Add a "prefer" directive to qmldir

The argument is the path from which further files from the module should
be loaded. This allows us to load potentially pre-compiled files
from a resource contained in a plugin. The qmldir file has to be stored
outside the plugin in order for the QML engine to find it, but the QML
files can now be stored inside the plugin.

[ChangeLog][QtQml] You can now specify that QML files in a QML module
should be loaded from a different place than the directory where the
qmldir file is found. To do this, add a "prefer" directive to the qmldir
file. The most useful application of this is adding the QML files as
resources to a plugin, and using qmlcachegen to pre-compile them. You
can then add their path inside the resource file system as "prefer"
path in order to make the engine load the pre-compiled files. The plain
files should still be installed next to the qmldir file so that they
remain visible to tooling.

Change-Id: Ib281b39230621b3762432095a47fb499412cbaa6
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 12 insertions, 2 deletions

diff --git a/src/qml/qml/qqmlimport.cpp b/src/qml/qml/qqmlimport.cpp
index 535b6713ba..0016d4bcc4 100644
--- a/src/qml/qml/qqmlimport.cpp
+++ b/src/qml/qml/qqmlimport.cpp
@@ -654,8 +654,18 @@ bool QQmlImportInstance::setQmldirContent(const QString &resolvedUrl,
                                           const QQmlTypeLoaderQmldirContent &qmldir,
                                           QQmlImportNamespace *nameSpace, QList<QQmlError> *errors)
 {
-    Q_ASSERT(resolvedUrl.endsWith(Slash));
-    url = resolvedUrl;
+
+    const QString preferredPath = qmldir.preferredPath();
+    if (preferredPath.isEmpty()) {
+        Q_ASSERT(resolvedUrl.endsWith(Slash));
+        url = resolvedUrl;
+    } else {
+        Q_ASSERT(preferredPath.endsWith(Slash));
+        if (preferredPath.startsWith(u':'))
+            url = QStringLiteral("qrc") + preferredPath;
+        else
+            url = QUrl::fromLocalFile(preferredPath).toString();
+    }
 
     qmlDirComponents = qmldir.components();