for all selected
 			QPixmap thumbnail = grab().scaled(
 				128, 128,
@@ -876,6 +882,8 @@
 			new StringPairDrag( QString( "tco_%1" ).arg(
 								m_tco->getTrack()->type() ),
 								dataFile.toString(), thumbnail, this );
+
+			m_isDragging = false;
 		}
 	}

[PhysSong]

Looks similar to #3926 to me.

[tresf]

@cyberdevilnl can you test against #4870 and confirm that it fixes this bug? If so, we'll close it as duplicate of #3926.

[ghost]

@tresf nope #4870 won’t solve this issue. src/core/Track.cpp should be updated for that.

Here is a list of files that probably should be updated to. Only Track.cpp causes troubles with Qt 5.12 but for more clean code I think they all should get a update. I'm willing to work on that, all I need is some time :-P, should a new issue be opened or just continue here for all these files?

src/gui/widgets/LcdSpinBox.cpp:102:		QApplication::setOverrideCursor( Qt::BlankCursor );
src/gui/widgets/Knob.cpp:603:		QApplication::setOverrideCursor( Qt::BlankCursor );
src/gui/editors/PianoRoll.cpp:1602:					QApplication::setOverrideCursor( c );
src/gui/editors/PianoRoll.cpp:1616:					QApplication::setOverrideCursor( c );
src/gui/editors/PianoRoll.cpp:2021:			QApplication::setOverrideCursor(
src/gui/editors/PianoRoll.cpp:2239:						QApplication::setOverrideCursor(QCursor(cursorShape));
src/gui/editors/PianoRoll.cpp:2244:					QApplication::setOverrideCursor(QCursor(cursorShape));
src/gui/editors/AutomationEditor.cpp:587:				QApplication::setOverrideCursor( c );
src/gui/editors/AutomationEditor.cpp:820:						QApplication::setOverrideCursor(
src/gui/editors/AutomationEditor.cpp:827:					QApplication::setOverrideCursor( c );
src/core/Track.cpp:707:			QApplication::setOverrideCursor( c );
src/core/Track.cpp:729:			QApplication::setOverrideCursor( c );
src/core/Track.cpp:941:			QApplication::setOverrideCursor( c );
src/core/Track.cpp:2728:			QApplication::setOverrideCursor( c );
src/core/Track.cpp:2735:			QApplication::setOverrideCursor( c );