Add confirm removal on mixer channels (#6691)

* Add confirm removal on mixer channels

Add confirm removal popup when the user calls the action "remove channel" on a mixer channel that is in use (receives audio from other channel or track). Set a config variable to keep track if the user don't want to be asked again. Adding a scroll on settings-general tab because there weren't enough space on the area.

* Core Mixer function channel in use

New core Mixer function to check if a given channel is in use (receives audio)

---------

Co-authored-by: Hyunjin Song <tteu.ingog@gmail.com>
Co-authored-by: saker <sakertooth@Gmail.com>

include/Mixer.h

@@ -202,6 +202,10 @@ public:
 	// rename channels when moving etc. if they still have their original name
 	void validateChannelName( int index, int oldIndex );
 
+	// check if the index channel receives audio from any other channel
+	// or from any instrument or sample track
+	bool isChannelInUse(int index);
+
 	void toggledSolo();
 	void activateSolo();
 	void deactivateSolo();

include/MixerView.h

@@ -95,6 +95,7 @@ public:
 
 	// notify the view that a mixer channel was deleted
 	void deleteChannel(int index);
+	bool confirmRemoval(int index);
 
 	// delete all unused channels
 	void deleteUnusedChannels();

include/SetupDialog.h

@@ -82,6 +82,7 @@ private slots:
 	void toggleLetPreviewsFinish(bool enabled);
 	void toggleSoloLegacyBehavior(bool enabled);
 	void toggleTrackDeletionWarning(bool enabled);
+	void toggleMixerChannelDeletionWarning(bool enabled);
 	void toggleMMPZ(bool enabled);
 	void toggleDisableBackup(bool enabled);
 	void toggleOpenLastProject(bool enabled);
@@ -141,6 +142,7 @@ private:
 	bool m_letPreviewsFinish;
 	bool m_soloLegacyBehavior;
 	bool m_trackDeletionWarning;
+	bool m_mixerChannelDeletionWarning;
 	bool m_MMPZ;
 	bool m_disableBackup;
 	bool m_openLastProject;

src/core/Mixer.cpp

@@ -825,5 +825,41 @@ void Mixer::validateChannelName( int index, int oldIndex )
 	}
 }
 
+bool Mixer::isChannelInUse(int index)
+{
+	// check if the index mixer channel receives audio from any other channel
+	if (!m_mixerChannels[index]->m_receives.isEmpty())
+	{
+		return true;
+	}
+
+	// check if the destination mixer channel on any instrument or sample track is the index mixer channel
+	TrackContainer::TrackList tracks;
+	tracks += Engine::getSong()->tracks();
+	tracks += Engine::patternStore()->tracks();
+
+	for (const auto t : tracks)
+	{
+		if (t->type() == Track::InstrumentTrack)
+		{
+			auto inst = dynamic_cast<InstrumentTrack*>(t);
+			if (inst->mixerChannelModel()->value() == index)
+			{
+				return true;
+			}
+		}
+		else if (t->type() == Track::SampleTrack)
+		{
+			auto strack = dynamic_cast<SampleTrack*>(t);
+			if (strack->mixerChannelModel()->value() == index)
+			{
+				return true;
+			}
+		}
+	}
+
+	return false;
+}
+
 
 } // namespace lmms

src/gui/MixerView.cpp

@@ -23,7 +23,9 @@
  */
 
 
+#include <QCheckBox>
 #include <QLayout>
+#include <QMessageBox>
 #include <QPushButton>
 #include <QScrollArea>
 #include <QStyle>
@@ -385,6 +387,12 @@ void MixerView::deleteChannel(int index)
 	// can't delete master
 	if( index == 0 ) return;
 
+	// if there is no user confirmation, do nothing
+	if (!confirmRemoval(index))
+	{
+		return;
+	}
+
 	// remember selected line
 	int selLine = m_currentMixerLine->channelIndex();
 
@@ -397,7 +405,7 @@ void MixerView::deleteChannel(int index)
 
 	// delete the view
 	chLayout->removeWidget(m_mixerChannelViews[index]->m_mixerLine);
-	m_racksLayout->removeWidget( m_mixerChannelViews[index]->m_rackView );
+	m_racksLayout->removeWidget(m_mixerChannelViews[index]->m_rackView);
 	delete m_mixerChannelViews[index]->m_fader;
 	delete m_mixerChannelViews[index]->m_muteBtn;
 	delete m_mixerChannelViews[index]->m_soloBtn;
@@ -409,56 +417,74 @@ void MixerView::deleteChannel(int index)
 	m_channelAreaWidget->adjustSize();
 
 	// make sure every channel knows what index it is
-	for(int i=index + 1; i<m_mixerChannelViews.size(); ++i)
+	for (int i = index + 1; i < m_mixerChannelViews.size(); ++i)
 	{
-		m_mixerChannelViews[i]->m_mixerLine->setChannelIndex(i-1);
+		m_mixerChannelViews[i]->m_mixerLine->setChannelIndex(i - 1);
 	}
 	m_mixerChannelViews.remove(index);
 
