UI: Correct custom property implementation

- Fixes Q_PROPERTY macro syntax
- Removes excessive notification declaration and slot
- Removes unneeded dynamic property
- Improves Themes versatility

UI/data/themes/Acri.qss

@@ -904,8 +904,8 @@ FocusList::item {
 
 /* Preview background color */
 
-* [themeID="displayBackgroundColor"] {
-    qproperty-displayBackgroundColor: #28282A;
+OBSQTDisplay {
+	qproperty-displayBackgroundColor: #28282A;
 }
 
 /* Preview/Program labels */

UI/data/themes/Dark.qss

@@ -695,8 +695,8 @@ QLabel#errorLabel {
 
 /* Preview background color */
 
-* [themeID="displayBackgroundColor"] {
-    qproperty-displayBackgroundColor: rgb(76, 76, 76);
+OBSQTDisplay {
+	qproperty-displayBackgroundColor: rgb(76, 76, 76);
 }
 
 /* Preview/Program labels */

UI/data/themes/Rachni.qss

@@ -1260,8 +1260,8 @@ QToolTip {
 
 /* Preview background color */
 
-* [themeID="displayBackgroundColor"] {
-    qproperty-displayBackgroundColor: rgb(35, 38, 41);
+OBSQTDisplay {
+	qproperty-displayBackgroundColor: rgb(35, 38, 41);
 }
 
 /* Preview/Program labels */

UI/data/themes/System.qss

@@ -138,8 +138,8 @@ QLabel#errorLabel {
 
 /* Preview background color */
 
-* [themeID="displayBackgroundColor"] {
-    qproperty-displayBackgroundColor: rgb(76, 76, 76);
+OBSQTDisplay {
+	qproperty-displayBackgroundColor: rgb(76, 76, 76);
 }
 
 /* Preview/Program labels */

UI/qt-display.cpp

@@ -19,6 +19,13 @@ static inline long long color_to_int(QColor color)
 		shift(color.alpha(), 24);
 }
 
+static inline QColor rgba_to_color(uint32_t rgba)
+{
+	return QColor::fromRgb(rgba & 0xFF,
+	                       (rgba >> 8) & 0xFF,
+	                       (rgba >> 16) & 0xFF,
+	                       (rgba >> 24) & 0xFF);
+}
 
 OBSQTDisplay::OBSQTDisplay(QWidget *parent, Qt::WindowFlags flags)
 	: QWidget(parent, flags)
@@ -53,13 +60,25 @@ OBSQTDisplay::OBSQTDisplay(QWidget *parent, Qt::WindowFlags flags)
 
 	connect(windowHandle(), &QWindow::visibleChanged, windowVisible);
 	connect(windowHandle(), &QWindow::screenChanged, sizeChanged);
+}
 
-	this->setProperty("themeID", "displayBackgroundColor");
+QColor OBSQTDisplay::GetDisplayBackgroundColor() const
+{
+	return rgba_to_color(backgroundColor);
 }
 
 void OBSQTDisplay::SetDisplayBackgroundColor(const QColor &color)
 {
-	backgroundColor = (uint32_t)color_to_int(color);
+	uint32_t newBackgroundColor = (uint32_t)color_to_int(color);
+
+	if (newBackgroundColor != backgroundColor) {
+		backgroundColor = newBackgroundColor;
+		UpdateDisplayBackgroundColor();
+	}
+}
+
+void OBSQTDisplay::UpdateDisplayBackgroundColor()
+{
 	obs_display_set_background_color(display, backgroundColor);
 }
 

UI/qt-display.hpp

@@ -8,6 +8,7 @@
 class OBSQTDisplay : public QWidget {
 	Q_OBJECT
 	Q_PROPERTY(QColor displayBackgroundColor MEMBER backgroundColor
+			READ GetDisplayBackgroundColor
 			WRITE SetDisplayBackgroundColor)
 
 	OBSDisplay display;
@@ -31,6 +32,7 @@ public:
 
 	uint32_t backgroundColor = GREY_COLOR_BACKGROUND;
 
-private slots:
+	QColor GetDisplayBackgroundColor() const;
 	void SetDisplayBackgroundColor(const QColor &color);
+	void UpdateDisplayBackgroundColor();
 };