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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
#include <QApplication>
#include <QSlider>
#include <QScrollArea>
#include <QScrollBar>
#include <QMainWindow>
#include <QLabel>
#include <QPushButton>
#include <QVBoxLayout>
#include <QGestureEvent>
#include <QPanGesture>
#include <QDebug>
#include "mousepangesturerecognizer.h"
class ScrollArea : public QScrollArea
{
Q_OBJECT
public:
ScrollArea(QWidget *parent = nullptr)
: QScrollArea(parent), outside(false)
{
viewport()->grabGesture(Qt::PanGesture, Qt::ReceivePartialGestures);
}
protected:
bool viewportEvent(QEvent *event)
{
if (event->type() == QEvent::Gesture) {
gestureEvent(static_cast<QGestureEvent *>(event));
return true;
} else if (event->type() == QEvent::GestureOverride) {
QGestureEvent *ge = static_cast<QGestureEvent *>(event);
if (QPanGesture *pan = static_cast<QPanGesture *>(ge->gesture(Qt::PanGesture)))
if (pan->state() == Qt::GestureStarted) {
outside = false;
}
}
return QScrollArea::viewportEvent(event);
}
void gestureEvent(QGestureEvent *event)
{
QPanGesture *pan = static_cast<QPanGesture *>(event->gesture(Qt::PanGesture));
if (pan) {
switch(pan->state()) {
case Qt::GestureStarted: qDebug() << this << "Pan: started"; break;
case Qt::GestureFinished: qDebug() << this << "Pan: finished"; break;
case Qt::GestureCanceled: qDebug() << this << "Pan: canceled"; break;
case Qt::GestureUpdated: break;
default: qDebug() << this << "Pan: <unknown state>"; break;
}
if (pan->state() == Qt::GestureStarted)
outside = false;
event->ignore();
event->ignore(pan);
if (outside)
return;
const QPointF delta = pan->delta();
const QPointF totalOffset = pan->offset();
QScrollBar *vbar = verticalScrollBar();
QScrollBar *hbar = horizontalScrollBar();
if ((vbar->value() == vbar->minimum() && totalOffset.y() > 10) ||
(vbar->value() == vbar->maximum() && totalOffset.y() < -10)) {
outside = true;
return;
}
if ((hbar->value() == hbar->minimum() && totalOffset.x() > 10) ||
(hbar->value() == hbar->maximum() && totalOffset.x() < -10)) {
outside = true;
return;
}
vbar->setValue(vbar->value() - delta.y());
hbar->setValue(hbar->value() - delta.x());
event->accept(pan);
}
}
private:
bool outside;
};
class Slider : public QSlider
{
public:
Slider(Qt::Orientation orientation, QWidget *parent = nullptr)
: QSlider(orientation, parent)
{
grabGesture(Qt::PanGesture);
}
protected:
bool event(QEvent *event)
{
if (event->type() == QEvent::Gesture) {
gestureEvent(static_cast<QGestureEvent *>(event));
return true;
}
return QSlider::event(event);
}
void gestureEvent(QGestureEvent *event)
{
QPanGesture *pan = static_cast<QPanGesture *>(event->gesture(Qt::PanGesture));
if (pan) {
switch (pan->state()) {
case Qt::GestureStarted: qDebug() << this << "Pan: started"; break;
case Qt::GestureFinished: qDebug() << this << "Pan: finished"; break;
case Qt::GestureCanceled: qDebug() << this << "Pan: canceled"; break;
case Qt::GestureUpdated: break;
default: qDebug() << this << "Pan: <unknown state>"; break;
}
if (pan->state() == Qt::GestureStarted)
outside = false;
event->ignore();
event->ignore(pan);
if (outside)
return;
const QPointF delta = pan->delta();
const QPointF totalOffset = pan->offset();
if (orientation() == Qt::Horizontal) {
if ((value() == minimum() && totalOffset.x() < -10) ||
(value() == maximum() && totalOffset.x() > 10)) {
outside = true;
return;
}
if (totalOffset.y() < 40 && totalOffset.y() > -40) {
setValue(value() + delta.x());
event->accept(pan);
} else {
outside = true;
}
} else if (orientation() == Qt::Vertical) {
if ((value() == maximum() && totalOffset.y() < -10) ||
(value() == minimum() && totalOffset.y() > 10)) {
outside = true;
return;
}
if (totalOffset.x() < 40 && totalOffset.x() > -40) {
setValue(value() - delta.y());
event->accept(pan);
} else {
outside = true;
}
}
}
}
private:
bool outside;
};
class MainWindow : public QMainWindow
{
public:
MainWindow()
{
rootScrollArea = new ScrollArea;
rootScrollArea->setObjectName(QLatin1String("rootScrollArea"));
setCentralWidget(rootScrollArea);
QWidget *root = new QWidget;
root->setFixedSize(3000, 3000);
rootScrollArea->setWidget(root);
Slider *verticalSlider = new Slider(Qt::Vertical, root);
verticalSlider->setObjectName(QLatin1String("verticalSlider"));
verticalSlider ->move(650, 1100);
Slider *horizontalSlider = new Slider(Qt::Horizontal, root);
horizontalSlider->setObjectName(QLatin1String("horizontalSlider"));
horizontalSlider ->move(600, 1000);
childScrollArea = new ScrollArea(root);
childScrollArea->setObjectName(QLatin1String("childScrollArea"));
childScrollArea->move(500, 500);
QWidget *w = new QWidget;
w->setMinimumWidth(700);
QVBoxLayout *l = new QVBoxLayout(w);
l->setContentsMargins(20, 20, 20, 20);
for (int i = 0; i < 100; ++i) {
QWidget *w = new QWidget;
QHBoxLayout *ll = new QHBoxLayout(w);
ll->addWidget(new QLabel(QString("Label %1").arg(i)));
ll->addWidget(new QPushButton(QString("Button %1").arg(i)));
l->addWidget(w);
}
childScrollArea->setWidget(w);
#if defined(Q_OS_WIN)
// Windows can force Qt to create a native window handle for an
// intermediate widget and that will block gesture to get touch events.
// So this hack to make sure gestures get all touch events they need.
foreach (QObject *w, children())
if (w->isWidgetType())
static_cast<QWidget *>(w)->setAttribute(Qt::WA_AcceptTouchEvents);
#endif
}
private:
ScrollArea *rootScrollArea;
ScrollArea *childScrollArea;
};
int main(int argc, char **argv)
{
QApplication app(argc, argv);
QGestureRecognizer::registerRecognizer(new MousePanGestureRecognizer);
MainWindow w;
w.show();
return app.exec();
}
#include "main.moc"
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