设置 Qt QPushButton 弹出菜单的位置（向右）

Question

我正在为 Qt 按钮小部件编写弹出菜单。每当单击按钮时，都会弹出一个菜单（在按钮下方）。

弹出菜单默认在下方左侧。

有没有办法让弹出菜单在按钮下方的右侧弹出？

没有设置位置的功能，请问有什么高深的方法吗？

这是一些代码（用于弹出菜单）：

QMenu *menuMode = new QMenu(this);
    min = menu ->addAction("In");
    mout = menu ->addAction("out");
ui->pushButtonMode->setMenu(menuMode);   //I am writing in MainWindow, that's there is ui

Answer 1

您应该为您的 QMenu 实施 eventFilter。在eventFilter方法中，您需要计算菜单显示的位置。

这里有一个例子：

.pro

TEMPLATE = app

QT     += widgets
SOURCES += main.cpp \
           dialog.cpp

HEADERS += dialog.h

FORMS   += dialog.ui

main.cpp

#include <QtWidgets/QApplication>

#include "dialog.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Dialog dia;
    return dia.exec();
}

dialog.h

#ifndef DIALOG_H
#define DIALOG_H

#include <QtWidgets/QDialog>
#include <QMenu>
#include "ui_dialog.h"

class Dialog : public QDialog
{
    Q_OBJECT
public:
    Dialog();

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

private:
    QMenu *menu;
    Ui::Dialog m_ui;
};

#endif

dialog.cpp

#include "dialog.h"

Dialog::Dialog()
{
    m_ui.setupUi(this);

    menu = new QMenu("menu", this);
    menu->installEventFilter(this);
    QAction *action = new QAction("action#1", this);
    menu->addAction(action);
    m_ui.pushButton->setMenu(menu);
}

bool Dialog::eventFilter(QObject * obj, QEvent *event)
{
    if (event->type() == QEvent::Show && obj == m_ui.pushButton->menu())
    {
        int menu_x_pos = m_ui.pushButton->menu()->pos().x();
        int menu_width = m_ui.pushButton->menu()->size().width();
        int button_width = m_ui.pushButton->size().width();

        QPoint pos = QPoint(menu_x_pos - menu_width + button_width,
                            m_ui.pushButton->menu()->pos().y());

        m_ui.pushButton->menu()->move(pos);
        return true;
    }
    return false;
}

Answer 2

这可以通过子类化 QMenu 并将弹出菜单移动到您想要的位置来完成 showEvent:

popupmenu.h

#ifndef POPUPMENU_H
#define POPUPMENU_H

#include <QMenu>

class QPushButton;
class QWidget;

class PopupMenu : public QMenu
{
    Q_OBJECT
public:
    explicit PopupMenu(QPushButton* button, QWidget* parent = 0);
    void showEvent(QShowEvent* event);
private:
    QPushButton* b;
};

#endif // POPUPMENU_H

popupmenu.cpp

#include "popupmenu.h"
#include <QPushButton>

PopupMenu::PopupMenu(QPushButton* button, QWidget* parent) : QMenu(parent), b(button)
{
}

void PopupMenu::showEvent(QShowEvent* event)
{
    QPoint p = this->pos();
    QRect geo = b->geometry();
    this->move(p.x()+geo.width()-this->geometry().width(), p.y());
}

mainwindow.cpp

...
PopupMenu* menu = new PopupMenu(ui->pushButton, this);
...
ui->pushButton->setMenu(menu);

看起来像这样：

Answer 3

另一种（恕我直言）更简单的方法是：

void MainFrame::Slot_ShowMenu()
{
    auto pMenu = new QMenu(this);

    connect(pMenu, &QMenu::aboutToHide, pMenu, &QMenu::deleteLater);

    ...

    // Retrieve a valid width of the menu. (It's not the same as using "pMenu->width()"!)
    int menuWidth = pMenu->sizeHint().width();

    int x = mUI.myQPushButton->width() - menuWidth;
    int y = mUI.myQPushButton->height();

    QPoint pos(mUI.myQPushButton->mapToGlobal(QPoint(x, y)));

    pMenu->popup(pos);
}

设置 Qt QPushButton 弹出菜单的位置（向右）

Set position (to right) of Qt QPushButton popup menu

c++

qt

popup

qmenu

qpushbutton