Implement drag&drop support for flatpaks

BUG: 495552

src/app/qml/RoomPage.qml

@@ -253,7 +253,6 @@ Kirigami.Page {
             id: timelineView
             messageFilterModel: root.messageFilterModel
             compactLayout: NeoChatConfig.compactLayout
-            fileDropEnabled: !Controller.isFlatpak
             markReadCondition: NeoChatConfig.markReadCondition
         }
     }

src/libneochat/chatbarcache.cpp

@@ -3,6 +3,10 @@
 
 #include "chatbarcache.h"
 
+#include <QMimeData>
+
+#include <KUrlMimeData>
+
 #include <Quotient/roommember.h>
 
 #include "eventhandler.h"
@@ -295,4 +299,17 @@ void ChatBarCache::clearCache()
     clearRelations();
 }
 
+void ChatBarCache::drop(QList<QUrl> u, const QString &transferPortal)
+{
+    QMimeData mimeData;
+    mimeData.setUrls(u);
+    if (!transferPortal.isEmpty()) {
+        mimeData.setData(u"application/vnd.portal.filetransfer"_s, transferPortal.toLatin1());
+    }
+    auto urls = KUrlMimeData::urlsFromMimeData(&mimeData);
+    if (urls.size() > 0) {
+        setAttachmentPath(urls[0].toString());
+    }
+}
+
 #include "moc_chatbarcache.cpp"

src/libneochat/chatbarcache.h

@@ -198,6 +198,8 @@ public:
      */
     Q_INVOKABLE void postMessage();
 
+    Q_INVOKABLE void drop(QList<QUrl> urls, const QString &transferPortal);
+
 Q_SIGNALS:
     void textChanged();
     void relationIdChanged(const QString &oldEventId, const QString &newEventId);

src/timeline/TimelineView.qml

@@ -31,11 +31,6 @@ QQC2.ScrollView {
      */
     required property bool compactLayout
 
-    /**
-     * @brief Whether the compact message layout is to be used.
-     */
-    property bool fileDropEnabled: true
-
     /**
      * @brief The TimelineMarkReadCondition to use for when messages should be marked as read automatically.
      */
@@ -268,8 +263,7 @@ QQC2.ScrollView {
         DropArea {
             id: dropAreaFile
             anchors.fill: parent
-            onDropped: drop => { _private.room.mainCache.attachmentPath = drop.urls[0] }
-            enabled: root.fileDropEnabled
+            onDropped: drop => _private.room.mainCache.drop(drop.urls, drop.getDataAsString("application/vnd.portal.filetransfer"))
         }
 
         QQC2.Pane {