UI/Qt: Set dark theme as reported by Qt

Previously, we did a bit of guessing. That approach was hacky and less reliable.
LadybirdBrowser · Nov 23, 2024 · f29b91b · f29b91b
1 parent e565e3c
commit f29b91b
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Showing 3 changed files with 11 additions and 25 deletions.
diff --git a/UI/Qt/InspectorWidget.cpp b/UI/Qt/InspectorWidget.cpp
@@ -14,20 +14,26 @@
 #include <QCloseEvent>
 #include <QGuiApplication>
 #include <QMenu>
+#include <QStyleHints>
 #include <QVBoxLayout>
 #include <QWindow>
 
 namespace Ladybird {
 
-extern bool is_using_dark_system_theme(QWidget&);
-
 InspectorWidget::InspectorWidget(QWidget* tab, WebContentView& content_view)
     : QWidget(tab, Qt::Window)
 {
     m_inspector_view = new WebContentView(this);
 
-    if (is_using_dark_system_theme(*this))
+    auto color_scheme = QGuiApplication::styleHints()->colorScheme();
+    switch (color_scheme) {
+    case Qt::ColorScheme::Dark:
         m_inspector_view->update_palette(WebContentView::PaletteMode::Dark);
+        break;
+    case Qt::ColorScheme::Light:
+    case Qt::ColorScheme::Unknown:
+        m_inspector_view->update_palette(WebContentView::PaletteMode::Default);
+    }
 
     m_inspector_client = make<WebView::InspectorClient>(content_view, *m_inspector_view);
 

diff --git a/UI/Qt/WebContentView.cpp b/UI/Qt/WebContentView.cpp
@@ -38,14 +38,13 @@
 #include <QPainter>
 #include <QPalette>
 #include <QScrollBar>
+#include <QStyleHints>
 #include <QTextEdit>
 #include <QTimer>
 #include <QToolTip>
 
 namespace Ladybird {
 
-bool is_using_dark_system_theme(QWidget&);
-
 WebContentView::WebContentView(QWidget* window, RefPtr<WebView::WebContentClient> parent_client, size_t page_index)
     : QWidget(window)
 {
@@ -584,7 +583,7 @@ static Core::AnonymousBuffer make_system_theme_from_qt_palette(QWidget& widget,
     translate(Gfx::ColorRole::Selection, QPalette::ColorRole::Highlight);
     translate(Gfx::ColorRole::SelectionText, QPalette::ColorRole::HighlightedText);
 
-    palette.set_flag(Gfx::FlagRole::IsDark, is_using_dark_system_theme(widget));
+    palette.set_flag(Gfx::FlagRole::IsDark, QGuiApplication::styleHints()->colorScheme() == Qt::ColorScheme::Dark);
 
     return theme;
 }

diff --git a/UI/Qt/main.cpp b/UI/Qt/main.cpp
@@ -26,25 +26,6 @@
 #    include <LibWebView/MachPortServer.h>
 #endif
 
-namespace Ladybird {
-
-// FIXME: Find a place to put this declaration (and other helper functions).
-bool is_using_dark_system_theme(QWidget&);
-bool is_using_dark_system_theme(QWidget& widget)
-{
-    // FIXME: Qt does not provide any method to query if the system is using a dark theme. We will have to implement
-    //        platform-specific methods if we wish to have better detection. For now, this inspects if Qt is using a
-    //        dark color for widget backgrounds using Rec. 709 luma coefficients.
-    //        https://en.wikipedia.org/wiki/Rec._709#Luma_coefficients
-
-    auto color = widget.palette().color(widget.backgroundRole());
-    auto luma = 0.2126f * color.redF() + 0.7152f * color.greenF() + 0.0722f * color.blueF();
-
-    return luma <= 0.5f;
-}
-
-}
-
 static ErrorOr<void> handle_attached_debugger()
 {
 #ifdef AK_OS_LINUX