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plasma-framework/private/kineticscroll.cpp
Adenilson Cavalcanti Da Silva da3ece21e8 Fixing kinetic scrolling with thinkpad 'scrollwheel' 
Since it generates lots of wheel events, it was re-triggering the bouncer
animation before it was completed. The result was a 'jittering' (d)effect.

I also increased the friction factor to make it scroll slower.


svn path=/trunk/KDE/kdelibs/; revision=1026404
2009-09-21 18:38:53 +00:00

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/////////////////////////////////////////////////////////////////////////
// kineticscroll.cpp //
// //
// Copyright(C) 2009 Igor Trindade Oliveira <igor.oliveira@indt.org.br>//
// Copyright(C) 2009 Adenilson Cavalcanti <adenilson.silva@idnt.org.br>//
// //
// This library is free software; you can redistribute it and/or //
// modify it under the terms of the GNU Lesser General Public //
// License as published by the Free Software Foundation; either //
// version 2.1 of the License, or (at your option) any later version. //
// //
// This library 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 //
// Lesser General Public License for more details. //
// //
// You should have received a copy of the GNU Lesser General Public //
// License along with this library; if not, write to the Free Software //
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA //
// 02110-1301 USA //
/////////////////////////////////////////////////////////////////////////
#include <QtCore/qglobal.h>
#include <QtCore/qmetatype.h>
#include <QGraphicsSceneMouseEvent>
#include <QTime>
#include <QDebug>
#include <QGraphicsWidget>
#include <QPoint>
#include "kineticscroll_p.h"
/* TODO:
* - write a factory to animation/state object
* - move timer based code to an implementation of the factory
* - write another implementation using QPropertyAnimation Qt 4.6
* - generalize code concerning viewport and other parameters
* - swap the 'magic numbers' for consts
* - consider if direct access to control state/velocity variables should
* be done directly or using functions
*/
namespace Plasma
{
class KineticScrollingPrivate
{
public:
KineticScrollingPrivate(): mScrollVelocity(0), timerID(0),
overshoot(40), bounceFlag(0), hasOvershoot(true)
{ }
void count()
{
t = QTime::currentTime();
t.start();
}
unsigned int elapsed()
{
return t.restart();
}
void verticalScroll(int value)
{
widget->setPos(QPoint(0, -value*10));
}
void horizontalScroll(int value)
{
widget->setPos(QPoint(-value*10, 0));
}
unsigned int timeDelta;
qreal scrollVelocity;
QPoint movement;
QPoint kinMovement;
qreal mScrollVelocity;
enum { None, Up, Down };
int timerID, overshoot, direction;
QPoint cposition, minimalPos, maximumPos;
char bounceFlag;
bool hasOvershoot;
QGraphicsWidget *widget;
QGraphicsWidget *scrollingWidget;
protected:
QTime t;
};
KineticScrolling::KineticScrolling(): d(0)
{
d = new KineticScrollingPrivate;
}
KineticScrolling::~KineticScrolling()
{
delete d;
}
QPoint KineticScrolling::movement()
{
return d->movement;
}
QPoint KineticScrolling::kinMovement()
{
return d->kinMovement;
}
qreal KineticScrolling::duration()
{
return d->timeDelta;
}
void KineticScrolling::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
doneOvershoot();
Q_UNUSED(event);
d->count();
d->scrollVelocity = 0;
d->movement = QPoint(0, 0);
d->kinMovement = QPoint(0, 0);
}
void KineticScrolling::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
QPoint temp = event->lastPos().toPoint() - event->pos().toPoint();
if (!temp.isNull()) {
d->movement = temp;
d->kinMovement += temp;
}
/* After */
setKineticScrollValue(movement());
}
void KineticScrolling::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{
d->timeDelta = d->elapsed();
QPoint temp = event->lastPos().toPoint() - event->pos().toPoint();
if (!temp.isNull())
d->kinMovement += temp;
if (d->timeDelta > 600) {
if (d->kinMovement.y() > 0)
d->kinMovement.setY(3);
else
d->kinMovement.setY(-3);
}
/* The after */
if (d->cposition.y() > 0) {
d->direction = KineticScrollingPrivate::Up;
} else if (abs(d->cposition.y()) >
abs(d->scrollingWidget->size().height() - d->widget->size().height())) {
d->direction = KineticScrollingPrivate::Down;
} else {
