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无法再从QTreeWidget获取qgest事件

gesture qt c++

jpo38 · 技术社区 · 6 年前

这非常简单,只需创建一个助手来捕获QGesture事件并通知指定的类。

#ifndef RMCWRAPPER_H
#define RMCWRAPPER_H

#include <QObject>
#include <QPoint>

class QWidget;

class TapAndHoldWrapper : public QObject
{
    Q_OBJECT

public:
    TapAndHoldWrapper( QWidget* parent, QObject* receiver = NULL, const char* slot = NULL );
    ~TapAndHoldWrapper();

    bool eventFilter(QObject *obj, QEvent *event);

signals:
    void requested( QPoint globalPos );

private:
    QWidget* m_parent;
};

#endif

手势.cpp

#include "gesture.h"

#include <QWidget>
#include <QEvent>
#include <QGestureEvent>

TapAndHoldWrapper::TapAndHoldWrapper( QWidget* parent, QObject* receiver, const char* slot ) : 
    QObject( parent ), m_parent( parent )
{
    m_parent->installEventFilter( this );
    m_parent->grabGesture( Qt::TapAndHoldGesture );

    if ( receiver && slot )
    {
        connect( this, SIGNAL(requested(QPoint)), receiver, slot );
    }
}

TapAndHoldWrapper::~TapAndHoldWrapper()
{

}

bool TapAndHoldWrapper::eventFilter(QObject *obj, QEvent *event)
{
    if ( event->type() == QEvent::Gesture && obj == m_parent )
    {
        QGestureEvent *gestevent = static_cast<QGestureEvent *>(event);
        if (QGesture *gest = gestevent->gesture(Qt::TapAndHoldGesture))
        {
            if ( gest && gest->state() == Qt::GestureFinished )
            {
                QPoint globalPos = gest->hotSpot().toPoint();
                emit requested( globalPos );
                return true;
            }
        }
    }
    // standard event processing
    return QObject::eventFilter(obj, event);
}

主控件.h :

#ifndef MAINWIDGET_H
#define MAINWIDGET_H

#include <QMainWindow>

class TapAndHoldWrapper;

class MainWidget : public QMainWindow
{
    Q_OBJECT

public:
    MainWidget(QWidget *parent = 0);

public slots:
    void showMenu( QPoint pt );

private:
    TapAndHoldWrapper* helper;
};

#endif

主控件.cpp

#include "mainwidget.h"
#include "gesture.h"

#include <QScreen>
#include <QGuiApplication>
#include <QTreeWidget>
#include <QLabel>
#include <QMessageBox>

MainWidget::MainWidget(QWidget *parent)
    : QMainWindow(parent)
{
    QTreeWidget* widget = new QTreeWidget(this);
    setCentralWidget(widget);

    helper = new TapAndHoldWrapper( widget, this, SLOT(showMenu(QPoint)) );
}

void MainWidget::showMenu( QPoint pt )
{
    QMessageBox::information( this, "", "gesture detected" );
}

主.cpp :

#include "mainwidget.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    MainWidget w;
    w.show();
    return app.exec();
}

TapAndHoldWrapper 用于捕捉事件并 MainWidget::showMenu QMainWindow 的中心小部件是 QLabel ,但当它是一个 QTreeWidget .

日志报告此错误(Qt 5.12中新增):

    W/libqtbug_gesture.so(22735): QMetaObject::invokeMethod: No such method
    QTreeWidget::inputMethodQuery(Qt::InputMethodQuery,QVariant)

QTreeWidget控件 widget->setInputMethodHints( Qt::InputMethodHint::ImhNone ); 但这无助于。。。

1 回复 | 直到 6 年前

jpo38 6 年前

由于这显然是一个Qt错误,唯一的解决办法就是解决它。点击和保持可以很容易地检测到,如下所示:

#ifndef RMCWRAPPER_H
#define RMCWRAPPER_H

#include <QObject>
#include <QPoint>
#include <QTime>

class QWidget;

class TapAndHoldWrapper : public QObject
{
    Q_OBJECT

public:
    TapAndHoldWrapper( QWidget* parent, QObject* receiver = NULL, const char* slot = NULL );
    ~TapAndHoldWrapper();

    bool eventFilter(QObject *obj, QEvent *event);

signals:
    void requested( QPoint globalPos );

private:
    QWidget* m_parent;
    QTime m_pressedAt;
    QPoint m_pressedPos;
};

#endif

#include "gesture.h"

#include <QWidget>
#include <QEvent>
#include <QGestureEvent>
#include <QAbstractScrollArea>

#if QT_VERSION >= QT_VERSION_CHECK( 5, 12, 0 )
// handle this manually, see https://bugreports.qt.io/browse/QTBUG-73326
#define HANDLE_TAP_AND_HOLD_MANUALLY
#endif

TapAndHoldWrapper::TapAndHoldWrapper( QWidget* parent, QObject* receiver, const char* slot ) : 
    QObject( parent ), 
    m_parent( parent )
{
    // optional in Qt 5.6. Required in Qt 5.12
    QAbstractScrollArea* area = dynamic_cast< QAbstractScrollArea* >( m_parent );
    if ( area )
        m_parent = area->viewport();

    m_parent->installEventFilter( this );

#ifndef HANDLE_TAP_AND_HOLD_MANUALLY
    m_parent->grabGesture( Qt::TapAndHoldGesture );
#endif

    if ( receiver && slot )
    {
        connect( this, SIGNAL(requested(QPoint)), receiver, slot );
    }
}

TapAndHoldWrapper::~TapAndHoldWrapper()
{

}

bool TapAndHoldWrapper::eventFilter(QObject *obj, QEvent *event)
{
#ifdef HANDLE_TAP_AND_HOLD_MANUALLY
    if ( event->type() == QEvent::MouseButtonPress && obj == m_parent )
    {
        QMouseEvent* mouseEvent = dynamic_cast<QMouseEvent*>( event );
        if ( mouseEvent->button() == Qt::LeftButton )
        {
            m_pressedAt = QTime::currentTime();
            m_pressedPos = mouseEvent->globalPos();
        }
    }
    else if ( event->type() == QEvent::MouseButtonRelease && obj == m_parent )
    {
        QMouseEvent* mouseEvent = dynamic_cast<QMouseEvent*>( event );
        if ( mouseEvent->button() == Qt::LeftButton )
        {
            int elapsed = m_pressedAt.msecsTo( QTime::currentTime() );
            if ( elapsed >= 500 )
            {
                if ( std::abs( m_pressedPos.x() - mouseEvent->globalPos().x() ) < 10 &&
                     std::abs( m_pressedPos.y() - mouseEvent->globalPos().y() ) < 10 )
                {
                    emit requested( mouseEvent->globalPos() );
                }
                // else, mouse moved too much, it's not a tap and 
            }
        }
    }
#else
    if ( event->type() == QEvent::Gesture && obj == m_parent )
    {
        QGestureEvent *gestevent = static_cast<QGestureEvent *>(event);
        if (QGesture *gest = gestevent->gesture(Qt::TapAndHoldGesture))
        {
            if ( gest && gest->state() == Qt::GestureFinished )
            {
                QPoint globalPos = gest->hotSpot().toPoint();
                emit requested( globalPos );
                return true;
            }
        }
    }
#endif

    // standard event processing
    return QObject::eventFilter(obj, event);
}

请注意,事件过滤器必须安装在视口上,而不是小部件本身。