Add QWaylandQuickOutput::pickClickableItem

A way to get the topmost item at the given position that accepts mouse buttons.

Change-Id: I518a8ae15d12ea4c464f06ee437d4cffe3e61115
Reviewed-by: Paul Olav Tvete <paul.tvete@theqtcompany.com>
Reviewed-by: Pier Luigi Fiorini <pierluigi.fiorini@gmail.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/src/compositor/compositor_api/qwaylandquickoutput.cpp b/src/compositor/compositor_api/qwaylandquickoutput.cpp
index 8abf6cbb1..0e25362fc 100644
--- a/src/compositor/compositor_api/qwaylandquickoutput.cpp
+++ b/src/compositor/compositor_api/qwaylandquickoutput.cpp
@@ -37,6 +37,7 @@
 
 #include "qwaylandquickoutput.h"
 #include "qwaylandquickcompositor.h"
+#include "qwaylandquickitem_p.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -102,6 +103,44 @@ void QWaylandQuickOutput::setAutomaticFrameCallback(bool automatic)
     automaticFrameCallbackChanged();
 }
 
+static QQuickItem* clickableItemAtPosition(QQuickItem *rootItem, const QPointF &position)
+{
+    if (!rootItem->isEnabled() || !rootItem->isVisible())
+        return nullptr;
+
+    QList<QQuickItem *> paintOrderItems = QQuickItemPrivate::get(rootItem)->paintOrderChildItems();
+    auto negativeZStart = paintOrderItems.crend();
+    for (auto it = paintOrderItems.crbegin(); it != paintOrderItems.crend(); ++it) {
+        if ((*it)->z() < 0) {
+            negativeZStart = it;
+            break;
+        }
+        QQuickItem *item = clickableItemAtPosition(*it, rootItem->mapToItem(*it, position));
+        if (item)
+            return item;
+    }
+
+    if (rootItem->contains(position) && rootItem->acceptedMouseButtons() != Qt::NoButton)
+        return rootItem;
+
+    for (auto it = negativeZStart; it != paintOrderItems.crend(); ++it) {
+        QQuickItem *item = clickableItemAtPosition(*it, rootItem->mapToItem(*it, position));
+        if (item)
+            return item;
+    }
+
+    return nullptr;
+}
+
+QQuickItem *QWaylandQuickOutput::pickClickableItem(const QPointF &position)
+{
+    QQuickWindow *quickWindow = qobject_cast<QQuickWindow *>(window());
+    if (!quickWindow)
+        return nullptr;
+
+    return clickableItemAtPosition(quickWindow->contentItem(), position);
+}
+
 /*!
  * \internal
  */