audqt: Dark theme adjustments

- Darken base color slightly from #383838 to #303030
- Fix very low contrast of toggle buttons (e.g. shuffle/repeat)
- Make widget QProxyStyles inherit from DarkStyle

src/libaudqt/audqt.cc

@@ -246,9 +246,9 @@ EXPORT QVBoxLayout * make_vbox(QWidget * parent, int spacing)
 
 EXPORT void setup_proxy_style(QProxyStyle * style)
 {
-    // set the correct base style ("fusion" or native)
+    // set the correct base style (dark or native)
     if (!strcmp(aud_get_str("audqt", "theme"), "dark"))
-        style->setBaseStyle(QStyleFactory::create("fusion"));
+        style->setBaseStyle(create_dark_style());
     else
         style->setBaseStyle(nullptr);
 

src/libaudqt/dark-theme.cc

@@ -28,6 +28,7 @@
 #include <QProxyStyle>
 #include <QStyle>
 #include <QStyleFactory>
+#include <QStyleOption>
 
 namespace audqt {
 
@@ -92,6 +93,10 @@ class DarkStyle : public QProxyStyle
     void polish(QWidget * widget) override { QProxyStyle::polish(widget); }
     void polish(QPalette & palette) override;
 
+    void drawPrimitive(PrimitiveElement elem, const QStyleOption * option,
+                       QPainter * painter,
+                       const QWidget * widget) const override;
+
     /* Qt 6.3+ no longer uses the theme icon "window-close" for tabs,
      * but instead forces a built-in icon. Override it back. */
 #if QT_VERSION >= QT_VERSION_CHECK(6, 3, 0)
@@ -111,6 +116,8 @@ void DarkStyle::polish(QPalette & palette)
     // normal colors
     // clang-format off
     palette.setColor(QPalette::WindowText,      QColor(0xf0, 0xf0, 0xf0));
+    // note that QFusionStyle brightens the Button color significantly:
+    // #2c2c2c actually results in a gradient from #3f3f3f to #363636
     palette.setColor(QPalette::Button,          QColor(0x2c, 0x2c, 0x2c));
     palette.setColor(QPalette::Light,           QColor(0x70, 0x70, 0x70));
     palette.setColor(QPalette::Midlight,        QColor(0x60, 0x60, 0x60));
@@ -120,7 +127,7 @@ void DarkStyle::polish(QPalette & palette)
     palette.setColor(QPalette::BrightText,      QColor(0xf0, 0xf0, 0xf0));
     palette.setColor(QPalette::ButtonText,      QColor(0xf0, 0xf0, 0xf0));
     palette.setColor(QPalette::Base,            QColor(0x20, 0x20, 0x20));
-    palette.setColor(QPalette::Window,          QColor(0x38, 0x38, 0x38));
+    palette.setColor(QPalette::Window,          QColor(0x30, 0x30, 0x30));
     palette.setColor(QPalette::Shadow,          QColor(0x00, 0x00, 0x00));
     palette.setColor(QPalette::Highlight,       QColor(0x15, 0x53, 0x9e)); // matches Adwaita-dark
     palette.setColor(QPalette::HighlightedText, QColor(0xff, 0xff, 0xff));
@@ -146,6 +153,32 @@ void DarkStyle::polish(QPalette & palette)
     // clang-format on
 }
 
+void DarkStyle::drawPrimitive(PrimitiveElement elem,
+                              const QStyleOption * option, QPainter * painter,
+                              const QWidget * widget) const
+{
+    if (elem == PE_PanelButtonCommand &&
+        ((option->state & (State_Sunken | State_On))))
+    {
+        // QFusionStyle draws pressed buttons with very low contrast,
+        // which makes it difficult to see if shuffle/repeat are active.
+        // As a workaround, darken them via palette adjustment.
+        QStyleOption option_copy = *option;
+        option_copy.palette.setColor(QPalette::Button,
+                                     QColor(0x1c, 0x1c, 0x1c));
+        QProxyStyle::drawPrimitive(elem, &option_copy, painter, widget);
+    }
+    else
+    {
+        QProxyStyle::drawPrimitive(elem, option, painter, widget);
+    }
+}
+
+QStyle *create_dark_style()
+{
+    return new DarkStyle();
+}
+
 void enable_dark_theme()
 {
     QApplication::setStyle(new DarkStyle());

src/libaudqt/libaudqt-internal.h

@@ -25,6 +25,7 @@
 class QPoint;
 class QScreen;
 class QString;
+class QStyle;
 
 namespace audqt
 {
@@ -33,6 +34,7 @@ namespace audqt
 void set_icon_theme();
 
 /* dark-theme.cc */
+QStyle *create_dark_style();
 void enable_dark_theme();
 void disable_dark_theme();