Improve DnD handling in read-only dirs

1. Places panel and tabbar update drag status in read-only dir
2. Don't create drop job in readonly directories

2 files changed, 62 insertions, 4 deletions

diff --git a/src/views/draganddrophelper.cpp b/src/views/draganddrophelper.cpp
index 2953233d0..efdec5b92 100644
--- a/src/views/draganddrophelper.cpp
+++ b/src/views/draganddrophelper.cpp
@@ -52,15 +52,43 @@ KIO::DropJob *DragAndDropHelper::dropUrls(const QUrl &destUrl, QDropEvent *event
             return nullptr;
         }
 
-        // Drop into a directory or a desktop-file
-        KIO::DropJob *job = KIO::drop(event, destUrl);
-        KJobWidgets::setWindow(job, window);
-        return job;
+        if (supportsDropping(destUrl)) {
+            // Drop into a directory or a desktop-file
+            KIO::DropJob *job = KIO::drop(event, destUrl);
+            KJobWidgets::setWindow(job, window);
+            return job;
+        }
     }
 
     return nullptr;
 }
 
+bool DragAndDropHelper::supportsDropping(const QUrl &destUrl)
+{
+    KFileItem item(destUrl);
+    return supportsDropping(item);
+}
+
+bool DragAndDropHelper::supportsDropping(const KFileItem &destItem)
+{
+    return (destItem.isDir() && destItem.isWritable()) || destItem.isDesktopFile();
+}
+
+void DragAndDropHelper::updateDropAction(QDropEvent *event, const QUrl &destUrl)
+{
+    if (urlListMatchesUrl(event->mimeData()->urls(), destUrl)) {
+        event->setDropAction(Qt::IgnoreAction);
+        event->ignore();
+    }
+    if (supportsDropping(destUrl)) {
+        event->setDropAction(event->proposedAction());
+        event->accept();
+    } else {
+        event->setDropAction(Qt::IgnoreAction);
+        event->ignore();
+    }
+}
+
 void DragAndDropHelper::clearUrlListMatchesUrlCache()
 {
     DragAndDropHelper::m_urlListMatchesUrlCache.clear();
diff --git a/src/views/draganddrophelper.h b/src/views/draganddrophelper.h
index 656cefe1b..0eee34a3d 100644
--- a/src/views/draganddrophelper.h
+++ b/src/views/draganddrophelper.h
@@ -10,6 +10,8 @@
 
 #include "dolphin_export.h"
 
+#include <KFileItem>
+
 #include <QList>
 #include <QString>
 #include <QUrl>
@@ -41,6 +43,34 @@ public:
     static KIO::DropJob *dropUrls(const QUrl &destUrl, QDropEvent *event, QWidget *window);
 
     /**
+     * Checks if the destination supports dropping.
+     *
+     * @param destUrl   URL of the item destination.
+     * @return          True if the destination is a directory and is writable, or it's a desktop file.
+     *                  False otherwise.
+     */
+    static bool supportsDropping(const QUrl &destUrl);
+
+    /**
+     * Checks if the destination supports dropping.
+     *
+     * @param destItem  The item destination.
+     * @return          True if the destination is a directory and is writable, or it's a desktop file.
+     *                  False otherwise.
+     */
+    static bool supportsDropping(const KFileItem &destItem);
+
+    /**
+     * Updates the drop action according to whether the destination supports dropping.
+     * If supportsDropping(destUrl), set dropAction = proposedAction. Otherwise, set
+     * dropAction = Qt::IgnoreAction.
+     *
+     * @param event     Drop event.
+     * @param destUrl   Destination URL.
+     */
+    static void updateDropAction(QDropEvent *event, const QUrl &destUrl);
+
+    /**
      * @return True if destUrl is contained in the urls parameter.
      */
     static bool urlListMatchesUrl(const QList<QUrl> &urls, const QUrl &destUrl);