TapHandler: add long-press feature

Add a longPressed signal, emitted when the point is held long enough.
Add the longPressThreshold to control how long that is.

Change-Id: I95a65f1e4c62eb41fb9ea02b14bdc3f16aa72ec2
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

2 files changed, 54 insertions, 1 deletions

diff --git a/src/quick/handlers/qquicktaphandler.cpp b/src/quick/handlers/qquicktaphandler.cpp
index e0e66be01c..f1bb2f96b6 100644
--- a/src/quick/handlers/qquicktaphandler.cpp
+++ b/src/quick/handlers/qquicktaphandler.cpp
@@ -83,6 +83,7 @@ QQuickTapHandler::QQuickTapHandler(QObject *parent)
     : QQuickPointerSingleHandler(parent)
     , m_pressed(false)
     , m_tapCount(0)
+    , m_longPressThreshold(-1)
     , m_lastTapTimestamp(0.0)
 {
     setAcceptedButtons(Qt::LeftButton);
@@ -127,11 +128,52 @@ void QQuickTapHandler::handleEventPoint(QQuickEventPoint *point)
     }
 }
 
+/*!
+    \qmlproperty longPressThreshold
+
+    The time in seconds that an event point must be pressed in order to
+    trigger a long press gesture and emit the \l longPressed() signal.
+    If the point is released before this time limit, a tap can be detected
+    if the other constraints are satisfied. The default value is
+    QStyleHints::mousePressAndHoldInterval() converted to seconds.
+*/
+qreal QQuickTapHandler::longPressThreshold() const
+{
+    return longPressThresholdMilliseconds() / 1000.0;
+}
+
+void QQuickTapHandler::setLongPressThreshold(qreal longPressThreshold)
+{
+    int ms = qRound(longPressThreshold * 1000);
+    if (m_longPressThreshold == ms)
+        return;
+
+    m_longPressThreshold = ms;
+    emit longPressThresholdChanged();
+}
+
+int QQuickTapHandler::longPressThresholdMilliseconds() const
+{
+    return (m_longPressThreshold < 0 ? QGuiApplication::styleHints()->mousePressAndHoldInterval() : m_longPressThreshold);
+}
+
+void QQuickTapHandler::timerEvent(QTimerEvent *event)
+{
+    if (event->timerId() == m_longPressTimer.timerId()) {
+        m_longPressTimer.stop();
+        emit longPressed();
+    }
+}
+
 void QQuickTapHandler::setPressed(bool press, bool cancel, QQuickEventPoint *point)
 {
     if (m_pressed != press) {
         m_pressed = press;
-        if (!cancel && !press && point->timeHeld() < m_multiTapInterval) {
+        if (press)
+            m_longPressTimer.start(longPressThresholdMilliseconds(), this);
+        else
+            m_longPressTimer.stop();
+        if (!cancel && !press && point->timeHeld() < longPressThreshold()) {
             // Assuming here that pointerEvent()->timestamp() is in ms.
             qreal ts = point->pointerEvent()->timestamp() / 1000.0;
             if (ts - m_lastTapTimestamp < m_multiTapInterval &&
diff --git a/src/quick/handlers/qquicktaphandler_p.h b/src/quick/handlers/qquicktaphandler_p.h
index c11d51ee03..0559089fbf 100644
--- a/src/quick/handlers/qquicktaphandler_p.h
+++ b/src/quick/handlers/qquicktaphandler_p.h
@@ -54,6 +54,7 @@
 #include "qquickitem.h"
 #include "qevent.h"
 #include "qquickpointersinglehandler_p.h"
+#include <QtCore/qbasictimer.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -62,6 +63,7 @@ class Q_AUTOTEST_EXPORT QQuickTapHandler : public QQuickPointerSingleHandler
     Q_OBJECT
     Q_PROPERTY(bool isPressed READ isPressed NOTIFY pressedChanged)
     Q_PROPERTY(int tapCount READ tapCount NOTIFY tapCountChanged)
+    Q_PROPERTY(qreal longPressThreshold READ longPressThreshold WRITE setLongPressThreshold NOTIFY longPressThresholdChanged)
 
 public:
     QQuickTapHandler(QObject *parent = 0);
@@ -74,20 +76,29 @@ public:
 
     int tapCount() const { return m_tapCount; }
 
+    qreal longPressThreshold() const;
+    void setLongPressThreshold(qreal longPressThreshold);
+
 Q_SIGNALS:
     void pressedChanged();
     void tapCountChanged();
+    void longPressThresholdChanged();
     void tapped(QQuickEventPoint *point);
+    void longPressed();
 
 protected:
     void handleGrabCancel(QQuickEventPoint *point) override;
+    void timerEvent(QTimerEvent *event) override;
 
 private:
     void setPressed(bool press, bool cancel, QQuickEventPoint *point);
+    int longPressThresholdMilliseconds() const;
 
 private:
     bool m_pressed;
     int m_tapCount;
+    int m_longPressThreshold;
+    QBasicTimer m_longPressTimer;
     QPointF m_lastTapPos;
     qreal m_lastTapTimestamp;