Reload stylesheet when CSS file changes (#6331)

* Reload stylesheet when CSS file changes

---------

Co-authored-by: Tres Finocchiaro <tres.finocchiaro@gmail.com>

include/LmmsStyle.h

@@ -26,6 +26,7 @@
 #ifndef LMMS_GUI_LMMS_STYLE_H
 #define LMMS_GUI_LMMS_STYLE_H
 
+#include <QFileSystemWatcher>
 #include <QProxyStyle>
 
 
@@ -60,6 +61,7 @@ public:
 private:
 	QImage colorizeXpm( const char * const * xpm, const QBrush& fill ) const;
 	void hoverColors( bool sunken, bool hover, bool active, QColor& color, QColor& blend ) const;
+	QFileSystemWatcher m_styleReloader;
 };
 
 

src/gui/LmmsStyle.cpp

@@ -25,14 +25,17 @@
 
 #include <array>
 
-#include <QFile>
 #include <QApplication>
+#include <QFile>
+#include <QFileInfo>
 #include <QPainter>
 #include <QPainterPath>
 #include <QStyleFactory>
 #include <QStyleOption>
 
+#include "embed.h"
 #include "LmmsStyle.h"
+#include "TextFloat.h"
 
 
 namespace lmms::gui
@@ -137,6 +140,29 @@ LmmsStyle::LmmsStyle() :
 	file.open( QIODevice::ReadOnly );
 	qApp->setStyleSheet( file.readAll() );
 
+	m_styleReloader.addPath(QFileInfo{file}.absoluteFilePath());
+	connect(&m_styleReloader, &QFileSystemWatcher::fileChanged, this,
+		[this](const QString& path)
+		{
+			if (auto file = QFile{path}; file.exists())
+			{
+				file.open(QIODevice::ReadOnly);
+				qApp->setStyleSheet(file.readAll());
+				TextFloat::displayMessage(
+					tr("Theme updated"),
+					tr("LMMS theme file %1 has been reloaded.").arg(file.fileName()),
+					embed::getIconPixmap("colorize"),
+					3000
+				);
+				// Handle delete + overwrite events
+				if (!m_styleReloader.files().contains(path))
+				{
+					m_styleReloader.addPath(path);
+				}
+			}
+		}
+	);
+
 	if( s_palette != nullptr ) { qApp->setPalette( *s_palette ); }
 
 	setBaseStyle( QStyleFactory::create( "Fusion" ) );