Changed setting state in a QGesture

Instead of having a protected setter for the state and forcing the application
developer to emit signals manually (which leads to misunderstanding - i.e. if
the started() signal should be emitted only once, or of the triggered() signal
should be emitted before the finished() signal, etc). So I've added an
protected updateState(state) function that sets the internal state and emits
appropriate signals depending on the old and new states.

Reviewed-by: Volker Hilsheimer
Reviewed-by: Richard Moe Gustavsen

4 files changed, 55 insertions, 40 deletions

diff --git a/src/gui/kernel/qgesture.cpp b/src/gui/kernel/qgesture.cpp
index 8075ad9..38e8851 100644
--- a/src/gui/kernel/qgesture.cpp
+++ b/src/gui/kernel/qgesture.cpp
@@ -197,11 +197,44 @@ Qt::GestureState QGesture::state() const
 }
 
 /*!
-  Sets this gesture's recognition state to \a state.
+  Sets this gesture's recognition state to \a state and emits appropriate
+  signals.
+
+  This functions emits the signals according to the old state and the new
+  \a state, and it should be called after all the internal properties have been
+  initialized.
+
+  \sa started, triggered, finished, cancelled
  */
-void QGesture::setState(Qt::GestureState state)
+void QGesture::updateState(Qt::GestureState state)
 {
-    d_func()->state = state;
+    Q_D(QGesture);
+    if (d->state == state) {
+        if (state == Qt::GestureUpdated)
+            emit triggered();
+        return;
+    }
+    const Qt::GestureState oldState = d->state;
+    d->state = state;
+    if (state != Qt::NoGesture && oldState > state) {
+        // comparing the state as ints: state should only be changed from
+        // started to (optionally) updated and to finished.
+        qWarning("QGesture::updateState: incorrect new state");
+        return;
+    }
+    if (oldState == Qt::NoGesture)
+        emit started();
+    if (state == Qt::GestureUpdated)
+        emit triggered();
+    else if (state == Qt::GestureFinished)
+        emit finished();
+    else if (state == Qt::NoGesture)
+        emit cancelled();
+
+    if (state == Qt::GestureFinished) {
+        // gesture is finished, so we reset the internal state.
+        d->state = Qt::NoGesture;
+    }
 }
 
 /*!
@@ -238,14 +271,13 @@ QGraphicsItem* QGesture::graphicsItem() const
 
     Resets the internal state of the gesture. This function might be called by
     the filterEvent() implementation in a derived class, or by the user to
-    cancel a gesture.  The base class implementation emits the cancelled()
-    signal if the state() of the gesture wasn't empty.
+    cancel a gesture.  The base class implementation calls
+    updateState(Qt::NoGesture) which emits the cancelled()
+    signal if the state() of the gesture indicated it was active.
 */
 void QGesture::reset()
 {
-    if (state() != Qt::NoGesture)
-        emit cancelled();
-    setState(Qt::NoGesture);
+    updateState(Qt::NoGesture);
 }
 
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qgesture.h b/src/gui/kernel/qgesture.h
index 0735160..7da37c4 100644
--- a/src/gui/kernel/qgesture.h
+++ b/src/gui/kernel/qgesture.h
@@ -81,7 +81,7 @@ protected:
     QGesture(QGesturePrivate &dd, QObject *parent);
     bool eventFilter(QObject*, QEvent*);
 
-    void setState(Qt::GestureState state);
+    void updateState(Qt::GestureState state);
 
