core/icon: ability to specify a fallback or check if an icon exists

src/core/iconimageprovider.cpp

@@ -11,7 +11,9 @@
 QPixmap
 IconImageProvider::requestPixmap(const QString& id, QSize* size, const QSize& requestedSize) {
 	QString iconName;
+	QString fallbackName;
 	QString path;
+
 	auto splitIdx = id.indexOf("?path=");
 	if (splitIdx != -1) {
 		iconName = id.sliced(0, splitIdx);
@@ -19,10 +21,17 @@ IconImageProvider::requestPixmap(const QString& id, QSize* size, const QSize& re
 		qWarning() << "Searching custom icon paths is not yet supported. Icon path will be ignored for"
 		           << id;
 	} else {
-		iconName = id;
+		splitIdx = id.indexOf("?fallback=");
+		if (splitIdx != -1) {
+			iconName = id.sliced(0, splitIdx);
+			fallbackName = id.sliced(splitIdx + 10);
+		} else {
+			iconName = id;
+		}
 	}
 
 	auto icon = QIcon::fromTheme(iconName);
+	if (icon.isNull()) icon = QIcon::fromTheme(fallbackName);
 
 	auto targetSize = requestedSize.isValid() ? requestedSize : QSize(100, 100);
 	if (targetSize.width() == 0 || targetSize.height() == 0) targetSize = QSize(2, 2);
@@ -55,12 +64,20 @@ QPixmap IconImageProvider::missingPixmap(const QSize& size) {
 	return pixmap;
 }
 
-QString IconImageProvider::requestString(const QString& icon, const QString& path) {
+QString IconImageProvider::requestString(
+    const QString& icon,
+    const QString& path,
+    const QString& fallback
+) {
 	auto req = "image://icon/" + icon;
 
 	if (!path.isEmpty()) {
 		req += "?path=" + path;
 	}
 
+	if (!fallback.isEmpty()) {
+		req += "?fallback=" + fallback;
+	}
+
 	return req;
 }

src/core/iconimageprovider.hpp

@@ -10,5 +10,10 @@ public:
 	QPixmap requestPixmap(const QString& id, QSize* size, const QSize& requestedSize) override;
 
 	static QPixmap missingPixmap(const QSize& size);
-	static QString requestString(const QString& icon, const QString& path);
+
+	static QString requestString(
+	    const QString& icon,
+	    const QString& path = QString(),
+	    const QString& fallback = QString()
+	);
 };

src/core/qmlglobal.cpp

@@ -5,6 +5,7 @@
 #include <qcoreapplication.h>
 #include <qdir.h>
 #include <qguiapplication.h>
+#include <qicon.h>
 #include <qjsengine.h>
 #include <qlogging.h>
 #include <qobject.h>
@@ -196,7 +197,16 @@ QVariant QuickshellGlobal::env(const QString& variable) { // NOLINT
 }
 
 QString QuickshellGlobal::iconPath(const QString& icon) {
-	return IconImageProvider::requestString(icon, "");
+	return IconImageProvider::requestString(icon);
+}
+
+QString QuickshellGlobal::iconPath(const QString& icon, bool check) {
+	if (check && QIcon::fromTheme(icon).isNull()) return "";
+	return IconImageProvider::requestString(icon);
+}
+
+QString QuickshellGlobal::iconPath(const QString& icon, const QString& fallback) {
+	return IconImageProvider::requestString(icon, "", fallback);
 }
 
 QuickshellGlobal* QuickshellGlobal::create(QQmlEngine* engine, QJSEngine* /*unused*/) {

src/core/qmlglobal.hpp

@@ -137,6 +137,12 @@ public:
 	/// > at the top of your root config file or set the `QS_ICON_THEME` variable to the name
 	/// > of your icon theme.
 	Q_INVOKABLE static QString iconPath(const QString& icon);
+	/// Setting the `check` parameter of `iconPath` to true will return an empty string
+	/// if the icon does not exist, instead of an image showing a missing texture.
+	Q_INVOKABLE static QString iconPath(const QString& icon, bool check);
+	/// Setting the `fallback` parameter of `iconPath` will attempt to load the fallback
+	/// icon if the requested one could not be loaded.
+	Q_INVOKABLE static QString iconPath(const QString& icon, const QString& fallback);
 
 	[[nodiscard]] QString shellRoot() const;