Create and init QQuickTheme from QtQuickControls2Plugin

Instead of creating and setting the QQuickTheme instance from each
style plugin (e.g. QtQuickControls2MaterialStylePlugin), create the
QQuickTheme instance in QtQuickControls2Plugin when the style is
being resolved, and just pass the instance to be initialized by the
style plugin(s). This avoids the problem that QQuickTheme API was
virtual, and sub-classes created from plugins would have vtables
destroyed before the QQuickTheme was destroyed.

Task-number: QTBUG-67062
Task-number: QTBUG-68087
Change-Id: I19e9ced5296b708c2668c30163389cb3da6be7cf
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 75 insertions, 42 deletions

diff --git a/src/imports/controls/qtquickcontrols2plugin.cpp b/src/imports/controls/qtquickcontrols2plugin.cpp
index e1b683e8..553060a1 100644
--- a/src/imports/controls/qtquickcontrols2plugin.cpp
+++ b/src/imports/controls/qtquickcontrols2plugin.cpp
@@ -37,10 +37,9 @@
 #include <QtCore/qdir.h>
 #include <QtCore/qfile.h>
 #include <QtCore/qfileinfo.h>
-#if !defined(QT_STATIC) && QT_CONFIG(library)
-#include <QtCore/qlibrary.h>
-#endif
+#include <QtCore/qpluginloader.h>
 #include <QtCore/private/qfileselector_p.h>
+#include <QtQml/qqmlfile.h>
 #include <QtQml/private/qqmldirparser_p.h>
 #include <QtQuickControls2/qquickstyle.h>
 #include <QtQuickControls2/private/qquickchecklabel_p.h>
@@ -59,6 +58,7 @@
 #include <QtQuickTemplates2/private/qquickoverlay_p.h>
 #include <QtQuickControls2/private/qquickclippedtext_p.h>
 #include <QtQuickControls2/private/qquickitemgroup_p.h>
+#include <QtQuickTemplates2/private/qquicktheme_p_p.h>
 
 #include "qquickdefaultbusyindicator_p.h"
 #include "qquickdefaultdial_p.h"
@@ -80,12 +80,11 @@ public:
     void registerTypes(const char *uri) override;
 
     QString name() const override;
-    QQuickTheme *createTheme() const override;
+    void initializeTheme(QQuickTheme *theme) override;
 
-#if !defined(QT_STATIC) && QT_CONFIG(library)
 private:
-    void loadStylePlugin();
-#endif
+    QList<QQuickStylePlugin *> loadStylePlugins();
+    QQuickTheme *createTheme(const QString &name);
 };
 
 QtQuickControls2Plugin::QtQuickControls2Plugin(QObject *parent) : QQuickStylePlugin(parent)
@@ -106,6 +105,11 @@ static QUrl fixupBaseUrl(QQmlExtensionPlugin *plugin)
 #endif
 }
 
+static bool isDefaultStyle(const QString &style)
+{
+    return style.isEmpty() || style.compare(QStringLiteral("Default"), Qt::CaseInsensitive) == 0;
+}
+
 void QtQuickControls2Plugin::registerTypes(const char *uri)
 {
     QQuickStylePrivate::init(fixupBaseUrl(this));
@@ -114,10 +118,15 @@ void QtQuickControls2Plugin::registerTypes(const char *uri)
     if (!style.isEmpty())
         QFileSelectorPrivate::addStatics(QStringList() << style.toLower());
 
-#if !defined(QT_STATIC) && QT_CONFIG(library)
-    // load the style's plugin to get access to its resources
-    loadStylePlugin();
-#endif
+    QQuickTheme *theme = createTheme(style.isEmpty() ? name() : style);
+    if (isDefaultStyle(style))
+        initializeTheme(theme);
+
+    // load the style's plugins to get access to its resources and initialize the theme
+    QList<QQuickStylePlugin *> stylePlugins = loadStylePlugins();
+    for (QQuickStylePlugin *stylePlugin : stylePlugins)
+        stylePlugin->initializeTheme(theme);
+    qDeleteAll(stylePlugins);
 
     qmlRegisterModule(uri, 2, QT_VERSION_MINOR - 7); // Qt 5.7->2.0, 5.8->2.1, 5.9->2.2...
 
