core: improve named icon detection

src/core/iconimageprovider.cpp

@@ -2,19 +2,136 @@
 #include <algorithm>
 
 #include <qcolor.h>
+#include <qcontainerfwd.h>
+#include <qdir.h>
+#include <qfile.h>
 #include <qicon.h>
 #include <qlogging.h>
 #include <qpainter.h>
 #include <qpixmap.h>
+#include <qsettings.h>
 #include <qsize.h>
 #include <qstring.h>
 
+namespace {
+// Get the system's color scheme preference
+bool getSystemDarkPreference() {
+	// Check KDE
+	const QSettings kdeSettings(QDir::homePath() + "/.config/kdeglobals", QSettings::IniFormat);
+	if (kdeSettings.value("General/ColorScheme").toString().toLower().contains("dark")) {
+		return true;
+	}
+
+	// Check GTK
+	const QSettings gtk4Settings(
+	    QDir::homePath() + "/.config/gtk-4.0/settings.ini",
+	    QSettings::IniFormat
+	);
+
+	return gtk4Settings.value("Settings/gtk-application-prefer-dark-theme", false).toBool();
+}
+
+QStringList listThemes() {
+	QStringList themes;
+	for (const auto& basePath: QIcon::themeSearchPaths()) {
+		const QDir dir(basePath);
+		if (!dir.exists()) continue;
+		themes.append(dir.entryList(QDir::Dirs | QDir::NoDotAndDotDot));
+	}
+
+	themes.removeDuplicates();
+	themes.sort();
+
+	return themes;
+}
+
+QStringList getThemes() {
+	QStringList themes;
+
+	const QStringList available = listThemes();
+	const bool preferDark = getSystemDarkPreference();
+
+	// If dark mode is preferred, prioritize dark themes
+	if (preferDark) {
+		for (const auto& theme: available) {
+			const QString lower = theme.toLower();
+			if (lower.contains("dark") || lower.contains("-night") || lower.contains("_dark")) {
+				themes.append(theme);
+			}
+		}
+	} else {
+		for (const auto& theme: available) {
+			const QString lower = theme.toLower();
+			if (lower.contains("light") || lower.contains("-day") || lower.contains("_light")) {
+				themes.append(theme);
+			}
+		}
+	}
+
+	for (const auto& theme: available) {
+		if (!themes.contains(theme)) {
+			themes.append(theme);
+		}
+	}
+
+	return themes;
+}
+
+QIcon findIconAcrossThemes(const QString& iconName) {
+	const QStringList themes = getThemes();
+	const QStringList categories = {"status", "apps", "actions", "places", "devices"};
+	const QStringList sizes = {"scalable", "symbolic", "16", "22", "24", "32", "48", "64", "128"};
+	const QStringList extensions = {".png", ".svg"};
+
+	for (const auto& base: QIcon::themeSearchPaths()) {
+		for (const auto& theme: themes) {
+			for (const auto& category: categories) {
+				for (const auto& size: sizes) {
+					for (const auto& ext: extensions) {
+						const QString path =
+						    QString("%1/%2/%3/%4/%5%6").arg(base, theme, category, size, iconName, ext);
+
+						if (QFile::exists(path)) {
+							return QIcon(path);
+						}
+					}
+				}
+			}
+		}
+	}
+
+	return QIcon();
+}
+
+} // namespace
+
 QPixmap
 IconImageProvider::requestPixmap(const QString& id, QSize* size, const QSize& requestedSize) {
 	QString iconName;
 	QString fallbackName;
 	QString path;
 
+	static bool pathsFixed = false;
+	static bool themeSet = false;
+
+	if (!pathsFixed) {
+		auto paths = QIcon::themeSearchPaths();
+		paths.append("/usr/local/share/icons"); // unix
+		paths.append("/usr/share/icons");       // tux
+
+		QIcon::setThemeSearchPaths(paths);
+		pathsFixed = true;
+	}
+
+	if (!themeSet) {
+		const QString selectedTheme = getThemes().first();
+		if (!selectedTheme.isEmpty()) {
+			QIcon::setThemeName(selectedTheme);
+		}
+
+		themeSet = true;
+	}
+
 	auto splitIdx = id.indexOf("?path=");
 	if (splitIdx != -1) {
 		iconName = id.sliced(0, splitIdx);
@@ -31,8 +148,37 @@ IconImageProvider::requestPixmap(const QString& id, QSize* size, const QSize& re
 	}
 
 	auto icon = QIcon::fromTheme(iconName);
+
 	if (icon.isNull() && !fallbackName.isEmpty()) icon = QIcon::fromTheme(fallbackName);
+	if (icon.isNull()) {
+		const QStringList loosePaths = {
+		    // homedir
+		    QString("%1/.local/share/icons/%2.png").arg(QDir::homePath(), iconName),
+		    QString("%1/.local/share/icons/%2.svg").arg(QDir::homePath(), iconName),
+		    // unix
+		    QString("/usr/local/share/icons/%1.png").arg(iconName),
+		    QString("/usr/local/share/icons/%1.svg").arg(iconName),
+		    QString("/usr/local/share/pixmaps/%1.png").arg(iconName),
+		    QString("/usr/local/share/pixmaps/%1.svg").arg(iconName),
+		    // tux
+		    QString("/usr/share/icons/%1.png").arg(iconName),
+		    QString("/usr/share/icons/%1.svg").arg(iconName),
+		    QString("/usr/share/pixmaps/%1.png").arg(iconName),
+		    QString("/usr/share/pixmaps/%1.svg").arg(iconName),
+		};
+
+		for (const auto& loosePath: loosePaths) {
+			if (QFile::exists(loosePath)) {
+				icon = QIcon(loosePath);
+				break;
+			}
+		}
+	}
+
 	if (icon.isNull() && !path.isEmpty()) icon = QPixmap(path);
+	if (icon.isNull()) {
+		icon = findIconAcrossThemes(iconName);
+	}
 
 	auto targetSize = requestedSize.isValid() ? requestedSize : QSize(100, 100);
 	if (targetSize.width() == 0 || targetSize.height() == 0) targetSize = QSize(2, 2);