QQuickStyle::availableStyles()

This allows us to introduce platform-specific styles, such as the iOS
style, and make them appear correctly in the Gallery example so that we
don't have to hard-code the lists separately for different platforms.

[ChangeLog][Controls][QQuickStyle] Added availableStyles() method that
returns the list of available built-in styles.

Change-Id: Ieea88577f402cbc52a844d6777e64c6bd55c5ab9
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 42 insertions, 5 deletions

diff --git a/src/quickcontrols2/qquickstyle.cpp b/src/quickcontrols2/qquickstyle.cpp
index f4fc1764..c8a3f19a 100644
--- a/src/quickcontrols2/qquickstyle.cpp
+++ b/src/quickcontrols2/qquickstyle.cpp
@@ -178,11 +178,9 @@ struct QQuickStyleSpec
 
         if (QGuiApplication::instance()) {
             if (!custom) {
-                const QString targetPath = QStringLiteral("QtQuick/Controls.2");
-                const QStringList importPaths = QQmlEngine().importPathList();
-
-                for (const QString &importPath : importPaths) {
-                    QString stylePath = findStyle(importPath + QLatin1Char('/') + targetPath, style);
+                const QStringList stylePaths = QQuickStylePrivate::stylePaths();
+                for (const QString &path : stylePaths) {
+                    QString stylePath = findStyle(path, style);
                     if (!stylePath.isEmpty()) {
                         style = stylePath;
                         resolved = true;
@@ -212,6 +210,20 @@ struct QQuickStyleSpec
 
 Q_GLOBAL_STATIC(QQuickStyleSpec, styleSpec)
 
+QStringList QQuickStylePrivate::stylePaths()
+{
+    const QString targetPath = QStringLiteral("QtQuick/Controls.2");
+    const QStringList importPaths = QQmlEngine().importPathList();
+
+    QStringList paths;
+    for (const QString &importPath : importPaths) {
+        QDir dir(importPath);
+        if (dir.cd(targetPath))
+            paths += dir.absolutePath();
+    }
+    return paths;
+}
+
 QString QQuickStylePrivate::fallbackStyle()
 {
     return styleSpec()->fallbackStyle;
@@ -307,4 +319,29 @@ void QQuickStyle::setFallbackStyle(const QString &style)
     styleSpec()->setFallbackStyle(style, "QQuickStyle::setFallbackStyle()");
 }
 
+/*!
+    \since 5.9
+    Returns the names of the available built-in styles.
+
+    \note The method must be called \b after creating an instance of QGuiApplication.
+*/
+QStringList QQuickStyle::availableStyles()
+{
+    QStringList styles;
+    if (!QGuiApplication::instance()) {
+        qWarning() << "ERROR: QQuickStyle::availableStyles() must be called after creating an instance of QGuiApplication.";
+        return styles;
+    }
+
+    const QStringList stylePaths = QQuickStylePrivate::stylePaths();
+    for (const QString &path : stylePaths) {
+        QDir dir(path);
+        styles += dir.entryList(QStringList(), QDir::Dirs | QDir::NoDotAndDotDot);
+        styles.removeAll(QStringLiteral("designer"));
+    }
+    styles.prepend(QStringLiteral("Default"));
+    styles.removeDuplicates();
+    return styles;
+}
+
 QT_END_NAMESPACE