Shared: Added ScrollArea widget

The ScrollArea can be used to display generic contents
inside a kinetic container.

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

2 files changed, 359 insertions, 0 deletions

diff --git a/shared/scrollarea.cpp b/shared/scrollarea.cpp
new file mode 100644
index 0000000..3e26993
--- /dev/null
+++ b/shared/scrollarea.cpp
@@ -0,0 +1,280 @@
+/****************************************************************************
+**
+** 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 <QCoreApplication>
+#include <QGraphicsScene>
+#include <QGraphicsSceneMouseEvent>
+
+#include "scrollarea.h"
+#include "kineticscroll.h"
+
+
+class ScrollAreaPrivate
+{
+public:
+    ScrollAreaPrivate(ScrollArea *q);
+
+    int offset;
+    int maximumOffset;
+    QGraphicsWidget *widget;
+    KineticScroll *kinetic;
+
+    bool isDragging;
+    int mouseDownPos;
+    int moveConstant;
+    int clickConstant;
+    ScrollArea *q;
+
+    QList<QGraphicsSceneMouseEvent *> ignoreList;
+
+    void reconfigure();
+    int smoothPos(int y);
+    bool isClickPossible(int y);
+    void sendClick(int x, int y);
+    void updateMaximumOffset();
+};
+
+
+ScrollAreaPrivate::ScrollAreaPrivate(ScrollArea *q)
+    : offset(0),
+      maximumOffset(0),
+      widget(0),
+      kinetic(0),
+      isDragging(false),
+      mouseDownPos(-1),
+      moveConstant(15),
+      clickConstant(25),
+      q(q)
+{
+
+}
+
+int ScrollAreaPrivate::smoothPos(int y)
+{
+    if (abs(mouseDownPos - y) <= moveConstant)
+        return y;
+    else if (mouseDownPos - y < 0)
+        return y - moveConstant;
+    else
+        return y + moveConstant;
+}
+
+bool ScrollAreaPrivate::isClickPossible(int y)
+{
+    if (isDragging || mouseDownPos < 0)
+        return false;
+    else
+        return abs(y - mouseDownPos) <= clickConstant;
+}
+
+void ScrollAreaPrivate::updateMaximumOffset()
+{
+    const int value = (!widget) ? 0 :
+        qMax<int>(0, widget->size().height() - q->size().height());
+
+    if (value != maximumOffset) {
+        maximumOffset = value;
+        emit q->maximumOffsetChanged();
+    }
+}
+
+void ScrollAreaPrivate::reconfigure()
+{
+    if (widget) {
+        widget->resize(q->size().width(), widget->size().height());
+        updateMaximumOffset();
+        q->setOffset(offset);
+    }
+}
+
+void ScrollAreaPrivate::sendClick(int x, int y)
+{
+    if (!q->scene())
+        return;
+
+    QGraphicsSceneMouseEvent *event;
+
+    event = new QGraphicsSceneMouseEvent(QEvent::GraphicsSceneMousePress);
+    event->setButton(Qt::LeftButton);
+    event->setScenePos(QPointF(x, y));
+    ignoreList << event;
+    QCoreApplication::postEvent(q->scene(), event);
+
+    event = new QGraphicsSceneMouseEvent(QEvent::GraphicsSceneMouseRelease);
+    event->setButton(Qt::LeftButton);
+    event->setScenePos(QPointF(x, y));
+    ignoreList << event;
+    QCoreApplication::postEvent(q->scene(), event);
+}
+
+
+
+ScrollArea::ScrollArea(QGraphicsItem *parent)
+    : QGraphicsWidget(parent),
+      d(new ScrollAreaPrivate(this))
+{
+    setFlag(QGraphicsItem::ItemHasNoContents);
+    setFlag(QGraphicsItem::ItemClipsChildrenToShape);
+
+    d->kinetic = new KineticScroll(this);
+    connect(d->kinetic, SIGNAL(signalMoveOffset(int)), SLOT(kineticMove(int)));
+}
+
+ScrollArea::~ScrollArea()
+{
+    delete d;
+}
+
+QGraphicsWidget *ScrollArea::widget() const
+{
+    return d->widget;
+}
+
+void ScrollArea::setWidget(QGraphicsWidget *widget)
+{
+    if (d->widget) {
+        d->widget->setParentItem(0);
+        d->widget->removeEventFilter(this);
+        d->widget = 0;
+    }
+
+    if (widget) {
+        d->widget = widget;
+        d->widget->setParentItem(this);
