QtWebEngine display black block when I called QWidget::winId() - c++

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QPushButton>
#include <QWebEngineView>
#include <qDebug>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
#if 1
auto btn = new QPushButton;
ui->gridLayout->addWidget(btn);
qDebug()<<btn->winId();
#endif
auto web = new QWebEngineView;
ui->gridLayout->addWidget(web);
web->load(QUrl("http://www.google.com"));
}
MainWindow::~MainWindow()
{
delete ui;
}
That's the whole code.
Windows 10 , Qt 5.5 .
When I turn on the switch, winId() would be called, then the QtWebEngine can not work rightly.
What should I do ?

Don't call winId() until the widget is visible. You could set an eventFilter that is activated on QEvent::Show, for further information see http://doc.qt.io/qt-5/qobject.html#installEventFilter

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I have written a code to print an Icon accessed from FontAwesome installed in the system. I would like to change the color for the Icon printed on the Screen.I have tried using QPixmap and QIcon,but to no avail.Attached the output :
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#include "ui_MainWindow.h"
#include <QPushButton>
#include <QGridLayout>
#include <QWidget>
#include <QLabel>
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QMainWindow(parent),
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ui->setupUi(this);
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I'm using QGraphicsDropShadowEffect to make my GUI look pretier. Minimal working sample:
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QGraphicsDropShadowEffect>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
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ui->setupUi(this);
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delete ui;
}
As you see, I have 3 buttons and want to have a fancy shadow at the top of every button. Although I set graphics effect on every button it can be seen only on the last button, heres the image:
How can I improve it and what is the cause?
This works:
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QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
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{
delete ui;
}
but seem not to be the best solution I can have.
It's the normal behavior of the function you are calling
see documentation
http://qt-project.org/doc/qt-4.8/qgraphicsitem.html#setGraphicsEffect
If effect is the installed on a different item, setGraphicsEffect()
will remove the effect from the item and install it on this item.

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Question asked twice: see Handling multiple ui files in Qt
I am new to Qt framwork , i have been given this simple task:
In the MainWindow , i have a submit button , once its clicked another total different window should appear
i thought of doing this by doing one extra UI file called From.ui file and to switch from MainWindow to Form once submit is clicked , this is my code:
//main.cpp
#include "mainwindow.h"
#include <QtGui/QApplication>
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MainWindow mainWindow;
mainWindow.setOrientation(MainWindow::ScreenOrientationAuto);
mainWindow.showExpanded();
return app.exec();
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#include "ui_mainwindow.h"
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: QMainWindow(parent), ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
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{
delete ui;
}
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#include "ui_form.h"
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QWidget(parent),
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{
ui->setupUi(this);
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{
delete ui;
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this code compiled perfectly , but its not doing as expected , once submit is clicked , nothing is done...
can you please tell me whats wrong ?
It seems that SubmitClicked slot is not connected to clicked event of your button
Put a cout/printf at the top of your SubmitClicked method to make sure that it is called.