Implement smooth-scrolling for horizontal and vertical scrollbars

Currently only a smoothscrolling was provided into the
scroll-direction, but not in case of the details-view where a
horizontal scrollbar might be shown too.

Some minor adjustments of the private KItemListSmoothScroller interface
will be done later...

1 files changed, 103 insertions, 0 deletions

diff --git a/src/kitemviews/kitemlistsmoothscroller_p.h b/src/kitemviews/kitemlistsmoothscroller_p.h
new file mode 100644
index 000000000..252c966c7
--- /dev/null
+++ b/src/kitemviews/kitemlistsmoothscroller_p.h
@@ -0,0 +1,103 @@
+/***************************************************************************
+ *   Copyright (C) 2011 by Peter Penz <[email protected]>             *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA            *
+ ***************************************************************************/
+
+#ifndef KITEMLISTSMOOTHSCROLLER_H
+#define KITEMLISTSMOOTHSCROLLER_H
+
+#include <libdolphin_export.h>
+
+#include <QAbstractAnimation>
+#include <QObject>
+
+class QPropertyAnimation;
+class QScrollBar;
+class QWheelEvent;
+
+/**
+ * @brief Helper class for KItemListContainer to have a smooth
+ *        scrolling when adjusting the scrollbars.
+ */
+class LIBDOLPHINPRIVATE_EXPORT KItemListSmoothScroller : public QObject
+{
+    Q_OBJECT
+
+public:
+    KItemListSmoothScroller(QScrollBar* scrollBar,
+                            QObject* parent = 0);
+    virtual ~KItemListSmoothScroller();
+
+    void setScrollBar(QScrollBar* scrollBar);
+    QScrollBar* scrollBar() const;
+
+    void setTargetObject(QObject* target);
+    QObject* targetObject() const;
+
+    void setPropertyName(const QByteArray& propertyName);
+    QByteArray propertyName() const;
+
+    /**
+     * Adjusts the position of the target by \p distance
+     * pixels. Is invoked in the context of QAbstractScrollArea::scrollContentsBy()
+     * where the scrollbars already have the new position but the content
+     * has not been scrolled yet.
+     */
+    void scrollContentsBy(qreal distance);
+
+    /**
+     * Does a smooth-scrolling to the position \p position
+     * on the target and also adjusts the corresponding scrollbar
+     * to the new position.
+     */
+    void scrollTo(qreal position);
+
+    /**
+     * Must be invoked before the scrollbar should get updated to have a new
+     * maximum. True is returned if the new maximum can be applied. If false
+     * is returned the maximum has already been reached and the value will
+     * be reached at the end of the animation.
+     */
+    // TODO: This interface is tricky to understand. Try to make this more
+    // generic/readable if the corresponding code in KItemListContainer got
+    // stable.
+    bool requestScrollBarUpdate(int newMaximum);
+
+protected:
+    virtual bool eventFilter(QObject* obj, QEvent* event);
+
+private slots:
+    void slotAnimationStateChanged(QAbstractAnimation::State newState,
+                                   QAbstractAnimation::State oldState);
+
+private:
+    /**
+     * Results into a smooth-scrolling of the target dependent on the direction
+     * of the wheel event.
+     */
+    void handleWheelEvent(QWheelEvent* event);
+
+private:
+    bool m_scrollBarPressed;
+    bool m_smoothScrolling;
+    QScrollBar* m_scrollBar;
+    QPropertyAnimation* m_animation;
+};
+
+#endif
+
+