From ac4bab991b0b258853611dd2b5662dc111fa6311 Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@digia.com>
Date: Wed, 22 Oct 2014 10:30:46 +0200
Subject: QSwipeGestureRecognizer: Prevent cancel in startup-phase.

Replace the boolean 'started' member by an enumeration which indicates
the startup phase. While in that phase, do not cancel when pressed
points are detected for fewer than 3 touch points.

Task-number: QTBUG-15768
Change-Id: Ic57b19e3002392fb632f551f615d80ada9831d34
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
---
 src/widgets/kernel/qgesture_p.h          | 10 ++++++++--
 src/widgets/kernel/qstandardgestures.cpp | 23 +++++++++++++++--------
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/src/widgets/kernel/qgesture_p.h b/src/widgets/kernel/qgesture_p.h
index 8668145d8a..183a2eba0f 100644
--- a/src/widgets/kernel/qgesture_p.h
+++ b/src/widgets/kernel/qgesture_p.h
@@ -134,11 +134,17 @@ class QSwipeGesturePrivate : public QGesturePrivate
     Q_DECLARE_PUBLIC(QSwipeGesture)
 
 public:
+    enum State {
+        NoGesture,
+        Started,
+        ThreePointsReached
+    };
+
     QSwipeGesturePrivate()
         : horizontalDirection(QSwipeGesture::NoDirection),
           verticalDirection(QSwipeGesture::NoDirection),
           swipeAngle(0),
-          started(false), velocityValue(0)
+          state(NoGesture), velocityValue(0)
     {
     }
 
@@ -150,7 +156,7 @@ public:
     qreal swipeAngle;
 
     QPoint lastPositions[3];
-    bool started;
+    State state;
     qreal velocityValue;
     QElapsedTimer time;
 };
diff --git a/src/widgets/kernel/qstandardgestures.cpp b/src/widgets/kernel/qstandardgestures.cpp
index 0822c04033..9e3cb473e5 100644
--- a/src/widgets/kernel/qstandardgestures.cpp
+++ b/src/widgets/kernel/qstandardgestures.cpp
@@ -283,7 +283,7 @@ QGestureRecognizer::Result QSwipeGestureRecognizer::recognize(QGesture *state,
     case QEvent::TouchBegin: {
         d->velocityValue = 1;
         d->time.start();
-        d->started = true;
+        d->state = QSwipeGesturePrivate::Started;
         result = QGestureRecognizer::MayBeGesture;
         break;
     }
@@ -297,9 +297,10 @@ QGestureRecognizer::Result QSwipeGestureRecognizer::recognize(QGesture *state,
     }
     case QEvent::TouchUpdate: {
         const QTouchEvent *ev = static_cast<const QTouchEvent *>(event);
-        if (!d->started)
+        if (d->state == QSwipeGesturePrivate::NoGesture)
             result = QGestureRecognizer::CancelGesture;
         else if (ev->touchPoints().size() == 3) {
+            d->state = QSwipeGesturePrivate::ThreePointsReached;
             QTouchEvent::TouchPoint p1 = ev->touchPoints().at(0);
             QTouchEvent::TouchPoint p2 = ev->touchPoints().at(1);
             QTouchEvent::TouchPoint p3 = ev->touchPoints().at(2);
@@ -354,12 +355,18 @@ QGestureRecognizer::Result QSwipeGestureRecognizer::recognize(QGesture *state,
         } else if (ev->touchPoints().size() > 3) {
             result = QGestureRecognizer::CancelGesture;
         } else { // less than 3 touch points
-            if (d->started && (ev->touchPointStates() & Qt::TouchPointPressed))
-                result = QGestureRecognizer::CancelGesture;
-            else if (d->started)
-                result = QGestureRecognizer::Ignore;
-            else
+            switch (d->state) {
+            case QSwipeGesturePrivate::NoGesture:
                 result = QGestureRecognizer::MayBeGesture;
+                break;
+            case QSwipeGesturePrivate::Started:
+                result = QGestureRecognizer::Ignore;
+                break;
+            case QSwipeGesturePrivate::ThreePointsReached:
+                result = (ev->touchPointStates() & Qt::TouchPointPressed)
+                    ? QGestureRecognizer::CancelGesture : QGestureRecognizer::Ignore;
+                break;
+            }
         }
         break;
     }
@@ -378,7 +385,7 @@ void QSwipeGestureRecognizer::reset(QGesture *state)
     d->swipeAngle = 0;
 
     d->lastPositions[0] = d->lastPositions[1] = d->lastPositions[2] = QPoint();
-    d->started = false;
+    d->state = QSwipeGesturePrivate::NoGesture;
     d->velocityValue = 0;
     d->time.invalidate();
 
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