Add note about precision of QNativeGestureEvent::delta; fix in Qt 7

We keep QVector2D storage Qt 6 BC (to avoid making QNativeGestureEvent
larger), but in Qt 7 we should return exactly the same value as given
(for what it's worth, in spite of this being overkill for panning a
reasonable distance).

Change-Id: Iecbd4c9b60ad9ae5e0466c7027b038ddb85b8c8b
Pick-to: 6.2
Reviewed-by: Volker Hilsheimer <[email protected]>

1 files changed, 7 insertions, 3 deletions

diff --git a/src/gui/kernel/qevent.cpp b/src/gui/kernel/qevent.cpp
index f7532d4481c..73a591f34ca 100644
--- a/src/gui/kernel/qevent.cpp
+++ b/src/gui/kernel/qevent.cpp
@@ -2837,18 +2837,22 @@ QNativeGestureEvent::QNativeGestureEvent(Qt::NativeGestureType type, const QPoin
     indicating that the target item should have its scale adjusted like this:
     item.scale = item.scale * (1 + event.value)
 
-    For PanNativeGesture, \a deltas gives the distance in pixels that the
+    For PanNativeGesture, \a delta gives the distance in pixels that the
     viewport, widget or item should be moved or panned.
 
+    \note The \a delta is stored in single precision (QVector2D), so \l delta()
+    may return slightly different values in some cases. This is subject to change
+    in future versions of Qt.
+
     \since 6.2
 */
 QNativeGestureEvent::QNativeGestureEvent(Qt::NativeGestureType type, const QPointingDevice *device, int fingerCount,
                                          const QPointF &localPos, const QPointF &scenePos,
-                                         const QPointF &globalPos, qreal value, const QPointF &deltas,
+                                         const QPointF &globalPos, qreal value, const QPointF &delta,
                                          quint64 sequenceId)
     : QSinglePointEvent(QEvent::NativeGesture, device, localPos, scenePos, globalPos, Qt::NoButton,
                         Qt::NoButton, Qt::NoModifier),
-      m_sequenceId(sequenceId), m_delta(deltas), m_realValue(value), m_gestureType(type), m_fingerCount(fingerCount)
+      m_sequenceId(sequenceId), m_delta(delta), m_realValue(value), m_gestureType(type), m_fingerCount(fingerCount)
 {
     Q_ASSERT(fingerCount < 16); // we store it in 4 bits unsigned
 }