QWebEngineView causes window to move slow-CodePudding

m trying to move my QMainWindow by using another widget inside QMainWindow.

Im moving my window by overriding :

void mousePressEvent(QMouseEvent *event)
void mouseMoveEvent(QMouseEvent *event)

in a QTabWidget. The window moves well and everything works fine if there is no QWebEngineView widget, but if add the QWebEngineView widget to a layout the movement of the window is laggy, any idea?

here is a minimal reproducible example:

mainwindow.h:

#include <QMainWindow>
#include <QMouseEvent>
#include <QtWidgets/QtWidgets>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
};

class MyTabWidget : public QTabWidget
{
    Q_OBJECT
    public:
    MyTabWidget(QWidget *parent = 0) : QTabWidget(parent){}
    protected:
    void mousePressEvent(QMouseEvent *event) override
    {
        QWidget::mousePressEvent(event);
        pressPoint = event->pos();
    }
    void mouseMoveEvent(QMouseEvent *event) override
    {
        QWidget::mouseMoveEvent(event);
        this->window()->move(this->window()->pos()   (event->pos() - pressPoint) );
    }

    private:
        QPoint pressPoint;
};
#endif // MAINWINDOW_H

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QWebEngineView>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    MyTabWidget *tabWidget = new MyTabWidget(this);
    ui->verticalLayout->addWidget(tabWidget);

    QWidget *widget = new QWidget(this);
    QHBoxLayout *hlayout = new QHBoxLayout(this);
    QWebEngineView *view = new QWebEngineView(this);
    widget->setLayout(hlayout);
    hlayout->addWidget(view);


    tabWidget->addTab(widget, "asd");
    view->load(QUrl("https://www.google.com/"));


}

MainWindow::~MainWindow()
{
    delete ui;
}

In this code if you delete everything related to QWebEngineView the window will move without lag.

Edit:

this example does the job but , is there a better way to do this?

setUpdatesEnabled(false); //This in mousePressEvent
bigVisualChanges();
setUpdatesEnabled(true); //This in mouseReleaseEvent

i dont like this way because for example if im watching a youtube video the image will freeze.

CodePudding user response：

Try to reimplement your mousePressEvent and mouseMoveEvent this way, with globalPosition() instead of pos(). Worked for me. Window started to move smoothly.

void mousePressEvent(QMouseEvent *event) override
{
    pressPoint = event->globalPosition().toPoint();
    QWidget::mousePressEvent(event);
}
void mouseMoveEvent(QMouseEvent *event) override
{
    QPoint delta = event->globalPosition().toPoint() - pressPoint;
    this->window()->move(this->window()->pos()   delta );
    pressPoint = event->globalPosition().toPoint();
    QWidget::mouseMoveEvent(event);
}

Update: For better web engine performance (page loading, video playing and webpage animations), build in release configuration.

Update2: test show https://youtu.be/QM3UXjipr8Q.