QIOSFileEngineAssetsLibrary: bail out early on non-existing dirs

QFileSelector::selectionHelper walks through the list of selectors
(on iOS, on my phone it's ("ios", "iOS", "en_NO", "unix", "darwin")),
creating paths and testing QDir::exists. This ends up in asset
file engine trying to load asset for something like:
"assets-library://assets/+iOS" etc. ALAssetsLibrary -assetForUrl:
returns nil for such url and we start iterating through the assets
library. On my phone (e.g.) this takes about ~6 seconds (to iterate
through pictures/videos I have), so the image picker is dismissed
~30 seconds after an image was actually selected in a picker view,
making an impression it's completely broken. Bail out early
on such url, we know we'll fail (with AssetsLibrary giving a warning
about invalid asset with UUID(null).

Pick-to: 6.5
Fixes: QTBUG-109120
Change-Id: Ia302f4151e3aade830e647a8a260479df2b29d4b
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm b/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm
index 0ca911f68b..312899f3d9 100644
--- a/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm
+++ b/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm
@@ -11,6 +11,7 @@
 #include <QtCore/qurl.h>
 #include <QtCore/qset.h>
 #include <QtCore/qthreadstorage.h>
+#include <QtCore/qfileselector.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -344,6 +345,17 @@ QAbstractFileEngine::FileFlags QIOSFileEngineAssetsLibrary::fileFlags(QAbstractF
 {
     QAbstractFileEngine::FileFlags flags;
     const bool isDir = (m_assetUrl == "assets-library://"_L1);
+    if (!isDir) {
+        static const QFileSelector fileSelector;
+        static const auto selectors = fileSelector.allSelectors();
+        if (m_assetUrl.startsWith("assets-library://"_L1)) {
+            for (const auto &selector : selectors) {
+                if (m_assetUrl.endsWith(selector))
+                    return flags;
+            }
+        }
+    }
+
     const bool exists = isDir || m_assetUrl == g_iteratorCurrentUrl.localData() || loadAsset();
 
     if (!exists)