@@ -229,45 +238,69 @@ QString QtQuickControls2Plugin::name() const
     return QStringLiteral("Default");
 }
 
-QQuickTheme *QtQuickControls2Plugin::createTheme() const
+void QtQuickControls2Plugin::initializeTheme(QQuickTheme *theme)
 {
-    return new QQuickDefaultTheme;
+    QQuickDefaultTheme::initialize(theme);
 }
 
-#if !defined(QT_STATIC) && QT_CONFIG(library)
-void QtQuickControls2Plugin::loadStylePlugin()
+QList<QQuickStylePlugin *> QtQuickControls2Plugin::loadStylePlugins()
 {
-    QFileInfo fileInfo = resolvedUrl(QStringLiteral("qmldir")).toLocalFile();
-    if (!fileInfo.exists() || fileInfo.path() == baseUrl().toLocalFile())
-        return;
-
-    QFile file(fileInfo.filePath());
-    if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
-        return;
-
-    QQmlDirParser parser;
-    parser.parse(QString::fromUtf8(file.readAll()));
-    if (parser.hasError())
-        return;
-
-    QLibrary lib;
-    lib.setLoadHints(QLibrary::PreventUnloadHint);
-    const auto plugins = parser.plugins();
-    for (const QQmlDirParser::Plugin &plugin : plugins) {
-        QDir dir = fileInfo.dir();
-        if (!plugin.path.isEmpty() && !dir.cd(plugin.path))
-            continue;
-        QString filePath = dir.filePath(plugin.name);
+    QList<QQuickStylePlugin *> stylePlugins;
+
+    QFileInfo fileInfo = QQmlFile::urlToLocalFileOrQrc(resolvedUrl(QStringLiteral("qmldir")));
+    if (fileInfo.exists() && fileInfo.path() != QQmlFile::urlToLocalFileOrQrc(baseUrl())) {
+        QFile file(fileInfo.filePath());
+        if (file.open(QIODevice::ReadOnly | QIODevice::Text)) {
+            QQmlDirParser parser;
+            parser.parse(QString::fromUtf8(file.readAll()));
+            if (!parser.hasError()) {
+#ifdef QT_STATIC
+                const auto plugins = QPluginLoader::staticInstances();
+                for (QObject *instance : plugins) {
+                    QQuickStylePlugin *stylePlugin = qobject_cast<QQuickStylePlugin *>(instance);
+                    if (!stylePlugin || parser.className() != QLatin1String(instance->metaObject()->className()))
+                        continue;
+                    stylePlugins += stylePlugin;
+                }
+#elif QT_CONFIG(library)
+                QPluginLoader loader;
+                const auto plugins = parser.plugins();
+                for (const QQmlDirParser::Plugin &plugin : plugins) {
+                    QDir dir = fileInfo.dir();
+                    if (!plugin.path.isEmpty() && !dir.cd(plugin.path))
+                        continue;
+                    QString filePath = dir.filePath(plugin.name);
 #if defined(Q_OS_MACOS) && defined(QT_DEBUG)
-        // Avoid mismatching plugins on macOS so that we don't end up loading both debug and
-        // release versions of the same Qt libraries (due to the plugin's dependencies).
-        filePath += QStringLiteral("_debug");
+                    // Avoid mismatching plugins on macOS so that we don't end up loading both debug and
+                    // release versions of the same Qt libraries (due to the plugin's dependencies).
+                    filePath += QStringLiteral("_debug");
 #endif // Q_OS_MACOS && QT_DEBUG
-        lib.setFileName(filePath);
-        lib.load();
+                    loader.setFileName(filePath);
+                    QQuickStylePlugin *stylePlugin = qobject_cast<QQuickStylePlugin *>(loader.instance());
+                    if (stylePlugin)
+                        stylePlugins += stylePlugin;
+                }
+#endif
+            }
+        }
     }
+    return stylePlugins;
+}
+
+QQuickTheme *QtQuickControls2Plugin::createTheme(const QString &name)
+{
+    QQuickTheme *theme = new QQuickTheme;
+#if QT_CONFIG(settings)
+    QQuickThemePrivate *p = QQuickThemePrivate::get(theme);
+    QSharedPointer<QSettings> settings = QQuickStylePrivate::settings(name);
+    if (settings) {
+        p->defaultFont.reset(QQuickStylePrivate::readFont(settings));
+        p->defaultPalette.reset(QQuickStylePrivate::readPalette(settings));
+    }
+#endif
+    QQuickThemePrivate::instance.reset(theme);
+    return theme;
 }
-#endif // !QT_STATIC && QT_CONFIG(library)
 
 QT_END_NAMESPACE