Shared: Added KineticScroll class

The KineticScroll can be used as a helper for kinetic widgets to generate
kinetic feedback. It consumes mouse events and emits signals with offset
movements.

Signed-off-by: Adriano Rezende <adriano.rezende@openbossa.org>

2 files changed, 224 insertions, 0 deletions

diff --git a/shared/kineticscroll.cpp b/shared/kineticscroll.cpp
new file mode 100644
index 0000000..fe937e9
--- /dev/null
+++ b/shared/kineticscroll.cpp
@@ -0,0 +1,159 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: openBossa - INdT (renato.chencarek@openbossa.org)
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** the openBossa stream from INdT (renato.chencarek@openbossa.org).
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QTime>
+#include <QTimer>
+
+#include "kineticscroll.h"
+
+#define MAX_SPEED 2000
+
+
+class KineticScrollPrivate
+{
+public:
+    QTimer *animation;
+    qreal animationSpeed;
+    QTime animationITime;
+    qreal animationAccel;
+    qreal accelConstant;
+    QTime time;
+    QTime lastTime;
+    int value;
+    int lastValue;
+};
+
+
+KineticScroll::KineticScroll(QObject *parent)
+    : QObject(parent), d(new KineticScrollPrivate)
+{
+    d->animation = 0;
+    d->accelConstant = 0.3;
+    d->value = d->lastValue = -1;
+    d->time = d->lastTime = QTime::currentTime();
+}
+
+KineticScroll::~KineticScroll()
+{
+    delete d;
+}
+
+void KineticScroll::mouseUp(int value)
+{
+    if (d->lastValue < 0 || d->animation)
+        return;
+
+    QTime t = QTime::currentTime();
+    qreal dv = value - d->lastValue;
+    qreal dt = (qreal)d->lastTime.msecsTo(t) / 1000;
+
+    if (dt == 0)
+        return;
+
+    kineticStart(dv / dt);
+    mouseCancel();
+}
+
+bool KineticScroll::mouseDown(int value)
+{
+    bool r = true;
+    if (d->animation) {
+        d->animation->stop();
+        d->animation->deleteLater();
+        d->animation = 0;
+        r = false;
+    }
+    d->lastValue = d->value = value;
+    d->lastTime = d->time = QTime::currentTime();
+
+    return r;
+}
+
+void KineticScroll::mouseMove(int value)
+{
+    if (d->lastValue < 0)
+        return;
+
+    int dv = value - d->value;
+    QTime t = QTime::currentTime();
+
+    d->lastValue = d->value;
+    d->lastTime = d->time;
+    d->value = value;
+    d->time = t;
+
+    emit signalMoveOffset(dv);
+}
+
+void KineticScroll::mouseCancel()
+{
+    d->value = -1;
+    d->lastValue = -1;
+}
+
+void KineticScroll::kineticStop()
+{
+    if (d->animation) {
+        d->animation->stop();
+        d->animation->deleteLater();
+    }
+
+    d->animation = 0;
+}
+
+void KineticScroll::kineticStart(qreal speed)
+{
+    d->animationSpeed = qBound<qreal>(-MAX_SPEED, speed, MAX_SPEED);
+    d->animationITime = QTime::currentTime();
+    d->animationAccel = -d->animationSpeed * d->accelConstant;
+
+    d->animation = new QTimer();
+    connect(d->animation, SIGNAL(timeout()), this, SLOT(animator()));
+    d->animation->start(10);
+}
+
+void KineticScroll::animator()
+{
+    QTime now = QTime::currentTime();
+    qreal dt = (qreal)d->animationITime.msecsTo(now) / 1000;
+    qreal speed = d->animationSpeed + d->animationAccel * dt;
+    qreal value = d->animationSpeed * dt + d->animationAccel * dt * dt / 2;
+
+    if (d->animationAccel * speed > 0) {
+        // just to notify animation finish
+        emit signalMoveOffset(0);
+        kineticStop();
+    } else {
+        emit signalMoveOffset(qRound(value));
+        d->animationSpeed = speed;
+        d->animationITime = now;
+    }
+}
diff --git a/shared/kineticscroll.h b/shared/kineticscroll.h
new file mode 100644
index 0000000..ffc8efb
--- /dev/null
+++ b/shared/kineticscroll.h
@@ -0,0 +1,65 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: openBossa - INdT (renato.chencarek@openbossa.org)
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** the openBossa stream from INdT (renato.chencarek@openbossa.org).
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef KINETICSCROLL_H
+#define KINETICSCROLL_H
+
+#include <QObject>
+
+
+class KineticScrollPrivate;
+
+class KineticScroll : public QObject
+{
+    Q_OBJECT
+
+public:
+    KineticScroll(QObject *parent = 0);
+    ~KineticScroll();
+
+    void mouseUp(int value);
+    bool mouseDown(int value);
+    void mouseMove(int value);
+    void mouseCancel();
+    void kineticStart(qreal speed);
+    void kineticStop();
+
+public Q_SLOTS:
+    void animator();
+
+Q_SIGNALS:
+    void signalMoveOffset(int);
+
+private:
+    KineticScrollPrivate *d;
+};
+
+#endif