Prevent folders from drag and dropping onto themselves in dolphin main view

Summary:
This patch aims to improve user experience by not allowing the user to drag and drop a folder into itself.

The current behavior shows a red message at the top which can then be closed by the user, instead of relying on that, this patch disables the option of dropping onto self and uses the "Invalid drop target cursor" to highlight the behavior.

BUG: 307747

Since spectacle is unable to screenshot the cursor overlay, find attached a photo of the screen.
{F3787651}

Test Plan:
1. Drag a folder.
2. Drop it onto itself.

Reviewers: #dolphin, elvisangelaccio, ngraham, rkflx, dfaure

Reviewed By: #dolphin, elvisangelaccio, rkflx, dfaure

Subscribers: rkflx, ngraham, elvisangelaccio, dfaure, anthonyfieroni, #konqueror

Tags: #dolphin

Differential Revision: https://phabricator.kde.org/D6281

1 files changed, 9 insertions, 2 deletions

diff --git a/src/views/draganddrophelper.h b/src/views/draganddrophelper.h
index 3153f06ef..e47f83ca8 100644
--- a/src/views/draganddrophelper.h
+++ b/src/views/draganddrophelper.h
@@ -22,9 +22,10 @@
 #define DRAGANDDROPHELPER_H
 
 #include "dolphin_export.h"
+#include <QList>
+#include <QUrl>
 
 
-class QUrl;
 class QDropEvent;
 class QWidget;
 namespace KIO { class DropJob; }
@@ -42,11 +43,17 @@ public:
      *                  is true.
      * @param event     Drop event.
      * @param window    Widget where the drop happened, will be used as parent of the drop menu.
-     * @return          KIO::DropJob pointer
+     * @return          KIO::DropJob pointer or null in case the destUrl is contained
+     *                  in the mimeData url list.
      */
     static KIO::DropJob* dropUrls(const QUrl& destUrl,
                                   QDropEvent* event,
                                   QWidget *window);
+
+    /**
+     * @return True if destUrl is contained in the urls parameter.
+     */
+    static bool urlListMatchesUrl(const QList<QUrl>& urls, const QUrl& destUrl);
 };
 
 #endif