 Q_SIGNALS:
     void started();
diff --git a/src/gui/kernel/qstandardgestures.cpp b/src/gui/kernel/qstandardgestures.cpp
index 2a5e7e8..89de7c8 100644
--- a/src/gui/kernel/qstandardgestures.cpp
+++ b/src/gui/kernel/qstandardgestures.cpp
@@ -114,9 +114,7 @@ bool QPanGesture::event(QEvent *event)
             killTimer(d->panFinishedTimer);
             d->panFinishedTimer = 0;
             d->lastOffset = QSize(0, 0);
-            setState(Qt::GestureFinished);
-            emit triggered();
-            setState(Qt::NoGesture);
+            updateState(Qt::GestureFinished);
         }
     }
 #endif
@@ -127,6 +125,7 @@ bool QPanGesture::event(QEvent *event)
 bool QPanGesture::eventFilter(QObject *receiver, QEvent *event)
 {
 #ifdef Q_WS_WIN
+    Q_D(QPanGesture);
     if (receiver->isWidgetType() && event->type() == QEvent::NativeGesture) {
         QNativeGestureEvent *ev = static_cast<QNativeGestureEvent*>(event);
         QApplicationPrivate *qAppPriv = getQApplicationPrivateInternal();
@@ -135,30 +134,28 @@ bool QPanGesture::eventFilter(QObject *receiver, QEvent *event)
         if (it == qAppPriv->widgetGestures.end())
             return false;
         QPanGesture *gesture = it.value().pan;
-        if (!gesture)
+        if (this != gesture)
             return false;
-        Qt::GestureState nextState = state();
+        Qt::GestureState nextState = Qt::NoGesture;
         switch(ev->gestureType) {
         case QNativeGestureEvent::GestureBegin:
             // next we might receive the first gesture update event, so we
             // prepare for it.
-            setState(Qt::GestureStarted);
+            d->state = Qt::NoGesture;
             return false;
         case QNativeGestureEvent::Pan:
             nextState = Qt::GestureUpdated;
+            event->accept();
             break;
         case QNativeGestureEvent::GestureEnd:
-            if (state() != QNativeGestureEvent::Pan)
+            if (state() == Qt::NoGesture)
                 return false; // some other gesture has ended
-            setState(Qt::GestureFinished);
             nextState = Qt::GestureFinished;
             break;
         default:
             return false;
         }
-        QPanGesturePrivate *d = gesture->d_func();
-        if (state() == Qt::GestureStarted) {
-            d->lastPosition = ev->position;
+        if (state() == Qt::NoGesture) {
             d->lastOffset = d->totalOffset = QSize();
         } else {
             d->lastOffset = QSize(ev->position.x() - d->lastPosition.x(),
@@ -166,14 +163,7 @@ bool QPanGesture::eventFilter(QObject *receiver, QEvent *event)
             d->totalOffset += d->lastOffset;
         }
         d->lastPosition = ev->position;
-
-        if (state() == Qt::GestureStarted)
-            emit gesture->started();
-        emit gesture->triggered();
-        if (state() == Qt::GestureFinished)
-            emit gesture->finished();
-        event->accept();
-        gesture->setState(nextState);
+        gesture->updateState(nextState);
         return true;
     }
 #endif
@@ -193,7 +183,6 @@ bool QPanGesture::filterEvent(QEvent *event)
         d->lastOffset = d->totalOffset = QSize();
     } else if (event->type() == QEvent::TouchEnd) {
         if (state() != Qt::NoGesture) {
-            setState(Qt::GestureFinished);
             if (!ev->touchPoints().isEmpty()) {
                 QTouchEvent::TouchPoint p = ev->touchPoints().at(0);
                 const QPoint pos = p.pos().toPoint();
@@ -202,10 +191,8 @@ bool QPanGesture::filterEvent(QEvent *event)
                 d->lastOffset = QSize(pos.x() - lastPos.x(), pos.y() - lastPos.y());
                 d->totalOffset = QSize(pos.x() - startPos.x(), pos.y() - startPos.y());
             }
-            emit triggered();
-            emit finished();
+            updateState(Qt::GestureFinished);
         }
-        setState(Qt::NoGesture);
         reset();
     } else if (event->type() == QEvent::TouchUpdate) {
         QTouchEvent::TouchPoint p = ev->touchPoints().at(0);
@@ -216,11 +203,7 @@ bool QPanGesture::filterEvent(QEvent *event)
         d->totalOffset = QSize(pos.x() - startPos.x(), pos.y() - startPos.y());
         if (d->totalOffset.width() > 10  || d->totalOffset.height() > 10 ||
             d->totalOffset.width() < -10 || d->totalOffset.height() < -10) {
-            if (state() == Qt::NoGesture)
-                setState(Qt::GestureStarted);
-            else
-                setState(Qt::GestureUpdated);
-            emit triggered();
+            updateState(Qt::GestureUpdated);
         }
     }
 #ifdef Q_OS_MAC
@@ -239,16 +222,14 @@ bool QPanGesture::filterEvent(QEvent *event)
         d->lastOffset = wev->orientation() == Qt::Horizontal ? QSize(offset, 0) : QSize(0, offset);
 
         if (state() == Qt::NoGesture) {
-            setState(Qt::GestureStarted);
             d->totalOffset = d->lastOffset;
         } else {
-            setState(Qt::GestureUpdated);
             d->totalOffset += d->lastOffset;
         }
 
         killTimer(d->panFinishedTimer);
         d->panFinishedTimer = startTimer(200);
-        emit triggered();
+        updateState(Qt::GestureUpdated);
 #endif
         return true;
     }
diff --git a/src/gui/kernel/qwidget_win.cpp b/src/gui/kernel/qwidget_win.cpp
index ce853d2..6647f3f 100644
--- a/src/gui/kernel/qwidget_win.cpp
+++ b/src/gui/kernel/qwidget_win.cpp
@@ -2074,6 +2074,8 @@ void QWidgetPrivate::winSetupGestures()
         needv = (vbarpolicy == Qt::ScrollBarAlwaysOn
                  || (vbarpolicy == Qt::ScrollBarAsNeeded && vbar->minimum() < vbar->maximum()));
         singleFingerPanEnabled = asa->d_func()->singleFingerPanEnabled;
+    } else {
+        winid = q->winId();
     }
     if (qAppPriv->SetGestureConfig) {
         GESTURECONFIG gc[2];