+        d->widget->installEventFilter(this);
+        d->widget->setPos(0, 0);
+        d->widget->setFlag(QGraphicsItem::ItemStacksBehindParent);
+
+        d->reconfigure();
+    }
+}
+
+int ScrollArea::offset() const
+{
+    return d->offset;
+}
+
+void ScrollArea::setOffset(int offset)
+{
+    if (d->widget) {
+        const int value = qBound<int>(0, offset, d->maximumOffset);
+
+        if (value != d->offset) {
+            d->offset = value;
+            d->widget->setY(-value);
+            offsetChanged();
+        }
+    }
+}
+
+int ScrollArea::maximumOffset() const
+{
+    return d->maximumOffset;
+}
+
+void ScrollArea::resizeEvent(QGraphicsSceneResizeEvent *event)
+{
+    QGraphicsWidget::resizeEvent(event);
+    d->reconfigure();
+}
+
+bool ScrollArea::eventFilter(QObject *object, QEvent *event)
+{
+    if (object == d->widget && event->type() == QEvent::GraphicsSceneResize)
+        d->reconfigure();
+
+    return false;
+}
+
+void ScrollArea::mousePressEvent(QGraphicsSceneMouseEvent *e)
+{
+    if (d->ignoreList.contains(e)) {
+        d->ignoreList.removeOne(e);
+        e->ignore();
+        return;
+    }
+
+    int y = e->pos().y();
+    d->mouseDownPos = y;
+    d->isDragging = !d->kinetic->mouseDown(y);
+}
+
+void ScrollArea::stopKinetic()
+{
+    d->kinetic->kineticStop();
+}
+
+void ScrollArea::mouseReleaseEvent(QGraphicsSceneMouseEvent *e)
+{
+    if (d->ignoreList.contains(e)) {
+        d->ignoreList.removeOne(e);
+        e->ignore();
+        return;
+    }
+
+    if (d->mouseDownPos >= 0) {
+        int y = e->pos().y();
+        if (d->isClickPossible(y)) {
+            d->sendClick(e->scenePos().x(), e->scenePos().y());
+            d->kinetic->mouseCancel();
+        } else {
+            d->kinetic->mouseUp(d->smoothPos(y));
+        }
+    }
+
+    d->mouseDownPos = -1;
+}
+
+void ScrollArea::mouseMoveEvent(QGraphicsSceneMouseEvent *e)
+{
+    if (d->mouseDownPos >= 0) {
+        int y = e->pos().y();
+        if (!d->isClickPossible(y))
+            d->isDragging = true;
+
+        if (abs(d->mouseDownPos - y) > d->moveConstant)
+            d->kinetic->mouseMove(d->smoothPos(y));
+    }
+}
+
+bool ScrollArea::kineticMove(int value)
+{
+    int finalOffset = offset() - value;
+
+    setOffset(finalOffset);
+
+    if (value == 0 || finalOffset != offset()) {
+        d->kinetic->kineticStop();
+        return false;
+    }
+
+    return true;
+}
diff --git a/shared/scrollarea.h b/shared/scrollarea.h
new file mode 100644
index 0000000..436c3a6
--- /dev/null
+++ b/shared/scrollarea.h
@@ -0,0 +1,79 @@
+/****************************************************************************
+**
+** 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 SCROLLAREA_H
+#define SCROLLAREA_H
+
+#include <QGraphicsWidget>
+
+class KineticScroll;
+class ScrollAreaPrivate;
+
+
+class ScrollArea : public QGraphicsWidget
+{
+    Q_OBJECT
+
+public:
+    ScrollArea(QGraphicsItem *parent = 0);
+    ~ScrollArea();
+
+    QGraphicsWidget *widget() const;
+    void setWidget(QGraphicsWidget *widget);
+
+    int offset() const;
+    void setOffset(int offset);
+
+    int maximumOffset() const;
+
+    void stopKinetic();
+
+signals:
+    void offsetChanged();
+    void maximumOffsetChanged();
+
+protected slots:
+    bool kineticMove(int value);
+
+protected:
+    bool eventFilter(QObject *watched, QEvent *event);
+    void resizeEvent(QGraphicsSceneResizeEvent *event);
+
+    void mousePressEvent(QGraphicsSceneMouseEvent *e);
+    void mouseReleaseEvent(QGraphicsSceneMouseEvent *e);
+    void mouseMoveEvent(QGraphicsSceneMouseEvent *e);
+
+private:
+    ScrollAreaPrivate *d;
+    friend class ScrollAreaPrivate;
+};
+
+#endif