d->direction = KineticScrollingPrivate::None;
d->mScrollVelocity = d->kinMovement.x() + d->kinMovement.y();
startAnimationTimer(30);
return;
}
d->mScrollVelocity = 5;
killTimer(d->timerID);
startAnimationTimer(50);
}
void KineticScrolling::wheelReleaseEvent(QGraphicsSceneWheelEvent *event)
{
if (d->direction == KineticScrollingPrivate::None) {
mousePressEvent(0);
/* Core */
d->timeDelta = d->elapsed();
int temp = event->delta();
temp *= -0.5;
d->kinMovement.setY(kinMovement().y() + temp);
/* After */
d->mScrollVelocity = kinMovement().y();
startAnimationTimer(30);
}
}
void KineticScrolling::startAnimationTimer(int interval)
{
if (d->timerID) {
killTimer(d->timerID);
d->timerID = 0;
}
d->timerID = QObject::startTimer(interval);
}
void KineticScrolling::timerEvent(QTimerEvent *event)
{
Q_UNUSED(event);
if (d->direction == KineticScrollingPrivate::None) {
d->mScrollVelocity *= 0.8;
if (qAbs(d->mScrollVelocity) < 5.0) {
if (d->timerID)
killTimer(d->timerID);
}
setKineticScrollValue( QPoint(d->mScrollVelocity, d->mScrollVelocity));
} else {
if ((d->timerID != 0) && (d->direction != KineticScrollingPrivate::None)) {
bounceTimer();
}
}
}
void KineticScrolling::setKineticScrollValue(QPoint value)
{
d->minimalPos.setY((-(d->widget->size().height())) + d->scrollingWidget->size().height()
-(d->overshoot));
d->minimalPos.setX((-(d->widget->size().width())) + d->scrollingWidget->size().width());
d->minimalPos.setY(qMin(d->overshoot, d->minimalPos.y()));
d->minimalPos.setX(qMin( 0, d->minimalPos.x()));
d->maximumPos = d->widget->pos().toPoint() - value;
d->cposition.setY(qBound(d->minimalPos.y(), d->maximumPos.y(), d->overshoot));
d->cposition.setX( qBound(d->minimalPos.x(), d->maximumPos.x(), 0));
d->widget->setPos(d->cposition);
if ((d->cposition.y() == d->overshoot) && d->hasOvershoot) {
d->direction = KineticScrollingPrivate::Up;
killTimer(d->timerID);
d->mScrollVelocity = 5;
startAnimationTimer(30);
} else if ((d->cposition.y() == d->minimalPos.y()) && d->hasOvershoot) {
d->direction = KineticScrollingPrivate::Down;
killTimer(d->timerID);
d->mScrollVelocity = 5;
startAnimationTimer(30);
} else
d->direction = KineticScrollingPrivate::None;
}
void KineticScrolling::bounceTimer()
{
int delta = 5;
if ((d->direction == KineticScrollingPrivate::Up) && (d->bounceFlag == 0))
delta = -5;
else if ((d->direction == KineticScrollingPrivate::Up) && (d->bounceFlag == 1))
delta = -2;
else if ((d->direction == KineticScrollingPrivate::Down) && (d->bounceFlag == 0))
delta = 5;
else if ((d->direction == KineticScrollingPrivate::Down) && (d->bounceFlag == 1))
delta = 2;
d->cposition.setY(d->cposition.y() + delta);
d->widget->setPos(d->cposition);
if ((d->direction == KineticScrollingPrivate::Up) && (d->cposition.y() < 0)) {
if (!d->bounceFlag) {
d->cposition.setY(d->overshoot/4);
d->bounceFlag = 1;
d->widget->setPos(d->cposition);
return;
} else {
d->bounceFlag = 0;
d->cposition = QPoint(d->cposition.x(), 0);
doneOvershoot() ;
}
} else if ((d->direction == KineticScrollingPrivate::Down) &&
((d->cposition.y() - d->overshoot) > d->minimalPos.y())) {
if (!d->bounceFlag) {
d->cposition.setY(d->minimalPos.y() + d->overshoot/4);
d->bounceFlag = 1;
d->widget->setPos(d->cposition);
return;
} else {
d->bounceFlag = 0;
d->cposition.setY(d->minimalPos.y() + d->overshoot);
doneOvershoot();
}
}
}
void KineticScrolling::doneOvershoot(void)
{
d->direction = KineticScrollingPrivate::None;
d->mScrollVelocity = 0;
killTimer(d->timerID);
d->timerID = 0;
}
void KineticScrolling::setWidgets(QGraphicsWidget *widget,
QGraphicsWidget *scrolling)
{
d->widget = widget;
d->scrollingWidget = scrolling;
if(d->widget->size().height() <= d->scrollingWidget->size().height()) {
d->hasOvershoot = false;
d->overshoot = 0;
}
d->widget->installEventFilter(this);
}
bool KineticScrolling::eventFilter(QObject *watched, QEvent *event)
{
const int threashold = 10;
if (!d->widget) {
return false;
}
if (watched == d->widget && event->type() == QEvent::GraphicsSceneResize) {
if(d->widget->size().height() <= d->scrollingWidget->size().height()+threashold) {
d->hasOvershoot = false;
d->overshoot = 0;
} else {
d->hasOvershoot = true;
d->overshoot = 40;
}
}
return false;
}
} // namespace Plasma
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