QWebView blank screen

nicholaslee

It is in my mainwindow.cpp in the function after setupUI

jsulm

@nicholaslee Can you show the code?
Also, you said it works if you press a buttons: do you execute exactly the same line when the button is pressed?

nicholaslee

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QString>
#include <QWebView>
#include <QUrl>
#include <QDesktopServices>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QString link = "https://nusmods.com/timetable/sem-1";
    ui->webView->load(QUrl(link));
}

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

void MainWindow::on_pushButton_clicked()
{
    QString link = "https://nusmods.com/timetable/sem-1";
    QDesktopServices::openUrl(QUrl(link));
}

Yes, its the same. All other websites work for webview

jsulm

@nicholaslee OK, you're loading inside MainWindow constructor - I'm not sure this is the problem as MainWindow is being constructed at that time. You can try to use http://doc.qt.io/qt-5/qtimer.html#singleShot-4 to delay the loading a bit.

JonB

@nicholaslee
I don't know but: load https://nusmods.com/timetable/sem-1 into a web browser and look at the source. The page generated does not contain literal HTML for the view; it's all generated in JavaScript. Is this the root of the problem?

nicholaslee

@JonB Yes, I think so, im not totally sure how webview works. How would I load the page if its generated in JavaScript?

jsulm

@nicholaslee Didn't you say that same page is loading fine when you press the button?

nicholaslee

@jsulm yes the button will open the browser and navigate to the URL.

But webview is just displaying a blank screen. Is there anyway to view it?

JonB

@nicholaslee
Put in a slot for http://doc.qt.io/archives/qt-4.8/qwebview.html#loadFinished. Check you do get there, and the value of ok.

nicholaslee

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QString link = "https://nusmods.com/timetable/sem-1";
    ui->webView->load(QUrl(link));

    void QWebView::loadFinished(bool ok);
}

@JonB sorry im still new to slots, do I just put it in like this?

It's giving me an error "invalid use of qualified-name 'QWebView::loadFinished"

jsulm

@nicholaslee said in QWebView blank screen:

void QWebView::loadFinished(bool ok);

This declares a function!
Please read http://doc.qt.io/qt-5/signalsandslots.html
You need to do

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QString link = "https://nusmods.com/timetable/sem-1";
    ui->webView->load(QUrl(link));

    connect(ui->webView, &QWebView::loadFinished, this, &MainWindow::handleLoadFinished);
}

void MainWindow::handleLoadFinished(bool ok)
{
...
}

nicholaslee

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QString link = "https://nusmods.com/timetable/sem-1";
    ui->webView->load(QUrl(link));

    connect(ui->webView, &QWebView::loadFinished, this, &MainWindow::handleLoadFinished);

}

void MainWindow::handleLoadFinished(bool ok){

    qDebug() << QString("Loaded");
}

@jsulm @JonB
Ive put in a slot and yes it prints out loaded but the webview is not showing anything. Btw thanks for the help!

JonB

@nicholaslee
You need to add qDebug() << ok; there, we need to know what value ok is being passed as.

nicholaslee

The value is passed as a 'true'

JonB

@nicholaslee
Then, fortunately or unfortunately, we've sent you down a wild goose chase, insofar as QWebView confirms that it has successfully completed loading the content. But it's good to know!

Then I can only guess/suggest as per earlier that (assuming you say it is not a https or redirection issue) the web kit is having problems with the JavaScript content? Check the actual content received in the QWebPage/QWebFrame to verify it's what you see in a working browser, and see if there are any signals received indicating it's having problems with the content?

agarny

@nicholaslee, you apparently solved your problem (since this is labelled "SOLVED"), but I cannot see what you had to do, if anything, to solve it. Would you mind sharing your findings, if any? (Yes, I am having the same problem with a JavaScript-generated page. I have yet to fully investigate the issue though.)