From c80564c1dfe202c3975ca0ff67e0b72b0352bf13 Mon Sep 17 00:00:00 2001 From: David Edmundson Date: Wed, 17 May 2023 09:06:03 +0300 Subject: [PATCH] Client: Always populate mimedata in drags It's possible for clients to perform a drag and drop operation within their own client without any mimeData. A user can directly access the original drag. On wayland without any mimedata it's impossible for a client to accept a drag as the mechansim involved is to either select a given mimedata entry or an empty string. Within Qt we always accept the first format if we accept a drag. When dragging within our own window we also start a wayland drag so will receive a cancel event from the compositor if the compositor doesn't believe the client has accepted the drag. This patch provides a dummy mimedata entry so that something can be accepted. Fixes: QTBUG-112161 Pick-to: 6.6 6.5 6.2 5.15 Change-Id: I6309d82e20545e10ebdb9dafde7e13a5e3be5ff2 Reviewed-by: Liang Qi (cherry picked from commit 32fedb6fa6579711b6cb192a2e3cfb7ad1264546) * asturmlechner 2023-10-24: Backported L1 literal as QString::fromLatin1 --- src/client/qwaylanddatadevice.cpp | 6 ++++++ 1 file changed, 6 insertions(+) --- a/src/client/qwaylanddatadevice.cpp +++ b/src/client/qwaylanddatadevice.cpp @@ -124,6 +124,12 @@ bool QWaylandDataDevice::startDrag(QMimeData *mimeData, Qt::DropActions supporte return false; } + // dragging data without mimetypes is a legal operation in Qt terms + // but Wayland uses a mimetype to determine if a drag is accepted or not + // In this rare case, insert a placeholder + if (mimeData->formats().isEmpty()) + mimeData->setData(QString::fromLatin1("application/x-qt-avoid-empty-placeholder"), QByteArray("1")); + m_dragSource.reset(new QWaylandDataSource(m_display->dndSelectionHandler(), mimeData)); if (wl_data_device_get_version(object()) >= 3)