 	// select the next channel
-	if( selLine >= m_mixerChannelViews.size() )
+	if (selLine >= m_mixerChannelViews.size())
 	{
-		selLine = m_mixerChannelViews.size()-1;
+		selLine = m_mixerChannelViews.size() - 1;
 	}
 	setCurrentMixerLine(selLine);
 
 	updateMaxChannelSelector();
 }
 
+bool MixerView::confirmRemoval(int index)
+{
+	// if config variable is set to false, there is no need for user confirmation
+	bool needConfirm = ConfigManager::inst()->value("ui", "mixerchanneldeletionwarning", "1").toInt();
+	if (!needConfirm) { return true; }
+
+	Mixer* mix = Engine::mixer();
+
+	if (!mix->isChannelInUse(index))
+	{
+		// is the channel is not in use, there is no need for user confirmation
+		return true;
+	}
+
+	QString messageRemoveTrack = tr("This Mixer Channel is being used.\n"
+									"Are you sure you want to remove this channel?\n\n"
+									"Warning: This operation can not be undone.");
+
+	QString messageTitleRemoveTrack = tr("Confirm removal");
+	QString askAgainText = tr("Don't ask again");
+	auto askAgainCheckBox = new QCheckBox(askAgainText, nullptr);
+	connect(askAgainCheckBox, &QCheckBox::stateChanged, [this](int state) {
+		// Invert button state, if it's checked we *shouldn't* ask again
+		ConfigManager::inst()->setValue("ui", "mixerchanneldeletionwarning", state ? "0" : "1");
+	});
+
+	QMessageBox mb(this);
+	mb.setText(messageRemoveTrack);
+	mb.setWindowTitle(messageTitleRemoveTrack);
+	mb.setIcon(QMessageBox::Warning);
+	mb.addButton(QMessageBox::Cancel);
+	mb.addButton(QMessageBox::Ok);
+	mb.setCheckBox(askAgainCheckBox);
+	mb.setDefaultButton(QMessageBox::Cancel);
+
+	int answer = mb.exec();
+
+	return answer == QMessageBox::Ok;
+}
 
 
 void MixerView::deleteUnusedChannels()
 {
-	TrackContainer::TrackList tracks;
-	tracks += Engine::getSong()->tracks();
-	tracks += Engine::patternStore()->tracks();
+	Mixer* mix = Engine::mixer();
 
-	std::vector<bool> inUse(m_mixerChannelViews.size(), false);
-
-	//Populate inUse by checking the destination channel for every track
-	for (Track* t: tracks)
+	// Check all channels except master, delete those with no incoming sends
+	for (int i = m_mixerChannelViews.size() - 1; i > 0; --i)
 	{
-		//The channel that this track sends to. Since master channel is always in use,
-		//setting this to 0 is a safe default (for tracks that don't sent to the mixer).
-		int channel = 0;
-		if (t->type() == Track::InstrumentTrack)
+		if (!mix->isChannelInUse(i))
 		{
-			auto inst = dynamic_cast<InstrumentTrack*>(t);
-			channel = inst->mixerChannelModel()->value();
+			deleteChannel(i);
 		}
-		else if (t->type() == Track::SampleTrack)
-		{
-			auto strack = dynamic_cast<SampleTrack*>(t);
-			channel = strack->mixerChannelModel()->value();
-		}
-		inUse[channel] = true;
-	}
-
-	//Check all channels except master, delete those with no incoming sends
-	for(int i = m_mixerChannelViews.size()-1; i > 0; --i)
-	{
-		if (!inUse[i] && Engine::mixer()->mixerChannel(i)->m_receives.isEmpty())
-		{ deleteChannel(i); }
 	}
 }
 

src/gui/modals/SetupDialog.cpp

@@ -112,6 +112,8 @@ SetupDialog::SetupDialog(ConfigTabs tab_to_open) :
 			"app", "sololegacybehavior", "0").toInt()),
 	m_trackDeletionWarning(ConfigManager::inst()->value(
 			"ui", "trackdeletionwarning", "1").toInt()),
+	m_mixerChannelDeletionWarning(ConfigManager::inst()->value(
+			"ui", "mixerchanneldeletionwarning", "1").toInt()),
 	m_MMPZ(!ConfigManager::inst()->value(
 			"app", "nommpz").toInt()),
 	m_disableBackup(!ConfigManager::inst()->value(
@@ -198,6 +200,18 @@ SetupDialog::SetupDialog(ConfigTabs tab_to_open) :
 	general_layout->setContentsMargins(0, 0, 0, 0);
 	labelWidget(general_w, tr("General"));
 
