Replace MultiPtHndlr.pointDistanceThreshold with PointerHandler.margin

It's not just useful for PinchHandler: TapHandler has a good use for it
too.  But unfortunately if the handler's parent Item has a custom mask,
we don't have a way to augment the mask with a margin; so if margin is
set, we assume the bounds are rectangular.

QQuickMultiPointHandler::eligiblePoints() now calls wantsEventPoint()
rather than bounds-checking the point directly: this adds flexibility,
potentially allowing an override in subclasses, if we need it later.

Task-number: QTBUG-68077
Change-Id: I65c95f00c532044a5862654e58c9c5f8c973df81
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/quick/handlers/qquickpointerhandler_p.h b/src/quick/handlers/qquickpointerhandler_p.h
index c7420bcec2..9644bb959f 100644
--- a/src/quick/handlers/qquickpointerhandler_p.h
+++ b/src/quick/handlers/qquickpointerhandler_p.h
@@ -70,6 +70,7 @@ class Q_QUICK_PRIVATE_EXPORT QQuickPointerHandler : public QObject, public QQmlP
     Q_PROPERTY(QQuickItem * target READ target WRITE setTarget NOTIFY targetChanged)
     Q_PROPERTY(QQuickItem * parent READ parentItem CONSTANT)
     Q_PROPERTY(GrabPermissions grabPermissions READ grabPermissions WRITE setGrabPermissions NOTIFY grabPermissionChanged)
+    Q_PROPERTY(qreal margin READ margin WRITE setMargin NOTIFY marginChanged)
 
 public:
     explicit QQuickPointerHandler(QObject *parent = nullptr);
@@ -106,10 +107,14 @@ public:
     GrabPermissions grabPermissions() const;
     void setGrabPermissions(GrabPermissions grabPermissions);
 
+    qreal margin() const;
+    void setMargin(qreal pointDistanceThreshold);
+
 Q_SIGNALS:
     void enabledChanged();
     void activeChanged();
     void targetChanged();
+    void marginChanged();
     void grabChanged(QQuickEventPoint::GrabState stateChange, QQuickEventPoint *point);
     void grabPermissionChanged();
     void canceled(QQuickEventPoint *point);
@@ -137,6 +142,7 @@ protected:
     bool parentContains(const QQuickEventPoint *point) const;
 
     friend class QQuickEventPoint;
+    friend class QQuickItemPrivate;
     friend class QQuickWindowPrivate;
 
     Q_DECLARE_PRIVATE(QQuickPointerHandler)