[ToolTipManager] Create DolphinFileMetaDataWidget on-demand again

This reverts b7fbd19a7660424e6839df37f12b33111408b1fc but creates the
widget only once and then reuses it.

However, ownership of a parent-less widget is transferred to the
`KToolTipWidget` but since we first request metadata, then show the
tooltip (or won't if the mouse moved on since), we cannot rely on
the `KToolTipWidget` exclusively.

Instead, when we still delete the widget ourself until we have
shown the `KToolTipWidget` once at which point it will handle the
life time for us.

This fixes parenting the widget to `DolphinView` which would make
it appear as a broken line in the top left of the window.

2 files changed, 21 insertions, 9 deletions

diff --git a/src/views/tooltips/tooltipmanager.cpp b/src/views/tooltips/tooltipmanager.cpp
index e80d45e61..637261702 100644
--- a/src/views/tooltips/tooltipmanager.cpp
+++ b/src/views/tooltips/tooltipmanager.cpp
@@ -38,7 +38,6 @@ ToolTipManager::ToolTipManager(QWidget* parent) :
     m_showToolTipTimer(nullptr),
     m_contentRetrievalTimer(nullptr),
     m_transientParent(nullptr),
-    m_fileMetaDataWidget(nullptr),
     m_toolTipRequested(false),
     m_metaDataRequested(false),
     m_appliedWaitCursor(false),
@@ -61,17 +60,13 @@ ToolTipManager::ToolTipManager(QWidget* parent) :
     connect(m_contentRetrievalTimer, &QTimer::timeout, this, &ToolTipManager::startContentRetrieval);
 
     Q_ASSERT(m_contentRetrievalTimer->interval() < m_showToolTipTimer->interval());
-
-    // Only start the retrieving of the content, when the mouse has been over this
-    // item for 200 milliseconds. This prevents a lot of useless preview jobs and
-    // meta data retrieval, when passing rapidly over a lot of items.
-    m_fileMetaDataWidget = new DolphinFileMetaDataWidget(parent);
-    connect(m_fileMetaDataWidget, &DolphinFileMetaDataWidget::metaDataRequestFinished, this, &ToolTipManager::slotMetaDataRequestFinished);
-    connect(m_fileMetaDataWidget, &DolphinFileMetaDataWidget::urlActivated, this, &ToolTipManager::urlActivated);
 }
 
 ToolTipManager::~ToolTipManager()
 {
+    if (!m_fileMetaDatWidgetOwnershipTransferred) {
+        delete m_fileMetaDataWidget;
+    }
 }
 
 void ToolTipManager::showToolTip(const KFileItem& item, const QRectF& itemRect, QWindow *transientParent)
@@ -85,6 +80,15 @@ void ToolTipManager::showToolTip(const KFileItem& item, const QRectF& itemRect,
 
     m_transientParent = transientParent;
 
+    // Only start the retrieving of the content, when the mouse has been over this
+    // item for 200 milliseconds. This prevents a lot of useless preview jobs and
+    // meta data retrieval, when passing rapidly over a lot of items.
+    if (!m_fileMetaDataWidget) {
+        m_fileMetaDataWidget = new DolphinFileMetaDataWidget();
+        connect(m_fileMetaDataWidget, &DolphinFileMetaDataWidget::metaDataRequestFinished, this, &ToolTipManager::slotMetaDataRequestFinished);
+        connect(m_fileMetaDataWidget, &DolphinFileMetaDataWidget::urlActivated, this, &ToolTipManager::urlActivated);
+    }
+
     m_contentRetrievalTimer->start();
     m_showToolTipTimer->start();
     m_toolTipRequested = true;
@@ -219,6 +223,9 @@ void ToolTipManager::showToolTip()
         m_tooltipWidget.reset(new KToolTipWidget());
     }
     m_tooltipWidget->showBelow(m_itemRect, m_fileMetaDataWidget, m_transientParent);
+    // At this point KToolTipWidget adopted our parent-less metadata widget.
+    m_fileMetaDatWidgetOwnershipTransferred = true;
+
     m_toolTipRequested = false;
 }
 
diff --git a/src/views/tooltips/tooltipmanager.h b/src/views/tooltips/tooltipmanager.h
index 066393344..c86c97f6b 100644
--- a/src/views/tooltips/tooltipmanager.h
+++ b/src/views/tooltips/tooltipmanager.h
@@ -77,7 +77,12 @@ private:
     QWindow* m_transientParent;
 
     QScopedPointer<KToolTipWidget> m_tooltipWidget;
-    DolphinFileMetaDataWidget *m_fileMetaDataWidget;
+    DolphinFileMetaDataWidget *m_fileMetaDataWidget = nullptr;
+
+    /// Whether ownership of the metadata widget was transferred
+    /// over to the KToolTipWidget (i.e. we should not delete it
+    /// anymore)
+    bool m_fileMetaDatWidgetOwnershipTransferred = false;
 
     bool m_toolTipRequested;
     bool m_metaDataRequested;