+	// General scroll area.
+	auto generalScroll = new QScrollArea(general_w);
+	generalScroll->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
+	generalScroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+
+	// General controls widget.
+	auto generalControls = new QWidget(general_w);
+
+	// Path selectors layout.
+	auto generalControlsLayout = new QVBoxLayout;
+	generalControlsLayout->setSpacing(10);
+
 	auto addLedCheckBox = [&XDelta, &YDelta, this](const QString& ledText, TabWidget* tw, int& counter,
 							  bool initialState, const char* toggledSlot, bool showRestartWarning) {
 		auto checkBox = new LedCheckBox(ledText, tw);
@@ -214,7 +228,7 @@ SetupDialog::SetupDialog(ConfigTabs tab_to_open) :
 	int counter = 0;
 
 	// GUI tab.
-	auto gui_tw = new TabWidget(tr("Graphical user interface (GUI)"), general_w);
+	auto gui_tw = new TabWidget(tr("Graphical user interface (GUI)"), generalControls);
 
 	addLedCheckBox(tr("Display volume as dBFS "), gui_tw, counter,
 		m_displaydBFS, SLOT(toggleDisplaydBFS(bool)), true);
@@ -236,14 +250,19 @@ SetupDialog::SetupDialog(ConfigTabs tab_to_open) :
 		m_soloLegacyBehavior, SLOT(toggleSoloLegacyBehavior(bool)), false);
 	addLedCheckBox(tr("Show warning when deleting tracks"), gui_tw, counter,
 		m_trackDeletionWarning, SLOT(toggleTrackDeletionWarning(bool)), false);
+	addLedCheckBox(tr("Show warning when deleting a mixer channel that is in use"), gui_tw, counter,
+		m_mixerChannelDeletionWarning,	SLOT(toggleMixerChannelDeletionWarning(bool)), false);
 
 	gui_tw->setFixedHeight(YDelta + YDelta * counter);
 
+	generalControlsLayout->addWidget(gui_tw);
+	generalControlsLayout->addSpacing(10);
+
 
 	counter = 0;
 
 	// Projects tab.
-	auto projects_tw = new TabWidget(tr("Projects"), general_w);
+	auto projects_tw = new TabWidget(tr("Projects"), generalControls);
 
 	addLedCheckBox(tr("Compress project files by default"), projects_tw, counter,
 		m_MMPZ, SLOT(toggleMMPZ(bool)), true);
@@ -254,8 +273,12 @@ SetupDialog::SetupDialog(ConfigTabs tab_to_open) :
 
 	projects_tw->setFixedHeight(YDelta + YDelta * counter);
 
+	generalControlsLayout->addWidget(projects_tw);
+	generalControlsLayout->addSpacing(10);
+
+
 	// Language tab.
-	auto lang_tw = new TabWidget(tr("Language"), general_w);
+	auto lang_tw = new TabWidget(tr("Language"), generalControls);
 	lang_tw->setFixedHeight(48);
 	auto changeLang = new QComboBox(lang_tw);
 	changeLang->move(XDelta, 20);
@@ -310,11 +333,15 @@ SetupDialog::SetupDialog(ConfigTabs tab_to_open) :
 	connect(changeLang, SIGNAL(currentIndexChanged(int)),
 			this, SLOT(showRestartWarning()));
 
+	generalControlsLayout->addWidget(lang_tw);
+	generalControlsLayout->addSpacing(10);
 
 	// General layout ordering.
-	general_layout->addWidget(gui_tw);
-	general_layout->addWidget(projects_tw);
-	general_layout->addWidget(lang_tw);
+	generalControlsLayout->addStretch();
+	generalControls->setLayout(generalControlsLayout);
+	generalScroll->setWidget(generalControls);
+	generalScroll->setWidgetResizable(true);
+	general_layout->addWidget(generalScroll);
 	general_layout->addStretch();
 
 
@@ -896,6 +923,8 @@ void SetupDialog::accept()
 					QString::number(m_soloLegacyBehavior));
 	ConfigManager::inst()->setValue("ui", "trackdeletionwarning",
 					QString::number(m_trackDeletionWarning));
+	ConfigManager::inst()->setValue("ui", "mixerchanneldeletionwarning",
+					QString::number(m_mixerChannelDeletionWarning));
 	ConfigManager::inst()->setValue("app", "nommpz",
 					QString::number(!m_MMPZ));
 	ConfigManager::inst()->setValue("app", "disablebackup",
@@ -1017,6 +1046,11 @@ void SetupDialog::toggleTrackDeletionWarning(bool enabled)
 	m_trackDeletionWarning = enabled;
 }
 
+void SetupDialog::toggleMixerChannelDeletionWarning(bool enabled)
+{
+	m_mixerChannelDeletionWarning = enabled;
+}
+
 
 void SetupDialog::toggleMMPZ(bool enabled)
 {