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/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtQuick module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qquickdraghandler_p.h"
#include <private/qquickwindow_p.h>
#include <QDebug>
QT_BEGIN_NAMESPACE
/*!
\qmltype DragHandler
\instantiates QQuickDragHandler
\inherits SinglePointHandler
\inqmlmodule Qt.labs.handlers
\ingroup qtquick-handlers
\brief Handler for dragging
DragHandler is a handler that is used to interactively move an Item.
Like other Pointer Handlers, by default it is fully functional, and
manipulates its \l target.
\snippet pointerHandlers/dragHandler.qml 0
It has properties to restrict the range of dragging.
If it is declared within one Item but is assigned a different \l target,
then it handles events within the bounds of the \l parent Item but
manipulates the \c target Item instead:
\snippet pointerHandlers/dragHandlerDifferentTarget.qml 0
A third way to use it is to set \l target to \c null and react to property
changes in some other way:
\snippet pointerHandlers/dragHandlerNullTarget.qml 0
At this time, drag-and-drop is not yet supported.
\sa Drag, MouseArea
*/
QQuickDragHandler::QQuickDragHandler(QObject *parent)
: QQuickSinglePointHandler(parent)
{
}
QQuickDragHandler::~QQuickDragHandler()
{
}
bool QQuickDragHandler::wantsEventPoint(QQuickEventPoint *point)
{
// If we've already been interested in a point, stay interested, even if it has strayed outside bounds.
return ((point->state() != QQuickEventPoint::Pressed && this->point().id() == point->pointId())
|| QQuickSinglePointHandler::wantsEventPoint(point));
}
void QQuickDragHandler::onGrabChanged(QQuickPointerHandler *grabber, QQuickEventPoint::GrabState stateChange, QQuickEventPoint *point)
{
if (grabber == this && stateChange == QQuickEventPoint::GrabExclusive)
// In case the grab got handled over from another grabber, we might not get the Press
initializeTargetStartPos(point);
enforceConstraints();
QQuickSinglePointHandler::onGrabChanged(grabber, stateChange, point);
}
void QQuickDragHandler::onActiveChanged()
{
if (!active())
m_targetStartPos = QPointF();
}
void QQuickDragHandler::handleEventPoint(QQuickEventPoint *point)
{
point->setAccepted();
switch (point->state()) {
case QQuickEventPoint::Pressed:
initializeTargetStartPos(point);
setPassiveGrab(point);
break;
case QQuickEventPoint::Updated: {
QPointF delta = point->scenePosition() - point->scenePressPosition();
if (!m_xAxis.enabled())
delta.setX(0);
if (!m_yAxis.enabled())
delta.setY(0);
if (active()) {
setTranslation(QVector2D(delta));
if (target() && target()->parentItem()) {
QPointF pos = target()->parentItem()->mapFromScene(m_targetStartPos + delta);
enforceAxisConstraints(&pos);
moveTarget(pos, point);
}
} else if (!point->exclusiveGrabber() &&
((m_xAxis.enabled() && QQuickWindowPrivate::dragOverThreshold(delta.x(), Qt::XAxis, point)) ||
(m_yAxis.enabled() && QQuickWindowPrivate::dragOverThreshold(delta.y(), Qt::YAxis, point)))) {
setExclusiveGrab(point);
if (auto parent = parentItem()) {
if (point->pointerEvent()->asPointerTouchEvent())
parent->setKeepTouchGrab(true);
// tablet and mouse are treated the same by Item's legacy event handling, and
// touch becomes synth-mouse for Flickable, so we need to prevent stealing
// mouse grab too, whenever dragging occurs in an enabled direction
parent->setKeepMouseGrab(true);
}
}
} break;
default:
break;
}
}
void QQuickDragHandler::enforceConstraints()
{
if (!target() || !target()->parentItem())
return;
QPointF pos = target()->position();
QPointF copy(pos);
enforceAxisConstraints(&pos);
if (pos != copy)
target()->setPosition(pos);
}
void QQuickDragHandler::enforceAxisConstraints(QPointF *localPos)
{
if (m_xAxis.enabled())
localPos->setX(qBound(m_xAxis.minimum(), localPos->x(), m_xAxis.maximum()));
if (m_yAxis.enabled())
localPos->setY(qBound(m_yAxis.minimum(), localPos->y(), m_yAxis.maximum()));
}
void QQuickDragHandler::initializeTargetStartPos(QQuickEventPoint *point)
{
if (target() && target()->parentItem() && m_targetStartPos.isNull()) { // prefer the m_targetStartPos we got when it got Pressed.
m_targetStartPos = target()->parentItem()->mapToScene(target()->position());
if (!target()->contains(point->position())) {
// If pressed outside of target item, move the target item so that the touchpoint is in its center,
// while still respecting the axis constraints.
const QPointF center = target()->parentItem()->mapFromScene(point->scenePosition());
const QPointF pointCenteredInItemPos = target()->parentItem()->mapToScene(center - QPointF(target()->width(), target()->height())/2);
if (m_xAxis.enabled())
m_targetStartPos.setX(pointCenteredInItemPos.x());
if (m_yAxis.enabled())
m_targetStartPos.setY(pointCenteredInItemPos.y());
}
}
}
void QQuickDragHandler::setTranslation(const QVector2D &trans)
{
if (trans == m_translation) // fuzzy compare?
return;
m_translation = trans;
emit translationChanged();
}
/*!
\qmlpropertygroup QtQuick::DragHandler::xAxis
\qmlpropertygroup QtQuick::DragHandler::yAxis
\qmlproperty real QtQuick::DragHandler::DragAxis::minimum
\qmlproperty real QtQuick::DragHandler::DragAxis::maximum
\qmlproperty real QtQuick::DragHandler::DragAxis::enabled
\c xAxis and yAxis control the constraints for horizontal and vertical
dragging, respectively.
\value minimum
The minimum acceptable value of \l {Item::x}{x} or \l {Item::y}{y}
to be applied to the \l target
\value maximum
The maximum acceptable value of \l {Item::x}{x} or \l {Item::y}{y}
to be applied to the \l target
\value enabled
Whether dragging in this direction is allowed at all
*/
QQuickDragAxis::QQuickDragAxis()
: m_minimum(-DBL_MAX)
, m_maximum(DBL_MAX)
, m_enabled(true)
{
}
void QQuickDragAxis::setMinimum(qreal minimum)
{
if (m_minimum == minimum)
return;
m_minimum = minimum;
emit minimumChanged();
}
void QQuickDragAxis::setMaximum(qreal maximum)
{
if (m_maximum == maximum)
return;
m_maximum = maximum;
emit maximumChanged();
}
void QQuickDragAxis::setEnabled(bool enabled)
{
if (m_enabled == enabled)
return;
m_enabled = enabled;
emit enabledChanged();
}
/*!
\readonly
\qmlproperty QVector2D QtQuick::DragHandler::translation
The translation since the gesture began.
*/
QT_END_NAMESPACE
|
